PG Thesis
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Item Performance of Ayar nutrient mix on rice grown in coarse sandy soil of Kasaragod(Department of Soil Science and Agricultural Chemistry, Colleg e of Agriculture, Padannakkad, 2024-12-27) Swetha, J; Binitha, N KThe study entitled “performance of ayar nutrient mix on rice grown in coarse sandy soil of Kasaragod” was carried out with the objective of characterization of rice growing soils of AEU 2 and modification and standardization of ayar nutrient mix for the rice grown in the coarse sandy soil. A comprehensive soil characterization study was conducted in AEU 2 by collecting 25 geo-referenced soil and plant samples. Bulk density of the collected samples ranges from 1.02-1.81 Mg m-³, particle density in this region had an average of 2.8 Mg m-³and moisture content ranges from 18.85-38.15%. The predominant soil texture recorded in this region was sandy. Soil reaction was acidic and non saline. Organic carbon content ranged from 0.30-1.68%. Soil was deficient in essential nutrients such as available nitrogen, potassium, calcium, magnesium, zinc and boron, while available phosphorus, sulphur and iron levels were sufficient. Silicon content of the soil was from 55.35 to 130.38 mg kg-1 and aluminum content ranges 198.8-289.5 mg kg-1. On analysis it was found that microbial biomass carbon value ranges 149.88-342.81 µg g-1, dehydrogenase ranges from 1.742-3.82 µmol min-1, phosphatase ranges 3.083-8.921 µmol min-1 and urease ranges from 0.729 1.569 µmol min-1 indicating the low biological activity of the soil. Plant analysis of the study area revealed widespread deficiencies in total nitrogen, manganese and boron, while phosphorus, potassium, calcium, magnesium, sulphur, iron, zinc and copper levels were generally sufficient. Biochemical analysis of grain samples showed total sugar values ranging from 434.2 to 693.76 µg mL-1, vitamin B1 ranging from 2.191 to 5.59 µg mL-1, vitamin B3 from 2.82 to 19.352 µg mL-1and vitamin B5 from 39.564 to 70.146 µg mL-1. The analysis of amino acids such as lysine and glycine were also done and their mean values are 0.057 µg mL-1 and 0.015 µg mL-1respectively. The ayar nutrient mix which had been previously formulated for banana was modified based on the data of nutrient availability in coastal sandy soils and formulated a mixture containing 15% calcium, 7.6% magnesium, 2% sulphur, 1.75% zinc and 1% boron. After one year of airtight storage, the mix showed no change in color or odour changes and remained lump-free. The results of the incubation study proved that treatment T4 (ayar at 30 kg/ha) resulted the highest available calcium, sulphur and boron levels across the four-month study period compared to the control (T1). The value of available magnesium was maximum for treatment T4 during the second and fourth month whereas it was maximum for treatment T3 in the first month. There was no significant change in the available zinc content for the first two months and in the next two months available zinc content was maximum for treatment T4. In the pot culture experiment, there were no significant changes among the various treatment means for the pH and EC of the soil. The organic carbon analysis showed that treatments T2 (KAU POP, 2016) and T6 (T2 + ayar at 25 kg/ha in two equal splits at active tillering and panicle initiation) recorded the highest values. Application of KAU POP and Ayar at 25 kg/ha during active tillering stage led to high levels of available nitrogen, potassium, zinc and aluminum. Treatment T6 was the best treatment with respect to available phosphorus, calcium, boron and silicon, while treatments T7 (T2 + ayar at 30 kg/ha during active tillering stage) and T8 (T2 + ayar at 30 kg/ha in two equal splits during active tillering and panicle initiation stage) were superior with respect to magnesium and sulphur, respectively. The results of the plant analysis during the harvest stage revealed that treatment T7 was superior with respect to total nitrogen, T3 for phosphorus and sulphur, T6 for total potassium and boron and T5 proved to be the best treatment for total calcium, iron and zinc. There was no significant difference among the various treatment means for total magnesium, copper and manganese content in the plant. Treatment T5 exhibited superior performance with respect to growth and yield parameters, including grains per panicle, grain yield, test weight and straw yield. Whereas plant height and leaf length were maximum in treatments T7 and T4, respectively. For the biochemical analysis of the grain treatment T4 had recorded the highest levels of glycine, vitamins B1, B3 and B5. T8 recorded maximum total sugar. Lysine levels showed no significant difference. The salient findings of the study suggest that the application of ayar at 25 kg/ha during the active tillering stage along with KAU POP recommendations (T5) as the best treatment as it improves the nutrient and economical status of the plant. The Ayar nutrient mix proved effective in ameliorating soil fertility constraints, enhancing rice growth and nutritional quality, making it a valuable resource for farmers cultivating rice in challenging coastal sandy soils.Item 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; 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 soils