Loading...
Theses
Browse
3 results
Search Results
ThesisItem Open Access Land evaluation and suitability rating of the major soils of Onattukara region(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1998) Premachandran, P N; KAU; Subramonia Iyer, MThe need for a scientific approach in inventorying and utilizing land resources most economically and efficiently is now universally accepted. Agricultural prosperity, to a great extent, depends on judicious use of soils and rational application of soils data. A reconnaissance soil survey of Onattukara region was undertaken to study the extent and distribution of the different soils for soil classification, land capability and irrigability classification and for subsequent land evaluation. The study reveals that Onattukara region extends over an area of 40,948 ha. The soil map showing the distribution of the identified twenty soil series has been prepared. The climatological data reveals that the soil moisture regime is , ustic and the soil temperature regime is isohyperthermic. The soils have been classified as per Soil Taxonomy (U.S. Soil Survey Staff, 1975) and Keys to Soil Taxonomy( U.S. Soil Survey Staff, 1994 and 1996). Ten series were classified under Entisols, SIX under Inceptisols, three under Ultisols and one under Alfisols. Based on the inherent soil characteristics and landscape features, the soils have been grouped into three land capability classes, nine capability subclasses and land capability map prepared. The soils were classified into five land irrigability classes, eight land irrigability subclasses and land irrigability map prepared. The soils were evaluated based on principles of land evaluation and rating of productivity parameters. The productivity rating of the soil propertIes agamst the productivity index for nee, coconut, sesamum ,cassava and banana were made and conclusions arrived at. Productivity rating shows that Kottakakam series is best suited for rice, Palamel, best for coconut and banana, Artuva and Mahadevikad, for sesamum and Palamel and Vallikunnam, for cassava. On the basis of the studies carried out, a land use is proposed for the twenty soil series of Onattukara region based on crop suitability ratings and crop suitability map prepared for the five crops taken for study. A proper soil survey interpretation provides information on soil potential, productivity and limitations in their sustained use. Soil survey information forms the major basis for land evaluation. A thorough knowledge of the potentialities and limitations of every piece of land is a prerequisite in its efficient utilization. A systematic survey is essential for the evaluation and classification of the soils based on their inherent soil characteristics, land capability, land irrigability and land suitability. A systematic survey and evaluation of the soils of Onattukara region was taken up to study, interpret, classify and to show their location and extent on base maps. It is hoped that the present study would open up avenues for further investigations on land evaluation, crop suitability and other management aspects for sustained use of soil resource data to the best advantage. This will also form the basis for microlevel planning for integrated and sustainable development of the region under Panchayat raj.ThesisItem Open Access Characterisation of Soils Under Reed (Ochlandra Travancorica Benth.) In the Western Ghats(Department Of Soil Science And Agricultural Chemistry,College Of Horticulture,Vellanikkara, 1999) Sujatha, M P; KAU; Jose, A IA study was carried out at the Kerala Agricultural University and the Kerala Forest Research Institute during 1993-1996 mainly to characterise the reed growing soils of Western Ghats. The study comprises four parts, viz., pedological / taxonomical characterisation of reed growing soils, evaluation of fertility status of reed growing soils, assessment of growth performance of reed in relation to soil fertility and study on litter decomposition and nutrient release from reed leaf litter. The pedological / taxonomical characterisation was carried out by digging representative soil profile (with 3 replications) at two different types of topography (flat-undulating and sloping) in two different elevations (200-300 m and 600-800 m) at four locations viz. Vazhachal, Pooyamkutty, Adimali and Pamba. Reed growing soils were found to carry litter on soil surface which was. under varying stages of decomposition. The colour of the surface soils was mostly in the hue of 7.5 YR and subsurface layers were dominated by either 5 YR or 10 YR. Fine fibrous roots were found to mat the soil surface giving granular and crumb structure. The subsurface layers were generally massive without any distinct structural development. Reeds were found to flourish on both shallow and deep soils. In pure reed brakes where upper canopy was closed, the undergrowth was completely absent. The content of gravel, especially the secondary gravel, was very low in these soils. In most of the cases the textural make up turned from sandy loam to sandy clay loam from top to bottom of the profiles. Bulk density was found to increase with increase in depth of the profiles while porosity and water holding capacity to showed a diminishing trend. These soils were strongly to moderately acid in reaction and in pure reed areas surface soils were more acid than subsurface soils. But in areas where reed was growing as undergrowth in teak and moist deciduous forest, surface soils were less acidic than subsurface soils. In general, exchangeable bases, exchange acidity, cation exchange capacity and percentage base saturation were found to show a diminishing tendency from surface to bottom of the profiles. Distribution of organic carbon, total and available N, total and available P and available K was in a decreasing trend with increase in depth of the profiles while total K was found concentrated in lower layers. In general, the change in location, elevation and topography was not found to exert any definite impact on the depth wise distribution of soil properties in these soils. These soils were classified under Ustic Kandihumult, Ustic Palehumult, Ustic Haplohumult,' Ustic Kanhaplohumult, Typic