PG Thesis
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Item Decomposition of leaf litter by oriculture(Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara, 2015) Nithya Jose; Sushama, P KItem Nutrient content and decomposition of leaf litter of Acacia mangium Willd as affected by season and field conditions(Department of Silviculture and Agroforestry, College of Forestry, Vellanikkara, 1995) Ramakrishna Hegde; Gopikumar, KA detailed experiment was conducted at the College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur, during the period from 1993 to 1995 to study the nutrient content and pattern of leaf litter decomposition of Acacia mangium Wild. During south west monsoon and north east monsoon seasons. The experiment was conducted both in home garden and open area. The rate of decomposition was faster in all the study situations. The initial nitrogen, lignin, C:N ratio and lignin : nitrogen ratio of leaf litter were found to exert profound influence on the rate of decomposition. The decomposition rate was found to be a function of time, soil moisture and soil temperature. The nutrient release pattern in almost all cases followed a characteristic biphasic model with an initial rapid phase followed by a slower latter phase. Among the different nutrients, potassium showed a faster rate of mineralisation in most of the situations while calcium and nitrogen mineralised slowly. Among the several mathematical models tried to predict the absolute amount of nutrients in the residual mass, the second order hyperbolic function was found to be good fit in most of the cases. Though the PH was not altered significantly by the decomposing litter mass, the content of most of the nutrient elements is found to be drastically influenced.Item 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 AAn 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.