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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.
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ThesisItem Open Access Influence of Water and Specific Anions and Cations on Physico-Chemical and Biological Properties of Soil(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1989) Jaya, V; KAU; Pushkala, SThe availability of nutrients either present in the soil or applied as fertilizer is governed by various factors like the physical, chemical and biological reactions in the soil. The present investigation is undertaken to study the direct and interaction effects of different levels of phosphorus, sodium and water on the physic-chemical and biological properties of soil. An experiment is laid out in the farm area of College of Agriculture, Vellayani. The lay out is in randomised block design with 18 treatments and three replications. Banana var. Nendran is used as the test crop. The treatment combinations include, three levels of phosphorus (control, 90 and 115 g P2o5/plant/annum), three levels of sodium (control, 68 and 136 g Na/plant/annum) and two levels of water (20 and 40 per cent depletion from field capacity moisture condition). Soil and plant analysis are done for the elements, nitrogen, phosphorus, potassium, calcium, magnesium and sodium. Initial soil samples and samples collected at 90, 180 and 270 days after planting are used for different physic-chemical analysis. Physical properties such as moisture parameter, bulk density, particle density, porosity, water holding capacity, volume of expansion and aggregation are done for all the soil samples. Total nutrient contents and hydraulic conductivity for the soil samples collected at the final stage are also done. Plant samples collected at the harvest are analysed for total nitrogen, phosphorus, potassium, calcium, magnesium and sodium. Biometric parameters such as plant height, number of leaves, girth of pseudostem and leaf area index are observed and recorded during three stages. Mycorrhizal counting is carried out, during all the stages, considering as three seasons. All the data are statistically analysed and interpreted. Phosphorus at the highest dose is beneficial for all the biometric parameters studied. In the case of sodium, it has an adverse effect on the girth of the pseudostem, even at the highest level of phosphorus. Leaf area index is very high in the presence of sodium and phosphorus even at 40 per cent depletion from field capacity. Soil phosphorous and soil moisture are negatively correlated with mycorrhizal percentage during second and third stage. Plant phosphorous and sodium positively correlated with the mycorrhizal percentage. Even with moisture at 40 per cent deplection from field capacity and lower amounts of phosphorous applied, the uptake of phosphorous by the plant is increased by mycorrhizal association. Higher levels of phosphorous and sodium increase the waterholding capacity and volume of expansion. Bulk density and particle density give optimum values with medium levels of phosphorous and sodium. Moisture percentage increased in plots with optimum sodium than with plots receiving higher dose of water with no sodium. Lower water level reduces bulk density and particle density. The mean weight diameter which is a measure of soil aggregation is positively correlated with soil phosphorous and negatively correlated with soil moisture. Optimum dose of phosphorous and sodium favour hydraulic conductivity of soil. Medium dose of sodium and phosphorous increase organic carbon and soil available nitrogen. Lower level of water is sufficient for increasing soil available nitrogen, soil available phosphorous and organic carbon, in the presence of sodium. Positive correlation exists between soil available phosphorous and mycorrhizal percentage in the first stage. Maximum phosphorous is available during the second stage with a negative correlation with mycorrhiza. Optimum dose of sodium and high level of phosphorous, increase the availability of available potassium, exchangeable calcium, and exchangeable magnesium. There is a positive correlation exist between soil moisture and soil sodium. As the plant grows the soil available potassium decrease. Higher levels of water, increase, exchangeable calcium and magnesium also. Total nutrient content of nitrogen, phosphorous and potassium are decreased with increasing phosphorous, sodium and water, which is, because of their increased availability. Plant phosphorous is related with soil available phosphorous. For optimum dose of phosphorous, lower level of water and higher level of sodium, the availability and uptake of potassium is at the optimum. Positive correlation obtained for plant phosphorous with mycorrhiza, soil sodium, soil available phosphorous, and mean weight diameter. Plant sodium is also positively correlated with soil available phosphorous, mycorrhizal population, plant phosphorous and hydraulic conductivity. Highest level of phosphorous and water and medium level of sodium favour the uptake of calcium and magnesium. For