Yield gaps in composite carp culture in eastern India

Abstract

To find out why average yields obtained by farmers are well below those obtained in research stations, carp cultivation practices of 142 farmers, chosen on the basis of multistage random sampling, were examined. The sample was drawn from South 24 Parganas district in the state of West Bengal in India. The respondents on average obtained 3.67 t/ha annually, but the range was 1.89?5.50 t/ha. The average annual yield at research stations was 8 t/ha, whereas that from the demonstration ponds maintained by the Fish Farmers Development Agency was 3.0 t/ha. The difference of 5 t/h, or 62.5%, constituted yield gap 1. The difference between the average yields obtained by farmers and those from the demonstration ponds was referred to as yield gap 2, which amounted to ? 0.67 t/ha, the value being negative because the average yield obtained by the farmers was 22% higher than that recorded from the demonstration plots. These differences were due to the amounts of inputs, the extent to which the farmers adopted the recommended practices, and other socio-economic factors. The study thus showed that the gap is due to the shortcomings of the technology itself and not due to any deficiency in adopting that technology and therefore can be bridged only by developing superior technology of fish production.