Write a note on the various methods used to replenish the nutrients in the fields.

Explanation

When crops are grown in the fields, they use all the nutrients present in the soil. These nutrients have to be replenished for the further cropping. Various methods and products are used for this purpose, which are as follows:
(i) Fertilisers: Fertilisers are chemicals which replenish the soil with the nutrients. They are produced in the factories and are inorganic products. Every fertiliser is rich in a particular nutrient. Some examples of fertilisers are urea, ammonium sulphate, potash. They help in getting better and healthy yields. But, excessive use of these chemicals is also harmful.
(ii) Manure: Manures are the organic products, which are obtained from dead plants and animal wastes. Dead plants and animal wastes are dumped in pits. They get decomposed with the help of microorganisms to become manure. Using manure not only improves the texture of the soil but also improves the water holding capacity of the soil.
(iii) Fallowing: Sometimes continuous growing of crops makes the soil barren or infertile. It needs to be left uncultivated so that it can regain its nutrients and fertility. This process of leaving soil uncultivated for one or more crop season is called fallowing
(iv) Crop rotation: If the same crop is grown in the field year after year, it will lead to the deficiency of certain minerals. It is due to the fact that same crops require only particular nutrients. To solve this problem farmers grow one pulse crop between the two cereal crops in the field. It is called crop rotation. The roots of the legumes have nodules which contain nitrogen fixing bacteria. These convert free atmospheric nitrogen into nitrates and increase the fertility of the soil.
(v) Mixed cropping : Sometimes two or more crops are grown simultaneously together in the same field. The crops are chosen in such a way that the nutrient needs of one crop are fulfilled by the other. Any leguminous crop, such as peas, soybeans or green beans and a cereal crop, like wheat or rice, are grown together in the same field. Cotton and groundnut crops are also often grown together.