Abstract
Phosphorus deficiency is a limiting factor for sustainable crop production in Barind Tract. Farmers commonly use P fertilizer and usually not lime or any manure. Therefore, a study was undertaken on phosphorus management in Grey Terrace soils of High Barind Tract for the two dominant cropping patterns wheat-T. Aman rice and chickpea-T. Aman rice during 2007-08 and 2008-09, with a major objective to reduce the rate of fertilizer P application by inclusion of manure or lime treatment. Experiments were designed with 16 treatments having different combinations of P fertilizer, manure (cowdung, poultry manure and pressmud) and lime (dololime). The rates of P application were 0, 16, 24 and 32 kg ha1 from TSP, that for cowdung, poultry manure, pressmud and lime were 5 t ha1, 3 t ha', 5 t ha1 and 2 t ha', respectively. Nitrogen, K, S, Zn and B were used at a recommended rate for all crops. Effects of various treatments were evaluated on the first crop (wheat or chickpea) and their residual effect on the second crop (T. Aman rice). Evaluation was made in terms of yield, yield components, nutrient uptake, economic analysis, and changes in soil properties. The treatments had significant influence on the grain yield of wheat (cv. Shatabdi) and chickpea (cv. BARI Chola 5). The highest grain yield of wheat was obtained from the treatment containing 24 kg P ha1 as TSP + 2 t lime ha1 as dololime which was statistically similar to the yield obtained with the treatment having same amount of TSP-P + 3 t ha1 poultry manure. For chickpea, the lime and poultry manure treatments along with application of 16 kg ha1 TSP-P produced the highest seed yield. The P control treatment always recorded the lowest grain/seed yields. The treatments had positive residual effect on T. Aman rice (cv. BRRI dhan 39). The grain yield of all crops showed positive correlation with the yield contributing characters. The various treatments had significant influence on the N, P, K, S and Zn uptake by the crops. Integrated use of poultry manure or lime with P fertilizer resulted in a higher P availability in soil. The treatments comprising poultry manure or lime or cowdung and 24 kg TSP-P ha1 for wheat and 16 kg TSP-P ha for chickpea were found the most economically viable treatments for the two cropping patterns. It is possible to reduce the rate of P application by 25-33% through manure (preferably poultry manure) or lime application to soil. Apparent nutrient balance analysis indicates a nutrient mining for N and K and nutrient accumulation for P, S and Zn for each cropping pattern under the present nutrient management system. On overall consideration, application of 24 kg ha1 TSP-P for wheat and 16 kg ha1 TSP-P for chickpea plus 3 t ha1 poultry manure or 2 t ha1 dololime along with the recommended rates of N, K, S, Zn and B is important in the sustenance of soil fertility and crop yield for the wheat-rice and chickpea-rice cropping patterns in High Barind Tract.