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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 Inter-relationship of applied nutrients on growth, productivity and latex flow characteristics of havea brasiliensis muell. arg.(Department of Agronomy, College of Agriculture, Vellayani, 1993) Punnoose, K I; KAU; Sreedharan, CThree field experiments were conducted in three locations representing the major rubber growing regions in South India to study the response to nutrient applications on growth characters, yield and latex flow characteristics and to study the inter-relationship between soil and plant nutrients on yield. It was also envisaged to assess the relative response in the different locations and to make economic analysis of the benefit of manuring. Three levels of 0, 40 and 80 N ha-1, 0, 30 and 60 kg P2O5 ha-1 and 0, 40 and 80 kg k2O ha-1 and two levels of 0 and 10 kg MgO ha-1 were used. A 33 x 2 partially confounded factorial split plot experiment in randomised block design with two replications was followed. The 80 kg level of N and 30 and 40 kg levels respectively of P and K were optimum for girth increment in all the locations. Application of Mg was also beneficial. For virgin bark thickness the 40, 30 and 40 kg levels of N, P and K respectively were sufficient in all the locations and application of Mg was not beneficial. For bark renewal 80 kg N was optimum at Thodupuzha whereas the 40 kg level was sufficient in the other locations. The 60 kg level of P was useful at Kulasekharam and Thodupuzha while 30 kg was sufficient at Balussery. The 40 kg level of K was optimum in all the locations and application of Mg was not beneficial. The 80 kg level of N gave the maximum weight of leaf litter in all places while for P and K the 30 and 40 kg levels respectively were sufficient. Magnesium was beneficial only at Balussery in one year. The 40, 30 and 40 kg levels respectively of N, P and K gave the highest total volume of latex in all the locations except at Balussery where 80 kg K was superior to 40 kg. Application of Mg was beneficial at Balussery while it had a reducing effect at Kulasekharam and no effect at Thodupuzha. Application of N and K reduced the plugging index and that of P and Mg increased it in all the locations. For dry rubber content, the 80 kg level of N was optimum at Kulasekharam while the 40 kg level was sufficient in the other locations. With regard to P and K the 30 and 40 kg levels respectively were sufficient. Application of Mg was beneficial only at Thodupuzha. In the case of yield of rubber 40 kg N and 30 kg P2O5 were found to be optimum in all locations. The 40 kg level of K2O was sufficient at Kulasekharam and Thodupuzha while the 80 kg gave the highest yield at Balussery. At Thodupuzha and Balussery application of Mg was beneficial while at kulasekharam it reduced the yield. Application of N increased the organic carbon content of soil. The available P, K and Mg contents of soil were increased by the application of the respective nutrients. The N, P, K and Mg contents of leaf and latex were increased by application of the respective nutrients. Application of P as rock phosphorus also increased the available Ca content of soil and Ca contents of leaf and latex. The yield of rubber was positively correlated with girth increment, rate of bark renewal, initial flow rate, total volume and dry rubber content of latex and negatively with plugging index. Yield was also positively correlated with the available N, P, K and Ca contents of soil N, K and Ca contents of leaf and P and K contents of latex and negatively correlated with Mg contents of soil and leaf. The strongest correlations with yield were given by soil N, latex P and K and leaf Ca. Total volume of latex was positively correlated with the available N, P, K and Ca contents of soil, N, K and Ca contents of leaf and P and K contents of latex. The dry rubber content of latex was positively correlated with the available N, P and Ca contents of soil, N, K and Ca contents of leaf and N, P, K and Ca contents of latex. The plugging index was positively correlated with the P and Ca contents and negatively with the N and K contents of soil, leaf and latex. Positive correlations, were obtained between soil and leaf nutrients, soil and latex nutrients and leaf and latex nutrients in the case of N, P, K and Ca. In the case of yield of rubber 40 kg N and 30 kg P were found to be optimum in all the locations. The 40 kg level of K was sufficient at Kulasekharam and Thodupuzha while the 80 kg level gave the highest yield at Balussery. Application of Mg was beneficial at Thodupuzha and Balussery while at Kulasekharam it reduced the yield. An overall evaluation of the economic analysis indicated that 40 kg N, 30 kg P2O5 and 40 kg K2O were the optimum doses in all the three locations. Application of Mg was profitable only at Thodupuzha.ThesisItem Open Access Rice based cropping system analysis in kerala(Department of Agronomy, College of Agriculture, Vellayani, 