Loading...
Kerala Agricultural University, Thrissur
The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively.
Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively.
On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs.
In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc.
During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU).
Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.
Browse
12 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 Leaf litter dynamics in acacia and eucalyptus plantations(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1997) Moossa, P P; KAU; Venugopal, V KAn investigation entitled “Leaf litter dynamics in Acacia and Eucalyptus plantations” was undertaken to study the leaf litter production, litter decomposition and nutrient release characteristics, and impact of Eucalyptus and Acacia monoculture plantations on the soil physico-chemical and biological characteristics during 1994-97. One hectare each of Acacia auriculiformis, Eucalyptus tereticornis and a moist deciduous forest coming under the Kulathupuzha range of Kerala Forest Department were selected for the study. Field experiment were conducted to determine the leaf litter production and decomposition characteristics of plantation and natural forest. Leaf litter collected at monthly intervals showed that highest litter production was in Acacia (9.4 t ha-1 year-1) followed by natural forest (6.67 t ha-1 year-1) and Eucalyptus (4.68 t ha-1 yaer-1). Pattern of litter production was unimodal in Acacia and natural forest while in Eucalyptus it was bimodal. Chemical analysis of litter samples of plantations and natural forest revealed that with respect to nutrient content fresh and leaf litter of Acacia and Eucalyptus is superior to natural forest whereas litter quality in terms of water soluble components, polyphenols, lignin and cellulose were superior in natural forest. Annual dry matter loss of leaf litter by decomposition followed the order natural forest > Acacia > Eucalyptus. Nutrient release pattern of major and micro nutrients were also worked out for the leaf litter during the process of decomposition and natural forest litter recorded the highest mobility for all the nutrients on decomposition. Improvement in soil physico-chemical properties were noticed due to leaf litter decomposition in the monoculture plantation and natural forest. Biological activity in terms of earthworm and nematode under monoculture plantation was significantly lower than that of adjacent natural forest. Microbial content of soil below the litter bag during different months of decomposition were low in Eucalyptus and Acacia. Chemical analysis of the profile samples of various plantations revealed lower nutrient status in respect of major and micronutrients compared to natural forest. The physical properties of the soil also recorded as unfavourable change in the monoculture plantations as compared to the adjacent natural forest. Proximate anlysis of soil organic matter and humus characterization of the soil organic matter separated from various plantations indicated a low rate of humification and condensation under Eucalyptus. Low humic acid and fulvic acid content in humus and dominance of fulvic acid over humic acid was also noticed in Eucalyptus plantations. Functional group analysis of humic acid and fulvic acid showed that humic material separated from natural forest contained higher quantity of total acidity, contributed by COOH and phenolic group compared to plantation soils. UV, IR, DTA and TGA analysis of humic acid and fulvic acid separated from various plantations showed no variation with respect to natural forest. Allelopathic effect of fresh leaf and leaf litter extract of various plantations on the germination and growth of rice and cowpea followed the order Eucalyptus > Acacia > natural forest and as the concentration decreased from 1: 2 to 1: 10, the allelopathic inhibition also decreased significantly. Allelopathic effect of soil extract also followed the order Eucalyptus > Acacia > natural forest. Thus it can computed that though the leaf litter production and litter quality of monoculture plantations are comparable with that of natural forest, leaf litter decomposition and nutrient released were significantly lower than that of natural forest. Soil physico-chemical properties, soil fertility and biological activities were also adversely affected by monoculture plantations.ThesisItem Open Access Partial substitution of muriate of potash by common salt for cassava (Manihot esculenta crantz) in oxisols of Kerala(Department of Soil Science & Agricultural Chemistry, College of Agriculture, Vellayani, 1995) Sudharmai Devi, C R; KAU; Padmaja, PField experiments were carried out in the College of Agriculture, Vellayani during 1991 to 1994 to study the possibility and extent of substitution of K of Muriate of Potash with the Na of common salt in Cassava variety M4 used as the test crop. Substitution of K was tried at 4 levels viz. 25, 50, 75 and 100 per cent of the recommended dose. Muriate of potash, replaced by wood ash and a combination of KHCO3 and NaHCO3 (eliminating chlorine source) also were included in the experiment. Plant growth characteristics like plant height and number of leaves did not vary significantly as a result of substitution. The maximum LAI was observed in the case of 50% K as MOP + 50% Na as CS treatment at all the growth stages. An increase in chlorophyll content was observed with NaCl substitution. In the early