Relative status and contribution of sediment phosphorus and nitrogen in carp culture system fertilized with various combinations of rockphosphate

Abstract

Growth performances of advanced fry of Indian major carps. Labeo rohita (Hamilton). Catla catla (Hamilton) and Cirrhinus mrigala (Hamilton), were examined in simulated pond systems using monthly application of the following fertilizers in six treatments: Mussoorie rockphosphate (MPR) in low (100 kg P2O5 ha−1) and high doses (200 kg P2O5 ha−1), single superphosphate (SSP) (50 kg P2O5 ha−1), single superphosphate mixed with rockphosphate (1:1 by weight: 50 kg P2O5), compost (C) (water hyacinth and cattle manure) and composted rockphosphate (MPR-C). The amount of available P in surface sediment of MPR-C did not differ from that in either the SSP or the MPR + SSP treatment, whereas the total and available N contents differed greatly. There was an inverse relationship between the time to reach phosphate peak of water and the retention time of fertilizer in surface sediments. It is evident that total P of surface sediment was the most significant contributor to fish growth in exclusively MPR treatments, whereas total P and total N of surface sediments are involved in the MPR treatments in combination with compost or SSP.