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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 Management of calcium, magnesium and boron deficiency for enhancing yield and quality in chilli (Capsicum annuum L.)(Department of Soil Science and Agricultural Chemistry, College of Agriculture ,Padanakkad, 2022-04-28) Anjitha K.; KAU; Sailaja kumari M SThe investigation entitled ‘Management of calcium, magnesium and boron deficiency for enhancing yield and quality in chilli’ was carried out at Instructional farm, Nileshwar, College of Agriculture Padannakkad, with an objective to develop nutrient management practices for mitigating calcium, magnesium and boron deficiency and to evaluate its effect on growth, yield and quality parameters. The field experiment was carried out during December 2020 to May 2021. The experiment was carried out with chilli variety Anugraha, in randomized block design with ten treatments and three replications. Treatment combinations were T1(KAU POP + lime (based on soil test)), T2 (T1 + 125 kg gypsum per hectare), T3 (T1 + 80 kg magnesium sulphate per hectare), T4 (T1 + 125 kg gypsum per hectare + 80 kg magnesium sulphate per hectare), T5 (T1 + foliar application of borax (0.2%)), T6 (T2 + foliar application of borax (0.2%)), T7 (T3 + foliar application of borax (0.2%)), T8 (T4 + foliar application of borax (0.2%)), T9 (KAU POP + dolomite (based on soil test)) and T10 (T9 + foliar application of borax (0.2%)). Soil application of amendments were done as a single dose and foliar nutrition was given four times in a 20 days interval. Analysis of experimental results showed that various treatments showed significant effect on growth characters, fruit quality parameters as well as nutrient content in both soil and plant, over KAU POP recommendation. Significant positive effect of treatments on plant root characters and total dry matter production was observed whereas plant height and days to 50% flowering were found to be non significant. Among the treatments, maximum tap root length (13.50 cm), root volume (23.23 cm3 ), root shoot ratio (0.16) and total dry matter production (2694.65 kg ha-1 ) were recorded in T8 (KAU POP + lime application based on soil test) +125 kg gypsum per hectare + 80 kg magnesium sulphate per hectare + foliar application of borax (0.2%). Various treatments showed significant influence on yield and yield attributes. Maximum fruit weight (37.16 g) and total fruit yield (4456.79 kg ha-1 ) was also observed in T8 and in case of fruit yield, it was significantly superior to all other treatments. Combined application of gypsum, magnesium sulphate and borax were effective and maximized fruit yield. 94 Soil analysis was carried out at flowering and harvest wherein, the treatments showed significant effect on soil pH, EC, available potassium, calcium, magnesium, sulphur, iron, manganese and zinc content whereas available nitrogen, phosphorus, copper and boron were not influenced by treatments. Addition of calcium and magnesium sources significantly increased available calcium and magnesium content in soil. Among the various treatments, the highest available calcium was recorded in T8 and was on par with T2, T6 and T4 at flowering. Highest available magnesium content was recorded in T9 and T10 at flowering and harvest respectively. Analysis of Index leaves at flowering and total plant analysis at harvest were carried out and it was found that plant nutrient content was significantly influenced by treatments. Significant effect of various treatments on plant nutrients except nitrogen and phosphorus was observed. Foliar application of borax significantly improved boron content in plants. Fruit quality parameters such as capsaicin, oleoresin, ascorbic acid and shelf life and total nutrient content were analysed and results showed significant positive response to treatments. Analysis of nutrient content in fruits showed that primary nutrients mainly, nitrogen and potassium, secondary nutrients and micronutrients in fruits were significantly influenced by various treatments. The treatment, T8 (KAU POP + lime based on soil test) +125 kg gypsum per hectare + 80 kg magnesium sulphate per hectare + foliar application of borax (0.2%)) recorded highest capsaicin (0.352 %), oleoresin (11.00 %), ascorbic acid (96.83 mg 100 g-1 ) and maximum shelf life (13.66 days) in chilli. The results obtained from the experiment revealed the significant influence of soil amendments over KAU POP recommendation and it can be concluded that combined application of gypsum, magnesium sulphate and borax was effective for increasing fruit yield and quality in chilliThesisItem Open Access Soil quality index and nutrient balance in rice-rice cropping system under long-term fertilizer experiment(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2021) Drishya, D S; KAU; Thulasi, VLong-term experiments provide the best possible platform for studying the changes in soil properties and processes, identifying emerging trends in nutrient imbalances and deficiencies and help to formulate future strategies for maintaining soil health and quality. The present study entitled “Soil quality index and nutrient balance in rice-rice cropping system under Long Term Fertilizer Experiment” was undertaken at