Amaranth to Zai Holes, Ideas for Growing Food under Difficult Conditions (ECHO, 1996, 397 p.) 28 additional technical notes about tropical agriculture A few alternate seed sources that we commonly use Amaranth - grain and vegetable Arid region farming primer (introduction...) Introduction Agricultural techniques for arid lands Citrus propagation and rootstocks Cucurbit seeds (introduction...) Literature cited Dry farming (introduction...) Fundamental principles Requirements I. Increase water absorption II. Reducing the loss of soil moisture III. Dry farming practices Muscovy ducks for png villages Fruit crops Fruit vegetables Grain crops Ground covers and green manures Green manure crops Industrial crops The lablab bean as green manure Leafy vegetables Leguminous vegetables The moringa tree Recipes to learn to eat moringa Miscellaneous vegetables The poor man's plow Pulses (grain legumes) Rabbit raising in the tropics Letter from fremont regier, mennonite central committee, Botswana (and earlier in Zaire) Roots and tubers Sunnhemp as a green manure The sweet potato Tropical pasture and feed crops The velvet bean as green manure

Amaranth to Zai Holes, Ideas for Growing Food under Difficult Conditions (ECHO, 1996, 397 p.)

28 additional technical notes about tropical agriculture

A few alternate seed sources that we commonly use

· CATIE (Centro Agronomico Tropical de Investigacion Ensenanza), BLSF, Turialba, Costa Rica, Central America. Supplies fruit and forest trees.

· Cornucopia: A Source Book of Edible Plants. Supplies sources for 7000 varieties (see EDN 35-6). From Kampong Publications, 1870 Sunrise Drive, Vista, CA 92084. Incl. postage: $37.50 US; $40.25 surface/$56 air overseas.

· CIMMYT (Centro Internacional de Mejoramiento de Maiz y Trigo), Londres 40, Apartado Postal 6-641, 06600, Mexico. Improved varieties of corn and wheat, including Quality Protein Maize.

· Fruit Spirit, Botanical Garden, Dorroughby, NSW, Australia 2480. Unusual fruit, nut, ginger and other crops.

· Multipurpose Trees and Shrubs: Sources of Seeds and Innoculants. By Peter C. Von Carlowitz, ICRAF, P.O. Box 30677, Nairobi, Kenya.

· High Altitude Gardens, P.O. Box 4619, Ketchum, ID 83340. Some vegetable selections suited to higher elevations.

· Inland & Foreign Trading Co., LTD., Block 79A, Indus Road #04(c)418/420, 0316, Singapore. Legumes, pasture grasses, special purpose trees.

· J.L.Hudson, Seedsman, P.O. Box 1058, Redwood City, CA 94064. Ethnobotanical catalogue of a wide variety of plants.

· National Tree Seed Centre (NTSP), PO Box 373, Morogoro, Tanzania; tel: +255 56 31 NTSP TZ. Provides more than 100 tree species for most purposes.

· Plants of the Southwest, Agua Fria, Rt 6 Box 11-A, Santa Fe NM, 87501. Phone and Customer Service Orders: (9-5 MST M-Fri.) (505)471-2212, Fax: (505)471-2212. Corn, cover crops and vegetables for arid gardens.

· Phoenix Seeds, P.O. Box 94619, Tazmania 7331, Australia. Vegetables, trees, winged beans, jicama.

· Richters Herb Specialists, Goodwood, ONT LOC 1AO Canada. Very complete herb listing.

· SETROPA, P.O. Box 203, 1400 A.E. Bussum, Holland. Trees and forages.

· Shivalik Seeds Corporation, 47 Panditwari, P.O. Prem Nagar, Dehra Dun-248 007 (UP), India. Phone: 91 135 683348. Fax: 91 135 29944. Seeds of a wide range of (agro)forestry, medicinal, horticultural, ornamental plants.

· Tomato Growers Supply Co., P.O. Box 2237, Fort Myers, FL 33902. Wide variety of tomato and pepper varieties.

· Twilley Seed Co., P. O. Box 65, Trevose, PA 19053, USA. Ordinary temperate vegetable and flower seeds.

· University of Hawaii, Seed Program, Dept. of Horticulture, 3190 Maile Way, Rm. 12, Honolulu, HI 96822. Limited range of selected/improved tropical vegetables and papayas.

Amaranth - grain and vegetable

amaranthus hypochondriacus, a. cruentus (grain) & a. tricolor (vegetable) amaranth
Compiled by G. Kelly O'Brien and Martin L. Price

Characteristics

Amaranth is a plant with an upright growth habit, cultivated for both its seeds which are used as a grain and its leaves which are used as a vegetble. Both the leaves and seeds contain protein of an unusually high quality. The grain is milled for flour or popped like popcorn. The leaves of both the grain and vegetable types may be eaten raw or cooked. The amaranths that are grown principally for vegetable use have better tasting leaves then the grain types.

Amaranth has been cultivated for more than 8,000 years, dating back at least to the Mayan civilization of South and Central America. It was a staple of the Aztecs and was incorporated into their religious ceremonies. In 1516 the conquistadores prohibited the growing of amaranth. In that area today only a limited amount of grain is grown, most of which is popped and mixed with honey to make "alegria" candy. However, much of the genetic base has been maintained because amaranth has continued growing in the area as a weed.

Amaranth is considered native to South and Central America, but over 400 varieties are found throughout the world in both temperate and tropical climates. Vegetable amaranth has been used in China for 400 years, and is commonly found in the Caribbean and Africa.

Amaranths are moderately branched from a main stem. Grain types form large loose panicles at the tips of the stems. Vegetable types form flowers and seeds along the stems. They are indeterminate in growth habit, but may set seed at a smaller size during short days. Grain amaranth grown in winter at ECHO (southern Florida) began flowering at less than half of the height of amaranth growing in May. Grain types may grow 1 to 2 meters tall and produce yields comparable to rice or maize. Amaranth has the "C-4" photosynthetic pathway (along with such plants as corn and sorghum), which enables it to be uniquely efficient in utilizing sunlight and nutrients at high temperatures. It is more drought-resistant than corn.

Nutritional value

As can be seen in Table I, amaranth is quite nutritious. Amounts of vitamin C, iron, carotene, calcium, folic acid and protein are especially high. There are reports that the incidence of blindness in children due to poor nutrition has been reduced with the use of 50 to 100 g of amaranth leaves per day. On a dry weight basis, the content of protein in leaves is approximately 30%. The presence of rather high amounts of oxalic acid and nitrates places some limitation on the quantity of amaranth leaves that can be consumed daily. The amount of oxalic acid is roughly the same as that found in spinach and chard. Excessive amounts (over 100 g per day?) may result in a level of oxalic acid that begins to reduce the availability of calcium in humans. This is especially a concern if calcium intake levels are low to begin with. Nitrate in vegetable portions of amaranth is a concern because it is hypothesized that nitrates may be chemically changed in our digestive tracts into poisonous nitrosamines. Evidence for this is lacking at the present time. Nevertheless, over 100 g per day may be an unsafe amount to eat, according to scientists. The levels of both oxalic acid and nitrates are reduced by boiling the leaves like a spinach, then discarding the water.

Amaranth grain has more protein than corn, for example, and the protein is of an unusually high quality. The protein is high in the amino acid lysine, which is the limiting amino acid in cereals like maize, wheat and rice. The protein is also relatively rich in the sulfur- containing amino acids, which are normally limiting in the pulse crops (e.g. beans). The "protein complement" of amaranth grain is very near to the levels recommended by FAO/WHO. It has a protein score of 67 to 87. Protein scores are determined by taking the ratio of the essential amino acids to the level for those amino acids recommended by FAO/WHO, and multiplying by 100. By comparison, wheat (14% protein) scores 47, soybeans (37%) score 68-89, rice (7%) scores 69, maize (9%) scores 35.

Although amaranth is theoretically close to the ideal, combining it with another grain increases the quality to very close to the FAO/WHO standards. Weight gain studies with rats point out, however, that the actual nutritional value is considerably less than would be expected from the above considerations. This is apparently due to certain anti-nutritional factors in raw amaranth. Performance is improved somewhat by cooking. For example, Dr. Peter Cheeke at the University of Oregon compared the rate of weight gain by 120 gram rats fed a corn-soybean diet to rats fed a diet of corn and seed from A. hypochondriacus, either raw or cooked. The average daily gain for rats on the corn-soybean diet during the first 20 days was 3.9 grams. Rats fed the corn-amaranth diet gained only 0.3 grams per day. The average daily gain for rats fed corn and cooked amaranth was 1.6 grams. Raw amaranth seed is extremely unpalatable to rats (i.e. they will not eat it readily). Cooked seed also does not seem to be very palatable, though it smelled good to Dr. Cheeke.

In another study, Dr. Cheeke found that after 11 days on a corn-amaranth diet, rats (which weighed 120 g initially) "had an unthrifty hunched-up appearance, and exhibited symptoms typical of semi-starvation". We phoned Dr. Cheeke to get his perspective on the seriousness of these negative results. He told us that there are definitely toxins and/or anti-nutritional factors in the raw grain, and that it is less of a problem with cooked grain. He said that a scientist in Australia had been feeding raw amaranth seed to poultry as the major component of the diet. He found that chickens went into spasms, convulsions, and finally died. This unidentified factor causes liver damage. Other problems are caused by saponins, including unpalatability.

But to keep this in perspective, Dr. Cheeke pointed out that there are few raw foodstuffs which do not have problems. Raw soybeans contain 10 kinds of toxins. Raw kidney beans will kill rats, but the problem is eliminated by cooking. The key seems to be to use the grain in moderate amounts, and to cook it. We asked whether we could say that there would be no problem unless people had little other than amaranth to eat. He thought that this was probably a fair statement.

It is our opinion that more research needs to be done before we can recommend amaranth grain as a major ingredient in animal feed. To our knowledge it has not been shown whether these factors decrease the value of amaranth in human nutrition. Until more work is done, however, the feeding trial results must moderate our otherwise enthusiastic promotion of grain amaranth.

Compiled from J.N. Cole, Amaranth: from the Past, for the Future Rodale Press, Emmaus, PA (1979)

Cultivation-vegetable types

There appears to be considerable latitude in choice of plant densities. One approach is to plant dense stands (5-10 cm spacing), and harvest by uprooting when the plants are 5-7 weeks old. Another common approach is to sow less densely (15-30 cm spacing), and harvest by cutting the stem tips and plucking tender leaves periodically beginning when the plants are about 15 cm tall (4-6 weeks old). Seeds may be planted in a nursery for subsequent transplanting or sown directly where plants are to be grown.

Transplanting is a very efficient use of seeds, and allows the growing area to be weeded just before the seedlings are transplanted. The very small size of the seeds, however, means that a few seeds go a long way. The number of seeds saved is probably not a sufficient justification for the extra work involved in transplanting. On the other hand, gaining a two-week jump on the weeds can be significant because amaranth seedlings are not vigorous growers when very young.

Planting in a nursery also reduces risk of loss due to disease such as damping off. Direct seeding involves much less labor, but incurs a greater risk of poor stand due to diseases and predators of young seedlings and to poor competition with weeds in the crucial initial couple of weeks. If direct seeding is used, sowing should probably be in rows to facilitate cultivation.

