Why do farmers plant leguminous crops in crop rotations/mixed cropping?

Explanation

(i) Legumes have bacteria on nodules which are on the roots of the plants. The bacteria on the nodules takes nitrogen from the air and fixes it into the soil, so that other plants that riquire nitrogen can use it as well.
(ii) Rotation of crops improves the fertility of the soil and hence brings about an increase in the production of food grains.
(iii) Rotation of crops helps in saving on nitrogenous fertilizers, becuase leguminous plants grown during the rotation of crops can fix atmospheric nitrogen in the soil with the help of nitrogen fixing bacteria.
(iv) Crop rotation adds diversity to an operation.