RARS, Pattambi and College of Agriculture, Vellanikkara. The objectives were set out to estimate soil quality index and NPK balance in rice-rice cropping system as affected by nutrient management practices under Long Term Fertilizer Experiment. The Long Term Fertilizer Experiment (LTFE) in rice-rice cropping system maintained (since 1997) at RARS Pattambi has been laid out in RBD consists of 12 treatments viz.,T1 : 50 per cent NPK, T2 : 100 per cent NPK, T3 : 150 per cent NPK, T4 : 100 per cent NPK + 600 kg ha -1 CaCO3 , T5 : 100 per cent NPK, T6 : 100 per cent NP, T7 : 100 per cent N, T8 : 100 per cent NPK + Farm Yard Manure (FYM) @ 5 t ha -1 , T9 : 50 per cent NPK + FYM @ 5 t ha -1 , T10 : 100 per cent NPK + in situ growing of Sesbania aculeata, T11 : 50 per cent NPK + in situ growing of Sesbania aculeata and T12 : Absolute control (No fertilizer or manures). The soil samples from 0-15 cm depth were collected from the different treatments of LTFE after the harvest of Virippu crop, 2020 and were analysed for various physical, chemical and biological properties. Principal Component Analysis (PCA) was performed to arrive at the Minimum Data Set (MDS) and Soil Quality Index (SQI) was formulated for different nutrient management practices. Integrated nutrient management with FYM and in situ green manuring with daincha recorded higher grain and straw yields of rice. The increase in fertilizer load into the soil resulted in increase in yields while the omission of primary nutrients resulted as decline in yields. Integrated Nutrient Management practice (INM) of application of FYM along with 100 percent NPK had lower bulk density (1.17 Mg m-3 ) and higher water holding capacity (43.65 %), higher levels of available nutrients and enzyme activities in the soil. However, dehydrogenase activity did not follow the same trend as that of microbial biomass carbon in treatments wherein fertilizers alone were applied indicating the chances of shift in the microbial populations as a result of the long term application of nutrient management practices. Principal Component Analysis (PCA) was performed for 28 soil attributes to develop the MDS and SQI was formulated using non linear scoring method. The MDS included bulk density, porosity, soil pH, permanganate oxidizable carbon, available N, total N, available sulphur, microbial biomass carbon, acid phosphatase and aryl sulfatase activities. The SQI ranged from 1.82 to 3.01. The SQI declined in the order of: T8> T10 >T9> T11> T4> T3> T2= T1> T5> T6 >T7> T12. The highest SQI was observed in T8 where 100 per cent NPK and FYM were applied. When the dosage of fertilizers was increased from 50% to 100% NPK on integration with FYM, the SQI increased. The soil quality index of the INM treatments (55.50 to 62.11%) and lime incorporation (52.98%) were categorized under medium category as per the computed Relative SQI (RSQI) values. The virippu crop (2020) under LTFE maintained at RARS Pattambi was monitored and various inputs and outputs regarding primary nutrients were assessed for balance predictions using NUTMON toolbox. The NUTMON toolbox includes five inflows, viz., mineral fertilizers (IN1), manure (IN2), atmospheric deposition (IN3), biological N fixation (IN4), and sedimentation (IN5), and five outflows, viz., harvested product (OUT1), crop residues (OUT2), leaching (OUT3), gaseous losses (OUT4), and erosion (OUT5). Nutrient flows like fertilizers, manures, crop residues and harvested outputs were monitored and measured during the experiment. Other flows like nitrogen fixation, leaching, and erosion were estimated by means of regression models from the data related to climate and crop parameters. Available NPK content of soils, rice grain, straw, stubbles, weeds and all inputs were analysed and stored in background database. The data were fed into the data processing module of the NUTMON toolbox to arrive at the partial and total balance of N, P and K in the experimental soil. The total balance of N, P and K were found to decline in order of: T3>T7>T8>T6>T5>T2>T4>T10>T9>T1>T11>T12 for N, T3>T8>T6>T10>T2>T5>T4>T9>T1>T11>T12>T7 for P and T3>T2>T5>T8>T9>T10>T4>T11>T1>T12>T7>T6 for K Summarizing the results, integrated nutrient management with FYM and in situ green manuring with daincha recorded higher yield and available nutrients in the soil. The incorporation inorganic fertilizers with FYM, daincha and lime maintain the soil quality index in the long run while, SQI was poor in control, imbalanced nutrition as well as in treatments where only fertilizers were incorporated. The balance sheet of P establishes the need for maintenance dose of P fertilizers in rice-rice cropping system. The negative balance of N and K indicate the need for supplementing the nitrogen pool and the possibility of mining of K on long term intensive cropping, respectively. Further study should be focused on monitoring the soil quality index at regular intervals and analyzing the effect of nutrient management practices on microbial diversity in rhizosphere and phyllosphere.ThesisItem Open Access Evaluation of water hyacinth co- composts for nutrient retention in lateritic soil(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2021) Anisha, V A; KAU; Durga Devi, K MWater hyacinth is a serious menace