Whether sown in the nursery or field, seeds need to be planted about 4 mm deep (or covered with 4 mm of soil) for good germination. Because of the shallow depth, special care must be taken to prevent drying out of the soil until plants are established. Tansplanting or thinning may be done in about two weeks when plants should be 5-10 cm tall. Delay in transplanting for even one week can reduce total yield. When harvesting by repeated clippings, a two- or three-week interval is common through the end of the season (usually the shortened days of fall). Both the yield and quality of leaves are higher with more frequent clippings. When the vegetative stage ends and flowering begins, subsequent harvests are lower in both quality and quantity. Flowering may be promoted by short days, water stress or other environmental stresses. The stress that comes with delayed transplanting also can cause the plants to flower more quickly. It is reported that plucking flower heads from the plant may prolong the vegetative phase of growth.

Amaranth is generally considered tolerant of nematodes and is even recommended as a rotation crop to reduce nematode populations for subsequent crops. However, one article reports the presence of root knot nematodes on amaranth roots. Control of nematodes is such a serious problem that it is important to know whether or not amaranth can be used to control them and/or whether it can be planted where nematodes are a problem. We will include this question in our list of research projects that could be done at Christian colleges. It is possible that the discrepancy in reported results is because varieties differ in their suceptibility to nematodes.

Amaranth is susceptible to damping-off disease, root rot, caterpillars and stem borers. It thrives in 30-35o C temperatures. It tolerates poor fertility and drought. However, plant quality is poor under stressful conditions. There is good response to fertilizer.

Cultivation-grain types

Recommendations for plant spacings vary widely for grain amaranth. One recommendation is to space 23 cm between plants and 75 cm between rows. This corresponds to a planting density of 38,000 plants per hectare (15,400 per acre). Seeding rates up to nine times this density have been used successfully! It would seem that if harvesting is to be done by hand the less dense spacings are advisable. This results in fewer but larger heads which can be harvested more quickly. Closer plant spacing may be advisable for mechanical harvesting.

The decision as to whether to transplant or direct seed is subject to the same considerations that were discussed for vegetable amaranth. Cultivation is essential until plants have reached a size where the leaf canopy can shade out weeds. After the plants are about 30 cm tall, it is helpful to mound soil from the centers of the rows up around the plants. This helps to reduce lodging (plants blowing over in the wind), suffocates weeds around the plant, and uproots weeds between rows.

Grain amaranth is grown from tropical lowlands to 3500 m in the Himalayas. In the tropics, altitudes above 1000 m are considered best. Although it tolerates droughts and low fertility, it does much better under conditions that are considered ideal for maize (corn). It may be intercropped with maize, beans, peppers or squash. In some pure stands it has yielded as well as the world average yields for maize or rice (2000 kg/ha).

Loss of the tiny seeds by shattering before or during harvest can be a problem, especially with mechanical harvesting. (There are approximately 1100 seeds per gram of amaranth.) The seeds are mature when they can be easily separated from the heads upon rubbing between the hands. Seeds can be chewed to test whether they have passed beyond the "dough stage." Heads should be cut from the stalk and side branches as soon as possible after they have reached maturity. Heads should be dried if necessary, keeping green plant parts to a mnimum. Once dry, the seeds are knocked from the heads, fofted through an ordinary window scree, and winnowed to remove chaff.

Although three or four farmers are planting small (around 10 acre) plots in the USA , as of this writing (1982), there appear to remain serious problems with mechanical harvesting. Primary among these problems are the tendency for plants to lodge, and the loss of grain during harvesting. Grain should be dried to about 9% moisture for safe storage. It is reported that grain remains viable for up to seven years. We left heads stacked in a building for 5 summer months (high humidity and temperatures in the 90's). Viability still appears to be high.

Preparation

Vegetable amaranth leaves and stems or entire plants may be eaten raw or cooked as spinach. As discussed earlier, however, cooking and discarding the water will remove potentially harmful oxalates and nitrates. The seeds from grain amaranth can be ground for use as a good quality flour for breads or pastries. It must be combined with wheat flour for a yeast dough. The Organic Farming and Research Center (Rodale) has used a 50:50 ratio successfully, but they sugest that the percent of amaranth could be even greater if desired. They state that "amaranth flour contributes to the sweetness and moistness of a baked good".

Alternatively, seeds can be popped like popcorn. The people at Rodale say that popped amaranth can be used: in confections bound with sorghum, molasses or honey; in high- energy granola and granola bars; in cheese spreads; to flavor salad dressings; in breadings for chicken and fish; in crackers, pie crusts and breads; and as toppings for casseroles and desserts. Several recipes can be found in the book Amaranth: from the Past, for the Future by Rodale Press.

Other reading material

We found the research results published in Proceedings of the Second Amaranth Conference to be especially helpful. It is available from Rodale Press, Emmaus, PA 18049 for $15.00. For those interested in larger-scale production, Amaranth Grain Production Guide 1982 would be helpful. As far as we know there is no charge. Order it from Rodale Press. Rodale has other material that would be helpful if you wish to pursue the subject in depth.

How do I harvest amaranth?

Basically, you must thrash it like mankind has always done until the invention of the thrashing machine. The three stages include: let the heads dry out, knock the grain from the heads, and winnow the grain. Many of you live where local folks know far more than I about such techniques. For others, here is what we do with small quantities of seed (which must be kept separate from other varieties). Cut the heads when the grain appears to be mature, and put them somewhere to dry. If left too long much of the grain may shatter (fall to the ground). Grain easily shatters from the dried heads. Put a few heads in a burlap bag and beat it against the cement floor a few times to knock it loose, or strike the bags with a stick. Then place the grain in a 5-gallon bucket (many other containers would be suitable).

You will notice that a lot of chaff comes along with the grain. This is where winnowing comes in. Place an empty 5-gallon bucket in front of a fan and, cautiously at first, pour some grain and chaff into the empty bucket. A steady wind will accomplish the same thing as the fan, but a gusty wind will cause problems. The grain is more dense and will fall closer to the fan than the chaff. Quickly one begins to get a feel for how far the buckets should be from the fan, and at what height to hold the one bucket in order for the grain to land in the empty bucket and the chaff to blow far enough to miss it. Pour the grain back and forth until it appears to be clean. Final cleanup can be done by swirling and shaking the grain around gently. Remaining chaff will "float" to the top like ice in water, and can be removed by hand.

Arid region farming primer

By Franklin W. Martin

Introduction

Why this primer is desirable. In every region of the world it is necessary to find or develop appropriate techniques for agriculture. A large part of the surface of the world is arid, characterized as too dry for conventional rain fed agriculture. Yet, millions of people live in such regions, and if current trends in population increase continue, there will soon be millions more. These people must eat, and the wisest course for them is to produce their own food. Yet, the techniques are so varied that only a very large volume would cover the entire subject. This publication is only a primer, an introduction to appropriate techniques. More extensive treatments are mentioned in the bibliography. In many cases the most suitable techniques for a particular region may be those already developed by the local inhabitants. In some cases it will be difficult to improve on local techniques, but at times even simple and inexpensive innovations may be almost revolutionary. This bulletin suggests that one must begin to improve local agriculture in arid zones by learning what is already there. Then both techniques and plants that may be useful in specific situations are suggested.

Definitions and degrees of aridity. Arid implies prolonged dryness, and is used with respect to the climate itself, and the land below it. In such regions the ability to produce agricultural crops is restricted. Usually on arid lands the potential evaporation of water from the land exceeds the rainfall. The land may be characterized according to the degree of aridity as dry forest, chaparral or brushland, grassland or savannah, or desert. The word, "arid" does not adequately characterize the soils, however, for they may vary in many ways. Often they are alkaline or saline.

Several degrees of dryness must be recognized. The first is where the dry climate is modified by seasonal rainy seasons. In such a region it might be possible to produce a wide range of annual crops during the short rainy season, enough to sustain animals and feed mankind, although few food or feed trees might be feasible without special techniques.

The second situation is a year round aridity, sometimes modified by light or irregular rains, which might make production of crops impossible.

The third situation is where water is brought in by wells, canals, or other means so that normal agriculture can exist, in spite of the aridity of the climate. This primer concerns the first two situations, but not the third. There are techniques suitable for all arid regions.

Principal arid regions of the world. The arid regions of the world are often very extensive, but in the tropics it is common, even on a small island, to find arid regions not far from regions of abundant rainfall. Some of the larger arid regions are:

However, while the above mentioned regions may constitute the most arid regions, nevertheless, there are many more areas, large and small, where aridity is a problem.

PRINCIPAL PROBLEMS OF AGRICULTURE IN ARID REGIONS
Water. Water is absolutely necessary for all plant and animal life. Plants have evolved that are capable of living and reproducing in semi arid, arid, and even desert regions. However, as aridity increases, fewer and fewer species are adapted, and the potential biomass is reduced.

Plants are adapted to aridity by several mechanisms. There are plants with a short life cycle that can germinate, grow, and produce during a very short period of available moisture. There are plants with deep or extensive root systems which have the ability to gather water over a wide area. There are plants which store up water in their tissues and release it very slowly. There are plants that are protected from water loss by wax or other impediments. There are plants with very small or narrow leaves, thus reducing water loss. There are plants in which the tissues themselves can withstand much desiccation without dying. Crop plants in arid regions may have any or a combination of such mechanisms.

Water that falls in arid regions may be of little use for crop plants because the amount is too small to penetrate the soil sufficiently, or it may run through a porous soil too quickly, or it may run off too quickly. Furthermore, weedy species may be so adept at utilizing scarce water that they rob the water from crops. On the other hand, some soils can store water so efficiently that is possible to grow crops in such soils over an extensive period of drought.

Water from rivers, lakes and wells in arid regions may have problems of quality, especially the presence of excess minerals. The use of irrigation water might lead to the accumulation of salts in the soil resulting in alkalinity or salinity, which might then limit crop production. The removal of salt from the soil is very difficult.

In all arid regions a major challenge is to manage water appropriately. The purpose of such management is to obtain water, to conserve it, to use it efficiently, and to avoid damage to the soil.

Heat and Wind. The major effects of heat and wind are to increase the rate of evaporation of water, and thus to increase the effects of aridity. Wind may also cause mechanical damage to crops. Both are combatted by changing the microclimate. The effects of winds can be reduced by windbreaks (lines of trees perpendicular to the direction of prevailing winds). Some useful tall species are tamarisk, casuarina, and eucalyptus. A windbreak can consist of trees and other plants of varying height. As a general rule, a windbreak is effective over an area two and a half times the height of the tree. One must remember, however, that a windbreak may also rob crops of light, water and nutrients. Thus, the advantages of a windbreak must be weighed against the disadvantages in any particular environment. Windbreaks can also be constructed of non-living materials, which are likely to be expensive.

Heat is received principally from the sun and can be reduced by shading. But, shading also reduces the yields of plants. A light shade such as that below a coconut planting or a protective screen or lathwork can be useful in reducing heat and retaining moisture, with only a minimum loss of yield.

Soils. Soils of the arid tropics are highly variable, as they are in any climate. Nevertheless, it is possible to make some generalizations about such soils. Because of the low rainfall and consequently reduced plant growth, organic material is produced slowly. Yet, again because of low rainfall, it may be broken down slowly as well. The amount of organic material in the soil, and thus the potential fertility, is likely to be high in semi-arid zones, low in deserts.

Because of low rainfall in desert soils minerals derived from breakdown of rocks are not leached from the soil. In some cases where the soil is periodically flooded or irrigated the soil might be saline as well. Such soils support few crops.

Soils of the semi-arid and arid zones might support few plants on the surface, but a good part of the biomass might be in the soil itself as roots. Shrubby desert plants often have very hard woody roots that may be a physical barrier to agriculture.

