Nutrients budget and effluents characteristics in polyculture of scampi (Macrobrachium rosenbergii) and Indian major carps ponds using organic inputs

Abstract

Experiments were conducted for the study of nutrient budget in farmers' ponds (0.4–0.6 ha) in Orissa, India, at stocking densities of 0.30–0.38/m2 for scampi (Macrobrachium rosenbergii) and 0.60–0.70/m2 for Indian major carps (Catla catla, Labeo rohita and Cirrhinus mrigala). The average initial body weights of scampi and the major carps were 0.02 and 8–10 g, respectively. The culture period was 272–292 days. Feed was the main input. The FCR (feed conversion ratio) varied from 1.78 to 1.83. Feed and cow dung were applied to these ponds as organic inputs. At harvest time, the average weight of scampi and carps varied from 73 to 92 g and from 718 to 820 g, respectively. Among all the inputs, feed alone accounted for 97.60% total nitrogen (N), 97.90% total phosphorus (P) and 94.72% total organic carbon (OC), respectively. The harvest of scampi and carps accounted for recovery of 52.45% N, 19.43% P and 18.12% OC, respectively. N, P and OC accumulated in sediment were 38.31, 71.40 and 69.50%, respectively. The median nutrient loads in the fish pond effluents were equivalent to 0.58 kg of inorganic N, 0.135 kg of P and 8.83 kg of total OC per ton of Indian major carps and scampi production.