growth stages there was no significant variation in the production of roots, but at the later stages there was significant difference in this aspect. The root volume at 2 MAP varied significantly between treatments. In general, there was an increase in total weight of plant with NaCI substitution upto 50% and thereafter a decrease with higher levels of substitution, at all growth stages. Significant treatment difference could be observed in tuber yield in both the years of the experiment. T3 (50% MOP +50% CS) registered the highest tuber yield and T5 the lowest. The bulking rate and Utilisation Index also differed significantly among treatments. The cooking quality of the tubers from T3 was as good as that of T1. Significant differences could be observed in total sugars, reducing sugars and sucrose content of fresh tubers under different treatments. With increasing levels of substitution, the content of total sugars increased. Sucrose content was found to increase with Na application upto 75% substitution of K by Na. Significant variation was observed in the crude protein, total amino acid and free amino acid content of tubers. Hydrocyanic acid, total phenols and crude fibre also differed significantly between treatments. The keeping quality studies revealed that tubers from T3 could be stored fresh up to 35th day in moist soil, whereas tubers from T1 could be stored only upto 12th day, without deterioration. Enzyme studies revealed significant difference in the activity of starch synthesising enzymes, but NRA at 6 MAP was not affected by different treatments. The uptake of N was highest in T1 and P and K in T3. Na uptake by T1 which received no Na was generally higher than other treatments receiving Na. Ca and Mg uptake also differed significantly between treatments. Changes in soil organic carbon, available P, available K and available Mg were statistically significant between treatments but that of Ca was significant only from 4 MAP onwards. Yield of tubers was positively and significantly correlated to the uptake of N, P, K, Na, Ca and Mg. Yield at harvest was positively and significantly correlated to the root weight and root volume and also to the bulking rate at 2 MAP. Path coefficient Analysis revealed that the maximum direct effect on yield was contributed by the drymatter of roots at 2 MAP. From the results, it can be concluded that in soils having low to medium status of K, the K of MOP can be substituted up to 50% by Na of commonsalt in cassava without affecting the quality and quantity of tubers.ThesisItem Open Access Morphological, physical and chemical characterization of the soils of North Kuttanad(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1997) Manorama Thampatti, K C; KAU; Jose, A JAn investigation was carried out at the College of Horticulture, Vellanikkara during 1992 to 1995 to evaluate the morphological, physical and chemical characteristics of soils of North Kuttanad and to assess the extent of toxic factors that pertained in the soil due to restricted movement of water under the influ- ence of Thanneermukkom regulator. The study was carried out in three parts, viz., (1) Morpho- logy and physicochemical characteristics, (2) Fertility characteristics and (3) Toxicity chara- cteristics. Fifteen soil profile were drawn from North Kuttanad to study the morphology and physicochemical characteristics of the area. The fertility characteristics were studied by collecting 97 surface soil samples (0-15 cm depth) from 27 padasekharams of the area during rainy and summer seasons (before and after the closure of Thanneermukkom regula- tor). Toxicity characteristics of the area were studied by collecting bulk soil samples (0-25 cm depth), surface water and ground water from the above sites during the same period. Morphological and physicochemical properties of the soils showed great degree of variation. Soils were dark brown to black in colour, sticky and plastic, subangular blocky in structure and sandy to clayey in texture, with random deposits of lime shells and humus. Presence of faint to prominent reddish yellow or brown mottles, rice roots and root canals were some of the special characteristics observed in the soil profiles. Soils of the area were highly acidic and mildly saline. Both soil acidity and salinity increased with depth. Organic carbon, CEC and ECEC of the area were higher compared to other parts of Kerala, but the base saturation was comparatively lower. The area was rich in almost all the essential nutrients except P. Fe, Al and S were present in toxic concentrations. Potential acidity of the area was very high and more than 70 per cent of it was contributed by hydrolytic acidity and the rest by exchangeable acidity. All the acidity characteristics increased with depth. The profile IX was grouped under order Inceptisol and all others under order Entisol. On evaluating the fertility characteristics of the area it was observed that the area experienced an increase in soil acidity and availability of N, P, Fe and Zn and a decrease in salinity, CEC, ECEC and available K, Ca, Mg, \.10 and Cu. However, the availability of all nutrients except P was above the deficiency level. Fe was present in toxic quantities. On a general comparison with that of pre-barrage period, the area experienced a reduction in salinity and an enhancement in soil acidity and availability of K, Ca and Mg. The Na content was reduced considerably in response to the reduction in salinity. The exchangeable and water soluble cations followed