30. A market gardener who does not have much money for buying fertilizers can still improve the fertility of the soil by a good crop rotation.
If the rotation is not good, the fertilizers are wasted.
31. If your vegetable garden is large enough, divide it into two parts, and every year grow vegetables only on one part, leaving the other part fallow or sowing it with cover crops.
Like that, each part of your vegetable garden produces one year and rests the next year, so that the soil is enriched.
32. Even on the beds where you do grow vegetables, you can still make a good rotation.
Rotation means to grow different vegetables one after another on the same bed.
Making better use of all parts of the soil
For example, plants with tap- roots, like carrots, take their nourishment deep down in the soil.
Plants with fibrous roots, like lettuces, take their nourishment near the surface.
By rotating your crops, you make the plants use all parts of the soil.
Making better use of mineral salts
For example, lettuces use a lot of nitrogen; tomatoes and onions use a lot of potash.
By rotating your crops, you make the plants use all the mineral salts in the soil.
Controlling insects and diseases
For example, when you grow onions, the insects and diseases which attack onions will develop. If you again grow onions after an onion crop, these insects and diseases remain on the field and develop further. But if you grow lettuce after an onion crop, the insects and diseases which attack onions do no harm to lettuce; they will just disappear.
33. Vegetables are plants that grow fast. They need a soil with plenty of mineral salts. Mineral salts are added to the soil by organic manures and chemical fertilizers.
34. Organic manures
These provide humus which improves the soil structure.
- Animal manure
This is the best organic manure. It has to be well mixed with the soil.
This can always be made by the market gardener himself. It is used instead of animal manure.
35. Chemical fertilizers
These are the commercial fertilizers you can buy.
Simple fertilizers add to the soil only one mineral salt. Nitrogenous fertilizers add only nitrogen. Phosphatic fertilizers add only phosphorus. Potassic fertilizers add only potassium.
There are also mixed or compound fertilizers, which add to the soil a mixture of mineral salts (nitrogen, phosphorus, potassium).
Different vegetables need different quantities of each fertilizer.
36. Dig three pits.
- Into pit 1 put herbage, leaves, small twigs, crop residues and food remnants. Pour on water fairly often to encourage rotting. Leave the contents of the pit to rot for about 1 month.
- After a month, move the contents of pit 1 into pit 2. What was at the top of pit 1 now goes to the bottom of pit 2. When pit 1 is empty, begin to fill it again as before.
- After another month, move the contents of pit 2 to pit 3. Fill up pit 2 with the contents of pit 1.
- At the end of the third month, put the compost from pit 3 on the fields. Continue, as before, to fill and empty the pits.
It takes about three months to make good compost
37. Nitrogen (N)
Nitrogen makes plants grow, especially the leaves. Apply nitrogen when you cultivate or transplant. In this way the fertilizer will be well used.
The chief nitrogen fertilizers are:
- ammonium sulfate,
- ammonium nitrate.
Plants need phosphorus to help them make their flowers and fruit.
Phosphorus is used mainly for vegetables of which the fruits are eaten, like beans and tomatoes, and those of which the roots are eaten, like carrots.
Phosphate fertilizers are best applied shortly before sowing or transplanting.
The chief phosphate fertilizers are:
- ordinary phosphates,
Potassium helps plants to resist drought and diseases, and to build up reserves.
It is used mainly for carrots, onions and tomatoes. Apply potassium fertilizers shortly before sowing or transplanting, at the same time as phosphates.
The chief potassium fertilizers are:
- potassium chloride,
- potassium sulfate.