1993) Chidananda Pillai, M R; KAU; Sreedharan, CWith the objectives of identifying the most economic crop combination for the double crop wet rice fields of Kerala and to assess soil fertility changes due to rice based cropping systems and also to find out the residual effects of the summer crops on the succeeding rice crops an investigation was conducted at the R.A.R.S. Pattambi in a split – split plot design, for a period of two years. The salient findings of the investigation are as follows. In the Cassava-rice-rice system 25 per cent saving was recorded for P and K for maximum grain yield of kharif rice than the recommended doses. A saving of 50 per cent each of P and K was recorded for the maximum straw yield than the recommended doses. In cowpea–rice-rice system for maximum grain yield of kharif rice there was a saving of 25 per cent of P and K than recommended doses. The same trend followed for the maximum yield of strew also. In groundnut –rice-rice system, for maximum grain yield of kharif rice there was a saving of 25 per cent of P and K than recommended doses. For the production of maximum straw yield full dose of recommended nutrients were required. In bhindi– rice-rice system for maximum grain yield of kharif rice there was a saving of 50 per cent of P and K than recommended doses. For the production of maximum straw yield full dose of recommended nutrients were essential. In rice-rice-rice system for maximum grain yield a saving of 25 per cent of P and K was recorded than recommended doses. For the production of maximum straw yield full dose of recommended nutrients were required. In fallow-rice-rice system for maximum grain yield full dose of recommended nutrients were essential, whereas for the production of maximum straw yield a saving of 25 per cent of P and K than the full dose was recorded. In cassava, rice and fallow systems for the manifestation of residual effect to the rabi rice, balanced nutrients at high doses are to be applied to the preceding kharif crop where as in the cowpea, groundnut and bhindi systems, residual effects of nutrients are seen manifested to the rabi rice crop even when the kharif rice crop is applied with medium doses of nutrients. There was a trend of slight decrease in the organic carbon content of the soil under all the cropping systems. The status of available nitrogen and potash after one and two year crop sequences also followed the above trend. Regarding the status of phosphorus in the soil, there was a slight increase after one and two year crop sequences. Cassava system produced maximum yield in terms of energy value followed by groundnut. From the economic point of view bhindi system gave the maximum net return. Maximum dry matter production (biomass production potential) was recorded in the cassava system followed by groundnut system. A vegetable crop like bhindi or a tuber crop like cassava seem to be more profitable than growing rice in summer season in the double crop wet rice fields of Kerala, rice being least economic. Among the cropping systems rice-rice-rice system generates maximum employment opportunities for the farm labourers with maximum job opportunities for women labourers as well.ThesisItem Open Access Effect of cover crops on nutrient dynamics in the rubber plantations(Department of Agronomy, College of Agriculture, Vellayani, 1995) Prathapan, K; KAU; Sreedharan, CThree field experiments were conducted at Bethany Estate, Mukkampala, Kanyakumari District from February 1991 to October 1993 to study the effect of cover crops on the nutrient dynamics in immature, mature rubber plantation and an open area. In Experiment I there were two cover crops viz. Pueraria phaseoloides and Mucuna braceata and five levels of NPK viz. 0:0:0, 0:30:30, 10:30:30, 0:60:60 with one year old RRII-105, replicated thrice and statistically laid in RBD. In Experiment II there was one cover crop Mucuna sp alone with five levels of NPK as above with 8 years old RRII-105 replicated 4 times and statistically laid in RBD. In Expt. III there were 10 microplots, with both cover crops. N, P, K, Ca, Mg content of both Hevea and cover crops were increasing as the crops growth progressed. Fertilizer application to cover crops improved the Hevea leaf nutrient content than the absolute control. Among the levels 10:30:30 was found optimum. Mucuna was found better than Pueraria in increasing the Hevea leaf nutrient content. Girth increment was better with 10:30:30. This was found to be optimum under both experiments. More height increment was observed in this level, as well as in cover cropped treatments when compared to absolute control. Biomass production of cover crops were maximum at 10:60:60 followed by 10:30:30 under both experiments. Biomass production, root weight and length were higher in Mucuna and it was found increasing as the crop growth progressed. Nodule count was higher in Pueraria and the fresh weight of nodule per plant was higher in Mucuna as the size of its nodule was