the same trend as that of available cations. Among the exchangeable cations Ca was the dominant basic cation instead of Na which occupied the same place during pre-barrage period. Acidity characteristics of surface samples behaved similar to that of profile samples. Pot- ential acidity and hydrolytic acidity recorded higher values during rainy season while exchangeable acidity was greater during summer. Among the components of exchange- able acidity exchangeable Al3+ dominated during rainy season, and exchangeable H+ dur- ing summer. The overall influence was greater for exchangeable A13+ as evidenced from the higher correlation coefficient (0.862**). The general soil properties and acidity characteristics of the bulk soil samples were similar to that of surface samples, showing a reduction in pH, EC, CEC and available, exchangeable and water soluble cations during summer compared to the rainy season. Among the different fractions of Fe, free and available forms were present in large quantities while exchangeable and water soluble forms were present in negligible quantities. All the fractions expressed a higher concentration during summer indicating more chances for severe Fe toxicity during that period. Mn was also present in large quantities. Compared to Fe, the concentration of different fractions of Mn were very small. The availability of Cu and Zn were also above the critical levels. The area was rich in AI. Reverse to that of Fe the different fractions of Al showed a lower concentration during summer. The free Al content was three times lesser than that of free Fe, while in exchangeable form Al expressed a higher concentration. The water soluble AI was very low. Surface water and ground water of the area were mildly acidic and saline during rainy season and they showed an increase during summer. The acidity exceeded the permissible maximum but the salinity was maintained below the permissible limit for agricultural and domestic purposes. Among the various elements present in water, Na and Cl- were the dominant ions expressing greater concentrations during summer in both surface and ground water. Based on SAR they were rated as moderately unsafe for irrigation during summer. The concentrations of K, Ca and Mg were within the permissible maximum for agricultural and domestic purposes. P was present only in traces. The Fe content was greater for ground water than surface water and it exceeded the permissible limit for drinking water. Though Mn was absent in ground water, it has already reached up to the permissible maximum in surface water. Al content exceeded the permissible maximum for domestic purposes. Cu, Zn, Cd and Pb were not detected in water. SO4-S, NH4-N and NO2+NO3- N contents of both surface and ground water were well below the critical levels suggested, but Cl' contents of both were sufficient to cause specific toxicity effect. The chlorinated hydrocarbon pesticides identi _ fied in the area were (X-HCH, y-HCH and DDT. They showed higher concentration during summer. Among the chlorinated hydrocarbons, DDT was present in larger quantities, though it was banned for agricultural uses, followed by (X-HCH. The concentration of y-HCH was comparatively small. The accumulation of fertiliser residues in the area was not so negligible. The highest concen- tration was observed for NH4-N during addi- tional crop season, at the time of basal dressing, both in soil and water. During punja season, a decrease of 55 to 60 per cent in soil and 10 to 12 per cent in water for NH4-N was observed. The content of N02+N03-N was comparatively low in soil due to continuous submergence. In water it was not as low as that of soil, indicating a major portion of N02+NOrN retained in water. P content of the area was very low. Its loss through drainage water was nil. A sizable quantity of K was also subjected to loss through drainage water, though the extent of loss was well below the level of N. Here also highest concentration was noted during additional crop season at the time of basal dressing both in soil and water. The study indicated that the area is subjected to severe pollution due to the accumulation of native toxic factors as well as residues of pesticides and fertilisers. The closure of Thanneermukkom regulator aggravates the situation by restricting the water movement.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, availability and transformation of magnesium in acid soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1992) Prema, D; KAU; Jose, A IThe investigation consisted of four parts, namely (1) magnesium status of soils in Kerala (2) evaluation of laboratory indices of Mg availability (3) transformation of applied Mg in soil and (4) pattern of Mg uptake by banana from different sources at different levels. In Part I, one hundred and fifty surface samples were collected from all over the State of Kerala, to study the status of Mg as well as properties in relation to the behaviour of Mg in these soils. In part 2, some selected chemical agents were tried in twenty selected soils in order to evolve a suitable extractant for available Mg. In Part 3, two acid rice soils of Kerala namely, Karappadam and laterite were incubated at field capacity for a period of 180 days with and without the addition of magnesium sulphate, magnesite and dolomite at the rate of 1250, 2500 and 3750 kg MgO ha-1, to monitor the pattern of release of Mg from applied sources . Soil samples were drawn regularly at 15 days interval for the determination of available