Browsing by Author "Sivakumar, C"

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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, C
Field 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.
Effect of modified urea forms on the performance of wet-seeded rice in acid laterite soils
(Kerala Agricultural University, 1996) Bridgit, T K; Jose mathew; Sivakumar, C
Field studies were conducted at the Regional Agricultural Research Station. Pattambi for three dry seasons during 1991 to 1993 tu evaluate the efficiency of modified urea forms in wet-seeded rice under puddled condition. The results indicated the remarkable response of wet-seeded rice to new urea forms over prilled urea in respect of growth, yield attributes and yield and N use efficiency. Split application on nimin coated urea (NCU) and inussorie rock phosphate coated urea (MRPU) recorded significant yield improvement over prilled urea (PU) and large granule urea (LGU) applied either fully as basal or in split doses.
Effect of nitrogen management practices on ammonia volatilization losses in transplanted rice
(Kerala Agricultural University, 1994) Anila Kumar, K; Menon, P K G; Sivakumar, C
Field experiments were conducted in kharif and rabi seasonsto study the volatilization losses under different nitrogen management practices in transplanted rice. The treatments receiving application of urea 111 three splits and the combined applica tion of urea and green leaves in 1:1 proportion on N basis recorded the lowest N loss through volatilization in both seasons. Seventy five per cent of ammonia volatilization was recorded within 6 days after fertilization. The loss was more during rabi season and the losses significantly increased with increase in pi I, I ICC>3~ and Nl Lj-N content of flood water.
Growth and nutrition of black pepper as influenced by decaying litter materials in soil
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1992) Sivakumar, C; Wahid, P A
An investigation on the growth and nutrition of black pepper (Piper nigrum L.) as influenced by decaying litter materials in soil was conducted at the College of Horticulture, Vellanikkara. The black pepper variety Panniyur – 1 was invariably used for the study. Biomass production in black pepper was significantly increased following the incorporation of organic materials into the soil compared to the control vines. When the different levels of organic sources were compared, total biomass production of the vine decreased at highest level (3 per cent) of application of coffee and black pepper leaves. This was attributed to allelopathic effect of the decaying material. There was a steady increase in biomass production with increasing level of garuga leaf application. Significant increase were noticed in the N ,P and K concentrations of leaf and stem, Mg concentration of leaf, S concentration of leaf and stem, Fe content of stem and foliar Mn content of the vine following the organic matter treatments as compared to control vines. The vine removed significantly higher quantities of N, p, K, Ca, Mg, S, Fe and Mn following the soil application of leaf materials as compared to the control vines. The average nutrient removal by a six – month – old black pepper vine to produce 11.19 g of shoot dry matter was 200.19 mg N, 18.92 mg P, 432.53 mg K, 155.89 mg Ca, 19.44 mg Mg, 12.33 mg S, 1517 µg Fe and 3546 µg Mn. The contribution of leaf to the total nutrient removal was more compared to that of stem. Significant increases in major and micronutrient availability in soil were noticed following the incorporation of leaf materials. On an average, the rate of organic carbon loss in laboratory incubation was the slowest in soil with coffee or silver oak leaves as the organic source and was fastest when the garuga was the organic source. The half – life values for organic carbon was the organic source. The half – life values for organic carbon loss varied from 91 – 193 days. The half – life values obtained for coffee, erythrina and black pepper leaves in field decomposition study were 40, 44 and 53 days respectively.
Leaching loss of nitrogen in waterlogged rice fertilized with different forms of urea
(Kerala Agricultural University, 1995) Anilakumar, K; Rajaram, K P; Sivakumar, C