Paddy Cum Fish Culture
Coastal saline soil extends from the main sea coast to a few or even 50 km at places interior to the main land. The ground water table under these soils is generally present at a shallow depth and contains high amount of soluble salts. These salts accumulate on the surface of the soil due to capillary rise of saline groundwater during dry periods of the year rendering the soil highly saline. Almost the entire area of the rain fed coastal saline soil is mono cropped in nature. The major agricultural crop of kharif is rice, grown during monsoon period when soil salinity is low. During the rest of the year, the land usually remains fallow due to high salt content of the soil.
In West Bengal, where the salinity is either low or lowered by fresh water discharge diluting the tidal water, the cultivation of fish is undertaken in paddy fields. In pokkali fields of Kerala, summer fallow months are utilized for brackish water aquaculture. The production of fish in such culture varies from 300 to 1000 kg/ha. The brackish water shrimp culture is introduced in a big way in such areas as the remuneration is very high. The species commonly cultured are Penaeus monodon, Penaeus indicus, Metapenaeus dobsonii and Metapenaeus monoceros.
In India, though six million hectares are under rice cultivation, only 0.03 per cent of this is now used for rice-fish culture. … The culture of fish in paddy fields, which remain flooded even after paddy harvest, serves an off-season occupation and additional income to the farmer.
Fish Culture In ‘Pokkali’ Fields
In Kerala, fish and prawn are cultured on rotational basis in Pokkali rice fields. These fields under the influence of Vembanad backwaters, which are in, turn controlled by tides. As these fields are flooded during southwest monsoon (June-Septemeber) rice is cultivated. Fish and prawns are cultured during other periods. Immediately after the harvest of rice, the fields are leased out for the culture of fish and prawns. The young of fish and prawns enter the fields from nearshore waters along with high tides. Suitable management cultures these young until harvest in May. These fields are rich in plankton owing to the decaying of paddy stumps. A prawn yield of 500-1,200 kg/ha has been obtained from Pokkali fields. After the prawn harvest, the water is drained off. Subsequently, the saline nature of rice fields is nullified because of the monsoon rains and the fields are again made fit for rice culture.