found bigger. Soil Moisture retention capacity was found higher under cover cropped plots at both shallow (0-30cm) and deeper (30-60cm) soil depths at-0.033 and -1.5 Mpa pressures than control. Pore space and aggregation percentage were improved whereas bulk density decreased. Among the levels of NPK 10:30:30 was found optimum in improving the soil physical properties. The percentage of improvement was found greater at shallow depth of soil than deeper. Soil moisture content during summer months were improved in the cover cropped area. The soil moisture in than the top soil (0-30cm) was lesser than the bottom soil (30-60cm) in Pueraria grown plots. This trend was reverse in the case of Mucuna. Growing of cover crops improved the microbial population of bacteria, fungi and phosphate solubilising organisms. The level 10:30:30 was found optimum for the better microbial activity. 10:30:30 was found optimum for better yield and Latex Flow Characteristics. Covercropping has increased the latex yield by 15-20%. 10:30:30 was optimum for better leaf litter production of Hevea. In cover cropped plots the leaf litter production was higher and wintering was delayed by 26-30 days over the control. This has enhanced 10 additional tapping days. Girth is positively correlated with cover crop biomass, nutrient uptake, soil available nutrients, soil moisture contents and Hevea leaf nutrient contents. Strongest correlation for girth was found with Hevea leaf N content, and uptake of N by cover crops, suggesting the importance of foliar diagnosis. Yield was negatively correlated with Mg content of soil.ThesisItem Open Access Nutrient- moisture interaction under phasic stress irrigation of sweet potato in summer rice fallows(Department of Agronomy, College of Agriculture,Vellayani, 1994) Muraleedharan, Nair; G, KAU; Muraleedharan, Nair; vA field experiment on sweet potato was laid out in the rice field fallowed during summer season at the Instructional Farm, College of Agriculture, Vellayani. The study was intended to work out of the irrigation schedule and fertilizer practice for sweet potato grown as a catch crop during the summer season of 1990 and 1991. The experiment was designed to economise the use of irrigation water as well as fertilizers by inducing phasic stress at certain phases of plant growth which are considered critical for sweet potato. The field experiment was laid out in a strip plot design replicated thrice with irrigation in horizontal strips and fertility levels in vertical strips. Irrigation water at full CPE was given during tuber initiation phase (10-30 DAP), full CPE at tuber maturity phase (80-100 DAP) and full CPE at tuber initiation and tuber maturity phases. The crop received irrigation at ½ CPE during the rest of the period of plant growth. Nitrogen and potassium were applied @ 25, 50 and 75 kg ha-1 and a uniform dose of P2 O5 @ 50 kg ha-1 and lime @ 500 kg ha-1 were applied. A control plot that received NPK @ 75:50:75 kg ha-1 and FYM @ 10 t ha-1 was maintained for treatment comparison. Growth characters were recorded at an interval of 21 days from planting and it was observed that providing irrigation at full CPE during tuber initiation phase resulted in significant increase in vine length and number of leaves plant-1. Enhanced rate of application of Nitrogen promoted the growth of vines, number of branches plant-1 and number of leaves produced plant-1. Potassium did not exert any influence on these growth characters. Growth analysis studies showed that the LAI was maximum in plots that received irrigation at full CPE during tuber initiation phase. Nitrogen substantially influenced the LAI, higher levels being significantly superior to the lower levels. Higher levels of potassium also influenced the LAI. The NAR and specific leaf weight were the highest in plots that received irrigation at ½ CPE during tuber initiation phase. Both NAR and CGR were high in the early stage of plant growth and decreased towards harvest. Increased rates of nitrogen supply decreased the NAR and specific leaf weight whereas no definite trend could be observed on CGR> Higher levels of potassium had a favourable influence on NAR and CGR. The dry matter of leaves, shoots, fibrous roots and tubers were significantly enhances by providing full CPE during tuber initiation phase. Increasing the level of nitrogen, influenced the dry matter in the aerial parts. The influence of K on dry matter production was not consistent. Tuber bulking rate showed a positive trend under irrigation at full CPE during tuber initiation phase. Nitrogen levels at 50 and 75 kg ha-1 had an overlapping influence on tuber bulking rate and both remained superior to 25 kg ha-1. Scheduling of irrigation did not exert any influence on the length and girth of tuber. However, an increase in the length and a corresponding decrease in the girth were noticed at enhanced rates of nitrogen supply. The number of tubers plant-1 showed a significant improvement by providing irrigation