Disease and Pest Problems. Arid regions have their fair share of disease and pest problems. However, these may often be quite different from those of wetter regions. Nematodes are often a severe problem in sandy soils. No general rules are useful, and indeed, agriculture anticipates diseases and pests, and their parasites as well.

Agricultural techniques for arid lands

Many of the techniques for agriculture in arid lands are not very different from those in other climatic zones. The unique problems of arid lands are almost entirely related to water or its effects over long or short times. Therefore, the discussion here revolves around two questions, "How to capture existing water", and "how to use water wisely".

How to Capture Existing Water. Much of the water that falls on arid lands is lost by runoff, deep penetration into sands, or by evaporation. Runoff can be captured for later use in natural or nature-like ways, or in manmade structures. These include the following:

1. Furrows, and diking of furrows, ditches, and pits following contours to slow the runoff of water and permit deeper penetration.

2. Similar structures reinforced by bench terraces, vegetative strips, or trees for alley cropping.

3. Crescent-shaped basins arranged to gather water for one or more trees.

4. Reservoirs of water, such as natural or constructed shallow basins along roads which capture runoff, earth structures that lead water into aquifers (underground streams), rock or clay-lined underground basins.

5. Other man-made structures. These include cisterns (household or community sized clay, stone, or concrete tanks, check dams (small structures that impede water movement in a stream), and conventional dams.

How to Obtain New Water. In many arid regions water can be obtained from wells. The depth of the well necessary to obtain water may vary a few to thousands of feet. Water in wells is either fossil (stored over impermeable layers for thousands of years), or from water that has entered the soil from rain, and is therefore stored rainwater. Both sources of water are limited and can be exhausted.

New water is also obtained by condensation from the air, either onto metal screens or plastic (the principle of the solar still) or onto foliage. Ingenious systems can be developed to capture this condensation. This source of water depends on nighttime temperatures that lower to the point of condensation.

How to Conserve Existing Water. Water that is conserved is just as valuable as water that is obtained, and is one of the best strategies for arid zones. There are many techniques, here presented only as lists.

Citrus propagation and rootstocks

by dr. Martin L. price, executive director

In response to various questions from overseas, we have tracked down some answers that are of general interest to our readers. These have been published in past issues of ECHO DEVELOPMENT NOTES. This technical note reprints those in their entirety. It also adds a couple of helpful tables that were provided by the Holm Citrus Nursery concerning characteristics of citrus rootstock and varieties of citrus.

FROM ISSUE #5:WHAT VARIETIES OF CITRUS WILL GROW TRUE FROM SEED? Jerry Larson with Double Harvest in Haiti asked us what varieties of citrus might come true from seed. I checked with Dr. Carl Campbell at the University of Florida Extension research center. Carl has given me many in-depth, insightful answers to tropical fruit questions sent by several of our readers. He said that a great number of citrus trees will come true from seed. There is a way that you can tell by examining a few seeds from the tree. Peel off the outer and inner seed coat. It the seed is polyembryonic, i.e. has many embryos, it will come true. I asked what it would look like if it were polyembryonic. Carl said that the various embryos would be convoluted upon each other. If it is mono-embryonic there will be one embryo with two distinct cotyledons. Almost any sweet orange will come true from seed, as well as key limes, grapefruit, tangerine and tangelo. Two varieties that will not come true from seed are temple and pomelo.

What are the advantages and disadvantages of growing citrus from seed when that is possible? One obvious advantage is that it is much less labor intensive to simply sow citrus seeds and eliminate the grafting step. Another advantage is that the seedling will most likely be free from viruses that sometimes get into the budwood that is used for grafting large numbers of trees. I asked Carl about reports that non-grafted citrus trees live longer, up to twice as long, as grafted trees. He said that this can be true, depending on the number and kinds of disease organisms that may be present in the budwood. If one uses certified disease-free budwood, and if there are no microorganisms present that we don't even know to look for yet, then there should be no difference in the longevity of the trees.

One advantage to grafting is that one can combine the best traits of the above ground part of the tree with the best adapted rootstock for the particular soils and conditions of the area. A seedling will tend to grow upright, tending toward a single trunk, and becoming quite thorny. A grafted tree will be more highly branched. The seedling tree will not fruit for 6-7 years, contrasted to the 3-4 years for a grafted tree. The earlier fruiting of the grafted tree is partly responsible for the more highly branched form of growth. Apparently the weight of the fruit after about 3 years bends the branches and causes new buds to begin growing, resulting in a more highly branched tree. But not all of the reasons for the differences between seedling and grafted trees are known.

If you live in an area where citrus is not a major crop but would like to introduce it, you might consider trying some of the polyembryonic seeds. If you are more adventuresome, in a few years also plant some accepted rootstock varieties for grafting using budwood from the new trees you have introduced. If you prefer to start with a Florida variety rather than a good local variety, and want only a few seeds, we can at times provide them. If you want larger amounts, we have located a supplier, Lawrence Reed at Holm Citrus Seed Co., who routinely ships overseas. Seed currently sells for $30 per pound plus airfreight. He can provide phytosanitary certificates if you so request and include your full address and phone number. I asked about the danger of introducing a new disease. He said this does not appear to be a problem with citrus seed. There has never been an instance where a citrus disease has been proven to have been introduced by seed. They are sending me a one page guide to help select seed for rootstock. I will send you a photocopy upon request. If you have money on deposit with us, we will be glad to place orders for you.

I asked Dr. Campbell to proof-read the above. He added that in some of the polyembyronic citrus, some of the embryos are of gametic origin and therefore do not come true. The percentage varies by species and variety.

FROM ISSUE #7: SUGGESTIONS FOR PURCHASE OF CITRUS SEEDS. Carl Berg, a Peace Corps volunteer in Ecuador, inquired about citrus rootstock and how best to introduce assorted varieties of citrus into his part of the country. I phoned Mr. Reed at Holmes Citrus Nursery for help.

There are five rootstocks that he recommends for anyone, anywhere (though he sells 18). These five are: sour orange, 'Carrizo' citrange, 'Swingle', 'Cleopatra' mandarin and Poncirus trifoliata. If there is no danger of freeze or frost, he would add to the list the following: Citrus macrophylla (for extremely warm climate, but poor fruit quality), 'Rangpur' lime, 'Palestine' lime, 'Milam' and volkameriana. We also sent Carl budwood of superior varieties to bud onto wild citrus. These will be used to bud the new rootstock when it is ready.

The prices per quart range from $30 to $125, so most of ECHO's collaborators would be unable to try more than perhaps one variety. I asked if he would be willing to prepare an assortment in smaller packets. He agreed to the following. You can send him $40 for an assortment of the first 5 mentioned above, all ten mentioned above, an assortment of citrus that will come true from seed (see E D N #5), or any combination of these. He will arrange packet size to make the bill come out to $40. We agreed to allow him some flexibility, as he would not have time for precise measurements, etc. You will receive approximately 1.5 pounds of seed. I would recommend that you add about $20 for airmail postage, as citrus seeds begin to lose viability within a couple weeks after removal from refrigerated storage. Alternatively, you may know someone in the States that is about to visit you. The seeds could be sent to them via UPS. Mr. Holmes is doing this as a favor to help your work and does not assume responsibility for delivery by international mail systems. Send your order, mentioning the ECHO package arrangement, to Mr. Chuck Reed, Reed Brothers' Citrus, P.O. Box 1863, Dundee, FL 33838 (Phone 813/439-1916).

I also asked about susceptiility to Phytophthora root rot. He said that rough lemon is one of the worst root stocks in regions where Phytophthora is a problem. It once was the primary root stock in Florida, but has been totally replaced. All citrus trees are susceptible to Phytophthora root rot to some degree. If a workman injures a root and the organism is in the soil, it can enter and damage the tree. It can then kill after a few months or just reduce production. Some trees in a row may become infected and others not. Budwood is not infected.

FROM ISSUE #12: ANSWERS TO SOME QUESTIONS ON CITRUS.Two of our readers asked some interesting questions about citrus. We called Larry Reed at Holm Citrus nursery who has so often been helpful. The questions and answers are of general interest, so I repeat them here.

Q. (From William Boykin in Zambia). "The navels, valencias and hamlins do not have the sweet flavors we had hoped. Is there anything we can do, or might it be the rootstock? We budded onto cape lemon."

A. The cape lemon rootstock is your major problem. Lemon rootstocks produce big quantities of fruit, but the quality is always poor. Lemon rootstock is for commercial juice production where they want to emphasize quantity. They then mix with smaller amounts of other juices to get the right taste. An advantage of the lemon stock is rapid growth, it being more vigorous than other stock. However, this also results in poor taste. Climate can also cause inferior taste. It would help if the climate were cooler. I would suggest budding onto either Carizzo or sour orange. They may not allow sour orange into the country because it is so susceptible to Tristeza. For example, Brazil's citrus industry was wiped out some years ago by tristeza. But it depends a lot on how virulent is the strain in your country. It is so good that I would take the risk and not worry too much about tristeza. My third choice would be Cleopatra mandarin. The disadvantage with it is foot rot. This world-wide problem is caused when workers injure the root while cultivating. It is most susceptible during the first 5 years. The safest thing would be to use a combination of rootstocks. Then it will be unlikely that you will be wiped out.

If you wish to plant some true-to-type seeds I would recommend two varieties: ridge pineapple or what is called "old sweet seedling." By the way, any true-to-type seedling [plant grown from seed that will give fruit like the parent tree] is susceptible to foot rot.

Q. (From Peter van Lonkhuyzen in Haiti). I have used budwood from some three year old trees that are not bearing fruit yet. Someone told me that by using such young trees my grafted trees will start bearing late and never will give good yields. Is this true?

A. A grafted tree will normally start bearing some fruit within a year. The fact that the parent trees you used were not bearing at three years suggests that they were seedlings. If so, you will have to wait about as long as if you had planted the seed.

There is one way you can get some quick budwood. Take budwood from a mature bearing tree and graft onto a rootstock in your area. As soon as this has grown to produce some branches, you can use this to bud other trees. They call this "first generation budwood." However, the second generation of trees should not be used for budding until they have started bearing.

Q. What rootstock should I use that is resistant to both drought and tristeza?

A. Sour orange is drought resistant, but if you want tristeza resistance also I would recommend Carizzo. Of course, even that is only drought resistant to a point. True-to-type seedlings will never tolerate drought as well as the normal rootstocks. I might also mention that a rooted cutting from any variety of citrus will have about half the normal life expectancy of a grafted citrus, due to susceptibility to a range of root diseases.

Q. How is it possible that in some places they have Washington naval trees without thorns while somewhere else the same variety has thorns?

A. There can be some differences in thorniness within a variety. In the one location they must have budded from trees that did not have thorns. You will still have some thorns of course. Alternatively, the thorny ones could be seedlings, as they tend to have more thorns.

Cucurbit seeds

Echo technical note a-2
As possible oil and protein sources for small scale and household use in the hot humid tropics
By Franklin W. Martin Mayaguez Institute of Tropical Agriculture Mayaguez, Puerto Rico

Introduction. Oils are necessary in the diet as a source of non-saturated fatty acids, in order to give flavor to foods, as sources of fuel for the body, and in addition, are used in the kitchen as a cooking medium. The problem of interest here is how to produce the oils needed at the level of the individual household, in the tropical household. This problem has several aspects of interest.

