INTEGRATED MANAGEMENT OF FERTILIZERS AND GREEN MANURES IN TRANSPLANT AMAN RICE

Abstract

Consecutive three years (2014, 2015 and 2016, each July to December) field experiments on transplant aman rice cv. BR11 under different levels of chemical fertilizers and green manures (Dhaincha (Sesbania aculeata) and Mimosa invisa) were conducted at Sher-e-Bangla Agricultural University, Dhaka. Crop growth dynamics, yield attributes and yields, soil fertility status, grain and straw quality were evaluated against the response of aman rice to the treatment variables. The treatments comprised two factors e.g. factor A: level of fertilizers (0, 50, 75 and 100% of recommended dose of fertilizer (RFD)) and factor B: levels of green manures management (0, 5 and 10 t ha -1 , incorporated 1 and 15 days before transplanting) and USG were tested. The experiments were carried out following split plot design with three replications. Recommended dose of fertilizer N = 83 kg ha xl

-1 , P = 20.96 kg ha -1 , K = 36.52 kg ha , S = 11 kg ha -1 , Zn = 1.5 kg ha -1 were applied in the form of Urea, Triple Super Phosphate (TSP), Muriate of Potash (MoP), gypsum and Zinc sulfate, respectively. Sixty-day dhaincha and Mimosa invisa were in - vitro incorporated before aman transplantation. Results of three consecutive years revealed that combination treatment 75% RFD along with Mimosa invisa @ 10 t ha -1 proved to be best respectively in producing maximum plant height (119.2, 110.3, 109.4 cm), effective tillers m -2 (468.3, 478.3, 451.0), LAI (8.72, 9.25, 8.34; at 75 DAT), LAD (60.83, 47.53, 25.50), AGDM (2221.0, 1893.0, 1873.0 g m -2 ), filled grains panicle -1 (251.5, 262.2, 228.8), translocation percentage (70.88, 70.79, 70.49%), grain yield (7.25, 8.57,5.59 t ha -1 ) and harvest index (46.55, 49.45, 41.72%) respectively in comparing to the other treatment combinations. On the other hand, three year, average minimum grain yield (4.55 t ha -1 ) was obtained without green manuring treatments and that was about 57% lower than the maximum (7.14 t ha -1 ) obtained from 75% RFD with 10 t ha -1 Mimosa invisa. On an average, quality of grain was increased markedly in respect of amylose (8.99%), CHO (1.65%), protein (9.46%), phosphorus (7.72%) and potassium (3.55%); and also that of straw nitrogen (44.58%), phosphorus (20.12%), potassium (4.72%) and sulfur (17.65%) due to 75% RFD with 10 t ha -1 Mimosa invisa. Furthermore the treatment developed soil nutrient status in respect of OM (79.66%), N (71.43%), S (43.77%), and Zn (42.69%) over soils without incorporations of green manures. Finally irrespective of years differences, economic analyses showed treatment 75% RFD with 10 t ha -1 Mimosa invisa had greater BCR (1.77) over farmer practice (1.29) when they used only 100% RFD. It may be concluded that incorporation of Mimosa invisa @ 10 t ha -1 in the soil 15 days before transplanting along with 75% RFD can be considered as a good agricultural practice for improvement of grain yield, grain and straw quality of transplant aman rice and soil nutrient status when 25% reduction in chemical fertilizer is a great realization.