in low land ecosystems and it’s spread has threatened water quality and aquatic life. Various biological, chemical and physical methods that have been employed to control the weed has yielded minimal results. Hence management through utilization is a viable strategy. It can be effectively utilized in many ways to support crop production. Co-composting has been proved as a promising technique for safe and quick disposal of the weed by utilizing the co-substrates viz., poultry manure, sawdust, biochar, glyricidia, paddy straw, dried leaves and cattle manure. As the weed accumulates N, P, K and other essential nutrients, compost made from water hyacinth can be utilized for improving soil fertility and crop production. Hence, the present investigation entitled “Evaluation of water hyacinth co-composts for nutrient retention in lateritic soil” was under taken in the Department of Soil Science and Agricultural Chemistry at College of Agriculture, Vellanikkara during 2020-2021. The objectives were; (i) To find out the suitable combination of water hyacinth and co-substrates for enhancing the quality of water hyacinth composts (ii) To assess the nutrient retention capacity of different co-composts in lateritic soil. Different co-substrates were collected from nearby areas and water hyacinth was collected from Kole lands of Thrissur. Water hyacinth and co-substrates were characterized prior to composting. Water hyacinth co-composts (vermi compost) were prepared using the aforesaid substrates in concrete tanks. The physical and chemical properties of the composting mixtures were recorded at 40 days interval starting from 20 days of composting until 100 days. The yield of water hyacinth co-composts was estimated and the various co-composts were characterized for their physical and chemical properties. Incubation study was conducted to evaluate the nutrient retention capacity of different water hyacinth co-composts in lateritic soil during December 2020 with eight treatments and three replications (soil+ 7 co-composts and soil alone as absolute control). The lateritic soil for study was collected from Instructional Farm, Vellanikkara and analysed for chemical properties. Compost amended soils were incubated for a period of 28 days and nutrient retention capacity (N, P, K, Ca, Mg, S, B, Zn) was estimated at 4 different time periods after incubation (7, 14, 21, 28 days). Data on characterization of co-substrates revealed that substrates vary in their chemical properties and nutrient content. Among the co-substrates, poultry manure possessed many favourable characteristics. Changes in physical and chemical properties of composting mixtures at different intervals indicated the progress of composting process and stage of compost maturity. All the co-substrates gave reasonably good yield of water hyacinth co-composts. A notable increase in compost yield to an extent of 159.7 per cent was realized in the biochar treatment. Addition of co-substrates improved the bulk density and porosity of water hyacinth co-composts. Application of co-substrates improved the pH of final compost. Highest increase was noticed in the treatment with paddy straw. Addition of paddy straw had significant adverse effect on the electrical conductivity of final co-compost (170.6 % increase in EC over water hyacinth sole treatment) and all the other treatments showed EC below maximum permissible limit for plant growth. The total carbon content of all the co-composts was higher than water hyacinth sole compost. Nitrogen content of the co-compost was improved to a greater extent by the application of paddy straw and poultry manure. Co-composts with sawdust, biochar and dried leaves had significantly lower quantity of nitrogen compared to water hyacinth sole compost. Glyricidia and poultry manure were highly effective in improving total phosphorus content of the co-compost. Total potassium content of water hyacinth compost was significantly improved with the addition of co-substrates like paddy straw and biochar, the extent of increase being 192 and 170 per cent, respectively. Carbon to nitrogen ratio of water hyacinth co-compost was significantly lowered by using poultry manure as a co-substrate. Addition of poultry manure improved all the three secondary nutrients viz., Ca, Mg and sulphur to a higher magnitude. No favourable effect was noticed on the boron content of co-compost by the addition of different co-substrates. However, Fe and Mn levels of final co-composts were considerably lower than the water hyacinth sole compost. This could be considered as a favourable effect of co-composting of water hyacinth with different substrates. Zinc content of the co-compost was significantly improved by the inclusion of co-substrate particularly with the use of poultry manure and dried leaves. Copper content of the co-compost was significantly higher with the addition of poultry manure as co-substate. The addition of co-compost to lateritic soil, improved retention of nutrients particularly nitrogen. The only exception was co-compost with paddy straw (0.9 per cent decrease in the nitrogen retention capacity). Irrespective of the treatments, cocompost retained all the phosphorus and boron present in the co-compost amended soil. The soil’s potassium, magnesium, sulphur