On a small scale, animal fats are more easily obtained from small animals than plant fats obtained from plants. Animal fats are fairly stable, can be used one or two weeks or more even without refrigeration, and are fairly well accepted. They do not contain sufficient non-saturated fatty acid (palm oils, however, are an exception to this rule.) Plant fats are therefore more useful to the body from a nutritional standpoint, but they are less stable, and easily turn rancid. Most plant oils occur as stored materials in seeds. To use the fats it is often necessary or at least desirable to remove the seed coats from the seeds. In order to obtain the nutritional value of the non-saturated fatty acids it is not necessary to extract the oils from the plants. Thus, the kernels can be used in many different ways. A convenient form to use the fats of some seeds is as a vegetable curd. This is prepared by grinding the seeds in water, filtering, and precipitating the protein with an appropriate agent such as lime juice, vinegar, or epsom salts. Most of the oil as well as the protein is extracted and precipitated, the former by occlusion in the protein.

In the hot humid tropics there is often a shortage of oil in the diet, or cooking oil in the kitchen. It is difficult to mature many of the most typical oil crops during the rainy season. While large scale techniques for extracting the oil are available in some cases, they are not necessarily the best for the small scale everyday needs of the tropical household. There is a need for appropriate crop sources of oil in the humid tropics, and for techniques for their use.

A suitable crop for oil production on a small scale should be an annual, or a perennial that produces during the first or second year. The oil-producing fruit or seed should be available year round, or, as an alternative, the seed should be storable so that oil can be produced year round. It is also very useful if the seeds that are sources of oils are also good sources of protein.

Principal tropical plant oil sources. In the tropics fats are obtained from the seeds of numerous plants, many wild or produced on only a local scale. The most important plant sources of oil in the tropics are given on Table 1. In terms of production per unit area, the oil palm, Elaeis guineensis Jacq. outproduces all other species as an oil source. These oils can be extracted at the household level, and are extremely useful. Palms need space and time to grow, of course, an thus are not convenient crops for the small household.

The soybean, peanut, and possibly the winged bean are suitable sources of high quality cooking oil, but are very difficult to extract on a small scale. They are all excellent as sources of non-saturated fatty acids in the diet. Cotton and okra seeds are other possibilities. Cotton seed is seldom produced on a household scale, but okra seed is often available on the small farm and can be considered a potential source of oil. In both crops the presence of gossypol or related substances in the seeds limits current use. However, lines low or free of gossypol are also feasible.

Cucurbitaceous seeds as oil sources. The uses of cucurbit seeds as sources of oils and proteins have been reviewed by Jacks, et al. (1972). After the hull is removed, cucurbit seeds contain about 50 percent oil and up to 35 percent proteins. Most of their oil is made up of non-saturated fatty acids, thus of high nutritional values. Conjugated fatty acids among some cucurbit oils make them highly useful as drying oils. [I.e. they combine readily with oxygen to form an elastic, waterproof film. Ed.] The proteins, on the other hand, are principally of the globulin type, and are deficient in lysine but also in sulfur-bearing amino acid. Protein efficiency ratios of about 30 to 70 (that of powdered skim milk is 80) have been measured. The PER improves with addition of lysine.

The uses of cucurbit seeds for their high protein and oil content have many precedents. In tropical Africa two species of Telfaria (see Table 2) are used for their large oily seeds. Hodgsonia, a perennial vine with large, fatty seeds, has been domesticated as an oil source in China (Chien, 1963), where it is known as the lard fruit. Cucurbita mixta was domesticated in pre-Colombian Mexico and Central America chiefly for its seeds, sources of protein and oil. The nutritive value of pumpkin seed is improved when the meal is mixed with soy flour or supplemental lysine (Craveola & Cervantes, 1965). In West Africa, the seeds of Citrullus lanatus are used as commercial sources of oil (Omidiji, 1977). These and seeds of Cucumeropsis edulis and Lagenaria siceraria are used in melon soups for their oil and protein content. Important species used for oil are given in Table 2.

As a general rule, cucurbitaceous plants prefer dry climates, and many are so riddled with disease in the humid tropics that production is impossible. When there is a pronounced dry season it is often possible to grow the vines, produce the fruits, and store the seeds for use as needed. A few species useful for their seeds can be grown in the humid tropics as shown by our experience in Puerto Rico. The most successful species are Benincasa hispida, the wax gourd, and Cucurbita moschata, the tropical pumpkin. If fruits are carefully protected from excess moisture, Lagenaria siceraria, the bottle gourd, can also be grown. In Table 3, experience at Mayaguez, Puerto Rico is summarized.

Benincasa hispida is perhaps the best of the cucurbits as a source of seed oil for the hot, humid tropics. It can be produced at any season of the year. During the rainy season the fruits are susceptible to rotting. They can be protected by growing the vines on trellises or by placing thick but porous supports between the fruit and the wet ground. The fruits are very large, and are very seedy. If the fruits are sound, they can be stored for many months, even a full year, until used. Or, the seeds can be removed and dried, as later discussed. Per hectare yields of these seeds have been estimated in our fields as 500 kg/hectare.

Uses of cucurbit seeds. Seeds of cucurbits can usually be readily separated from the stringy pulp to which they are attached. Sometimes a light fermentation for 24-72 hours of the wetted seeds is useful to clean the seeds of pulp. The cleaned seeds are carefully washed and can then be processed for use or dried for storage.

Fresh, wet seeds sometimes are chewed without further processing. They also can be toasted, with or without light salting. Or, they can be cooked into soups with or without removing hulls. Naked or almost naked seeds of Cucurbita pepo are especially desirable for such uses because of the lack of seed coat. This means, also that the concentration of oil and protein are very high, and the concentration of fiber is very low in the edible part.

If the seeds are to be stored, they should be carefully dried in the sun or at lowest settings in an oven. Stored seeds retain most of their nutrient content for years and are convenient for rapid later use. The seeds can then be cooked with or without dehulling, or can be ground into a nutritious oily meal.

At our own laboratories we have emphasized the preparation of vegetable curds from cucurbit seeds as an unique method of using the protein and oil. In table 4, the results of tests in Mayaguez, Puerto Rico are summarized.

All of the cucurbits with the exception of the Luffa species produced a very satisfactory vegetable curd, as good as tofu from soybeans. These curds were rich in protein and oil and contained no more than minor and insignificant traces of the seed coat. However, the vegetable curds are usually very fine and difficult to separate from the whey by filtration. In one case, Benincasa, the use of vinegar or lime juice yields a better, more manageable curd.

We consider these results preliminary but very promising. Studies of the protein and oil content of the Benincasa seeds and curd are planned.

Although hand presses can be used to remove oil from cucurbit seed, we consider these and solvent based practices unsuitable for the small household. We have not yet found a satisfactory solution to the need to produce cooking oil from the seed by small scale household processes.

Thus, preliminary consideration of cucurbita seeds as sources of vegetable oils are promising. Extensive further studies are needed to select appropriate species and varieties, and to develop appropriate techniques at the household level.

SOURCE OF FAT LIMITATION NOTE
African Oil palm Awkward for small scale production
Coconut Palm Awkward for small scale production
SoybeanTropical Varieties needed. Suitable in many areas
Peanut Suitable in many areas
Safflower Requires dry climate
Sesame Needs dry climate
Sunflower Pollination often poor in tropics
Flax Not adapted to the tropics
Castor bean Not suitable for household production
Cotton seed Not suitable for household production
Okra Under investigation, probable small to large scale value

SPECIES NOTES
Benincasa hispida Wax gourd. Appears very suitable for the hot, humid tropics. Seeds seldom used for food.
Citrullus lanatus Watermelon, selected varieties. Definite preferences for dry climate, a West African species.
Cucumeropsis edulis Egusi. Definite preference for dry areas. Used in West Africa.
Cucurbita maxima Squash. Domesticated chiefly for its flesh principally temperate zone.
Cucurbita mixta Squash. Domesticated and used for edible seeds. Dry area.
Cucurbita moschata Pumpkin. Seeds edible, but this species is grown chiefly for its flesh.
Cucurbita pepo Squash. Widely used for its fruits and to a lesser extent for its seeds.
Hodgsonia macrocarpa Lard fruit. Recently domesticated in China, subtropical.
Lagenaria siceraria Bottle gourd. Seeds edible, but used chiefly in West Africa, prefers dry conditions.
Luffa acutangula Angled luffa. Seeds and seed oils very bitter, poisonous
Luffa cylindrica Sponge gourd. Seed and seed oils bitter, may be poisonous.
Telfairia occidentalis Oyster nut. Seeds roasted or rendered, wet tropical Africa.
Telfairia pedata Oyster nut. Seeds roasted or rendered, dry tropical Africa.

SPECIES WINTER SUMMER
Benincasa hispida Excellent yields Excellent yields, fruit rots
Citrillus lanatus Low yields Complete failure
Cucumeropsis edulis Low yields Complete failure
Cucurbita mixta Fair yields Complete failure
Cucurbita moschata Good yields Fair yields
Lagenaria siceraria Excellent yields Fair yields
Luffa acutangula Fair yields Fair yields
Luffa cylindrica Fair yields Fair yields
Telfairea occidentalis Low yields Low yields

Literature cited

1. Chien, H.S.U. 1963, "Lard Fruit", domesticated in China. Euphytica 12(3): 261-262.

2. Craviota, R. O., & Cervantes, M. 1965, Estudio sobre proteinas y aminoacidos de alimentos mexicanos. Ciencia 24: 83-88.

3. Curtis, L. C. 1948. The use of naked seed in cucurbita pepo as a source of high quality liquid vegetable fat, as a high analysis protein, as a new confection, and as a sandwich spread. Proc. Amer. Soc. Hort. Sci. 52:403-406.

4. Jacks, T. J., Henserling, T. P., and Yatsu, L. Y., 1972, Cucurbit seeds I. Characteristics and uses of Oils and Proteins. A. review. Econ. Bot. 26:135-141.

5. Omidiji, M. O., 1977, Tropical Cucurbitaceous Oil plants of Nigeria. Vegetables of the Hot Humid Tropics, 2:37-39.

Dry farming

Echo technical note a-8

DEFINITION:Dry Farming is the profitable production of crops, without irrigation, of land with a low average or highly variable rainfall.

Fundamental principles

1. Farm practices must conserve and utilize the available rainfall to the fullest extent.
2. Quick maturing, drought resistant crops must be grown.

Requirements

1. Rainfall must be greater than 10 inches per year (250mm).
2. Wind and heat must not cause excessive evaporation at critical stages of plant growth.
3. Soil should be deep (preferably 10 feet - 3 meters) with no clay, sand, or gravel seams to interfere with capillary movement of water. The minimum feasible soil depth is 18 inches (450mm) but water storage capability and drought resistance increases with increasing soil depth.

To obtain maximum storage of moisture under any rainfall condition, the soil must absorb as much water as possible when it rains and losses by evaporation or transpiration must be kept to a minimum.

I. Increase water absorption

A. PREVENT A WATER SEAL AT SURFACE. Probably the greatest deterrent to a high rate of water absorbtion is the tendency for soils to puddle at the surface and form a seal against water intake. The beating action of raindrops tends to break down cloddiness and disperse the soil.

1. By tillage, create a rough, cloddy surface which lengthens the time necessary for the rain to break down the clods and seal the surface. For seed bed preparation in general, small seeds should have a finer, mellower bed than large seeds.

2. After harvest, create a stubble mulch on the surface. Such material not only prevents raindrops from inpinging directly on the soil, but impedes the flow of water down the slope, increasing absorbtion time.

