Question

A farmer ,after planting rice 1 season, planted groundnuts in the next season. Why?

Answer 1

Crop rotation. When a plant grows, it constantly sucks few nutritions (depends on plant) from soil. After harvesting that crop, those nutrients may not be available in soil. To bring it back, crops are rotated periodically.

Then why groundnut in particular?

Did you ever observed this nodules in groundnut root?

Thanks to rhizobia, a bacteria. First it infects groundnut root and help to convert atmospheric Nitrogen (N2) to N. Plants cannot use Nitrogen available in air directly. It must converted to use. Rhizobia helps to do natural conversation of Nitrogen. So it not only makes plant to get nitrogen but also Nitrogen traces are left in soil even after harvesting crop.

Answer 2

To manage the nutrition level of the soil