Phosphate and phosphatase distribution in sediment depths of rockphosphate treated carp culture system

Abstract

Distribution pattern of phosphates (A1-P, Ca-P, Fe-P), available-P, citrate soluble-P and phosphatases (acid and alkaline) was examined in three sediment layers (0–2.5 cm, 2.6–5.0 cm, 5.1–7.5 cm) of carp (Cirrhinus mrigala) culture system fertilized with varying levels (43.66 kg and 87.32 kg P) and frequencies (7, 15 and 30 days) of rock phosphate. Whereas layer differences of phosphate and phosphatases were significant in any of the treatments employed, significant treatment differences were restricted to first and second layer, but not in third layer implying that uppermost layer was the most active site of treatment action. Large variations in fish yield among six treatments were directly related with P-content of surface sediments, and hence P-level of overlying water. The variations of alkaline phosphatases in the first layer of sediment in each treatment was strongly influenced by Al-P (99.78%), available-P (0.16%) and Fe-P(0.05%), whereas the variations in second layer was mainly affected by Al-P (99.02%). None of these factors were related to the small variations of alkaline phosphatase in third layer of sediment.