B. REDUCE THE RUNOFF OF WATER. To the extent that waterlogging is not a problem, the runoff of water and its attendant erosion must be stopped.

1. Cropland should be as level as possible.

2. All tillage and plantings must run across (or perpendicular to) the slope of the land. Such ridges will impede the downward movement of water.

3. For every two feet of vertical drop or 250 feet of horizontal run, the field should either have bunds or contour strips (details of these practices are discussed later).

II. Reducing the loss of soil moisture

A. REDUCING SOIL EVAPORATION. Water in the soil exists as a continuous film surrounding each grain. As water near the surface evaporates, water is drawn up from below to replace it, thinning the film. When it becomes too thin for plant roots to absorb, wilting occurs.

1. Shelter belts of trees or shrubs reduce wind speeds and cast shadows which can reduce evaporation 10 to 30 percent by itself and also reduce wind erosion.

2. Mulching reduces the surface speeds of wind and reduces soil temperatures.

3. Shallow tilling can create a dirt mulch 2 to 3 inches deep which dries out easily but is discontinuous from the subsurface water, preventing further loss. Tillage must be repeated after each rain to restore the discontinuity. This is most workable where rainfall occurs in a few major rainfalls with relatively long intervals in between.

B. REDUCING TRANSPIRATION. All growing plants extract water form the soil and evaporate it from their leaves and stems in a process known as transpiration.

1. Weeds compete not only for soil nutrients, but water as well and so their control is critical.

2. Selection of crop is significant as well. Dwarf varieties have less surface and so lose less water. Some plants close their stomae when it is hot, reducing their water loss. Others, like corn, curl their leaves during hot afternoon and open them at night, effectively changing their surface area in response to conditions.

3. In dry farming, the number and spacing of plants is reduced so that fewer plants compete for soil moisture. The exception to this occurs when allowances for insect, bird, and rodent loss must be made at planting.

4. Where rainfall is frequently marginal to insufficient, drought "insurance" can be obtained by clear fallowing a sufficient area. An area clear of growing vegetation with a properly maintained stubble and soil mulch can retain 20 to 70 percent of the precipitation received until the next year. Where 5 to 6 acres each year per family have been so set aside in India, the specter of famine due to drought has been eliminated.

5. Post harvest tillage will create stubble and dirt mulches and destroy weeds before the onset of the dry season.

III. Dry farming practices

Dry farming builds upon a knowledge of general agriculture but carries out its practices in the light of the significant probability that this year or next will be a drought. The following agriculture practices are discussed with this back-ground.

A. BUNDING. The first essential step in dry farming is bunding. The land is surveyed and level contours determined every hundred feet. For unusual slopes, it is recommended that for every fall of two feet, a bund 18 to 24 inches in height be constructed. Even when land is fairly flat, a 12 inch high bund every 250 feet is still found useful. Excess storm water is released by constructing periodic waste weirs with a sill of one-half bund height. This will retain water and minimize the loss of topsoil.

In order to make the bunds, land must be marked by the surveyor with bund lines. A few feet on either side of it, the land should be plowed and harrowed. The bund former should be worked along the bund twice, side by side, leaving a furrow in between. This furrow in the middle should be filled in with soil from the plowed portions on both sides, by means of a scraper. The outlets or "waste weirs" should be constructed of stones.

The natural drainage of the area must not be completely stopped but should be controlled by providing suitable outlets for excess storm water to pass gradually, without carrying much silt with it, and after fully saturating the soil and subsoil. The major natural drains in each village area or watershed must be properly maintained so that all fields have some outlet for the extra storm water.

B. STRIP CROPPING. Strip cropping is a technique that serves to control erosion and increase water absorbtion thereby maintaining soil fertility and plant response. In effect, it employs several good farming practices such as crop rotation, contour cultivation, stubble mulching, etc.

By growing in alternating strips crops that permit erosion and exposure of soil soil and crops that inhibit these actions, several functions are performed:

1. Slope length is maintained.
2. Movement of runoff water is checked.
3. Runoff water is desilted.
4. Absorption of rainwater by soil is increased.
5. Dense foliage of the erosion resisting crop prevents rain from beating directly on the soil surface.

Strips are, of course, planted perpendicular to either the slope of the land or the prevailing wind direction, according to whether water or wind presents the more serious erosion potential. Additionally, crops which do not resist erosion should be rotated with crops which do. Research has shown that:

1. A normal seed rate of groundnut (peanut) is an efficient and suitable crop for checking erosion.

2. The normal seed rate of leguminous crops other than goundnut does not provide sufficiently dense canopy to prevent raindrops from beating the soil surface; is should be raised to three times the normal seed rate.

3. On the average, the most effective width of contour strips for cereals such as sorghum and millet is 72 feet and for the intervening legume, 24 feet. As slopes vary, so do the optimum strip widths, as shown below:

C. SUMMER FALLOW. All of the principles of water conservation and utilization pertaining to dry-farming will not make a crop grow if sufficient rain does not fall. Where the soil depth exceeds 18 inches (450mm), however, it has been shown that it is possible to store water as soil moisture from one year to the next by the use of proper summer fallow techniques. With a soil depth of 10 to 15 feet, up to 75% of the incident water may be retained though 20% to 40% is more normal. Thus, in an area that averages sufficient rainfall for crop growth, it will be rare that the sum of the stored water and incident water will not be sufficient for crop production. Where families in India have faithfully set aside 5 to 6 acres for summer fallow each year, drought-induced famine has been virtually eliminated.

The partial loss of a crop in the year of fallow is offset to a great extent by a very much increased yield in the year of cropping. Such increased yield in a year of failure of the general crop in the surrounding areas, has a far greater value than a normal crop of a good season.

In order to accomplish this objective, the soil must be loose and permeable to soak up the rainfall and the dirt/stubble and mulch must be maintained to minimize evaporation. The land is worked with a tine-cultivator followed by occasional harrowing, particularly after rainfall, and weeds (which use as much or more water as crops) must not be allowed to grow. Though this expenditure on cultivation is relatively small, neglecting to provide the surface mulch at any time may cause more moisture to evaporate in a few, hot days than would fall during the whole season.

Experience has shown that where rainfall is 10 to 15 inches per year (250 to 375 mm/yr.) a clear fallow every other year is necessary and, at 15 to 20 inches per year (375 to 500mm/yr.), every third year.

D. MULCHES:

1. MECHANISM OF SOIL DRYING. Water easily enters porous soil and, as it seeps downward, becomes absorbed as films of water around the soil grains. These films form a continuous column of water to the surface of the soil. The film tends to remain the same thickness around all the soil grains with which it is in contact. This film of water in the soil is known as the capillary water and is the source of water for the plants.

The sun, wind, and dry air will cause evaporation at the surface, thus reducing the thickness of the film at the surface. The thicker films in the subsoil will rise to equalize the distribution again. This will continue until the films are so thin that the plant roots can draw no further moisture from them. The result is drought.

2. STUBBLE MULCH. Stubble mulching aims at disrupting the soil drying process by protecting the soil surface at all times, either with a growing crop or with crop residues left on the surface during fallows. To be effective, at least one ton per hectacre must cover the surface, and the maximum benefit per unit residue is obtained at about two tons per hectacre. Benefit may still be obtained at 8 tons per hectacre.

The first benefit of a stubble mulch is that wind speed is reduced at the surface by up to 99%, significantly reducing losses by evaporation. In addition, crop and weed residues can improve water penetration and decrease water runoff losses by a factor of 2 to 6 times and reduce wind and water erosion by factors of 4 to 8 relative to a bare fallow field.

There are two limitations to the advantages of stubble mulch farming:

a. Dead surface vegetative matter can provide a home/breeding ground for plant diseases, insects or rodents. Use of a mulch not related to the succeeding crops will minimize much of the disease and insect effects. Use of stubble mulch only in the dry season will minimize all biological activity.

b. For decomposition, the ideal carbon to nitrogen ratio (C/N) is 25 to 30. Dry, woody, or non-green straw, stalks, etc. have a C/N of 50 to 100. This tends to slow decomposition and deplete soil nitrogen temporarily. Nitrogen is a major requirement for protein synthesis by plants. A stubble mulch during a biologically active period such as the rainy season, should only be used when either:

1. Soil nitrogen is very high.
2. Plant nitrogen needs are very low (such as cassava).
3. A nitrogen-containing fertilizer is used.

To obtain the benefit of mulching on soil structure without causing temporary de-nitrification, the mulch can be composted before adding it to the soil. Rapid bacterial action in the tropics makes composting less beneficial than in temperate climates but may still be worthwhile.

3. DIRT MULCH. Dirt mulching aims at disrupting the soil drying process with tillage techniques that separate the upper layer of the soil from the lower layers, making the soil moisture film discontinuous. In addition the soil surface is made more receptive to water intake.

Principles of dirt mulching:

a. Effectiveness increases with increasing depth to a limit of to 4 inches (75 to 100mm).

b. Increasing the dirt mulch depth decreases the available fertile soil.

c. The effectiveness of dirt mulches decrease with age. Consequently it must be recreated by shallow tillage of harrowing after each rain or each month (whichever is more frequent).

d. The crumb form of dirt mulch (particles greater than 1mm) is more effective and resists wind erosion more than the dust form.

e. Dirt mulches can only be properly made when the soil is moist.

f. For a climate with a "rainy" growing season and a hot, windy, dry season, dirt mulching should only be performed during the rainy season and with a growing crop to slow the wind and water and hold the soil.

The improper use of a dirt mulch presents serious erosion potential. The "dust bowl" condition in the great plains of the U.S. that destroyed or damaged millions of acres of prime cropland was a direct consequence of the abuse of the dirt mulch.

E. PLOWING/TILLAGE PRACTICES. Plowing, when the soil is in the proper condition, wears the soil into thin layers, and forces the layers past each other. If the soil is too wet when plowed (especially if it is heavy), the soil crumbs or granules are destroyed, thus puddling or compacting the soil. When the soil is too dry, the soil tends to pulverize and form dust. Plows with steep moldboards have the greatest pulverizing action upon the soil. The plow with the less steep moldboard has less tendency to puddle the soil and is of less draft.

1. Purposes of Tillage Operations:

a. To produce a rough, cloddy surface that will increase moisture absorption and reduce runoff, as well as erosion from wind and water.

b. To control/destroy weeds that compete with crop for sunlight, nutrients, and water.

c. To destroy or prevent the formation of a hard pan (sole) which can develop after repeated shallow plowing or harrowing. This hard pan can stunt root growth, reduce water storage, and check the capillary rise of water from the subsoil.

d. Promote bacterial activity by aerating soil, encouraging the decay of residues and the release of nutrients.