at full CPE during tuber initiation phase. The total number of tubers plant-1 was increased by high rates of N, but did not influence the number of marketable tubers. Application of K at 50 kg ha-1 promoted the production of more tubers. Tuber yield was significantly influenced by irrigation wherein providing full CPE during tuber initiation phase resulted in superior yield of both total and marketable tubers. Tuber yield was maximum at 50 kg ha-1 each of nitrogen and potash. Vine yield was significantly enhanced by higher rates of applied nitrogen. The harvest index and utilization index were enhanced by the application of irrigation water at full CPE during tuber initiation phase. Application of N at 25 kg ha-1 resulted in the production of high starch content whereas the sugar content was increased upto the highest level of 75 kg ha-1. The uptake of nitrogen by vines and tubers showed a progressive increase by applying full CPE during tuber initiation phase. Application of higher levels of nitrogen invariably promoted the uptake of N, P and K by the plant. Application of potash at 50 or 75 kg ha-1 also resulted in higher uptake of potassium. The fertility status of the soil did not show a positive trend by scheduling of irrigation. The plots that received the lowest dose of nitrogen, invariably recorded the highest level of available phosphorus. Available potassium content was also high in plots that received higher rates of potash. Irrigation at full CPE during tuber initiation and/or tuber maturity phase recorded significantly higher water use efficiency and net returns as compared to including stress during tuber initiation phase. Nitrogen and potash both at 50 kg ha-1 recorded the maximum water use efficiency and net returns from sweet potato cultivation.ThesisItem Open Access Weed management in sole and intercropped coconut gardens(Department of Agronomy, College of Horticulture, Vellanikkara, 1990) Savithri, K E; KAU; Sreedharan, CField experiments were conducted during the period from 1986 to 1989 at the Agricultural Research Station, Mannuthy, Thrissur to develop weed management practices for sole and intercropped coconut gardens. There were three fields trials. In trial - I the treatments comprised of three manual methods (digging once, digging twice and sickle weeding), six chemical methods (paraquat three sprays, glyphosate 0.4 kg ha-1, glyphosate 0.8 kg ha-1 dalapan followed by paraquat, paraquat + diuron and paraquat followed by glyphosate), two combinations of manual and chemical methods (2,4-D + diuron immediately after sickle weeding and glyphosate followed by digging) were compared with weed free and unweeded control in underplanted coconut garden. In trial - II, the treatments comprised of two manual methods (spade weeding and sickle weeding ), one cultural method (growing cowpea as an intercrop) two cultural + chemical methods (cowpea followed by paraquat or glyphosate), three pre-emergence herbicides + post-emergence herbicide (diuron followed by paraquat, oxyfluorfen followed by paraquat and atrazine followed by paraquat ) were compared with weed free and unweeded control in coconut+ banana cropping system. Unweeded control in coconut banana cropping system was compared with that in sole crop of coconut . In trial III, the treatments tried in coconut+banana cropping system were eveluated in sole crop of banana and there were thirteen treatments . All these three trials were laid out in Randomised Block Design and replicated thrice.ThesisItem Open Access Effect of nutrition as Influenced by irrigation on growth and yield of oil palm (Elaeis guineensis Jacq)(Department of Agronomy, College of Agriculture, Vellayani, 1994) Thomas, Varghese P; KAU; Sreedharan, CA field experiment was conducted in the oil palm plantations of the Central Plantation Crops Research Institute (CPCRI) Research Centre, Palode, Kerala to study the response of mature oil palm to fertilizer and irrigation applications with respect to growth, yield and uptake of nutrients. There were four levels of fertilizers viz: F0- 0:0:0, F1-600: 300: 600, F2- 1200: 600: 1200 and F3-1800: 900: 1800 g N : p20 : k20 palm-1 year-1. The three levels of irrigation were: I0-no irrigation, I1-45 1 palm-1 day-1 and I2-90 1 palm-1 day-1. The 4x3 factorial experiment was laid out in randomised block design with three replications. The study was also envisaged to establish the importance of leaf nutrient ratios of yield group of palms and its application in identifying nutrient limitations through the Diagnosis and Recommendation Integrated System (DRIS) approach in oil palm. The influence of various climatic parameters on yield of oil palm was studied by relating the monthly yield of oil palm in the field experiment with the monthly weather variables as far behind as 42 months before harvest. Fertilizer application of 1200 g N+600 g P2O5+ 1200 g K2O palm-1 year-1 was found to improve the growth characters such as annual leaf production, number of leaves on the