If vegetables of the same family are grown in the same soil every year, the pests and diseases continue to multiply and build up into greater problems. Aside from pests and diseases, growing other vegetables from other families gives a soil an opportunity to rest. This practice is called crop rotation and it helps prevent diseases, reduces pests, and improves the soil. Crop rotation is a system of planting a particular crop family in different areas of the garden each season and not in the same plot. By simply moving crop families each season, many pests and diseases are unable to follow and left without a host, they will die out and are not able to become established as problems.
Crop rotation helps improve the soil by the crop families using different nutrients.
For example, leaf crops use more Nitrogen, fruit crops use more Potassium, root crops use more phosphorous, and legumes can put Nitrogen back into the soil. Rotation can give the best use of the soil without depleting the soil of a particular nutrient. Crop rotation can also give the soil a chance to recover lost nutrients. For crop rotation, the land should be divided into five areas. A fallow is helpful to give the soil time to rest and recover.