increasing sodium availability, only optimum dose of phosphorous is required. Sodium at the optimum dose improve soil hydraulic properties. Optimum dose of phosphorous and sodium improves many of the physic-chemical properties of the soil. In the presence of mycorrhiza, even lower levels of phosphorous is sufficient to meet the plant requirement. With more levels of phosphorous, sodium and water, the study can extended in relation to plant growth. Yield factor is not considered in the present study.ThesisItem Open Access Assessment of selective retention sites of cadmium and lead in tomato (Lycopersicon esculentun Mill)(Department of Soil Science Agricultural Chemistry,College of Horticulture,Vellanikkara, 2004) Vanisri, K; KAU; Sam Kurumthottical, TThe bio-availability of the toxic heavy metals like cadmium and lead together with its selective retention sites in tomato (Lycopersicon esculentum Mill.) was one of the major concerns in the crop. For this, pro-calculated quantities of cadmium and lead were applied to the soil mainly as water-soluble sources (cadmium chloride and lead nitrate respectively) to assess the finite objectives envisaged in the study. In order to meet the objectives, a pot culture experiment was conducted in the Vegetable Research Farm attached to the Department of Olericulture, College of Horticulture, Vellanikkara during the rabi season of 2003 with five treatments and four replications. Pre-treatment analyses of all basic inputs and soil were carried out to quantify the possible inclusion of heavy metals from them. After providing pre-calculated quantities of metals in pots, 42 day old and uniformly grown tomato plants of variety Sakthi were transplanted to pots. The plants were allowed to establish till majority of the plants (50 per cent) were at the turning stage. Biometric observations on the plants due to the impact of the metals were recorded. Fruits as and when they turned ripe were harvested with proper acknowledgment to their identity in treatments for yield and its subsequent dry weight. At harvest, the plants were carefully uprooted, cleaned properly and separated into root and shoot portions. After recording the weight of each portions, these parts were taken for analysis. Post-harvest soil samples were also collected and analysed to see the extent of availability of major nutrients and heavy metals, particularly cadmium and lead. All the inputs including soil maintained variable amounts of cadmium and lead, with maximum metal load contributed from phosphatic sources. It is seen that growth of tomato plants in pots, particularly under the influence of different levels of cadmium and lead, manifested differential growth and development. Internally also, the plants exhibited differential metal load and retention patterns apart from recording variation in the uptake of major nutrients. A brief resume of the major influence of different levels of cadmium and lead in soil and on the tomato plants is presented hereunder. Variation in cadmium levels in soil could influence significant variations In the available nutrient status in post-harvest soil samples. Accordingly, an increase in metal load permitted enhanced potassium availability in soil while the same status had an opposite effect particularly with respect to the available phosphorus and nitrogen. The nitrogen content of root and shoot of tomato plants was seen to be positively influenced with higher levels of cadmium application. However, a reverse trend in nitrogen content was observed with lower levels of application except for the shoot portions observed from Treatment 4. Among the various plant parts analysed, the fruits maintained the maximum nitrogen content and this content was roughly observed to be twice as that of its content in roots. Enhancement in cadmium level in soil resulted in a corresponding increase in the phosphorus content of roots, shoot and fruits. As observed for nitrogen, fruit portion maintained the maximum phosphorus content. A very similar trend was noted for the potassium content in tomato, consequent to the application of different levels of cadmium. Much before an apparent growth or' yield reduction was noted in tomato with cadmium application, the tomato plants readily exhibited certain characteristic symptoms, which could be associated with the metal toxicity on that plant. Preliminary indications appeared on leaves with such leaves picking up yellowing and inter-veinal chlorosis depending upon the metal load. At high concentrations of the metal, invariable splitting up of the stem at the collar region leading to complete death of such plants has been noted. As concentration of the cadmium load increased beyond 1.5 mg kg" soil, the tomato plants failed to fruit and at the highest concentration of the metal envisaged in the study (2.0 mg Cd kg" soil), the very establishment of the transplanted tomato crop was questioned. However, the successful survival and fruiting of the transplanted tomato plants was noted only at lower levels of cadmium addition (0.5 and 1.0 mg Cd kg" soil). Lower doses of