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Food Resources Sustainable Agriculture

Crop Rotation

The growing of different kinds of crops on a piece of land in a preplanned succession is known as crop rotation. In the rotation of crops, leguminous crops like pulses, beans, peas, groundnut and Bengal gram are sown in-between the seasons of cereal crops like wheat, maize and pearl millet. The leguminous plants are grown alternately with non-leguminous plants to restore the fertility of the soil. When the cereal crops like rice, wheat, maize are grown in the soil, it uses up a lot of nitrogenous salts from the soil. If another crop of cereal is grown in the same soil, the soil becomes nitrogen deficient. So by rotation a leguminous crop is grown. There plants have the ability to fix atmospheric nitrogen to form nitrogen compounds through the help of certain bacteria present in their root. These nitrogen compounds go into the soil and make it more fertile. After the leguminous plants utilize some of the nitrogen compounds, the rest of it is left in the soil to enrich it. Thus, planting a leguminous plant will result in nitrogen rich soil and when a cereal is grown in this soil there is increase in food grain production.

Advantages of crop rotation

Rotation of crops improves the fertility of the soil and hence, brings about an increase in the production of food grains.

Rotation of crops helps in saving on nitrogenous fertilizers, because leguminous plants grown during the rotation of crops can fix atmospheric nitrogen in the soil with the help of nitrogen fixing bacteria.

Rotation of crops help in weed control and pest control. This is because weeds and pests are very choosy about the host crop plant, which they attack. When the crop is changed the cycle is broken. Hence, pesticide cost is reduced.

Crop rotation adds diversity to an operation.

Selection of crops for rotation

Selection of crops for rotation depends on soil condition, moisture condition, length of rainy season, type of inputs available (irrigation, fertiliser, pesticide, labour and machine power), risk involved, duration of crop (annual, biennial or perennial) and marketing and processing facilities. In rainfed areas, where moisture is limited and the soil is light, millets are preferred. On the other hand if soil is heavy, sorghum is grown. If soil is compact the crops selected are castor and pigeonpea. Either crop is grown in kharif season and field is kept vacant during rabi season. Alternately fields are kept vacant for moisture conservation and rabi crop of mustard, chickpea, linseed, safflower, barley and wheat are grown on conserved moisture.

Selection of crops for rotation

Areas with assured soil moisture throughout the year have the potential for higher yield. In these areas, under ideal conditions two to four crops can be produced. Rice, wheat, sugarcane, potato and berseem are some of the major components of crop rotation. Vegetables and flowers are grown in areas close to the cities for higher income.

To decide which crops to select for the purpose of crop rotation, so that the farmer gets maximum benefit, assessment of crop rotations is necessary.

Assessment of crop rotaion

Ideally, the evaluation of a crop is done on the basis of total production and the amount of input used, but when different crops are grown in the same field the assessment becomes difficult. Different methods of crop assessment are adopted.

Cropping Index