2. Time of Tillage:

a. Plowing, like planting, is sensitive to moisture and neither should be done when soil is either too wet or dry. In the arid and semiarid tropics, proper moisture conditions are likely to occur only at the beginning of the rainy season and should be done on the same day. If possible, planting should immediately following plowing, with seed rows centered on the furrow slices. A crosswise harrowing will cover seeds and close air spaces, thus creating a dirt mulch and keeping out the drying winds. If the crop is then harrowed/cultivated several times during the season, especially after rains, much moisture will be conserved. The proper soil moisture condition for plowing is indicated by a manual soil test. The usual test is to squeeze a handful of soil. If it sticks together in a ball and does not readily crumble under slight pressure by the thumb and finger, it is too wet for plowing or working. If it does not stick in a ball, it is too dry. When examining soils, samples should be taken both at and a few inches below the surface. Soil that sticks to the plow or to other tools is usually too wet. A shiny, unbroken surface of the turned furrow is another indication of excessive soil moisture. In general, sandy soils and those containing high proportions of organic matter bear plowing and working at higher moisture contents than do heavy clay soils.

b. In semi-arid regions, the soil after harvest time is generally too dry for good plowing. Yet if the field is left uncultivated, this dry condition may become even worse and weeds will also grow and go to seed. The field should be harrowed (or plowed without moldboard) and crop residues left to form a stubble mulch to absorb/retain moisture and soil until the rains return. Stubble should not be immediately covered and incorporated in the soil unless rodent or insect infestation is heavy (and even then burning should be considered). It has been well demonstrated that it is normally impossible to raise the soil organic matter content in areas where temperatures are high for long 0periods. When moisture is present, the rates of oxidation are extremely high and incorporated organic matter is lost quickly. The benefits thus derived from decomposition, as occurs in the more temperate regions, are not normally experienced. When left on the surface, however, organic matter does not decay so rapidly. Incorporation with the soils will tend to depress the levels of available nitrogen, to the detriment of crops if soil nitrogen is low. If soil nitrogen levels are adequate, the incorporation of residues to the soil may be beneficial if done with spring plowing at the start of the rainy season.

3. Depth of Plowing

a. Variation with Soil Type. Generally speaking, heavy clay soils should be plowed deeper than light, sandy soils, in order to promote circulation of the air and bacterial activity. Deep plowing on sandy soils, which are naturally porous and open, tends to disconnect the seed bed from the subsoil and speeds soil drying by too free a circulation of air in the soil.

b. Depth Affects Moisture Reservoir. In semi-arid climates, the greatest advantage to be gained from deep plowing (5-8 inches) is the development of a comparatively large moisture reservoir. When land is not plowed more than 3 or 4 inches deep for a period of years, a hard plow sole is very likely to form, through which roots and rain can only penetrate with difficulty. A shallow plow sole will saturate quickly with rainwater and increase runoff rates. As a rule, tillage below 5-6 inches also causes increased evaporation rates, losing precious water. This deep plowing need not necessarily be done annually. Depending on soil and rainfall, a deep plowing of 5-6 inches every 2 to 5 years is satisfactory. As noted earlier, the soil mulch attains maximum effectiveness at a depth of 3-4 inches which can be maintained with a hand harrow/cultivator.

c. Exposure of Acidic Subsoil. Deep plowing in some clay and loam soils will reduce yields for one or two seasons afterward as a result of an acidic subsoil. This may be dealt with by liming the soil (neutralizing the acidity) or by varying the depth of the plowing slowly so that the acidic subsoil is exposed a little at a time. This practice will also eliminate the plow sole.

4. Seed Bed Preparation. In general, smaller seeds require a finer, mellower seed bed than larger seeds. Seeds germinate and plants grow more readily on a reasonably fine, well prepared soil than on a coarse, lumpy one, and thorough preparation reduces the work of planting and caring for the crops. It is possible to overdo the preparation of soils. They should be brought to a granular rather than a powder-fine condition for planting.

F. PLANTING

1. In rows: Planting of crops should be in rows to permit inter-tillage as described later.

2. Planting density: Limited moisture dictates the necessity for wider row spacing and lower rates of seeding (by one-half to two-thirds) than are used in moisture abundant areas. The resulting reduced plant population provides more moisture and nutrients per plant and thus enhances the possibility of the crop reaching maturity before the supplies are exhausted. Cereals should be planted 7 to 14 inches (18 to 35 cm) apart and crops such as millet, sorghum, sesame, safflower, etc. in rows 28 to 42 inches (70 to 105 cm) apart. In some cases, the practice of planting 2 or 4 rows and skipping one is successful in further increasing the efficiency of moisture utilization. In general, with limited rain, higher seed rates produce more straw/stubble at the expense of grain production. (See Table II, below)

G. INTERTILLAGE/INTERCULTIVATION. Crops sown in rows can take advantage of intertillage practices which serve three basic functions:

1. Easy weeding without meticulous hand labor. Weeds compete for moisture and nutrients, thus they should be destroyed while small, before they have grown more than 2 or 3 leaves. If seeds are broadcast, or thickly sown, they can at best only be cultivated manually, a back-breaking task.

2. Increase the formation of nitrates by bacteria. Intercultivation aerates the soil and forms a mulch of dead weeds and stubble on which bacteria operate and form nitrates. Cultivation for this purpose should be undertaken during the early period of plant growth, and should be relatively deep, on the order of 2-3 inches.

3. Intertillage conserves moisture by the formation of a dirt mulch as described earlier. It is imperative that cultivation be performed after rainfalls. Even a light rain can re-form capillary connections between the stored soil moisture and the surface of the ground. After a few drying days like that, it is possible for soil moisture to be lower than before the rainfall.

H. CROP ROTATION AND VARIETIES.

1. UNIQUE ASPECTS OF CROP ROTATION FOR DRY FARMING. One of the first principles of dry farming with regard to cropping practices is that crop rotation as practiced in more humid regions is not necessarily recommended in semiarid lands. The following constitute the chief differences:

a. Only a limited number of crops are adapted to the climatic conditions and the farmer must sow the crop best suited to the moisture conditions encountered at that time.
b. Moisture is so dominantly limiting, that "soil improving" crops are much less effective than in more humid areas.

c. Success with rigid or complex sequences is difficult in the face of widely varying rainfall.

2. REASONS FOR CROP ROTATION. There are five basic reasons why crop rotation should be practiced:

a. Moisture Conservation: Any system of crop rotation should be planned with moisture requirements as the main consideration. For a given set of climatic conditions, a crop may be described as either moisture dissipating or conserving. After harvest of a moisture conserving crop, the soil contains more moisture than at planting. This reserve of moisture can help guarantee the succeeding crop. (see paper on Determining the Water Needs of Plants). Crops which are sown in rows so that intertillage and dirt mulching can be practiced tend to be moisture conserving. Under sowing may also assist in conservation. Moisture may be insufficient to both grow a crop and conserve enough water to ensure the succeeding crop. In such a case it is necessary to utilize the dirt and stubble mulched fallow in the rotation. If annual rainfall is 10 to 15 inches (250 to 375 mm) this will be needed at least every other year; if rainfall is 15 to 20 inches (375-500mm) at least one in every three. In the West African sahel drought may be expected one year in four. Between 1968-1973 the rate was one year in two. In a situation like this, setting aside mulched fallow each year for moisture conservation will significantly aid survival. Where this has been faithfully practiced in similar areas in India, the specter of famine by drought has been virtually eliminated.

b. Pest Control. Where related crops are successively planted in the same place, viruses, molds, blights, and selective insect pests tend to build up in the soil. Crop rotation that leaves at least two years in between subject plants in the same location will eliminate the abnormal buildup of most such pests for most crops.

c. Erosion Control. Plants which are thickly planted or which produce a thick ground cover tend to resist erosion much better than those which are intertilled or tend to be moisture conserving. Loss of soil due to erosion is a significant dry farming problem and erosion controlling crops should be included in a rotation, preferably in a strip cropping mode.

d. Soil Nutrients and Structure. When related crops are successively planted, specific soil minerals and nutrients are withdrawn faster than they can be replaced by decay or subsoil movement. This selective depletion causes a soil to be "worn out" quickly. Simple rotation of crops makes depletion more uniform so that soils "wear out" more slowly. The planting of legumes (such as gram or groundnut or alfalfa) with their nitrogen fixing capabilities tends to restore soil fertility. The use of green manures (plowing under of a green crop, such as alfalfa, rather than harvesting) can also aid soil nutrients and texture but benefits may be short lived in the tropics and difficult for Third World farmers. The planting of any deep or thickly rooted plants (such as grasses, alfalfa, etc.) tends to improve soil structure and draw subsoil nutrients to the surface like a natural fallow and can increase pasturage during dry periods. Crops like cassava which require relatively little soil nutrients may also be grown for rotation or when soil is almost worn out.

e. Distribution of Labor and Risk. It is generally advisable for the subsistence farmer to grow all crops in the rotation scheme simultaneously, apportioning to each crop the fraction of fields that it requires. This helps the scheduling and distribution of labor at the bottlenecks (planting, harvesting, etc.) so that the entire crop need not be done simultaneously. There is also a reduced risk of total crop failure and increased variety/nutrition in the diet.

3. CROPS AND VARIETIES. Choice of varieties is important. Varieties which have proven excellent in irrigated or high rainfall areas are generally unsuited for dryland conditions. Many attempts at dryland farming have failed, largely due to lack of recognition of the requirements for the variety selection.

a. Variety Requirements For Dry Farming

1. Short-stemmed varieties with limited leaf surface minimize transpiration.

2. Deep, prolific root systems enhance moisture utilization.

3. Quick-maturing varieties are important in order that the crop may develop prior to the hottest and driest part of the year and mature before moisture supplies are completely exhausted.

b. Climatic Requirements of Crops in Brief

1. The TABLES below list favorable conditions for various annual crops.

HIGH TEMPERATURE TOLERANCE
Cotton, Groundnut, Chilies, (favor jute & yams only in humid tropics)

DROUGHT RESISTANCE
Common Millet, Barley, Chickpeas, Safflower (lower temperatures), Sorghum, Bullrush Millet, [Phaseolus] crops, [radiatus] (gram mung bean), Cassava, Castorbean, Sesame, Groundnut (Spanish variety), Pigeon peas, Sunflower

LOWER TEMPERATURES FAVOR
Wheat, Potato, Sugar, Tomato, Safflower

VERY HIGH RAINFALL
Rice, Cassava, Yam tolerance

WIDE CLIMATIC TOLERANCE
Size, Soybean, Groundnut (Valencia & Virginia type), [Phaseolus lunatis,] Kenaf, Hemp, Sweet Potato, Sugar Cane, Tobacco

Muscovy ducks for png villages

Echo technical note b-2

(This is an original manuscript by F. Bauer, Poultry Research Center, Labu, Papua New Guinea. It has merely been retyped by ECHO to make it more compact for airmail.)

Breed description

The Muscovy is a heavy bird, suitable mainly for meat production. Under good management, with proper feeding, the drakes (male ducks) will reach 4.0-4.5 kg and the ducks 2.0-2.5 kg at 16 weeks, which is usually the age at which the birds are sold to be eaten. Most of the Muscovys are pure white but black ones also exist. There is also a full range between black and white. All the birds develop red flesh around their eyes and at the base of their bills. In older drakes, it may even appear on the back of the neck and wings. With good feed, the ducks will lay about 90 eggs per year and will hatch ducklings very successfully. The breed is very hardy and can get alot of its feed requirement in foraging. Traditionally, the PNG Farmer does not feed its poultry and relies on natural incubation for breeding. The Muscovy duck is ideally suited for the PNG village conditions.

Raising ducklings from 0 to 6 weeks

A. Site of the projects. For a duck project, choose a place:

(1) close to the village, to be able to look after the ducks easily,
(2) where there is good shade (if the ducks stay a long time in the sun, they may get sick),
(3) where there is green fresh grass for the ducks to eat and find insects,
(4) not close to a pig fence (very often, pigs kill and eat ducks),
(5) where hawks do not usually fly,
(6) near a creek or pond, if possible.

Avoid places that are dry, sunny, or covered with kunai grass.