addition of cadmium had exhibited negative influence on growth and development in tomato with the manifestation of significant reduction in number of branches, leaf length, leaf number, plant height, the production of trusses and subsequent reduction in yield. Reduction in growth and yield of tomato plants from different levels of application of cadmium, necessarily brought significant reduction in dry matter yield, whose influence is clearly reflected in the roots, shoot and fruits portions underlining a negative influence of cadmium on the dry matter production. At all levels of cadmium application, there was sufficient retention of the metal in plant whether it is root, shoot or fruits Roots of tomato are seen to preferentially harbour more of cadmium than its other plant parts particularly at higher levels of addition. However, at lower levels of addition, shoots preferred to maintain more cadmium than its root portions. Increasing levels of lead invariably decreased the root nitrogen content . significantly while shoots content of nitrogen increased generally with lower doses of metal addition. Variation in, lead levels permitted a significant increase in the phosphorus content in roots, shoot and fruits. No specific trend was noted in the retention of potassium by roots while shoot portions indicated significant influence of the same by offering differential content of potassium in them. Among all the plant parts, fruits maintained the maximum nitrogen, phosphorus and potassium content. Higher doses of lead rendered some fruits, if not all with certain malformations. This together with the total absence of any phyto-toxicity testifies that the tomato plants are able to tolerate high concentrations of lead inside them. Quite contrary to the expectations, an unusual increase in dry matter production was observed from lead treated tomato plants. Lead application in soil, irrespective of its levels, permitted maximum accumulation of the metal in fruits followed by shoots and roots. All accumulations noted in the plant were observed to be significant, projecting serious concern for the silent inclusion of lead in the economically important part of the plant. Variable amounts of cadmium and lead have been detected in the post-harvest soils indicating that the entire quantity of the applied cadmium and lead could not be completely absorbed by the plant.ThesisItem Open Access Vermicompost Enriched with Organic Additives for Sustainable Soil Health(Department of Soil Science and Agricultural Chemistry College of Agriculture, Vellayani, 2004) Sheeba, P S; KAU; Ushakumari, KAn investigation was carried out at the Instructional Farm, attached to the College of Agriculture, Vellayani to evaluate the effect of vermicompost enriched with organic additives viz., neem cake and bone meal on physico-chemical and biological properties of soil, to evaluate its impact on crop performance and the feasibility of substituting farmyard manure and inorganic fertilizer using amaranthus as test crop. The study consist of three parts 1) Preparation and analysis of vermicompost and enriched vermicompost 2) laboratory incubation experiment 3) Field experiment. On enriching biowastes with neem cake and bone meal, improved the manurial value of vermicompost produced using earthworm species Eudrillus eugeniae. C/N ratio was reduced by enrichment. Microbial population also increased considerably by enriching vermicompost with organic additives. Second part of our investigation was an incubation study and it was conducted to evaluate relative efficiency of enriched vermicompost to release nutrients from soil and its influence on physico-chemical and biological properties of soil. The results revealed that available nitrogen, phosphorus and potassium content of the soil increased upto 45 days of incubation then the availability slowly declined. Organic carbon, pH and EC increased whereas bulk density reduced due to the effects of various organic sources. Application of organic matter had a positive effect on microbial count also. Third part of the study was field experiment, and it was laid out in RBD with 10 treatments and three replications. The biometric observations viz., plant height, number of leaves, number of branches, stem girth, leaf stem ratio all were significantly influenced by different treatments. Significant differences were observed among yield attributing characters like yield per cutting (t ha-1), total yield per plant (g plant-1), total marketable yield (t ha-1), and total dry matter production (t ha-1). Highest yield per cutting was recorded by the treatments T0 (FYM + full NPK), T4 (EVC – NC two per cent + full NPK) and T8 (EVC – NC 1 per cent + BM 1 per cent + full NPK]. With respect to plant contents of nutrients, for nitrogen, highest value was recorded by the treatment T4 (EVC – NC two per cent + full NPK), for P, highest value was recorded by T6 (EVC – BM two per cent + full NPK) and for K, highest value was recorded by the treatment T8 (EVC – NC 1 per cent + BM 1 per cent + full NPK). For plant uptake highest values were