crown, dry matter production of leaf, trunk and bunches, total dry matter production and the crop growth rate. Increase in yield attributes such as number of female inflorescences, sex ratio, average single fruit weight and the number of bunches at F2 level contributed to the significantly high FFB yield at F2 level of fertilizer application. Both palm oil and palm kernel oil production were also maximum at F2 level. For the uptake of nutrients N,P and K by palm parts as well as by the palm as a whole, the F2 level of fertilizer application was found to be the optimum. It was observed that 79% of the total uptake of N, 77% of P and 82% of K are removed annually through leaves and bunches from the system. A K-Mg antagonism was also detected in nutrient uptake. The yield of palm was found positively correlated with leaf production, leaf area, net assimilation rate, number of bunches produced, vegetative dry matter, P and K in soil and the total uptake of N, P and K by the palm. Both net income and benefit cost ratio were also found favorable at F2 level of fertilizer application. Irrigation at I2 level has resulted in increased leaf production, leaflets per leaf, leaf area, leaf dry matter, mesocarp dry matter and the bunch dry matter. Physiological parameters like relative water content, leaf water potential, stomatal resistance, leaf temperature and net photosynthesis were all favourable at I2 level of irrigation. Female flower production, sex ratio, single fruit weight and number of bunches produced were also more in I2 treatment. This has resulted in increasing FFB production at I2 level. Palm oil production was also more at I2 level. Total uptake of N, P, K and Ca were also found to be maximum at I2 level of irrigation. The net profit and benefit cost ratio were also maximum at I2 level. Leaf nutrient ratios of palms in different yield groups: were used to evolve parameters and norms for Diagnosis and Recommendation Integrated System (DRIS) in oil palm. The range of nutrient ratios within the zones of balance, moderate imbalance and imbalance were determined which were also illustrated through DRIS charts for three nutrient combinations. The DRIS approach was used to evaluate the nutrient balancing of the different treatments of the field. The order of relative importance of the five nutrients was determined using nutrient imbalance index (NII) values as indicated below: K> P> N> Mg> Ca The F2 level of fertilizer application in the experiment was found to be the most balanced among the tested fertilizer levels. The possibility of magnesium becoming a potential limiting nutrient at higher levels of fertilizer application has been brought out from the study. The superiority of balanced nutrition in increasing total dry matter production and bunch yield became evident from the study. The studies on climatic relationship with yield revealed that the pattern of variation in monthly yield remained the same inspite of irrigation throughout the summer months. The relationship of monthly yield of oil palm with monthly climatic parameters was evaluated up to a period 42 months before harvest. When eight climatic parameters were considered together, the influence of these weather parameters at seven specific lag periods viz. 1-4, 9-10, 13-16, 20-23, 25-28, 32-33 and 37-40 were found important for oil palm. Of these the lag 25-28 was found to be the most important as the relationship of climatic parameters with yield at this period was more. Relative humidity, maximum temperature and rainfall were identified as the most important variables influencing palm yield. Using results obtained from regression studies yield prediction models were constituted. It is concluded that yield prediction using the three or more variables is possible for oil palm 26-28 months in advance of harvest. The salient findings from the study is that a fertilizer dose of 1200g N+ 600 g P2O5+ 1200 g K2O palm-1 year-1 and irrigation level of 90 l palm-1 day-1 applied through drip system during the summer months are required to obtain maximum FFB yield from mature oil palm. The order of importance of nutrients for oil palm is determined as K> P> N> Mg> Ca. With the above level of fertilizer application the palms were found to have a more balanced nutrition. However continued application of fertilizers might possibly lead to magnesium deficiency unless corrective measures are adopted. Relative humidity, maximum temperature and rainfall are found to be the most important climatic parameters influencing oil palm yields. The influence of climatic parameters at seven lag periods 1-4, 9-10, 13-16, 20-23, 25-28, 32-33 and 37-40 were found to be more pronounced on palm yield. From these studies it became possible to predict oil palm yields 26-28 months in advance using models based on these weather parameters.ThesisItem Open Access Status and availability of sulphur in the major paddy soils of Kerala and the response of rice to sulphatic fertilizers(Department of Agronomy, College