Browsing by Author "Greeshma Suresh."

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    Residue distribution and mobility of chlorantraniliprole formulations in soil and it's uptake by rice (Oryza sativa L.)
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2023-03-28) Greeshma Suresh.; Thomas George
    The study entitled ‘Residue distribution and mobility of chlorantraniliprole formulations in soil and its uptake by rice (Oryza sativa L.)’ was conducted at the Department of Soil Science and Agricultural Chemistry and the laboratory attached to the All-India Network Project (AINP) on Pesticide Residues, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala during 2018-22. The main objectives of the experiment were to investigate and understand the persistence, transformation, and mobility of chlorantraniliprole in soils and leachate water and the uptake and dissipation of residues in rice (Oryza sativa L.) The study was conducted in laterite and coastal alluvium soils of Kerala. The representative soil samples of laterite soil were collected from the fields located within the campus of the College of Agriculture, Vellayani and coastal alluvium soils from the wet lands of the Integrated Farming System Research Station, Kerala Agricultural University, Karamana (8.4736 ⸰N; 76.914 ⸰E). The physical and chemical properties of respective soils revealed that, laterite soil was moderately acidic (pH 5.7) and coastal alluvium soil was strongly acidic (pH 5.2) in nature. The bulk density and particle density of the laterite soil was 1.60 and 2.65 Mg m-3and 1.36 and 2.57 Mg m-3 for coastal alluvium soil respectively. The electrical conductivity was 0.27 and 0.28 dS m-1 for laterite and coastal alluvium soil respectively. The cation exchange capacity of the soil was found to be 3.41 and 5.18 cmol (+) kg-1 for laterite and coastal alluvium soils respectively. The organic carbon was high in coastal alluvium soil (1.07 %) than laterite soil (0.63 %). The estimated major primary nutrient content was, available nitrogen (203 kg ha-1 and 338.69 kg ha-1); available phosphorus (21.7 kg ha-1and 14.48 kg ha-1); available potassium (228 kg ha-1and 121 kg ha-1) respectively. The secondary nutrients such as calcium, magnesium and sulphur were found to be 250, 42 and 43 ppm for laterite soil and 230, 132, 98 ppm for coastal alluvium soil respectively. A suitable method was validated for standardizing the analytical procedures for estimation of chlorantraniliprole residues in soil, plant, water, grains and straw by QuEChERS method and liquid-liquid partitioning using dichloromethane (DCM) in water. The residues were estimated and quantified by using LC-MS/MS and the method gave satisfactory recovery values of chlorantraniliprole for soil, water, and plant with good RSD (%) for recoveries. The analytical procedures gave good recovery for the chlorantraniliprole residues when spiked with 0.01, 0.05, 0.10, 0.5 and 1.0 levels and LOQ of chlorantraniliprole was determined as 0.01 mg kg-1. The recovery percentage ranged from 90.34 - 96.12 and 84.91 - 95.57 in laterite and coastal alluvium soils respectively. Similarly, the recovery percentage ranged from 97.72 - 99.75, 94.93 - 96.16, 88.97- 95.43 and 89.63- 95.43 respectively in water, plant, straw, and grains. The studies on persistence of chlorantraniliprole in laterite (S1) and coastal alluvium soils (S2) were performed under two different soil moisture conditions viz., field capacity (M1) and flooded (M2) by spiking (1, 2 and 4 mg kg-1) under laboratory conditions. The residues were estimated and quantified by using LCMS/ MS method. The half- life of chlorantraniliprole in the laterite soil when applied at 1, 2 and 4 mg kg-1 levels under the field capacity were 10.01, 15.67 and 21.16 days and the half- life 7.45, 10.25 and 12.69 days under flooded condition respectively. Similarly, the half- life of chlorantraniliprole in the coastal alluvium soil when applied at 1, 2 and 4 mg kg-1 levels were 13.84, 17.10 and 23.88 days under the field capacity and 9.18, 10.72 and 13.35 days under flooded condition respectively. The persistence was higher in coastal alluvium soil and degradation of chlorantraniliprole was faster at flooded condition than in field capacity condition for both the soils. Application of chlorantraniliprole at higher concentrations resulted in prolonged persistence compared to lower application levels. Mobility of chlorantraniliprole in laterite and coastal alluvium were assessed by analyzing the residue at different depths after loading 150μg of chlorantraniliprole followed by subsequent elution with 20ml, 40ml, 80ml and 160 ml of water equivalent to 50mm, 100mm, 200mm and 400mm rainfall. Majority of the residues were accumulated in 0- 5cm cross sections of the tube and presence of residues in lower layers were indicated by increasing the level of irrigation. The percentage of chlorantraniliprole residues in top 0 -5 cm in laterite soil was 63.73, 52.31, 31.48 and 27.77 and coastal alluvium was 73.46, 56.58, 34.48 and 25.70 on elution with 20ml, 40ml, 80ml and 160 ml of water respectively. Leaching potential was higher for laterite soil compared to coastal alluvium soil due to presence of low clay and organic matter content. Chlorantraniliprole residues were detected in leachate water for soil columns eluted with 160 ml of water for both the soils, whereas, the residues detected in leachate water was below limit of quantification (LOQ) in soil columns eluted with 20, 40 and 80 ml of water. Research data