Growth and Economics of Silver Barb (Barbonymus gonionotus) in Rice-fish-vegetable Integrated Culture System at Different Stocking Densities in a Rainfed Arid Zone
Sustainable integrated farming involving the combination of rice-fish-vegetables requires advanced technology to be adopted in crop production in arid zones characterized by red or yellow soil. In the present study, we used suitable and varying stocking densities of Silver barb (Barbonemus gonionotus) and evaluated in a structured production and economic framework under four treatments (T1, T2, T3, and T4) assigned with a stocking density of 10, 20, 30 and 40 fish/decimal, respectively. We used standard methods of water, soil, and plankton monitoring of the rice field. The study showed that lower stocking density provided the fish with more spaces and less competition for food resulting in higher growth performance in T1 compared to other treatments. Although stocking density did not show any significant (P>0.05) effect in rice, straw and vegetable production in all the treatments, the highest rice and straw production at T4 could be ascribed to the improvement in soil fertility by the accumulation of fish excreta and subsequent release of nutrients from the soil by the higher number of fish in that treatment. The best fitted polynomial regression line obtained between gross yield and net yield with different stocking densities of Silver barb described an inevitable fluctuation in net yield of fish with increasing stocking density. Despite the stable growth performance of fish in T1, a combined effect of lower total input cost, higher yield of fish and rice, and economical vegetable production, T2 showed a significantly (P<0.05) higher total return. Furthermore, the benefit-cost ratio (BCR) for rice-fish-vegetables integrated culture system in the rain-fed rice field was also high. In conclusion, this study revealed that maintaining a stocking density of 20 fish/decimal was economically profitable for rice-fish-vegetables integrated culture systems in arid zones on a global scale.