CHANGES OF PHYSICAL AND CHEMICAL PROPERTIES OF POST HARVEST SOIL OF T. AMAN RICE AS INFLUENCED BY ORGANIC AND INORGANIC PHOSPHORUS

Abstract

Due to low organic mailer content the agricultural soils of Bangladesh has poor physical and chemical condition. Moreover, the continuous use of phosphorus (P) fertilizers build-up of excessive P in many cultivated soils has created an interest in the combined use of organic and inorganic P fertilizer. Hence, a field experiment was conducted at the Bangabandhu Sheikh Mujibur Rahman Agricultural University Farm, Gazipur, Bangladesh during the Aman season of July 2008 to January 2009 to investigate the effects of combined application of inorganic phosphorus (Pi) and organic phosphorus (1),,)on the changes of physical and chemical properties of soil after T. Aman cultivation. The eight treatments were To, Control/ no fertilizers; T" recommended dose offertilizers; Tz, 50% P through TSP and 50% P through cowdung; T), 75% P through TSP and 25% P through cowdung; T" 50% P through TSP and 50% P through poultry manure; Ts, 75% P through TSP and 25% P through poultry manure; To, 50% P through TSP and 50% P through household wastes; T1, 75% P through TSP and 25% P through household wastes. The experiment was laid out in randomized complete block design (RCBD) and replicated thrice. The physical and chemical properties of the soils were influenced directly by the above mentioned treatments. The physical properties of soil such as particle density and bulk density at different soil depth and plough pan decreased in response to addition of organic matters whereas no significant changes were found in response to inorganic P. The rate of improvement of chemical properties such as organic carbon (OC), cation exchange capacity (CEC), total nitrogen, available Phosphorus (P), exchangeable potassium (K), available sulphur(S), exchangeable calcium (Ca), exchangeable magnesium (Mg) and exchangeable sodium (Na) was higher with inorganic plus organic amendment than to inorganic alone. In addition, soil pH decreased in all treatments. Based on the above results it is suggested that the combined use of inorganic and organic P significantly improve physical and chemical properties of post harvest T. Aman soil.