Soil organic carbon and nutrient uptake vis-a-vis growth and yield of pearl millet (Pennisetum glaucum) as influenced by water and nitrogen in Typic Haplustept soil

Field experiments were conducted during 2003-04 to monitor the soil organic carbon and the nutrient uptake by pearl millet (Pennisetum glaucum L.) under different combinations of irrigation water and nitrogenous fertilizer treatments. In both the years, days of maturity increased with increase in nitrogen doses in irrigated plots. Application of nitrogen induced higher leaf area index, but the difference in 80 and 120 kg N/ha levels were found to be significant. The increase in biomass accumulation was faster in irrigated plots than the rainfed and it increased with N treatment. The 1000-grain weight increased significantly with successive N levels, but the increment was pronounced only up to 40 kg N/ha in rainfed and up to 120 kg N/ha in irrigated treatment. Grain yield varied significantly with nitrogen application rates as compared to those plots that received no N. Mean yield in irrigated plots was also significantly higher than the unirrigatd plots. Nitrogen content in pearl millet grain was more in irrigated plots and also increased with N doses but no such relations could be established with irrigation as well as nitrogen doses for P and K, while N, P and K content in straw did not show any statistical relationship with either irrigation or fertilizer treatments. During both the rainy (kharif) seasons 2003 and 2004, the soil organic carbon increased at harvest in comparison to that at sowing of the crop, in surface (0-15 cm) and subsurface (15-30 cm) layers; whereas no change or reduction in soil organic carbon content was found in the deeper (30-45 and 45-60 cm) layers. The increments were more in irrigated plots (I(1)), as compared to rainfed plots (I(0)), possibly due to more use efficiency of the fertilizers.