Mq and at 60 days interval for the determination of other important chemical properties. In Part 4, a field experiment of banana was conducted to study the response to applied Mg.ThesisItem Open Access Evaluation of acidity parameters in wetland soils of Kerala in relation to nutrient availability(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1995) Usha, P B; KAU; Thomas, Varghese (Guide)Soil acidity is a major constraint in the wetland rice soils of the tropics, which has got aggravated in recent times with the introduction of high yielding varieties of rice and intensive use of fertilizers. Kerala State, with its unique geomorphology, climate, hydrology and other environmental factors has led to the formation of wetland soils with specific physico-chemical and mineralogical properties. These soils sustain a major part of the rice tracts in the State. Attempts to bring these lands under rice cultivation brought to light the intensity and severity of soil acidity in the natural as well as manmade wetlands of this region. Though studies have started way back in 1920 to tackle the problem of acidity and associated nutritional factors, a detailed study to unveil the intricate physico- chemical phenomena contributing to acidity and an economic and efficient methodology to alleviate the severity of acidity has not been attempted so far. Hence a study has been conducted to evaluate the acidity parameters in relation to nutrient availability in wetland rice soils of Kerala. Twelve major wetland rice soils have been identified and classified according to Soil Taxonomy. They belong to natural as well as manmade wetlands, some of them having been indigenously classified and known by vernacular names like Kari land (acid peat), Karapadam (riverine alluvium), Kayal land (lake bed sediments), Pokkali lands (saline acid), Kole lands (flood plain), Kaipad lands (saline marsh). Twelve profile samples representing the major wetland rice soils comprising an area of 6 lakh ha have been subjected to detailed investigations for morphological, physical, chemical, mineralogical and electro chemical parameters. Surface samples, each at a radial distance of 5 km from the twelve locations were collected and subjected to detailed studies to evaluate the acidity parameters and acidity generating factors. Studies were also taken up to observe the kinetics of pH and nutrient availability under submergence for different intervals of time. A comparative study on the efficacy of different methods of estimating the lime requirement was also taken up. From the detailed investigations on the evaluation of acidity parameters of wetland rice soils of Kerala, it has been observed that there exists a great extent of variation with respect to the severity of acitive acidity in the profile and surface samples. Barring Chittoor soils which were slightly alkaline, all the soils under study were acidic in reaction. The profile and surface samples of Kari soil of Thakazhi and Pokkali soil of Njarakkal recorded the highest active acidity with a dry soil pH around 3.2. The rating of these surface soils on the basis of active acidity was Kari ≥ Pokkali > Karapadom > Vellayani > Kayal > Kole > Wyanad > Pattabi > Kaipad > Karamana > Kattampally. However, with respect to the mean values of pH of profile samples the rating was Kari > Pokkali > Kole > Kayal > Karapadom > Vellayani > Wyanad > Pattambi > Karamana > Kattampally > Kaipad. All the soils having high active acidity recorded high exchange, non-exchange and potential acidity with significant correlation between them. It was observed that major part of potential acidity of wetland soils of Kerala was constituted by non-exchange acidity due to the preponderance of Kaolinite clay minerals and high content of sesquioxides. Highest values for potential acidity were recorded by 18-30 cm. of Kari and surface layers of Pokkali profiles. Based on mean potential acidity of surface samples the soils could be rated as Kari > Pokkali > Kayal > Karapadom > Kole > Pattambi > Kattampally > Vellayani > Kaipad > Karamana > Wyanad. HOWEVER, WITH RESPECT TO PROFILE SAMPLES THE SEQUENCE WAS Kari > Pokkali > Kayal > Karapadom > Kole > Wyanad > Vellayani > Kattampally > Pattambi > Kaipad > Karamana. From the correlations worked out, it was found that aqueous pH (1:1) under dry condition was a more reliable parameter for evaluating acidity in the wetland rice soils of Kerala than pH under wet condition or in salt solution, because this parameter gave more significant correlations with acidity generating factors and available nutrients. It was also observed that available sulphur determined both active and potential acidity rather than total sulphur in sulphur rich soils. Path coefficient analysis of acidity contributing factors indicated that exchangeable aluminium was the best parameter for measurement of acidity, 87 per cent of variation in exchange acidity, 57 per cent of variation in non- exchange acidity and 63 per cent of variation in potential acidity. Comparison of different methods for calculating lime requirement proved the superiority of exchangeable aluminium method for the wetland rice soils of Kerala. Lower rates of lime requirement were observed by this method for Kattampally, Wyanad, Karamana, Pattambi and Kaipad soils. Studies on submergence showed that wetland rice soils of Vellayani, Karamana, Karapadom, Kole, Kaipad, Kattampally and Wyanad do not require lime to raise the Ph for rice cultivation because all these soils attain a