and zinc retention capacity could be improved when amended with water hyacinth co-compost. In general, soil with biochar co-compost showed significantly high retention capacity with respect to plant nutrients particularly nitrogen. Further study should be focused on field experiments to test the agronomic efficiency of different water hyacinth co-composts, testing suitability of various crop residues and organic wastes as co-substrates and to derive suitable substrate combinations and ratios to eliminate the adverse effects of co-substrate on compost quality.ThesisItem Open Access Soil test crop response studies in cluster bean (Cyamopsis tetragonoloba L.) in lateritic soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellanikkara, 2022) Ayisha, V V; KAU; Rajalekshmi, KCluster bean, commonly known as guar, is a legume crop cultivated as a vegetable, green manure and forage crop. India is the leading producer of cluster bean in the world and accounts for around 80 per cent of global production. The generalised application of fertilizers by farmers result in under or over fertilization, lowering production and profitability while also polluting the environment. So the emphasis on soil test based balanced fertilizer recommendation has become more pertinent in the current scenario of high fertilizer costs and yield maximisation programmes. Hence, the investigation entitled “Soil test crop response studies in cluster bean (Cyamopsis tetragonoloba L.) in lateritic soils of Kerala” was undertaken. The study was conducted at College of Agriculture, Vellanikkara in lateritic soils (Ultisol) in the STCR field during 2020-2021 with the objective of developing soil test based fertilizer prescription equation for cluster bean using inorganic fertilizers alone and with the combined use of organic manures. A fertility gradient experiment was conducted to create soil fertility gradient in the field by applying graded doses of N, P and K fertilizers and raising fodder maize var. CO1. After the development of fertility gradient, the main STCR experiment was conducted in the same field with the test crop, cluster bean var. Pusa naubahar. The treatment structure consisted of four levels of nitrogen (0, 10, 20 and 40 kg ha-1 ), four levels of phosphorous (0, 30, 60 and 120 kg ha-1 ) and four levels of potassium (0, 40, 80 and 120 kg ha-1 ) along with three levels of FYM (0, 15 and 25 t ha-1 ). The basic parameters such as nutrient requirement (NR) and contributions of nutrients from soil (CS), fertilizer (CF) and FYM (COM) were computed from the field experimental data. The nutrient requirements (NR) for cluster bean were worked out as 0.68, 0.05 and 0.22 kg N, P2O5 and K2O to produce one quintal yield. The contributions from soil (CS) were estimated as 9.84, 2.29 and 1.99 per cent of N, P2O5 and K2O respectively. The contributions from fertilizer (CF) were calculated as 90.90, 3.29 and 10.82 per cent and that from FYM (COM) were 7.17, 1.92 and 2.96 per cent for N, P2O5 and K2O respectively. From the above basic data, fertilizer prescription equation for specific yield targets of cluster bean in the lateritic soils were derived as follows, NPK alone: FN = 0.74*T - 0.11*SN FP2O5 = 1.47*T – 1.59*SP FK2O = 2.05*T- 0.22*SK NPK + FYM (IPNS) FN = 0.74*T - 0.11*SN – 0.08*ON FP2O5 = 1.47*T – 1.59*SP – 1.34*OP FK2O = 2.05*T - 0.22*SK – 0.33*OK Where, FN, FP2O5 and FK2O = Fertilizer N, P2O5 and K2O in kg ha-1 T = Yield target in q ha-1 SN, SP and SK = STV for available N, P and K in kg ha-1 . ON, OP and OK = Amount of N, P and K supplied through FYM in kg ha-1 . The multiple regression model calibrated with yield as dependent variable and soil test results and inorganic fertilizer doses as independent variables had 62.5 per cent predictability. The yield of cluster bean increased with the application of NPK alone and IPNS viz. NPK plus FYM treatment and the magnitude of increase was higher under IPNS over NPK alone. The study is useful to adjust fertilizer doses based on yield target and available resources of organic manure with the farmers. The equations developed for cluster bean should be tested in places with similar agro climate and soil situations for validation.ThesisItem Open Access Approaches to assess chlorpyrifos degradation in northern laterite soils of Kasaragod (AEU 11)(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Padanakkad, 2022) Arya, P R; KAU; Binitha, N KThe investigation on “Approaches to assess chlorpyrifos degradation in northern laterite soils of Kasaragod (AEU 11)” was undertaken with the objective to evaluate the impact of physical, chemical and biological methods on degradation of chlorpyrifos in laterite soils. The study was carried out during 2019 – 2021 at College of Agriculture, Padannakkad in two incubation experiments. The incubation experiment no. 1 was carried out to know the pattern and time required for degradation of chlorpyrifos in soil. Northern laterite soils (AEU 11) collected from Pilicode were selected for the study. Pot culture study was conducted in five pots filled with 10 kg soil and drenched with chlorpyrifos (20 EC) at the concentration of 2.5 ml/L. Soil was analyzed at weekly intervals and results from the incubation study showed that chlorpyrifos content