revealed that, type of soil, level of irrigation and depth of soil column influenced the mobility of chlorantraniliprole in soil The field experiment was conducted at the research fields of the Integrated Farming System Research Station, Karamana, Kerala Agricultural University. The study proposes to understand the probable side effects and residue accumulation in leaf, grains, and straw after the use of two different formulations of chlorantraniliprole viz., chlorantraniliprole 18.5 SC (Coragen ) and chlorantraniliprole 0.4 % G (Ferterra) each at 30 and 40 g a.i per ha, respectively in rice, the most important staple crop of Kerala, when applied to the treatment plots. The frequency of application was single - 25 days after transplanting (DAT), double (25 and 50 DAT) and triple (25, 50 and 75 DAT) applications. The persistence and dissipation pattern in soil and plant and the respective half-life values were calculated under field condition. The calculated half-life values of chlorantraniliprole for foliar (Coragen 18.5 SC) applications for T1 (single), T2 (double) and T3 (triple) were 6.93, 7.24, 8.9 days, respectively. Similarly, half-life for soil application of chlorantraniliprole (Ferterra 0.4 % G) T4 (single), T5 (double) and T6 (triple) were 7.63, 8.2, and 10.8 days respectively, in soil. The half-life values in plants were 9.15, 11.8 and 12.59 days for T3, T5 and T6, respectively. Chlorantraniliprole residues in straw and grains obtained from field study were also estimated. The residues detected in straw for treatments T3, T5 and T6 were 0.183, 0.076 and 0.282 mg kg-1 respectively. The residues in T1, T2 and T4 were found to be below the limit of quantification (LOQ). The residues in fresh grains and after parboiling were estimated and from which the extent of removal of residues was determined. The parboiling of grains was found to be an effective method of decontamination by higher dissipation of residues. In the case of grains, the initial residues detected in T3, T5 and T6 were 0.143, 0.283 and 0.382 mg kg-1 and on parboiling, this was reduced to 0.045, 0.106 and 0.159 mg kg-1 respectively. The per cent dissipation after parboiling were 68.53, 62.54 and 58.37 per cent for T3, T5 and T6, respectively. The studies on metabolism/ transformation products of chlorantraniliprole revealed that, no toxic metabolites were detected in soil or any plant parts. The soil enzyme activity tests were used as a measure of metabolic activity of micro-organisms in soil from field application. The residual effect of chlorantraniliprole formulations on soil microbes were also assessed indirectly using enzyme assays viz., dehydrogenase and urease activities in soil. The soil samples were collected from field experiment plot, at 0th, 15th, 30th, 45th and 60th day after application of chlorantraniliprole. In coastal alluvium soil, the dehydrogenase as well as urease activity was reduced due to the residual effect of chlorantraniliprole. Granular formulation (Ferterra 0.4 G) had more impact on activity of soil microbes, compared to foliar formulation (Coragen 18.5 SC). The frequency of application also influenced the soil microbial activity and the enzyme activities approached to control conditions by the 75th day after the last application for all the treatments except T6. Leachate study was conducted in tray by application of Ferterra 0.4 % G in two soils viz., laterite and coastal alluvium soil under cropped condition and collection of leachate water as well as soil for residue analysis. The dissipation pattern showed higher persistence of chlorantraniliprole in coastal alluvium soil than laterite soil, but residues detected in leachate water was more in laterite soil. In brief, laterite soils had higher dissipation potential than coastal alluvium soils. The persistence of chlorantraniliprole under field capacity condition was higher than flooded condition for both the soils. The mobility of chlorantraniliprole was found to be slightly higher in laterite soil compared to coastal alluvium soil and indicates its moderate mobility behavior. There exists a possibility of groundwater pollution with the application of higher concentration of chlorantraniliprole or due to heavy rainfall. The application of chlorantraniliprole formulations on crops in laterite soil may cause higher risk of groundwater contamination than coastal alluvium soils. The presence of higher amount of organic matter content in coastal alluvium soils is responsible for reducing the downward flow in soil profile to an extent. Field study revealed that, foliar application had lower residual effect than soil application of chlorantraniliprole. The frequency of application and type of formulation also affect the residual activity in soil and plants. Soil microbial activity was reduced initially but shifted to normal conditions within 60 days after application for single and double application, and by 75 days in the case of triple application of chlorantraniliprole (Ferterra 0.4 % G). The present findings may be used for modelling the environmental fate of chlorantraniliprole in laterite and coastal alluvium soils under different moisture levels and field conditions. The optimum use of chlorantraniliprole with recommended dosage on crops and soil along with field application of organic matter can prevent the ground water contamination significantly. Detailed study in undisturbed soil column is recommended in future studies to give better insight on leaching and mobility of chlorantraniliprole in soil.