Nutrient management for basmati rice (oryza sativa L) in wetlands

Abstract

A field experiment was conducted at the Instructional Farm, College of Agriculture, Vellayani from September 2001 to January 2002 to derive an optimum package for nutrient management for basmati rice in wetland condition. The experiment was laid out in factorial RBD with three replications. The treatments consisted of three levels of N (60, 90 and 120 kg N ha"), two sources of N (SI: SO per cent N as FYM and SO per cent N as chemical fertilizer and S2 : SO per cent N as vermicompost and SO per cent N as chemical fertilizer), two NPK ratios (2 : 1 : 1 and 2 : 1 : I.S) and an absolute control thereby forming 13 treatment combinations. Results of the experiment revealed that the effect of both N levels and NPK ratios had significant influence on most of the biometric and yield attributing characters and yield of basmati rice. Nitrogen @ 120 kg ha-I and NPK ratio of 2 : 1 : I.S were found significantly superior to lower levels. Eventhough the effect of sources of N was significant on plant height and dry matter production, the effect was not visible on the yield attributing characters and yield of the crop. A significant linear increase in grain yield was recorded upto 90 kg N ha-I , and thereafter the increase in grain yield was marginal. But the straw yield increased linearly with increase in N level and was also significantly influenced by the sources of nitrogen. NPK ratio of 2 : 1 : I.S recorded higher grain and straw yield. Nitrogen @ 120 kg ha-I and NPK ratio of 2 : I : I.S produced the highest grain protein content. The cooking time of grains increased with increase in N level. Nitrogen @ 120 kg ha-I and NPK ratio of 2 : I : I.S recorded the highest uptake of nutrients. Use of vermicompost for substituting 50 per

1'9 cent N resulted in the highest uptake of Nand P while the effect on K uptake was not significant. An increase in N application resulted in an increase in available N and P status of the soil after the experiment. Nitrogen @ 120 kg ha ", use of vermicompost for substituting 50 per cent Nand NPK ratio of 2 : 1 : 1.5 registered significantly superior available K status in the soil. The maximum NUE in terms of agronomic efficiency and apparent recovery was observed at 90 kg N ha-! and thereafter it decreased with the increase in N level. Application ofNPK in 2 :. 1 : 1.5 ratio also resulted in higher NUE. Sources of N were significant only with respect to apparent recovery and substituting 50 per cent N with vermicompost registered superior value. The physical optimum dose of N for grain yield and agronomic efficiency were worked out to be 109.24 and 94.67 kg N ha-! respectively. Straw yield exhibited a linear response to applied nitrogen. An increase in N level increased the disease incidence while a significant reduction in disease incidence was observed with the NPK ratio of 2 : 1 : 1.5 over 2 : 1 : 1. The highest net returns and BCR were recorded when FYM was used to substitute 50 per cent of nitrogen. Increase in N levels upto 90 kg ha-! and application of NPK in' 2 : 1 : 1.5 ratio was found profitable. So a fertilizer dose of 90 : 45 : 67.5 kg NPK ha-! with 50 per cent N as FYM and 50 per cent N as chemical fertilizer can be recommended for maximizing the yield and returns of basmati rice in wetlands.