Question

Why do farmers cultivate plants of pea family

Answer 1

The pea plant is part of the group of plants referred to as leguminous plants. The importance of planting wheat plant and other cereals with legumes such as pea, is that the legumes are able to fix nitrogen into the soil.
Wheat plant and other starchy plants deplete the nitrogen sources in the plant unlike the legumes that do the opposite. Nitrogen is important to plants as it is useful in making plant protein.
The legumes do this by the action of symbiotic bacteria in their root such as the actinobacteria. These bacteria convert nitrogen from the atmosphere into nitrates and nitrites and enriching the soil with nitrogen.