B. Housing. A small house of 3 x 5 m, made out of bush material will be enough for 20 ducklings. Make two windows to give plenty of light inside this house, as ducklings will not grow well in a dark place. Make the house cat and dog proof. In a corner of the house, make a small, covered room (of about .5 x .5 x .3 m) where the ducklings can go and sleep or huddle together out of the wind if they are cold. On the floor, put some deep litter. This can be sawdust, shavings, coffee skin or dry, finely chopped kunai. This deep litter should never become wet.

C. Feeding. Although it is a bit costly, it is recommended to feed the ducklings with a commercial feed for the first six weeks. Broiler starter, pullet starter, broiler finisher are suitable. Do not use layer mash or crumble, pullet grower or developer as these feeds are too low in protein. A duckling will eat about 3 kg of feed for this period. At the end of the fifth week, start to feed some locally produced feed with the commercial ration. Anything that people eat is suitable for ducklings. Choko, both leaves and fruits is very good for ducks. Cook the feed.

D. Water. Water must be available inside the house all the time. Troughs made out of bamboo are quite good. It is better to have a creek or a pond where the ducks will be able to drink and wash later on, but it is not absolutely necessary. 44 gallon drums cut lengthwise, or a big cooking pot in the ground will be enough, provided that they are refilled regularly.

E. Looking after the ducklings. On the coast, and up to 1000 m, the ducklings can look after themselves very well. For the first five weeks, they must stay inside the house all the time. During the sixth week, they can start to go out, a few hours every day. It would be best to have somebody to check them during that time. In the Highlands (above 1000 m), cold weather might be a problem for the first two weeks. Here are a few possible solutions: (1) Keep the ducklings in a centrally situated brooder for two weeks before distribution. (2) Make a small round enclosure, about one meter in diameter with flat iron, woven bamboo, strong cardboard box, etc. and cover it with old bags, leaving an uncovered strip, about 30 cm wide in the middle. Put a kerosene lamp inside the enclosure, in the strip not covered by the bags. (3) Take a box (beer carton or the like) and make a few holes in it. Every night, or when the weather is very cold, put the ducklings in the box and close it. Let the ducklings out in the morning, or when the weather improves. During the day, do not keep the ducklings inside the box for more than two hours. (A beer carton will be enough for 10 ducklings.)

Raising ducks from six weeks to four months

After six weeks, the ducks can be fed entirely on locally produced feed-sweet potatoes, taro, banana, pumpkin, choko, etc. Anything good for people is good for ducks. The food must be cooked. To know how much feed to give to the ducks, follow this simple rule: If the ducks eat everything within half an hour and nothing is left, they are still hungry. Cook more next time. If after half an hour, the ducks start to wander away from the feed, and some of it is still left, they have had enough.

Feeding ducks locally produced feed is not enough. Every day, they must be able to graze. It is only in grazing that ducks will get the protein necessary for their growth. These proteins will mainly be insects and grass seeds which are not found on bare ground or in short grass. Even a very big fence will not give enough grazing land because as soon as all the grass is finished, the ground will be laid bare and hard by grazing and trampling of the duck feet. There must be no fence around a duck house. A fenced-in project is a project which will fail. It is better to have a few ducks lost to dogs or other predators than to have the whole flock dying due to protein deficiency. Protein deficiency will result in:

(1) Poor growth-the duck will never be heavy enough to eat,
(2) no feathers-the duck will be cold, sick and will die,
(3) no eggs-the duck will never lay eggs.

The best way to look after ducks after six weeks is to keep them overnight in the house, Let the ducks out at about 8 o'clock in the morning. They will be hungry and active and look for insects and grass. Before sunset, feed the ducks. It will help if the owner always calls his ducks in the same manner (call, bell, etc. ). They willcome quickly by themselves and will not need to be rounded up. Lock the duck for the night. Put water in the house. At four months, the ducks will have reached their biggest weight. Under village conditions, it will be about 2.0 kg for the drakes and 1.2 kg for the ducks. They should then be eaten or sold as after that their meat will become quite tough. Do not keep a small duck in the hope that it will grow fatter. It is usually a waste of time and feed.

Breeding ducks
As it is cheaper for a farmer to produce his own ducklings than to buy them from the outside, he should do his own breeding. Only the best ducks and drakes must be kept for breeding. In this way only, the ducklings hatched on the project will be strong and healthy. Do not keep any birds that have deformed wings, with the tip of wings pointing outside. Otherwise, there will be more and more of them on the project. Do not keep any bird that is smaller than the rest of the flock. Big parent birds produce big ducklings. The ducks kept for breeding will be the heaviest ones, of round appearance and with a belly that is close to the ground. The drake will be the heaviest one, with a belly parallel to the ground. Do not keep any drake which looks like it is standing with the breast much higher than the belly. Do not keep more than 10 ducks for breeding. Otherwise, it is probable that the garden produces will be in short supply to feed the flock and all the birds will do poorly. Keep two drakes for up to five ducks and three for up to ten ducks. Ducks can be kept for up to three years, but drakes should be changed every second year as after that they do not mate regularly and fertility decreases.

Laying

Under village conditions, ducks will start to lay eggs at 8 1/2 - 9 months of age. The first eggs will be small and should not be used for hatching. Small eggs are likely to be sterile (they will not produce a duckling) and even if they hatch, the duckling will be small and weak and will probably die within the first week. An egg is big enough for hatching when it weighs more than 72 g or if its diameter is more than 45 mm. The easiest way to check if an egg is suitable for breeding is to make a hole of exactly 45 mm in a piece of plywood or timber. If the egg passes through the hole, it is too small and must be eaten or sold. If it does not pass through the hole, it must be kept for breeding. The poultry Research Centre at Labu has a few of these measuring holes.

A duck will lay between 10 and 20 eggs. After that it will become broody and sit. If the ducklings are taken away from the mother after hatching, it will start to lay again after two to four months, depending on feeding. There is no laying seasons for ducks in Papua New Guinea. They lay all through the year. If it happens that, in a project, ducks are not laying after 12 months, there is something wrong. Most probably, the ducks are underfed and protein deficient. They will never lay eggs and all the ducks should be eaten or sold and the project terminated. However, it happens that healthy ducks (fully feathered, weighing more than 1.3 kg) do not lay, for some, yet unknown, reason. If this happens, shift the project to a new site, in a different type of vegetation. If there is no improvement within the next six months, terminate the project. In many projects, it happens that a duck does not lay. It should be eaten or sold as soon as it is noticed. A non-laying duck can be recognised by the following signs: (1) it is heavier than the other birds,
(2) the flesh around the eyes is very red, like a drake instead of being pink or orange,
(3) the space between the two pelvic bones (pointing on both sides of the vent) is about one finger wide instead of 2 or 3.

Nests

Nests should be provided for the ducks to lay their eggs. There should be at least as many nests as there are mothers. Otherwise, they will disturb each other for favorite nests or try to sit two to a nest which is a bad thing. Two mothers in a nest will hatch less ducklings than one alone as more eggs will roll out and more ducklings will be trampled under their feet.

The nests should be about 30 x 30 x 40 cm (12 x 12 x 16") and be covered. This should prevent two mothers sitting together and drakes attempting to mate a sitting mother. Put a strip of timber, about 5 cm (2") wide in front of the nest, to prevent eggs from rolling out and to provide bedding such as sawdust, coffee skin, etc. Keep the nest clean at all times.

Role of the drake
It is widely believed on Papua New Guinea that a male is necessary for a female bird (chicken, duck, turkey, etc.) to lay eggs. This is not true. A female bird will lay as long as it has enough good feed and it is not sick. If a male (rooster, drake, tom turkey, etc.) is present, the birds will mate and the eggs wil be fertile and hatch. If there is no mate, the egg will be sterile, will rot, and will never hatch even if the mother sits. If a duck does not lay, do not blame the drake and try to replace it, but improve feeding or look for disease.

Handling of eggs
Another false belief is that if eggs are handled by people, they will not hatch anymore. Fresh eggs can be picked up and stored in a house for up to seven days. They will still be hatched if given to a duck to sit on. Eggs that are warm because a mother is sitting on them can also be handled but they must be quickly put back under the mother, before they cool off. A warm egg which cools off for a long time will become bad and rot. However, if eggs roll out of the nest during the night, it usually pays to put them back in the nest as most of them will still hatch. This is true at least for the coastal areas.

Hatching
Muscovy ducks have to sit for five weeks (35-37 days) before the ducklings will hatch. It will take between 12 and 24 hours between the first crack on the shell and the times when the duckling is fully out. As a rule, do not try to help the duckling to hatch. The only exceptions are if the duckling's head is already free but the rest of the body is "glued" to the egg shell or if the shell is cracked all around and the duckling does not have the strength to make the complete break through.

Do not enlarge a small crack. Normally, all the eggs should hatch within two days (as the ducklings start to develop inside the eggs only when the mother starts to sit non-stop). If after these two days there are still some eggs left, they should be checked. If the egg looks blue or has blue spots or streaks, or if when it is shaken it sounds like water is inside, it is bad and must be thrown away.

If the egg looks shiny and white, and if it stays warm even if the mother walks away for a while, it is a good one. It will be best to give it to another sitting mother. If there are none, the old mother can keep sitting, but not more than two weeks otherwise it will lose too much weight and might die. When there are no more eggs in the nest, clean it and put some fresh bedding material in it.

Care of the ducklings
It is best to raise the ducklings away from the rest of the flock as quite often drakes or other ducks will pick at and kill day old ducklings as they come out of the nest. Take the ducklings away from the mother as soon as they are completely dry and fluffy and raise them in the way described earlier. One can either use a part of the old duck house or build a completely new one to raise these new batches of ducklings. Experience has shown that the best results are obtained if commercial feed is used for the first six weeks. Otherwise, mortality will be very high. At the end of the sixth week, the ducklings can go out on their own and join the rest of the flock.

Do not keep more than 40 ducklings at any time. Otherwise, it is most likely that garden produces will be in short supply and the ducks will not grow well. If more than 40 ducklings hatch at about the same time, it would be best to sell some to other interested farmers. Eat or sell the ducks as they reach 4 months unless some are needed to replace older ducks or drakes. When this new stock is mature and starts to breed, eat or sell the older ones. Do not let your breeding stock increase to more than 10 duck and 3 drakes as bigger numbers will not fit with subsistence farming.

Fruit crops

Tropical fruit tree crops are extremely variable in almost all relevant characteristics, including method of propagation, growth habit, use of the fruit, nutritional value, and adaptation. While seldom used as staple foods, their nutritional contribution (frequently vitamin C and sometimes vitamin A), is of great importance. Most fruits contain carbohydrates, frequently in the form of sugars, and often as starch. Relatively easy crops to produce wherever they are adapted, fruit crops are a welcome and useful addition to any small farm.

ECHO has budwood available from some superior varieties of some of these fruit trees. Budwood must be grafted to an appropriate rootstock within a very short time. If it is properly treated, some budwood will last for almost 1 week. If you are interested in obtaining budwood for grafting to trees overseas and you are presently in the U.S. and plan to pass through Florida, ECHO can supply you with scions (budwood) if you drop in just before flying overseas. Budwood may not be available at all seasons. Another option would be for us to send it via overnight express to you. You would need to cover the express charges. (ECHO also has a good video on grafting and also has available rootstock for visitors to practice grafting techniques). Fruit trees for which we only have seed are labeled "S"; those available for budwood cuttings are labeled "BW". Some of the seeds have short viability, and therefore are not kept in the seedbank, but we can put you on a waiting list and send seeds for these in season. We also sell grafted trees, but do not ship these. Some of the best trees in ECHO's collection are the following:

See A Comparison of Selected Tropical Fruit Crops

· Atemoya.Annona squamosa x A. cherimola. (S) Thrives in lowland tropics; seeds will usually become another atemoya but occasionally grows into one of the parents-grafting very common; germination time averages at about 4 weeks; delicious fruit.