of Horticulture, Vellenikkara, 1995) Purushothaman Nair, N; KAU; Thajuddin, EA series of investigations were undertaken entitled “ Status and availability of sulphor in the major paddy soils of Kerala and the response of rice to sulphatic fertilizers” at College, of Hortculture, Kerala Agricultural University, Vellanikkara from 1990 to 1994 with the objectives: (i) to assess the sulphor status of major paddy soils of Kerala (viz. alluvial and brown hydromorphic) (ii) to identify and appropriate soil test procedure for estimation of available sulphor in these soils (iii) to determine the critical levels of sulphor in the soils and plant (iv) to study the response of rice to two popular sulphatic fertilizers of Kerala (viz. ammonium sulphate and ammonium phosphate sulphate) and (v) to assess the sulphur use efficiency of 35S labelled ammonium sulphate and ammonium phosphate sulphate. The studies were conducted in four parts. In Part 1 of the studies, 105 samples each from alluvial and brown hydromorphic soils were collected from 10 rice growing districts of Kerala based on area under rice crop, estimated soluble SO4-S, adsorbed SO4-S, total sulphur content and organic + non sulphate sulphur contents. The soils were classified in to categories of low, medium and high based on the available SO4-S extracted by CaCl2. From this part of the study it was found out that 56 per cent of alluvial soils and 83 per cent of brown hydromorphic soils were deficient in sulphor. Sulphur deficient locations and sulphur sufficient locations were delineated. Sulphur status map for rice soils of Kerala was prepared. In Part II, representative soils belonging to three status categories (low, medium and high) were collected from 30 locations each of alluvial and brown hydromorphic types and conducted a pot culture with two treatments (S0 and S40 kg S ha-1) with two replications. These soils were analysed with 12 methods of sulphur estimation using different extractants. The relative yield of grain, straw and total biomass and relative uptake of nutrient S were estimated. Correlations between relative yields and sulphur extracted by different methods were studied. From this the suitability of the methods were evaluated. It was found that all the 12 methods studied could extract available SO4 – S satisfactorily. Scatter diagrams were drawn with relative yields of grain, straw, biomass and uptake of S against the sulphur extracted by different extractants. The critical levels were worked out following the Cate and Nelson procedure. The best suitable extractants for the estimation of sulphur in alluvial soil and brown hydromorphic soil were found out by assessing the responsiveness of rice in soils classified as deficient by each extractant. It was observed that in alluvial soil the critical levels varied between 5 to 22 ppm for different extractants. Monocalcium phosphate was to be the best extractant for alluvial soils. In brown hydromorphic soil the critical levels varied between 6 ppm to 20 ppm. Monocalcium phosphate + acetic acid was found to be the best extractant for brown hydromorphic soils. Relationship between plant content of S and relative yield of grain studied by Cate and Nelson procedure showed that in alluvial soil 0.075 per cent S and in brown hydromorphic soil 0.08 per cent S in plant at harvest were critical concentrations below which response to applied sulphur can be expected. In Part III of the studies, two locations having sulphur deficiency, one each falling under alluvial and brown hydromorphic soil, were selected for field experiments (CSRC, Karamana – alluvial and RARS, Pattambi –brown hydromorphic). Field experiments were conducted in these two locations for two seasons (Kharif and Rabi 1992-93) with nine treatments (control – S0, 4 levels of ammonium sulphate – S10, S20, S30, and S40 and 4 levels of ammonium phosphate sulphate - S10, S20, S30, and S40 kg S ha-1 in 2x4+1 factorial RBD with 3 replications). The results revealed that sulphur levels significantly increased yield of grain and straw and growth attributes like productive tillers. Sink capacity and dry matter production were increased by sulphur application. Among the two sources ammonium phosphate sulphate was found to be superior to the other. Agronomic efficiency, physiological efficiency and apparent recovery efficiency showed that the efficiencies were maximum at low level of sulphur (10 kg S ha-1). Sulphur levels increased, S, N and K uptake. The ratios of nutrients removed per ton showed that the ratios of these nutrients to sulphur narrowed down with sulphur application over control. The gross income, net income and B: C ratio were higher for sulphur application and the highest values were for 30 kg S ha-1. The physical optimum levels ranged between 25.34 to 31.47 and the economic optimum levels ranged between 23.06 and 28.73 for the sources in two locations at the two seasons. The economic optimum levels of AS and APS were 27 and 25 kg S ha-1 