was reduced to 34.76% within 60 days. Significant decrease on soil pH (2.29%) was noticed after the application of chlorpyrifos. Chloride and phosphate ions were increased during the incubation period due to release of these ions from the chlorpyrifos compound during the degradation process. Microbial biomass carbon (8.2%) in soil was reduced significantly. Based on the results and findings from the incubation experiment no.1, duration of incubation experiment no.2 was decided for 60 days. The incubation experiment no. 2 was carried out to assess the best method of degradation of chlorpyrifos in laterite soil. The experiment was laid out in CRD with 12 treatments and three replications. Physical, chemical and biological agents were applied and evaluated to study their effect on degradation of chlorpyrifos. The treatment combinations were control (T1), hydrogen peroxide-5% (T2), Fenton reagent -0.5% (T3), hydrogen peroxide-5% + Fenton reagent -0.5% (T4), Pseudomonas fluorescens (T5), Trichoderma viride (T6), Pseudomonas fluorescens + Trichoderma viride (T7), sunlight – 6hrs (T8), ultra violet – 4hrs (T9), sunlight – 6hrs + ultra violet – 4hrs (T10), soil under saturated condition at 5 cm level of submergence (T11) and soil under saturated condition at 5 cm level of submergence with azolla (T12) Results from the incubation study revealed that combination of Pseudomonas fluorescens + Trichoderma viride showed the highest rate (74.99%) of chlorpyrifos degradation followed by Pseudomonas fluorescens (69.94 %) and Trichoderma viride (66.35 %) within 60 days. Effect of chlorpyrifos application on chemical properties of soil was studied at biweekly intervals. Soil pH was found to be significantly decreased throughout the incubation period. Highest pH (5.09) was recorded in treatment T10 (sunlight + UV light) whereas lowest in T4 (4.93). Effect of treatments on chloride ions in soil were found to be non significant, however it was continuously increased throughout the incubation period. Phosphate ions in soil decreased significantly in the initial period followed by gradual increase in the phosphate ions in soil. In the 8th week, 106 T5 recorded the highest phosphate ions (31.80 mg kg-1 ) while T1 recorded the lowest phosphate ions (28.86 mg kg-1 ) in soil. The effect of treatment application on soil biological properties were studied and showed that chlorpyrifos has inhibitory effect on microbial biomass carbon, dehydrogenase, phosphatase and urease activities of the soil immediately after chlorpyrifos application but later restored the activities. The treatments that received biological agents were not much affected with respect to the biological properties of the soil. Biological treatments such as T5 recorded the highest dehydrogenase activity (11.74 µg TPF g-1 soil day-1 ) while the T6 recorded the highest phosphatase activity (17.06 µg PNP g-1 soil hr-1 ) of the soil. Treatment T7 recorded the highest microbial biomass carbon (99.15 µg g-1 ) and the urease activity (36.16 µg NH4 + -N g-1 soil hr-1 ) in soil. There was a significant effect with respect to the two treatments maintained under submergence. The leachate from the chlorpyrifos treated soils were analysed at biweekly intervals. Treatments showed significant effect on leachate of chlorpyrifos residue at sixth and eighth week intervals. Treatment T11 (2598.62 µg L-1 ) showed the highest degradation followed by T12 (3318.07 µg L-1 ). The growth of azolla was normal during the initial period, later decaying of azolla was noticed. Growth of azolla was inhibited under the chlorpyrifos treatment because it could not tolerate the residual effect of chlorpyrifos. The results from the investigation revealed that chlorpyrifos degradation using combination of Pseudomonas fluorescens + Trichoderma viride had the best potential to remove the residues of chlorpyrifos insecticide present in treated soils. Biological treatments are recorded as the prominent agents in chlorpyrifos degradation and also maintains the soil health. On account of these findings, we can recommend the use of biological agents in combination or alone, as an ideal approach for degradation of chlorpyrifos in laterite soilsThesisItem Open Access Assessment of soil quality in the post - flood scenario of AEU 9 in Pathanamthitta district of Kerala and generation of GIS maps(Department of Soil Science and Agricultural chemistry, College of Agriculture, Vellayani, 2021) Shafna, S H; KAU; Gladis, RA study entitled “Assessment of soil quality in the post-flood scenario of AEU 9 in Pathanamthitta district of Kerala and generation of GIS maps” was carried out during 2018-20 with the objective to evaluate the soil quality in the flood affected areas of AEU 9 of Pathanamthitta district, to work out the soil quality index and to generate maps of various soil attributes and quality indices using GIS techniques. Survey conducted to identify the flood affected areas in AEU 9 of Pathanamthitta district revealed that the flood affected panchayats includes Kaviyur, Thumbamon, Kulanada, Thottapuzhassery, Kallupara, Mezhuvely, Panthalam, Kozhanchery, Aranmula, and Mallapally. All these panchayats were severely affected by flood havoc and submergence that occurred in Manimala, Pamba and Achankovil rivers during