Response of cotton to split application of nitrogen, phosphorus and potassium

摘要

Field experiment was carried out during Summer 1999 at Cotton Research Station, Srivilliputtur to evaluate the response of summer irrigated cotton to split application of major nutrients. The experimental field was sandy clay loam with a pH of 8.2.The soil was medium in available nitrogen and phosphorus and high in available potassium. The treatments included application of recommended dose of fertilizers (RD) - 1/2 N + full P and K as basal + 1/2 N at 45 days after sowing (DAS) T_1, RD full P andK basal + N in 2splits 45 and 60 DAS (T_2), RD full P as basal + N and K in two splits 45 and 60 DAS (T_3), RD no basal + N, P and K in 2 splits 45 and 60 DAS (T_4), T_3 + extra P and K each 20 kg/ha~(-1) in 1 split 45 DAS (T5) and T_3 + extra P and K each 20 kg ha~(-1) in 2 splits 45 and 60. DAS (T_6). The experiment was raised in randomized complete block design with four replications. The test variety was SVPR 2. Recommended package of practices were adopted except nutrient management. Biometric observations, yield attributing characters and seed cotton yield were recorded at harvest. Significant increase in the plant height and the number of monopodia/plant was observed with the recommended level of fertilizers applied as 1/2 nitrogen + full phosphorus and potassium as basal and 1/2 N at 45 days after sowing (T_1) indicating the role of nitrogen applied as basal in promoting the early growth (Table 1). Application of entire phosphorus as basal and nitrogen and potassium in two equal splits at 45an 60 days after sowing recorded more number (16.33/plant) of sympodia and was comparable with the application of all the major nutrients in two splits on 45 and 60 days after sowing by skipping basal application. The highest number of bolls/ plant (18.5) was registered by applying all the major nutrients as top dressing on 45 and 60 days after sowing and was comparable with the application of entire phosphorus as basal and N and K as top dressing on 45 and 60 days after sowing (T_3).