registered by the treatments T4, T6 and T8 for N, P and K respectively. With respect to quality characters, treatments with organic sources of plant nutrients viz., T8 [EVC- NC 1 per cent + BM 1 per cent + full NPK) recorded highest value for -carotene content in all the three cuttings, for moisture content T3 (VC+1/2NPK) recorded the highest value in all cuttings, for protein T4 (EVC – NC two per cent + full NPK) recorded the highest value in all cuttings. For fibre content treatment T1(Full NPK as mineral fertilizer) recorded the highest value and T2 (VC + full NPK) recorded the lowest value. Oxalate content is also influenced by different treatments. Vermicompost enriched with bone meal and treatment received NPK alone recorded highest oxalate content. Post harvest analysis of the soil indicated that organic carbon, available phosphorus, pH, EC and microbial count were increased by applying enriched vermicompost. But available nitrogen and available potassium were slightly decreased. Bulk density was found to be influenced favourably. From the investigation it was proved that enriched vermicompost established its superiority over other organic sources and POP recommendation with respect to soil health and quality of amaranthus. Study also revealed the feasibility of substituting FYM and inorganic fertilizer with enriched vermicompost.ThesisItem Open Access Soil test crop response studies on ginger in laterite soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Horticulture,Vellanikkara, 2001) Jayalakshmi, M; KAU; Hassan M ATo establish soil test based balanced fertilizer prescription for ginger variety Maran in laterite soils of Kerala, an investigation was undertaken at the College of Horticulture, Vellanikkara. The field study consisted of fertility gradient experiment and STCR experiment. The fertility gradient experiment was conducted during March-April 2000 in the farm attached ,to the College. The desired gradient in soil fertility was created in "<; - .t one and the same field by applying graded doses of N, P and K fertilizers and raising fodder maize var. Co. I. The STCR experiment was conducted in the same field during May-Nov 2000 using the test crop, ginger variety Maran. The treatments consisted of fractional factorial combinations of four levels of N (0, 50, 100 and 200 kg ha-I), three levels of P (0,37.5, 75kg P205 ha-I) and five levels of K (0, 37.5, 75, 150 and 300kg K20 ha-I) along with three levels of farmyard manure (0, 15 and 30 t / ha) fitted in a response surface desi~n. Using multiple regression model, the fertilizer adjustment equation for N at varying soil test values for available N for maximum rhizome yield (t ha-I) of ginger in laterite soil was derived as FN = 153 - O.28SN where FN is fertilizer N (kg hal) and SN is soil available N (kg ha-l ). At varying soil test values for organic carbon % (OC) and Phosphorous kg / ha the above equations become FN = 312.94 - 518.4 OC and FP = 79.8 - O.94SP for maximum rhizome yield. The behaviour of fertilizer K was found to produce responses other than 'normal' and hence optimization could not be done for fertilizer K for maximum rhizome tuber yield at varying soil test values. The nutrient requirements of ginger variety Maran were estimated to be 2.1, 0.3, S.6kg N, P20S and K20 respectively to produce one kg of rhizome. In the laterite soil, the efficiencies of contribution of nutrients from the soil for ginger were calculated as 10.1,6.9 and 44% N, P20S and K20 respectively. The fertilizer efficiencies were worked out as 27.3, 10.9 and S3.2% N, P20S and K20 respectively. The efficiencies of contribution of nutrients from farmyard manure were calculated as 30, 7 and 60% N, P20S and K20 respectively. From the above basic data, fertilizer prescription equations for specific yield targets of ginger var. Maran in the laterite soil were derived as given below. Without FYM FN =7.8T - 0.37 SN FP =2 .. 8T - 0.64 SP FK = 10.6T - 0.833 K With FYM FN = 7.8T - 0.37SN - 1.11 ON FP = 2.8T - 0.64 SP - 0.7 OP FK = 10.6T - 0.835 SK - 1.13 OK. Where, FN, FP, FK - Fertilizer N, P20S, and K20 respectively in Kglha. T - Target of fresh rhizome yield in t/ha. SN, SP, SK - Soil available N, P and K in kg/ha respectively. ON,OPOK - quantities of N, P and K supplied through organic manure in kg/ha. Based on the fertilizer prescription equations ready reckoners were developed for different yield targets. The study has revealed the superiority of fertilizer application over the semi quantitative approach followed in the soil testing laboratories and the generalized package of practices recommendation followed in the state for the crop. The fertilizer dose can be adjusted based or. the specific objective and available resources of the farmer. To know the influence of native elements on yield soil and plant samples were analyzed for micronutrient contents. In soil Ca, Mg and Mn showed positive correlations and Zn, Fe showed negative correlations with yield. In plant leaf magnesium and rhizome manganese showed positive correlation and rhizome iron showed negative correlation. Further