115. You have already learned that when all the gas has been made, the material that is left in your biogas unit is a very rich fertilizer.
116. It does not have a bad smell, and the parasites that were in the animal wastes and the weed seeds that were in the plant wastes are no longer harmful.
117. You can spread this new fertilizer on your fields to help your plants grow well.
Put fertilizer everywhere
118. Do not put the fertilizer all in one place. Put a little of it everywhere on your fields. In this way, all of your plants will grow better.