The crops grown in the fields consume lot of nutrients from the soil. If the crops are planted continuously, season after season all the nutrients and the minerals of the soil get exhausted. This affect the yield and it also affect the quality of soil. So the nutrients once consumed by a crop must be replenished so that the soil gets all its nutrients back and it will be ready for the next harvest. This is done by rotation of crops. The alternate plantation of leguminous plants replenishes the soil with all its important nutrients . By adding manures and fertilizers to the soil also improves the quality of soil.