path analysis was carried out to know the nutrient interactions.ThesisItem Open Access Investigations on the salinity problems of pokkali and kaipad areas of Kerala state(Department of Soil Science & Agricultural Chemistry, College of Agriculture, Vellayani, 1977) Samikutty, V; KAU; Aiyer, R SThe saline soils of the State viz., Pokkali, Kaipad and Orumundakan are coastal saline soils, which cover an area of about 30,000 hectares, cropped to a single crop of paddy. The profile characteristics of the soil reveal that they are Entisols. They contain varying levels of soluble salts depending upon their nearness to sea, backwater, or their situation on the flood plains of rivers and their nearness to the river mouths. The electrical conductivity of the saturation extract (ECe) of these soils range between 7.6 to 226.3 mmhos/cm showing differences in the magnitude of salinity encountered, prior to the soils being leached in summer months. Though the soils are exhibiting extremely high levels of salinity in the summer months, they get decreased rapidly below critical levels for growing a successful saline resistant paddy crop by July-August. The observed SAR and ESP values ranging to the maximum values of 25.0 and 26.3 in the months of February-March rapidly get decreased to 1 to 3 by between August and November. These low levels of salinity are maintained till December-January with an occasional spurt in salinity levels dependent on the opposing hydrological situation caused by the flood and rain waters on the one hand from east to west and the tidal waters from the west to the east on the other. The long period of nearly six months, when salinity in the soils are below critical levels, indicate the possibility of introducing a two crop system instead of one, provided nurseries are raised in non – saline uplands and transplanting resorted to in the raised mounds: previously leached free of soluble salts during the monsoon. The cationic-anionic composition of the soils reveal that they are Na-Mg-Cl-SO4 type of coastal saline soils. About 50 per cent of the soils studied have a pH below 5.5 and 15 to 20 per cent of the soils have lime requirement of more than 5 tons per hectare. In general the soils are extremely poor in phosphates and rich in potash. Application of non-magnesium containing lime materials at the time of mounding and subsequent leaching together with basal application of phosphate prior to planting are likely to enhance the yields of paddy in these areas. In short, the methods of management are highly location-specific calling for intensified research. The occurrence of saline water in the pits between the mounds even during the cropping period indicates the possibility of mixed rice culture with piscicultureThesisItem Open Access Dynamics and interaction of zinc and boron with phosphorus in ultisol(Department of soil science and Agricultural chemistry, College of Horticulture,Vellanikkara, 2015) Semsheer, M; KAU; Sureshkumar, PThe recent soil fertility assessment of the entire state has revealed that more than 60% of the soils in the state are having high P status due to continuous application of P fertilizers like factomphos and bone meal. It was also established that 15% of the soils are deficient in zinc and about 60% of soils are deficient in boron. Antagonistic interaction of P with zinc has already been well established. However studies on interaction of P with boron are limited. Thepresent study was undertaken in the above background in the Dept. of Soil Science and Agricultural Chemistry during the period from 2013-2015 to understand the chemistry, dynamics and bioavailability of zinc and boron with respect to the P status of the soil, which in turn will help in modifying the fertilizer prescription in terms of quantity and method of application of these nutrients. In order to achieve the objective of elucidating the dynamics of Zn and B as influenced by P status in lateritic soils and to optimize the level of P for balanced nutrition of cowpea with respect to Zn and B, 18 lateritic soil samples (Ultisol), six each coming under low, medium and high P status were identified from an initial 100 soil samples and characterized. A potculture experiment with cowpea as a test crop was conducted in three soils, one each with low, medium and high average P status. Soil and plant samples were collected at flowering and at harvesting stages and analyzedfor nutrient content. The distribution of fractions of inorganic P in the three soils showed that Fe bound P was the dominant fraction contributing to more than 50% of the total inorganic P. The soluble P fraction was about 6% in all the three soils. Fe and Al-P were the main fractions contributing to the available pool initially.Among the fractionsof boron, readily soluble boron recorded the lowest, where as the contribution of residual boron was the highest. Available P status in soils with low and medium P increased due to the application of P while it decreased in soil with high P. The soil with high P soil showed that the application of phosphorus lead