August 2018. A total of seventy five geo referenced surface soil samples were collected from the flood affected panchayats and analyzed for various physical, chemical and biological attributes. Minimum data set of soil indicators for computing soil quality was selected using principal component analysis. The selected parameters were sand content, bulk density, available B, available S, available K, available Mn and organic carbon. Scores and weights were assigned to each selected indicator, and computed the soil quality index. GIS techniques were used to generate thematic maps of various soil attributes and soil quality indices. Sediment deposition was observed in all panchayats, while highest deposition of sand and silt were observed in Aranmula and Thumbamon panchayats. The flood did not cause much alteration in the soil texture of AEU 9 of pathanamthitta. The dominant textural class was loam. The particle density and bulk density of soil ranged from 2.07 to 2.45 and 0.87 to 1.76 Mg m -3 respectively. More than 89 per cent of the soils showed porosity in the range of 50 to 80 per cent. The soil moisture content ranged between 15.2 to 50.8 per cent. The water holding capacity and water stable aggregates ranged from 25.4 to 62.4 per cent and 38.6 to 68.5 per cent respectively. 137The electrical conductivity of soil ranged between 0.05 and 0.40 dS m -1 . Post flood soil showed an increase in the organic carbon status of the soil. Majority (95 %) of soil comes under medium and high organic carbon status after flood. About 54.7 per cent of the soils are medium in available N content. Available phosphorus content varied between 8.10 and 104 kg ha -1 with a mean of 31.9 kg ha -1 and available potassium varied between 78.7 and 493 kg ha -1 with a mean of 246 kgha -1 . The post flood soils are adequate in available sulphur (92 %) and deficient in boron status (100 %). The soil quality analysis revealed that majority of soils had high soil quality index (86.7%). Land quality index was very low in 64 % of soils while 32 % samples showed low land quality index. Nutrient index for nitrogen was low in most of the panchayats, medium and high for phosphorus, potassium and organic carbon. The results of the study revealed that most of the soil became strongly acidic after flood. Organic carbon, potassium, phosphorus and sulphur are high and medium status while nitrogen is low in most of the panchayats. Deficiency of calcium and magnesium increases after flood. The entire study area showed deficiency of boron. The results outline the need for regular liming to control soil acidity and alleviate calcium deficiency. It is also suggested to supplement magnesium and boron to improve soil quality.ThesisItem Open Access Assessment of soil quality in the post - flood scenario of AEU 9 in Pathanamthitta district of Kerala and generation of GIS maps(Department of Soil Science and Agricultural chemistry, College of Agriculture, Vellayani, 2021) Shafna, S H; KAU; Gladis, RA study entitled “Assessment of soil quality in the post-flood scenario of AEU 9 in Pathanamthitta district of Kerala and generation of GIS maps” was carried out during 2018-20 with the objective to evaluate the soil quality in the flood affected areas of AEU 9 of Pathanamthitta district, to work out the soil quality index and to generate maps of various soil attributes and quality indices using GIS techniques. Survey conducted to identify the flood affected areas in AEU 9 of Pathanamthitta district revealed that the flood affected panchayats includes Kaviyur, Thumbamon, Kulanada, Thottapuzhassery, Kallupara, Mezhuvely, Panthalam, Kozhanchery, Aranmula, and Mallapally. All these panchayats were severely affected by flood havoc and submergence that occurred in Manimala, Pamba and Achankovil rivers during August 2018. A total of seventy five geo referenced surface soil samples were collected from the flood affected panchayats and analyzed for various physical, chemical and biological attributes. Minimum data set of soil indicators for computing soil quality was selected using principal component analysis. The selected parameters were sand content, bulk density, available B, available S, available K, available Mn and organic carbon. Scores and weights were assigned to each selected indicator, and computed the soil quality index. GIS techniques were used to generate thematic maps of various soil attributes and soil quality indices. Sediment deposition was observed in all panchayats, while highest deposition of sand and silt were observed in Aranmula and Thumbamon panchayats. The flood did not cause much alteration in the soil texture of AEU 9 of pathanamthitta. The dominant textural class was loam. The particle density and bulk density of soil ranged from 2.07 to 2.45 and 0.87 to 1.76 Mg m -3 respectively. More than 89 per cent of the soils showed porosity in the range of 50 to 80 per cent. The soil moisture content ranged between 15.2 to 50.8 per cent. The water holding capacity and water stable aggregates ranged from 25.4 to 62.4 per cent and 38.6 to 68.5 per cent respectively. 