· Barbados Cherry.Malpighia glabra. Propagated by cuttings, not by seed. High in vitamin C.

· Black Sapote. Diospyros digyna. (S).

· Carambola. Averrhoa carambola. (S, BW). Available Aug-June.

· Cherimoya. Annona cherimola. (S). This creamy Andean fruit requires close management (hand pollination and careful harvesting). Requires >1500 m elevation at equator and >1200 mm rain during growing season.

· Jaboticaba. Myciaria cauliflora. Available late fall/spring. (EDN 32-2, 34-2).

· Loquat. Eriobotyra japonica. (S, BW). Seeds viable for 8 days, available Feb-Mar.

· Papaya. Carica papaya (S). Sunrise, Waimanalo, Malaysia exotica. New Cariflora var. (EDN 15-4, 26-3, 32-1, 41-3).

· Passionfruit. Passiflora edulis. (S). Purple. Yellow produces a large oblong fruit with great juice yield; hand-pollinate to collect pure seed. (EDN 29-3).

· Soursop (Guanabana). Annona muricata.

· Surinam Cherry. Eugenia uniflora.. High in vitamin A.

· Jujube. Ziziphus sp. Burmese 'Salay Zee Thee'. Prolific bearer; thorny; cold, drought and flood tolerant.

Fruit vegetables

Crops in the category of fruit vegetables are a group of species almost entirely from two families, Cucurbitaceae and Solanaceae, which have little in common except that they are fruits. Most are of modest nutritional value, but all contain useful dietary fiber. Few are highly valuable as fruit vegetables, including the tropical pumpkin, the pepper, and the tomato. Others could be exploited for their seeds, which are especially rich in proteins and oils. However, others contain poisonous seeds (e.g., Luffa). Some produce edible leaves or shoot tips. Some species, especially tomato and pepper, are used as condiments and may contribute useful amounts of nutrients to the diet in this form. Some may have one or many improved varieties, which should be compared to local varieties for best results.

See A Comparison of Fruit Vegetables

· Achuffa (Pepino de Comer).Cyclanthera edulis. Fruits like hollow cucumber, may also be stuffed before cooking or pickling. Temporarily out of stock.

· Bottle gourd.Lagenaria siceraria. (Calabash or Birdhouse gourd). Edible only when very small. (EDN 8-3). Gourds used as containers/vessels; very prolific in subtropics. Buffalo gourd. Cucurbita foetidissima. Roots used for firewood; seed rich in oil and protein; requires long periods of warm dry weather; edible oil made from crushed seeds; native Americans used fruit, pulp, and vines as soap.

· Cucuzzi (Italian squash).Lagenaria sp. Does well in very hot weather; fruits harvested when 18" long; can be used as a container when dried.

· Eggplant.Solanum melongena. Selected varieties of purple, white and striped available. (EDN 14-4).

· Loofah (sponge gourd). Luffa acutangula. Preferred as a vegetable; ridged fruit eaten when young. Luffa cylindrica. Smooth fruit, edible when young. Both species are vigorous climbing vines. Seeds toxic.

· Okra. Hibiscus esculenta. African type; likes the hot weather, but will produce in winter, unlike most okras.

· Pepper, Ensalada. Capsicum chinense. Perennial; produces small fruits that are usually not hot but have the taste and smell of hot peppers. Leaves can be cooked like spinach. Also available is Capsicum frutescens.

· Pumpkin. Cucurbita moschata. Tropical or Calabaza varieties: La Primera, Brian, CBDE, Trinidad, and Tropical mix. Seminole varieties: Acorn, Ingram Billie, Hardy, and Seminole mix. Vigorous, productive vines. (EDN 8-3, 18-2, 37-3).

· Snake gourd. Trichosanthes cucumerina. Young fruits eaten cooked; climbing vine.

· Tamarillo or Tree tomato.Cyphomandra betacea. Red Andean fruits used raw, in juice or jams. Requires high altitudes. Low-germination seeds available only.

· Tomato. Lycopersicon esculentum. Varieties with high vitamin A: Alcobaca-Beta (in breeding, its hybrids have high betas and extended shelf life), Floradade-Beta, Kewalo-Beta. Disease-resistant varieties offered individually or as a variety trial: Hayslip, Florida MH1, Tropic, Walter, Floradade. Others (can bear in summer): Open-pollinated-Matlinka, Saladette; Hybrids-Solar Set, Heatwave: not very disease-resistant but are able to set fruit at higher temperatures. Seed cannot be saved, as they are hybrids. (EDN 24-1, 32-1, 36-4).

· Wax gourd or Chinese wintermelon. Benincasa hispida. Best cucurbit for seed oil in hot humid tropics; flesh eaten as a summer squash; the fruit can be stored for many months. (EDN 2-5, 8-3).

Grain crops

Grain crops are those that produce an edible dry seed which can be stored for a long period of time. The seeds of grain crops are normally milled to produce a flour, but sometimes they are softened by cooking and/or chemical treatment. The majority have high protein content accompanied by a good content of B vitamins. Some have fair to high oil content and/or Vitamin E. In addition, most have good quantities of carbohydrates, usually as starch. As a group, the grains are used chiefly in the production of breads. Grain crops are literally the staff of life for billions of people. The three most important food crops in the world are wheat, rice, and corn. Somewhat similar grasses include pasta wheat, barley, sorghum, pearl millet, rye, and triticale (a potentially important hybrid between wheat and rye).Teff is a major grain crop in Ethiopia. Buckwheat is an important grain crop from China, but it is not a grass. Amaranth, kaniwa, and quinoa, used extensively in the past by American Indians, are highly nutritious non-grass grains (called pseudo-cereals). Varietal differences are important ingrains. Individual cultivars often have particular seasonal and climatic adaptations. As a rule, crops are planted during a wet season and must mature during dry weather.

See A Comparison of Grain Crops.

· Amaranth.Amaranthus cruentus: Mexican R104 (Rodale). Manna: good producer. Amaranthus hypochondriacus: low growth habit, easy to harvest mechanically (Rodale). HH4/HH5-large yellow heads, excellent yields (USDA). (EDN 3-1, 4-1, 16-5, 23-6).

· Buckwheat. Fagopyrum esculentum. Cool, humid climates. Harvest two months after planting. Short season high altitude nurse crop used to shade ground; green manure; seed high in lysine; used in honey production ;wide soil tolerance; not for hot areas; needs good soil moisture throughout growing season; frost-intolerant. (EDN 10-3, 38-2).

· Corn. Zea mays. Blue-100 day, large full ears, dark blue kernels, drought tolerant and disease resistant; Posole-100 day, large plump ears, drought tolerant flour corn. Papago-80 day, small slender cream-colored ears, drought tolerant flour corn. Rio Grande Red-110 day, 7 ft stalks, 1-2 ears of dark red kernals, this is a drought tolerant flour corn. Larger quantities available from Plants of the Southwest. [Sweet corn: see Miscellaneous Vegetables.] (EDN 16-1, 20-3,4,5, 21-3, 23-6, 28-2).

· Kaniwa. Chenopodium pallidicaule. High protein (16-19%), with well-balanced amino acids; does well on poor, rocky soils at high elevations; also survives frost; temporarily out of stock but would appreciate any sources or information on this plant.

· Millet. Echinochloa turnerana. (Channel Millet)-temporarily out of stock.

· Eleusine coracana (Dragon's Claw or Finger Millet). Less susceptible to bird damage than other millets listed below, low protein, long storage life, sea level to 2500 meters, cool moist climate; tillers.

· Pennisetum americanum (Candlestick Millet). Similar to Pearl millet.

· Pennisetum glaucum (Pearl Millet). Grain not as susceptible to Striga as other species, but very bird susceptible. Plant residue used for livestock feed, house building, fencing, and fuel. Harvesting may be irregular.

· Setaria italica (Foxtail Millet). Cooked whole, or made into meal, plant is used for hay or silage. Highly drought tolerant. Sea level to 200 m.

· Panicum sp. (Proso or Hog's Millet) Used as human and animal food, much the same as rice, or in flour. Short season, high in amino acids and carbohydrates. Wide soil variety, not frost tolerant, low water requirement, but not as drought resistant as other grains, due to shallow roots.

· Oats, Naked. Avena nuda. An oat that has no hull.

· Quinoa. Chenopodium quinoa. High protein; seeds eaten like rice; grows well at high elevations on poorly drained lands, in cold areas and in drought. Day-neutral and equatorial varieties available (EDN 4-4, 11-3, 46-1,2,3). 'Ingapirca' has very low saponins requiring only light washing; best for very high altitudes, 3000-3600 m on equator; wind, frost and drought tolerant; 400-800 mm rain/yr; not tolerant of humidity. 'Tunkahuan' also has low saponins requiring only light rinsing; 2200-3400 m on equator; 600- 1200 mm rain/year, humidity-tolerant. 'Appelawa', 'Kaslala' are our Bolivian types, and 'Colorado 407' is a Chilean type.

· Sorghum. Sorghum bicolor. Giza 114-stalks also burned as fuel (Egypt). Bird-resistant-dwarf variety low in tannins; do not roast (EDN 46-5)(EDN 25-1, 32-6). Sweet Sorghum and Striga-resistant varieties available.

· Teff. Eragrostis tef. Red and White types. Ethiopian staple in bread. Small seeds, self-pollinated, 3' tall, matures in 4 months.

Ground covers and green manures

This group includes any rapidly growing crop that covers and protects the soil and that can be left as a mulch or plowed under to enrich the soil. Legumes are emphasized because of their ability to fix nitrogen and the large amount of foliage (and thus organic matter) produced. As a group, these crops are adapted principally to the hot, somewhat moist, tropics, but some are adapted to all tropical climates. They can all be established by seed, but some root at the nodes and can be established from cuttings. ECHO does not provide inoculants; see Agroforester, Liphatec, and BNF in listing at back for sources.

· Butterfly pea. Clitoria ternatea. Very drought tolerant, but does not compete well with weeds.

· Cowpea. Vigna unguiculata, V. vexillata. See Pulses.

· Hairy Indigo. Indigofera hirsuta. Summer cover crop in Florida; reseeding annual; nematode-suppressant; prefers well drained and droughty sites; for hay and grazing.

· Jack bean. Canavalia ensiformis. Drought tolerant; see under Leguminous Vegetables. (EDN 12-1, 20-2).

· Kudzu, tropical. Pueraria phaseoloides. Not the weedy temperate kudzu (EDN 12-6, 42-5).

· Lablab bean. Dolichos lablab . White, Rongai, and Highworth are excellent field varieties. Choose one or a variety trial; see under Leguminous Vegetables. (EDN 12-1).

· "Lee" or American Joint Vetch. Aeschynomene americana. Green manure and forage good for low areas or drainage ditches, >1000 mm rain.

· Sword bean. Canavalia gladiata. Drought tolerant; see under Leguminous Vegetables.

· Sunnhemp. Crotalaria juncea is becoming popular in East Africa. Crotalaria ochroleuca is an upright, non-vining legume; good for intercropping. Not poisonous to livestock, unlike most Crotalarias (EDN 26-5). C. ochroleuca may have poisonous seeds, forage before it goes to seed.

· Tephrosia. Tephrosia vogeli