Kanhaplustult, Ustic Hurnitropept, Ustoxic Hurnitropept, Ustic Dystropept, Ustoxic Dystropept, Oxic Ustropept and Lithic Dystropept at sub group level. The content of gravel, especially the secondary gravel was low in the 'Surface soils of reed growing soils. These soils were sandy loam in texture with low bulk density and moderately high water holding capacity and porosity. In general, these soils were strongly acidic in reaction with high content of organic carbon and available N and K. But the status of available P was very low. Contents of available Ca and Mg were in moderate quantities. Cation exchange capacity was also high, but the percentage base saturation was low. Significant variation with respect to various soil properties viz., gravel, silt, clay, bulk density, porosity, water holding capacity, pH, organic carbon, available N, K, Ca, Mg and percentage base saturation was observed due to change in location. Change in elevation was found to exert significant impact on bulk density, porosity, organic carbon and cation exchange capacity. In general variation in topography was not found to exert any significant and definite impact on various soil properties. Results in general reveal that reed bamboo play a significant role in conserving soil and its fertility. Number of matured culms / ha was found to be a better parameter injudging the growth performance of reed and Class I reed was found to have higher number of matured culms / ha than Class II and Class Ill. Soils of Class I reed was significantly acidic and contained higher organic carbon but lower available N and K than the class Ill. The model fitted through stepwise regression relating number of culms to different soil properties viz., soil pH, organic carbon, available N, P and K was Y = 501.0420 - 179.881920xI + 16.1516x12 + ! .9450XIX2 where Y= number of culms / ha, XI = soil pH and X2 = organic carbon. Dry weight of both culms and leaves per hectare and uptake of N, P and K were significantly high in Class I than the other two classes. The models fitted through stepwise regression relating dry weight of culms and leaves with the uptake ofN, P and K were YI=-1294.29 + 37.265N + 321.410 P + 226.442K, Y2=2.1 + 38.403 + 187.2 K where YI is the dry weight ofculms / ha and Y2 is the dry weight of leaves / ha. Reed growing soils were found to conserve comparatively higher content of soil moisture. Mass loss during decomposition of reed leaf litter was highly influenced by rainfall and the annual decomposition rate constant did not vary significantly (0.229 and 0.234) at two sites studied. The time required for 50 per cent and 95 per cent decomposition was 3 and 13 months respectively. Based on the concentration and absolute content, the nutrient mobility from decomposing reed leaf litter was in the order K > N > Mg > Ca > P.ThesisItem Open Access Status and impact of heavy metals in selected soils and crops of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1999) Usha Mathew; KAU; Alice AbrahamStatus of Cu, Zn, Ni, Pb and Cd in samples of selected soils, fertilizers, manures and crops were estimated. A critical analysis of the total content of these heavy metals in the soils studied here revealed that Cu arid Cd are existing beyond the critical level in the some of the samples. In the wetland soils, content of all heavy metals was lowest for phytotoxicity and food safety in samples from absolute control plots of rice PME at Pattambi, Moncompu and Kayamkulam and highest in samples from plots receiving maximum quantity of organic manures and inorganic fertilizers. The DTPA extractable form is only a very minor part of their total content. The heavy metal load of the commonly used P fertilizers in Kerala is found to be highly variable. Zn is the highest contaminant followed by Pb, Ni, Cd and Cu. With respect to manures commonly used in Kerala, Zn is the most abundant among the five elements studied followed by Cu. Retention of heavy metals was found to be more in the roots of all plants compared to the above ground portions except Zn in amaranthus. The grain, straw and root of rice plants collected from PME plots which were receiving organic manures and inorganic fertilizers continuously for several years had a distinctly higher content of all heavy metals compared to the samples obtained from absolute control plots. The content of Cu in rice samples and that of Zn and Cu in the fodder samples from sewage farm exceeded the critical level to express phytotoxicity. In some of the samples of amaranthus and cowpea, content of Zn, Pb and Cd exceeded the food safety standards prescribed in Germany. Studies on the pattern of retention of applied Cd and Ni in undisturbed soil columns of important soil types of Kerala showed that retention of Cd and Ni was more in the top than in the bottom layers. Higher retention and lower leaching loss of applied Cd and Ni was observed in the columns not treated with FYM. Pot culture studies have shown a significant reduction in yield of rice, sesame and cowpea at various levels of Cd and Ni with and without FYM. Nutrient content of seed, shoot and root showed variations but did not reveal any specific pattern in various crops. In cowpea, low levels of Cd and Ni in the absence of FYM stimulated nodulation and nitrogen content. Intake of Cd and Ni in various plant parts of rice, sesame and cowpea was in the order root> shoot> seed. It was more in the presence of FYM than in its absence. The toxic effects of Ni on growth and yield parameters were of lesser magnitude compared to Cd especially in rice and cowpea. Maximum accumulation of Cd in edible portions was recorded by sesame with no ill effect on germination. However a moqerate accumulation of Cd in rice seeds resulted in significant reduction in germination. An alarming observation obtained from the study was that almost all samples of rice grains exceeded the food safety standard of 1 mg Cd kg-1 indicating that rice, the staple food of the people of Kerala is contaminated with Cd, the most hazardous heavy metal for human health. This pioneer study on the heavy metal status of selected soils and crop plants of Kerala has brought out the need for conducting detailed studies on these aspects.