respectively. There was no residual effect in general, except that at brown hydromorphic soil sulphur @ 40 kg ha-1 could contribute to meet the requirement of sulphur for the succeeding crop in producing more grain yield. In Part IV of the studies, a pot culture experiment with 35 S labelled AS and APS was conducted at Radiotracer lab. The radioassay and chemical analysis were conducted. The soil and levels of S were same as that of field experiment. The specific activity of grain and straw increased with higher levels of 35 S application. The sulphur use efficiency in alluvial soil was highest at sulphur rate of 20 kg S ha-1. In brown hydromorphic soil sulphur use efficiency was highest at 30 kg S ha-1. Sulphur taken up from fertilizer significantly increased with sulphur levels in both the soils. A-values were on par for different levels in both the soils. Brown Bydromorphic soil showed higher A-value, sulphur use efficiency and total sulphur taken up from fertilizer.ThesisItem Open Access Applicability of diagnosis and recommendation integrated system (Dris) in coconut palm (Cocos nucifera L.)(Department of Agronomy, College of Horticulture, Vellanikkara, 1994) Mathewkutty, T I; KAU; Tajuddin, EA study on the applicability of diagnosis and recommendation integrated system (DRIS) in coconut palm (Cocos nucifera L.) was conducted at the department of Agronomy, college of Horticulture, Vellanikkara during 1991-’94. The study was conducted using coconut population of var. West Coast Tall being maintained at three research stations of Kerala Agricultural University namely, Regional Agricultural Research Station, Pilicode; Agricultural Research Station, Mannuthy and Coconut Research Station, Balaramapurm. Eight hundred palms varying in their yield from 5.8 to 162.7 nuts per palm per year were selected for developing DRIS norms. Leaf samples were collected from the 14th frond and were analysed for macro and micronutrients namely N, P, K, Ca, Mg, S, CI, Fe, Zn and Mn employing titrimetric, spectrophotometric, flame photometric or atomic absorption spectrophotometric method depending on the element. DRIS norms were developed using the data generated from the chemical analysis of leaf samples using the methodology of Beaufils (1973). The palm population was divided into low-and high-yielding subpopulations. The means and variances of nutrient concentration as well as their ratios (totalling 90 including inverse ratios) were worked out for the two subpopulations. The variance ratios were then computed for each nutrient and each nutrient ratio to examine their statistical significance and those discriminating significantly between the two subpopulations were considered for DRIS norms. When both the ratio and its inverse form were significant, the one which had a higher variance ratio was selected. Mean values of the selected individual nutrients and nutrient ratios of the high yielding sub population formed the DRIS norms. Five nutrients and 33 nutrient ratios were selected on the basis of higher variance ratios as DRIS norms. Thirty one DRIS charts involving selected three-nutrient combinations can be constructed from the selected nutrient ratios. A qualitative assessment of nutritional imbalance involving three nutrients is possible by utilising these DRIS charts. DRIS technique also provides another approach that can accommodate any number of nutrient ratios in which nutrient indices are worked out using DRIS norms and the observed nutrient ratios for the plant under test. The DRIS index for a nutrient indicates its relative abundance among the nutrients considered in its computation. Lower the value of the index for a nutrient, greater is its requirement. The accuracy of diagnosis of nutritional imbalance by DRIS approach was tested for ten selected nutrients in palm receiving varying levels of NPK under a factorial experiment. From this it was observed that DRIS index for a nutrient varied not only with the applied level of that nutrient but also with the applied level of other nutrients and an improvement in yield with increase in DRIS index value was obtained for the application of K. The overall nutritional balance of a palm is given by the nutrient imbalance index (NII) which is the sum of the nutrient indices irrespective of the sign. A strong negative relationship was observed between this NII and yield. DRIS norms developed on the basis of different yield cut-off values showed that they were affected by the criterion used for dividing the population into low-and high-yielding groups. Similarly DRIS norms developed for different soil type as well as for different climatic situations under the same soil type had also shown variations indicating their influence on DRIS. A comparison of DRIS approach with critical level approach indicated that DRIS could supplement information on balance or imbalance of nutrients in coconut palm and it could be used beneficially in nutrient management programmes in conjunction with critical level approach.