to the fixation of phosphorus in to insoluble forms whereas, if P was not applied there was solubilisation of Fe-P and Al- P resulting in increased its availability. Plant adsorbed P from soluble P led to its depletion at the end of vegetative phase. Applied P got transformed into Fe-P and Al- P initially, which along with native occluded P got transformed to calcium bound P which is contributing to the available pool at later stages. Application of Zn was found to reduce Al-P and Fe-P due to the formation of insoluble zinc phosphate. Application of Zn and B reduced the Ca-P, probably due to the formation of zinc phosphate and Calcium borate. In case of zinc fractions, water soluble + exchangeable fraction and organic matter occluded zinc was directly contributing to the available pool. The other Zn fractions except amorphous iron oxide occluded zinc were contributing to the available pool indirectly through water soluble + exchangeable fraction. Application of P reduced the water soluble + exchangeable zinc fraction where as the application of boron enhanced the transformation of zinc into this fraction especially when boron was applied without P. Application of P resulted in adsorption of zinc into specifically adsorbed zinc. With respect to boron fractions, readily soluble boron and oxide bound boron were directly contributing to the available pool where as binding of boron with organic matter as well as its transformation to residual boron reduced boron availability. All the fractions of boron were contributing to available pool indirectly through readily soluble fraction of boron. Application of phosphorus was found to reduce the readily soluble boron due to anion competition. The applied boron either remained in the soluble form or getting transformed to specifically adsorbed, oxide bound, organic matter bund boron. Boron application along with P reduced the readily soluble boron. Application of Zn increased the Zn content in plant. However, the application of P with and without B reduced the Zn content in plants. Application of P and Zn reduced the boron content in plants and application of boron with and without phosphorus recorded the highest boron content. The highest grain yield was recorded in soil with medium P, while the high P status in soil either due to native P or due to applied P reduced the yield resulting from induced lower uptake of zinc and boron. Thus, at high levels of P, enough quantities of soluble zinc should be assured, over and above the quantities of this element precipitated as zinc phosphate, both by optimizing the pH and applying enough quantities of Zn. Similarly H3BO3 and H2BO3 - ions should be enough to overcome competition from H2PO4 - ion at root surface.ThesisItem Open Access Studies on exchange equilibria and its prediction on some acid soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellayani, 1988) Swarnavi, S; KAU; Pushakala, SMore than 70 per cent of the upland soils of Kerala are acidic. The acidity of the soil is primarily associated with the presence of hydrogen and aluminium in exchangeable form. The soil solution aluminium in acid soil infertility clearly establishes the agronomic significance of aluminium ion equilibria in soils. The present study, entitled “Studies on exchange equilibria and its prediction on some acid soils of Kerala” was conducted to find out(1) the effect of different concentrations of aluminium in the electrolyte solution on exchange equilibria in soils (2) the influence of different cations on the free energy and various selectivity coefficients (3) the dependence of different selectivity coefficients on potassium, calcium and magnesium saturation of soils (4) the role of organic matter on cation exchange equilibria with special reference to potassium, calcium, magnesium and aluminium. Cation exchange equilibria involving aluminium- potassium, aluminium – calcium and aluminium- magnesium were studied in three soil types, viz., Kari, laterite and redloam soils, differencing in their texture and organic matter content. The normalized exchange isotherms for different soils and cationic systems were drawn and the results were interpreted in terms of different selectivity coefficients and approximate free energy change of the exchange reactions. From the study on the effect of different electrolyte concentration of aluminium on aluminium – potassium, aluminium- calcium and aluminium – magnesium exchange, an increasing aluminium adsorption was observed with an increase in electrolyte concentration of aluminium. The adsorption of aluminium was maximum in soils with high organic matter content. The normalized exchange isotherms of aluminium for different cationic systems and soils lay above the diagonal, suggested the preferential adsorption of aluminium over other cations. Except the Gapon selectivity coefficient, all the other coefficients (KKDO, KV and KN) increased upto a certain value of base saturation and then decreased. The value of KG increased with increase in base satuation. Among the various selectivity coefficients, KN was found to be