The land that we need for growing food is very important. We can't afford to spoil it. There are many ways in which farmers could make better use of the land and grow good crops without the help of factory-made chemicals.
If it is farmed with care, the land will go on giving us enough food to eat for thousands of years to come.
One method of careful farming is called crop rotation.
Different kinds of plants take different nutrients from the soil and leave others behind. The same crop planted year after year takes out the same nutrients.
One year, corn is planted. This will take out certain nutrients from the soil. The following year, alfalfa will be planted. The alfalfa will put back the nutrients absorbed by the corn.