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1980 - 198911990 - 19951
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Subject: Agronomy × Author: KAU × Author: Viswambharan, K × End date: 2009 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Agronomic evaluation of chemical and bio-agents on phosphorus dynamics in red loam soils of southern Kerala
    (Department of Agronomy, College of Agriculture, Vellayani, 1995) Viswambharan, K; KAU; Sasidhar, V K
    Three field experiments were conducted at the Instructional Farm, College of Agriculture, Vellayani during 1992-'93 for two season to study the effect of chemical and bio-agents on phosphorus dynamics in the red loam soils of Southern Kerala. In the experiment No.1 four treatments such as no anions, hydroxide, carbonate and silicate were tested under three levels of phosphorus such as no phosphorus, 50% phosphorus and 100% phosphorus. From the study, it was revealed that carbonates have more desorbing power for phosphorus than the other anions tested. These were reflected in the yield and yield attributes, available phosphorus content of the soil, soil phosphorus fractions, nitrogen and phosphorus uptake of plants. Among the combinations, carbonate anion with 50% phosphorus gave the highest yield. In the experiment No.2, three treatments such as no chelates, EDTA and DTPA were tested with three levels of phosphorus such as no phosphorus, 50 % phosphorus and 100% phosphorus. From the study it has been revealed that EDTA gave better response than other chelates tested. These were reflected in the yield, yield attributes, available phosphorus content of the soil, soil phosphorus fraction, nitrogen and phosphorus uptake of plants. Among the combinations EDTA with 50% phosphorus gave the highest yield. In the experiment No.3, four levels of microbial agents such as no microbes, VAM, PB and VAM + PB were tested with three levels of phosphorus such as no phosphorus. 50% phosphorus and 100% phosphorus. From the study it has been revealed that VAM + PB gave the highest response. This was reflected in the yield attributes, available phosphorus content of the soil, soil phosphorus fractions, nitrogen and phosphorus uptake of plants. Among the combinations VAM+PB with 50% phosphorus gave the highest yield.
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    ThesisItemOpen Access
    Effect of agro - techniques on soil loss ,surface run and soil moisture storage in hill slopes
    (Department of Agronomy, College of Horticulture, Vellanikkara, 1980) Viswambharan, K; KAU; Sasidhar, V K
    A field experiment was conducted at the Instructional Farm, Vellanikkara during September 1979 to May 1980 to study the effect of various Agro-Techniques on soil loss, surface runoff and soil moisture storage in hill slopes. The experiment was conducted with the main objective of studying the effect of groundnut intercropping as well as the different methods of planting of tapioca on reducing soil and water losses in hill slopes. The experiment was laid out in a Randomised Block Design with five treatments and four replications. The treatments consisted of (1) tapioca alone in mounds, (2) tapioca in mounds with groundnut as intercrop, (3) tapioca alone in ridges across the slope, (4) tapioca in ridges across the slope with groundnut as intercrop and (5) uncultivated bare fallow as a control. The experiment was conducted in field runoff plots of 24.3M x 2.7M size. The runoff from the field were collected directly into water proof polyethylene lined earthen tanks and measured after each rainfall. Only rainfalls more than 12.5 cm were taken for the purpose of the study. From the experiment it is observed that AIm index was better correlated with runoff as compared to other erosion indices. Similarly EI15 index was better correlated with soil loss. Maximum runoff and soil loss occurred in uncultivated bare fallow. Among the various cultivation methods, tapioca in mounds registered maximum soil and water losses. Groundnut intercropping as well as tapioca planting in ridges across the slope were effective in reducing soil and water losses. Uncultivated bare fallow runoff plots recorded the maximum losses of N,P and K being 107.47kg, 28.476kg, and 82.479kg/ha respectively. Among the Agro-Techniques, tapioca in mounds recorded the maximum loss of N,P and K being 44.01kg, 14.845kg and 39.08 kg/ha respectively during the entire season. However, the nutrient losses from other plots were meagre. Maximum retention of rainfall was recorded by tapioca in ridges across the slope with groundnut as intercrop. The pH and conductivity of runoff water were not significantly influenced by different treatments. During the dry periods maximum storage and minimum depletion of sub soil moisture were recorded by uncultivated bare fallow plot. The growth and yield of tapioca were not significantly affected by the groundnet intercrop. Maximum yield of tapioca was recorded by the treatment of planting tapioca in ridges across the slope without intercrop. The yield of the intercropped groundnet was not affected by various cultivation methods of tapioca.