the most dependent one and KG the least dependent. The dependence followed the order KN > KV > KKDO > KG. The negative values of free energy change for different cationic systems suggested the preferential adsorption of potassium, calcium and magnesium over aluminium. Among these cations potassium was found to be adsorbed with more energy, followed by calcium, magnesium, and then by aluminium. The values of free energy change showed the following order of preference for the competing cations: K > Ca > Mg > Al. From the study it can be concluded that potassic fertilizers can be effectively used in acid soils of Kerala, because of its high retention and minimum leaching loss. Compared to potassium, calcium and magnesium were adsorbed with less bond energy and hence to maintain a higher concentration of these cations in the soil exchanger, a considerable amount of calcium and magnesium should be supplied by frequent application of lime. To evaluate correctly the response of applied potassic fertilizers and liming material in different soils, efforts should be made to relate exchange behaviour of potassium, calcium and magnesium to the nature and relative proportion of different soil clay minerals. Similarly, the extension of the predictive approach essentially meant for binary system need special attention in order to make the studies on cation exchange equilibria more realistic and field oriented.ThesisItem Open Access Characterisation of soil and water of Palakkad eastern plains in relation to growth and nitrogenase content of Azolla spp.(Department of soil science and agricultural chemistry, College of horticulture,Vellanikara, 2015) Bhavyasree, K T; KAU; Jayasree Sankar, SA study intended for “Characterization of soil and water of Palakkad eastern plains in relation to growth and nitrogenase content of Azolla spp.” was undertaken in the Department of Soil Science &Agricultural Chemistry, College of Horticulture, KAU, Vellanikkara during 2013-2015. The objectives of the study were to conduct a survey of Azolla spp. in the rice growing tracts of Palakkad eastern plains and to identify soil and water quality parameters congenial for the growth and nitrogenase content of Azolla spp. The preliminary survey conducted in the four block panchayaths of Palakkad eastern plains to identify the prevalence of Azolla revealed two blocks viz. Chittoor and Kollengode to be positive with respect to Azolla and hence, further study was restricted to the grama panchayaths of these blocks. Characterization of soil and water was done in both Azolla growing and non-growing regions. Composition of Azolla collected from different locations was also determined. In order to ascertain the nitrogenase enzyme activity, samples of Azolla collected from five different locations were subjected to Acetylene Reduction Assay (ARA). Among the soil parameters, significant difference was noticed between Azolla growing and non-growing locations with respect to pH , EC, organic carbon, available N, P , total Fe, Mn and Zn in contrast to potassium and copper which did not show any pronounced variation. Soil pH, EC, available P, total Fe, Mn and Zn were comparatively lower in Azolla growing regions. However, available nitrogen in soil was more in Azolla growing locations. Heavy metals like Cd, Cr, Ni and Pb were below the detectable limits in soil. Analysis on flood water quality showed significant effect in the Azolla growing regions on parameters like pH, temperature and dissolved oxygen, Fe, Mn, Zn and Cu. Soil analysis data revealed the pH, EC, soluble Fe, Mn, Zn and Cu to be lower under Azolla growing conditions. Heavy metals like Cd, Cr, Ni and Pb were below the detectable limits. Presence of Azolla decreased the flood water temperature but increased the dissolved oxygen content. On comparison, the composition of Azolla revealed a prominent and significant correlation with location on its content of carbon, nitrogen, phosphorus, potassium and also the C/N ratio. Moisture content varied from 94 to 95 per cent, variation in carbon and nitrogen content was from 22.9 to 39.5 per cent and 2 to 4 per cent respectively among the locations studied. The C/N ratio ranged from 9 to 14. Crude protein content of Azolla registered values between 16 and 22 per cent. The content of phosphorus ranged between 0.20 and 0.23 per cent whereas that of potassium was in the range of 1.2 to 1.5 per cent. Correlation worked out between soil parameters and composition of Azolla disclosed a significant positive effect of soil P on the nitrogen, crude protein and phosphorus content of Azolla. However, soil P was negatively correlated with the C/N ratio of Azolla. Nitrogenase enzyme activity quantified was profoundly affected by the locations. The amount of ethylene produced extended from 192 to 236 nmole ethylene g-1 h-1. It showed a significant negative correlation with soil pH and EC. The study has given valuable information on the influence of soil and flood water quality parameters and locations on Azolla which could be used for further investigations on its nutrient dynamics.
