EFFECTS OF FERTILIZER, MANURE AND WATER MANAGEMENT ON THE NUTRIENT AVAILABILITY, LEACHING, SOIL FERTILITY AND PRODUCTIVITY UNDER RICE- RICE CROPPING PATTERN

Abstract

Three experiments were conducted at the net house and research field of Sher-e-Bangla Agricultural University during January 2013 to June 2014 to study the effects of fertilizer, manure and irrigation on the nutrient availability, leaching, soil fertility and productivity under rice-rice cropping pattern. A net house experiment with 30 (2 levels of irrigation x 5 fertilizer treatments x 3 replications) undisturbed soil columns (40 cm length and 30 cm diameter) was set up at a net-house of SAU, with rice growing in boro and T. aman seasons during January 2013-December 2013. Soil cores were placed on the plastic containers and leachate collection systems were developed. BRRI dhan29 and BRRI dhan33 were grown on the cores with two levels of irrigation (I 1 : continuous flooding I 2 : saturated condition) and fertilizer treatments (T 0 : Control T 1 : RDCF, T 2 : 50% NPKS + 5tha -1 cowdung, T 3 : 50% NPKS + 5 tha -1 compost, T 4 : 50% NPKS+ 3.5 tha -1 poultry manure. The leachate samples were analyzed for nutrient during the growing seasons. The leachate nutrient concentration varied with irrigation, fertilizer and time of sample collection. Higher levels of leachate N, K and S concentrations were found in the T 4 treatment. Phosphorus leaching decreased with increasing days from transplantation but N and S leaching were in similar trend during the rice growing period. Application of organic plus inorganic fertilizer increased the level of organic matter, P and K availability of post experiment soils. Application of poultry manure increased more the soil pH, available P and level of organic matter in post-experiment soils. The continuous flooded irrigation in combination with different fertilizer treatments increased the level of K in post-harvest soil. A field experiment involving 2 levels of irrigation and 8 fertilizer treatments (2x8x3= 48 plots) were applied in the boro rice field soil and without rice planted soil (PVC pipe installed fallow area) during January 2014-June 2014. The experiment was laid out in split plot design with irrigation (I 1 : traditional irrigation i.e. continuous flooding and I 2 : saturated condition) to the main plots and fertilizers to the sub plots. The fertilizer treatments were T 0 =Control, T 1 =N 120 P 25 K 60 S 20 Zn 2 (RDCF), T 2 =50% NPKS + 5 tha -1 cowdung, T 3 =70% NPKS + 3 tha -1 cowdung, T 4 =50% NPKS + 5 tha

compost, T 5 =70% NPKS + 3 tha -1 compost, T 6 =50% NPKS + 3.5 tha -1 poultry manure, T 7

=70% NPKS + 2.1 ton poultry manure ha -1 . Boro- T. aman rice experiments were conducted previously in the same plots with the application of same treatments from 2012. The effect of residual and renewal application of fertilizer and manure influenced the pore-water nutrient availability, yield and the fertility of post experiment soils. The higher grain yields were obtained in inorganic plus organic treatments. The highest grain yield was obtained from I 2 T 7 , I 2 T 5 and I 1 T 5 treatment combinations. The higher concentrations of N, P and K were found in the pore-water of T 6 and T 7 treatments where higher yields were also obtained. Porewater

P concentrations decreased with increasing days after transplantation. At flowering stage, the highest pore-water P was found in I 1 T 4 treatment combination. Higher concentrations of pore-water K were found into the core (fallow area) than rice root zone area (outside) during the cropping season. Higher N, P and K concentrations were found in the post-harvest soils (root zone area and fallow area) where manures were applied. The higher levels of organic matter were found in the post-harvest soils of T 2 treatment of rice root zone area (1.60%) and the soils of fallow area (1.59%). The application of poultry manure increased the pH of the soil. Another field experiment was conducted at SAU Farm with rice growing in boro and T. aman seasons during July 2013 to June 2014. The three levels of irrigation (I 1 : continuous flooding, I 2 : saturated condition and I 3 : Alternate wetting and drying) and eight fertilizer treatments (similar to expt. 2) were applied in this experiment. The highest T. aman rice yield was found from I 2 T 2 and the highest grain yield of boro rice (7.94 t/ha) was recorded with the treatment combination I 1 T 7 . The pH of 6.9 was obtained in the soil where inorganic fertilizer and poultry manure were applied.