137The electrical conductivity of soil ranged between 0.05 and 0.40 dS m -1 . Post flood soil showed an increase in the organic carbon status of the soil. Majority (95 %) of soil comes under medium and high organic carbon status after flood. About 54.7 per cent of the soils are medium in available N content. Available phosphorus content varied between 8.10 and 104 kg ha -1 with a mean of 31.9 kg ha -1 and available potassium varied between 78.7 and 493 kg ha -1 with a mean of 246 kgha -1 . The post flood soils are adequate in available sulphur (92 %) and deficient in boron status (100 %). The soil quality analysis revealed that majority of soils had high soil quality index (86.7%). Land quality index was very low in 64 % of soils while 32 % samples showed low land quality index. Nutrient index for nitrogen was low in most of the panchayats, medium and high for phosphorus, potassium and organic carbon. The results of the study revealed that most of the soil became strongly acidic after flood. Organic carbon, potassium, phosphorus and sulphur are high and medium status while nitrogen is low in most of the panchayats. Deficiency of calcium and magnesium increases after flood. The entire study area showed deficiency of boron. The results outline the need for regular liming to control soil acidity and alleviate calcium deficiency. It is also suggested to supplement magnesium and boron to improve soil quality.ThesisItem Open Access Utilisation of potassium rich crop residues for retention of potassium in lateritic soil(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2021) Sreelakshmi, P; KAU; Durga Devi, K MPotassium is a versatile vital nutrient for regular plant and animal growth and development. It is regarded as a "quality nutrient" because of its multifunctional role in metabolism. Kaolinite clay minerals prevalent in lateritic soils of Kerala, have lower activity and prevent the retention of available forms of potassium. Potassic fertilisers are often overlooked in fertiliser schedules due to their high unsubsidized cost. There are some K rich organic sources that are ignored by the farmers and are left or burnt in the soil. The utilisation of organic K resources like rice straw and plantain compost made from banana wastes are regarded good alternatives for synthetic potassic fertilisers. The present investigation consisted of three experiments viz., (i) assessment of decomposition dynamics of rice straw and its K release, (ii) K adsorption study on rice straw and prepared plantain compost and (iii) an incubation study in lateritic soil with different sources of potassium. The decomposition rate of rice straw has increased with the period of its incubation and it showed only a partial decomposition of 51.9 % at 90 days due to the presence of more amount of lignin, cellulose and hemicellulose content which takes more time for its degradation. The potassium release rate increased to 84.28 % at 90 days of its decomposition. The adsorption study on rice straw with different levels of KCl solution at different periods of decomposition revealed that as the solution concentration increased, the quantity of K adsorbed on rice straw also increased along with the increase in incubation period. Similarly, plantain compost that was prepared using vermi technology also showed an increased trend in the value of quantity of K adsorbed on compost as the KCl concentration increased. Because of its smaller particle size and larger surface area, plantain compost has stronger adsorption and buffer power than rice straw. Rice straw with potash (T1), plantain compost with potash (T2), wood ash, FYM with potash (T3), rice straw with lime and potash (T4), plantain compost with lime and potash (T5), wood ash, FYM with lime and potash (T6), lime and potash (T7), potash alone (T8), and absolute control (T9) treatments were used in the incubation study. The physico-chemical characteristics of soil such as pH, EC, organic carbon, available N, P, Ca, Mg, S, Fe, Cu, Zn, and Mn were determined at initial and final days of incubation. Data on the different fractions of soil K indicated that the treatment containing rice straw with lime and Muriate of potash (T4) showed the higher value of total K, exchangeable K and non-exchangeable K after 90 days of incubation. The reason might be that the presence of more inter planar sites in rice straw has trapped the K+ ions in fixed form since the material is not completely decomposed. At the same time incorporation of rice straw has enhanced the CEC of the soil thus enhancing greater adsorption of exchangeable K from unavailable forms by mass effect. The current study showed that combining organic K resources with lime and K fertilisers resulted in significant increases in soil K fractions. Integrated application of rice straw with lime and K fertiliser can be considered as the best method for long-term cultivation because it has the ability to retain and release more K, particularly nonexchangeable, exchangeable, and total K, allowing for continuous uptake of K by the crops for normal growth and development. The usage of plantain compost in combination with lime and Muriate of potash has resulted in increased availability of K as well as micronutrients by maintaining favourable pH.ThesisItem Open Access Effect of salinity on carbon mineralisation under different land uses in Pokkali ecosystem(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2022) Anju, Sajan; KAU; Sreelatha, A