1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Soil temperature and moisture characteristics as influenced by inter-cropping of fodder crops in coconut garden(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1993) Asok, P I; Pushkala, SAn investigation was undertaken to study the effect of fodder grasses grown as inter crop in coconut garden on the soil characteristics. The observations were carried out from the already laid out experimental plot in the farm area of college of Agriculture. The layout was in randomised block design with six treatments and four replications. The treatments included guinea grass, congo, signal grass, setaria grass, molassess grass, hybrid napier and contrest. Soil samples were collected from two depths namely 15 cm and 30 cm from the surface. The samples were collected during March-April, July-August and December-January. The soil analysis was done for moisture, porosity, bulkdensity, particle density and water holding capacity. The infiltration rate and hydraulic conductivity were carried out at the close of the experiment. Chemical analysis was done for nitrogen, phosphorous, potassium, calcium and magnesium. The effect of growing fodder crops on soil moisture content was not significant. The thick canopy of guinea and congosignal grass could retain moisture in the field. The water holding capacity in the control plot was less than the fodder plot. So the competition for water would be minimum for coconut and fodder crops. The soil moisture was negatively correlated with soil temperature. Setaria and molasses grass could conserve moisture on the surface while other grasses could retain moisture on the subsurface layer. Fodder grass roots improved the structure of the soil. Bulk density values were reduced. The changes on particle density and porosity values were negligible. The hydraulic conductivity value observed for setaria grass was highest and the lowest value was recorded by guinea grass. Infiltration rate showed no significant difference among treatments. Soil temperature values were brought down by fodder grass cultivation during daytime, insulated the soil when it was cooled. There was no significant effect on the chemical properties of the soil namely, soil reaction , available nitrogen, available potassium, exchangeable calcium and exchangeable magnesium. Soil phosphorous level shown by the setaria grass was high, which was positively correlated with the soil temperature. Inter-cultivation with fodder grass in coconut garden, is not deteriorating the physical properties, but it can improve the hydraulic characteristics and thermal properties thereby leading to an increase in the coconut yield.Item Classification of the upland soils of Kerala(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1993) Bindu Kumari, A; Subramonia iyer, MSoil taxonomy is one of the well accepted popular system of soil classification through which soil information can be communicated globaly. Inorder to have the soil Taxonomy information of the uplands of Agricultural Rsearch Station and Centres under Kerala Agricultural University and CWRDM, Calicut one representative profiles were examined described analysed for physical chemical and mineralogical properties and with the available site and climatic parameters and from the results of the present study the soil were classified as per Soil taxonomy (1975). All the soils are gravelly, clay loam to clayey texture with kaolinitic to mixed mineralogy with expanding 2:1 minerals at Pampadumpara, Ambalavayal and Kannara. At Calicut the clay fraction is more than non clay fraction. Irrespective of the profiles, the profiles are with ustic moisture regime and isohyperthermic temperature regime. The temperature regime at Pampadumpara and Ambalavayal is hyperthermic. Based on the degree of weathering revealed by silt/clay ratio the profiles can be arranged with a decreasing degree of weathering Calicut > Kottarakara > Balaramapuram > Vellayani > Pampadumpara > Ambalavayal > Thiruvalla > Pillcode > Vellayani II > Tavanur > Odakkali > Vellanikkara > Kannara Based on the available information and results of the present study, keys the profile in to the following taxa as per soil Taxonomy (1975). 1. Balaramapuram Fine loamy kaolinitic isohyperthermic family of kandic Haplustalf. 2. Vellayani Fine loamy kaolinitic isohyperthermic family of Typic Kandiustults. 3. Thiruvalla Fine loamy mixed isohyperthermic 4. Odakkali family of Tropustults. 5. Kottarakara Clayey skeletal kaolinitic 6. Vellanikkara isohyperthermic family of Typic 7. Pilicode Kandiustults 8. Pampadumpara Fine loamy mixed isohyperthermic family Haplustalf. 9. Kannara Fine loamy mixed isohyperthermic 10. Ambalavayal family of Haplustalf. 11. Calicut Clayey skeletal kaolinitic isohyperthermic family of kandiudlts 12. Tavanur Fine clayey kaolinitic isohyperthermic family of petroferric Dystropepts. The family charactors reveal that thesee soils are with less availables water capacity, low cation exchange capacity. Soil temperature is not a problem in these soils. The typic subgroup indicates lesser problems of water logging. The argillic and kandic endopedon indicates low nutrient holding capacity and presence of low active clays (LAC) warranting special soil management measures for increase crop production like split application of fertilizers. Ustic moisture regime is indicative of prevalent water stress in these profiles sites. The order Ultisol , Alfisol and even inceptisol is indicative of highly weathered soil of varied horizon development and less fertility because of lower percentage bases saturation (PBS) The present study gives a “soil basis” for the global communication and appreciation of the valuable research results of these research institutions. The research results, the crop performance from all these research institution are to be gathered and critically analysed with the “soil basis” as a future line of work.Item Phosphorus dynamics in an ultisol(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2005) Smitha, M S; Sureshkumar, PA pot culture experiment was carried out at Radiotracer laboratory of College of Horticulture, Vellanikkara, using laterite soil (Ultisol), from the main campus of Kerala Agricultural University with the objectives to trace the fate of fertilizer P and to study the dynamics of P by the addition of amendments. The experiment included 13 treatments of three levels of P and four amendments and an absolute control. Amendments were added to the respective treatments and kept for wetting and drying cycles for two weeks 32P labelled KH2PO4 (32P @ 0.4mCig-1 P) was added as per the treatments. Seeds of cowpea @ 3 seeds pot -1 were sown. Application of Phosphorus at different levels significantly contributed to available P status different P fractions i.e. non occluded Al-P and Fe-P, P sorbed by carbonate, occluded P and Ca-P in a linear fashion at all the stages of crop growth i.e. just before sowing, flowering and harvesting. The amendments also contributed to the above pools. Among the amendments Pongamia leaves was found to have better influence in contributing to the above pools except for Ca-P, where lime was found to have a better influence. This was supported by the data on plant P content, where the increasing levels of P and amendments improved the plant P content at 15 DAS, flowering and at harvest. Further Ca-P fraction was dominantly contributing to the available P suggesting that applied P might get transformed to non occluded Al-P and Fe-P, occluded P as well as P sorbed by carbonate, which might be slowly transformed to Ca-P fraction probably Ca (H2PO4)2, the soluble form which is contributing to available P. It was observed that, non occluded Al-P and Fe-P was contributing to plant P as time proceeded due to solubilisation of this fraction. Application of P at increasing level and amendment significantly increased the dry weight of pods and haulm. Radioactive 32P labelled with the applied phosphorus could be traced out in the available pools and fractions of P only at just before sowing, flowering. Percentage of P derived from applied P were the highest for higher level of P and amendment sodium silicate.