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Item Effect of organic sources on nitrogen availability in flooded rice soils(Kerala Agricultural University, 1989) Anilakumar, K; Johnkutty, I; Hassan, M A; Menon, P K GA study was conducted during the rabi season of 1982 to study the changes of N in the lateritic rice soil as well as in the rice plant as influenced by flooding in the presence of various organic and inorganic sources of nitrogen. The results revealed that daincha treated plots were able to liberate more nitrogen in the soil as well as in the solution than farm yard manure or azolla treated or urea alone treated plots. In general the NH4-N content in the soil showed a progressive decrease from tillering to harvest (11.13 - 1.99 ppm). The chemical kinetics of NOj-N, hydrolysable-N, non-hydrolysable N, organic carbon and total N were not influenced by the various treatments. Urea applied alone or in combination with daincha was found better for increased N uptake by the rice plant.Item Kinetics of silicon in relation to different levels of major nutrients in the lateritic flooded rice soils(Kerala Agricultural University, 1990) Anilakumar, K; Johnkutty, I; Hassan, M A; Menon, P K GItem Effect of NPK fertilizers on the availability of micronutrients in submerged laterite rice soils of Kerala(Kerala Agricultural University, 1992) Anilakumar, K; Hassan, M A; Johnkutty, I; Menon, P K GItem Mineralisation pattern of applied urea in rice soils(Kerala Agricultural University, 1993) Anilakumar, K; Rajaram, K P; Johnkutty, I; Jose MathewA laboratory incubation study was conducted to find out the pattern of transformation and mineralisation of applied urea under submerged condition in the three major rice soils of Kerala. The hydrolysis of urea to ammonium was influenced by the soil reaction and organic matter content. The formation of oxidised N products like nitrate and nitrite was meagre due to lack of adequate oxygen to carry out the process of nitrification. This avoided the chances of N loss through denitrificalion in the waterlogged rice soils.Item Long term effect of continuous fertilization by organic and inorganic sources on rice productivity(Kerala Agricultural University, 1993) Anilakumar, K; Johnkutty, I; Kamalam JosephPooled analysis of grain yield data for25 years (1961 to 1985) generated from a permanent manurial experiment with tall indica rice varieties revealed that during the first crop season (kharif), the treatment receiving combined application of cattle manure and NPK was significantly superior to others. The above treatment was on par with combined application of cattle manure, green leaves and NPK during the second crop season (rabi). The increases in yield by the former treatment over NPK alone were 7.6 and 5.6 per cent respectively during kharif and rabi seasons.Item Effect of forms of urea on the yield of rice(Kerala Agricultural University, 1993) Johnkutty, I; Mathew, P B; Kumar, V RField trials conducted in the farmers' fields at eight different farming situations for four seasons proved that large granule urea (LGU) is an economic and efficient source of N for low land rice, especially in areas with heavy rnonsoonic rains . LGU having no extra cost either in production or application over the ordinary prilled urea (PU) offers greater potential for efficient N nutrition in rice. The results also reveal that the entire quantity of LGU can be broadcast as a single basal dose.Item Changes in nutrient availability and uptake in transplanted rice under shallow and deep submergence(Kerala Agricultural University, 1994) Anilakumar, K; Johnkutty, I; Menon, P K G; Sivakumar, CField experiments were conducted to study the changes in electro-chemical properties and nutrient availability in soil and soil solution in transplanted rice during kharif and rabi season under deep (20 cm) and shallow (10 cm) submergence, respectively. The pH of soil and soil solution increased up to 30 days after transplanting (DAT), then decreased and again increased slightly at 50% flowering stage. Redox potential of soil decreased rapidly during kharif season while during rabi season, the values increased up to 30 DAT and thereafter stable values were recorded. Concentration of nutrients in soil and soil solution decreased with crop growth except in the case of soil P during kharif season and soil solution Ca during both the seasons. Availabilit y of nutrients in soil and soil solution except for P and Mg was more during kharif season, while the nutrient uptake was higher during rabi season. Application of P and K during rabi season was effective in areas where P and K were applied once in two seasons. Significant difference in yield was obtained only during rabi season.Item Influence of biostimulants on rice productivity(Kerala Agricultural University, 1995) Johnkutty, I; Palaniappan, S PItem Time course leaf n concentration in rice under different nitrogen application strategies and development of simulation models(Kerala Agricultural University, 1999) Johnkutty, I; Kandasamy, O SAn experiment was conducted at the Tamil Nadu Agricultural University. Coimbalore dunn£ the kharif and rahi seasons of l'J'M-"96. lu study the time CIHIISC leaf N cmicetnraiion in lowland ria under diilercntN timings. Application of I 50 kg N ha"1 m six staggered sPllts/rom planting to heading or m tnree splits Irom early tillering Ul heading suslamed the leal'N eoncenlration at increased levels for higher grain yields. Early N application and limitation of N supply at later stages decreased the plant N con contrail on during grain filling stages and reduced the grain yield. Continued application ol Fertilizer N until heading stage favoured maintenance of N concentration in leaves during ilic posl-anlnests period, resulting in high grain yields. Based on the natural behaviour of time course leat'N concentration, simulation models «cre evolved based on the prediction ability and test of significanceItem Relationship among leaf nitrogen content, SPAD and LCC values in rice(Kerala Agricultural University, 2000) Johnkutty, I; Gracy Mathew; Thiyagarajan, T M; Balasubramanian, V