KSoil forms the largest storehouse for terrestrial organic carbon, encompassing approximately two-thirds of the carbon in the ecosystem. This plays a pivotal role in reducing atmospheric CO2 and combating global warming and related concerns. Differences in land use have a considerable effect on soil organic carbon pools and fluxes. Mineralisation of soil organic carbon enhances CO2 emission into the atmosphere and salinity of soil can affect the rate of this process. In this context, an investigation was carried out with the objective to study the effect of salinity on carbon mineralisation under different land uses in Pokkali ecosystem. The study was conducted by collecting georeferenced surface soil samples (0- 20 cm) from three land uses of Pokkali ecosystem namely rice-prawn, rice alone and prawn alone from Kumbalangi, RRS, Vyttila and Kadamakkudy respectively. The samples were analyzed for different soil properties such as pH, electrical conductivity (EC), particle size, cation exchange capacity, bulk density and estimated soil organic carbon pools such as soil organic carbon, labile carbon, water soluble carbon and microbial biomass carbon. Soil organic carbon stocks and dehydrogenase activity were also estimated as per standard procedures. Carbon mineralisation was studied by a laboratory incubation experiment for 74 days where two sets of soil (with and without 1% paddy straw) was amended with different concentrations of CaSO4 and Na2SO4 alone or both in combinations of 40 and 80 mmol per kg soil in order to get the desired change in electrical conductivity similar to field conditions. The mean pH registered for rice-prawn, rice alone and prawn alone land uses were under neutral range and mean EC were less than 4 dS m-1. Soil texture of rice-prawn and rice alone belonged to clay and prawn alone in sandy clay loam class. Cation exchange capacity was highest in rice-prawn and lowest in prawn alone land use. The highest mean bulk density was observed in prawn alone and the lowest in rice-prawn land uses. The results revealed that rice-prawn land use recorded the highest organic carbon pools and prawn alone land use recorded the lowest organic carbon pools. Rice-prawn land use recorded higher content of soil organic carbon, labile carbon, water soluble carbon, microbial biomass carbon and total carbon followed by rice alone land use due to abundance of organic matter in these soils. The maximum soil organic carbon stock was recorded in rice alone (26.46 Mg ha -1) and minimum in rice-prawn (22.53 Mg ha -1) land use. The maximum dehydrogenase activity was recorded from rice alone (2959.697 µg TPF h-1 g-1) and the lowest from prawn alone (2132.491 µg TPF h-1 g-1) land uses. Carbon mineralisation study revealed that CO2 evolved from soil decreased with time. The maximum CO2 was evolved on day 11 for rice-prawn and prawn alone land uses and day 17 for rice alone land use and declined steadily thereafter. The maximum cumulative CO2 was recorded from the treatments other than control (without paddy straw and salts). The lowest mean cumulative CO2 in the control was recorded from rice- prawn (7.2 mg 100 g-1) land use and the highest recorded from prawn alone (26.48 mg 100 g-1) followed by rice alone (25.15 mg 100 g-1) land uses. A significant positive correlation was observed between pH, dehydrogenase activity and total organic carbon with cumulative CO2 in all land uses. After 74 days of incubation study, the pH of control was reduced and that of other treatments (with paddy straw and salts) was increased in all land uses. The EC of the treatments with salts amendments were more than 4 dS m-1 in all land uses before the start of incubation. After the incubation period, EC decreased in all salt amendments of different land uses and increased in treatments without salt amendments. Dehydrogenase activity and total carbon were found higher in the treatments with paddy straw and salts than in control. Relatively higher dehydrogenase activity was recorded in rice-prawn land use followed by prawn alone and rice alone land uses. The EC was positively correlated with dehydrogenase activity which stimulated carbon mineralisation in these soils. In these land uses, there was no discernible difference between paddy straw and salt amended treatments with respect to carbon mineralisation. Both the dehydrogenase activity and the total carbon content contributed to carbon mineralisation process. In Pokkali ecosystems, rice-prawn land use recorded the highest soil organic carbon pools and the lowest carbon mineralisation, indicating the existence of an environment that is conducive for building organic carbon which is crucial for sequestering more carbon into these soils. As the salinity increased carbon mineralisation was also increased. The rice cultivation in the low saline phase reduces salinity by leaching out the accumulated salts, whereas prawn farming does not. Therefore, prawn alone land use remains saline throughout the year, resulting in increased carbon mineralisation and decreased carbon sequestration. This study emphasizes the importance of integrated rice-prawn farming systems in Pokkali lands to maintain soil quality and slow down the global warming through increased carbon sequestration.