pH value of 5.5 within two weeks of submergence. Consequently there was increased availability of nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese and silica. However, zinc, copper and sulphur were found to decrease by prolonged submergence. The detailed investigations conducted under this study on the evaluation of acidity parameters of wetland rice soils of Kerala in relation to nutrient availability have unveiled many intricate phenomena of soil acidity which are of great theoretical and practical significance. Contrary to the conventional concept that liming is a must in all acid soils, the present study underlines the cheap and easy method of alleviating acidity of certain wetland rice soils by optimum submergence and scientific water management. Further the study has revealed the feasibility of liming in soils with severe acidity based on specific methods of estimating the lime requirement of soils. However it is necessary to confirm the results of these in- vitro studies by adequate field studies in specific wetland rice tracts of Kerala State.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.ThesisItem Open Access Standardisation of plant part as an index of potassium status in banana, musa (AAB Group) nendran(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1994) Sumam George; KAU; Padmaja, PA field experiment in Musa (AAB group) Nendran, the most popular commercial fruit crop of Kerala was undertaken from August, 1991 to May, 1992 with seven graded levels of K as treatments replicated thrice. The soil, medium in N and P and high in K status belonged to the taxonomic class ‘loamy kaolinitic isohyperthermic aeric tropic fluvaquents’. The effects of higher levels of K on all important growth characters of the crop like height of pseudostem, girth of pseudostem at different heights from the ground level, total number of leaves, number of functional leaves, total leaf area, leaf area index and total dry matter production were more pronounced from the shooting stage of the crop after the plants had received the full dose of K supply. Uptake of major nutrients N, P and K showed increasing trend with increase in K supply. Uptake of Ca showed a negative relationship with increasing K application while Mg uptake showed an inconsistent pattern. Uptake of micronutrients Fe, Mn, Cu and Zn were maximum at K3 level of application (225 g K2O plant-1). Soil content of available K increased while exchangeable Ca and Mg contents decreased at higher levels of K supply. The maximum bunch yield of 26.18 t ha 1-which was significantly higher than all other treatments was recorded at K3 level (225 g k2O plant-1) This level also resulted in maximum values for all the yield attributing characters like number of hands bunch-1, number of finger bunch-1, weight of hand, length of finger, girth of finger and weight of finger. By adopting this recommendation a net fertilizer saving of 75g K2O plant-1 Can be achieved which is equivalent to 312.5 kg of muriate of potash costing Rs. 2000 at the present market rate. Over and above this, increase in yield obtained by doing so is 4500 kg ha-1. Additional income that could be generated by the way of sale of this at the rate of Rs. 8 kg-1 works out to Rs. 36000. Thus a total saving of Rs. 38000 ha-1 can be achieved by following the suggested recommendation. Path coefficient analysis of yield attributes showed that the character number of finger bunch-1 is having the maximum direct effect on yield followed by girth of fruit and weight of fruit. Quality characters of the fruit namely total and non reducing sugars, shelf life and flesh peel ratio showed significant and positive trend towards K nutrition. Correlation coefficient were worked out between bunch yield and important crop characters. Balance sheet of nutrients in soil after harvest of the crop was worked out to assess the final soil status of nutrients in relation to the initial status. Petiole of the third leaf up to shooting stage of the crop and that of the flag leaf there after was selected as the index of K status of the plant as the K content of the same was found to hold the maximum relationship with bunch yield at all the growth stages. The critical K levels in the petiole for maximum yield as well as maximum response to fertilizer application at each stage were determined which were found to be 1.30 per cent and 1.02 per cent respectively at early vegetative stage, 1.28 per cent and 1.06 per cent respectively at late vegetative stage, 1.80 per cent and 1.36 per cent respectively at shooting stage, 2.43 per cent and 1.98 per cent respectively at post shooting stage, 2.50 per cent and 1.80 per cent respectively at bunch maturation stage and 2.47 per cent and 1.80 per cent respectively at harvest stage. The critical K content in soil for economic yield worked out to 286.5 kg K2O ha-1 at early vegetative stage, 276.5 kg K2O ha-1 at late vegetative stage, 271.o kg K2O ha-1 at shooting stage, 239.o kg K2O ha-1 at post shooting stage, 245.0 kg K2O ha-1 at bunch maturation stage and 236.0 kg K2O ha-1 at harvest stage. Graphs were plotted relating petiole K content to soil K content at important growth stages of the crop based on quadratic regression models to provide information on soil K content at a particular stage if the petiole K content at that stage is known. Linear regression models were developed relating soil K content to fertilizer dose to find out the quantity of fertilizer to be applied to bring the soil level to the critical level.
