Effect of municipal solid waste compost on phosphorous content of rice straw and grain under submerged condition

Abstract

The effect of municipal solid waste compost (MSWC) on the phosphorous content of submerged rice was studied. Experiments were conducted during the three consecutive wet seasons from 1997 – 1999 on rice grown under submergence, at the Experimental Farm of Calcutta University, West Bengal, India. A sequential extraction method was used to determine the various phosphorous fractions in MSWC and cow dung manure (CDM), traditional manure for comparison. Phosphorous (P) was significantly bound to the organic matter and Fe and Al oxides in MSWC and CDM. P content in rice grain was higher than straw. P bound with organic matter in MSWC best correlated with straw P (r = + 0.99**) and grain P (r = + 0.99**) contents. The P bound with Fe, Al and Ca in MSWC was highly correlated with P content of grain (r = + 0.99**, + 0.93* and + 0.97** respectively) and straw (r = + 0.98**, + 0.95** and + 0.99** respectively). The saloid bound P (readily available P) of MSWC was also correlated significantly with straw (r = + 0.94*) and grain P ( + 0.91*). The P content of rice grain ( + 0.99**) and straw ( + 0.99**) was best correlated Fe-P followed by Al bound P in CDM. Single application of MSWC or CDM resulted in lower P content of rice grain and straw but the increase was spectacular when MSWC and CDM was applied in conjunction with fertilizer. The increase in P availability to the plants by the application of MSWC might be due to blocking of absorption sites and/or releasing soluble P with time.