An Asian Journal of Soil Science

H. M. Pushpa ¹, R. C. Gowda ², D. V. Naveen ¹, T. Bhagyalakshmi ¹, D. C. Hunumanthappa ¹

Affiliations
1 Department of Soil Science and Agricultural Chemistry, University of Agricultural Chemistry, G.K.V.K., Bengaluru(KARNATAKA), IN
2 Department of Soil Science and Agricultural Chemistry, University of Agricultural Chemistry, G.K.V.K., Bengaluru (KARNATAKA), IN

Abstract

No Abstract

Keywords

Root biomass, Root length, Nutrient contents, Nutrient uptake

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D. V. Naveen ¹, R. C. Gowda ¹, B. Mamatha ¹

Affiliations
1 Department of Soil Science and Agricultural Chemistry, College of Agriculture, University of Agricultural Science, G.K.V.K., Bengaluru (Karnataka), IN

Abstract

Field experiment was conducted at Zonal Agricultural Research center, Kathalagere, during Kharif 2008. To study persistence and residues of pyrazosulfuron-ethyl in soil and ground water in transplanted rice ecosystem were estimated using HPLC technique. Pyrazosulfuron-ethyl was applied at 25 g a.i. ha^-1 and 50 g a.i. ha^-1 with and without addition of recommended farm yard manure in transplanted rice. The study revealed that the residue of pyrazosulfuron-ethyl in soils ranged from 0.0103 and 0.0199 mg kg^-1, respectively with FYM at recommended and double the recommended dose on 2^nd day of application. And without FYM the residues were 0.0116 and 0.0229 mg kg^-1, respectively. The residues were detected up to 35 days only. The half-life of pyrazosulfuron-ethyl ranged from 16.6 to 21 days. The results revealed that the residues of pyrazosulfuronethyl were below the detectable level in the post harvest soil, paddy grain and straw. No residues of pyrazosulfuron-ethyl were detected in ground water up to two weeks after the application of pyrazosulfuron ethyl. After two weeks the residues were detected in ground water collected from both the piezometers which were applied with recommended and double the recommended dose of pyrazosulfuron-ethyl. The residues ranged from 0.0071 to 0.0042 mg kg^-1 between 21^st and 28^th day, respectively, after which the residues were below the detectable level both at recommended and double the recommended level of application. A maximum of 0.0154 mg kg^-1 on 21^st day and minimum of 0.0023 mg kg^-1 of pyrazosulfuron ethyl residues on 35^th day were detected in the underground water.

Keywords

Pyrazosulfuron-Ethyl, Half-Life, HPLC.

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D. V. Naveen ¹, R. C. Gowda ¹, T. H. Hanumantharaju ¹, T. Bhagyalakshmi ¹

Affiliations
1 Department of Soil Science and Agricultural Chemistry, College of Agriculture, University of Agricultural Science, G.K.V.K., Bengaluru (Karnataka), IN

Abstract

Sorption studies were conducted with pyrazosulfuron-ethyl using batch equilibration technique and HPLC analysis. Four different paddy growing soils of Kathalagere, Mandya, Mudigere and Mangalore soil of Southern transitional zone, Southern dry zone, Hilly zone and Coastal zones of Southern Karnataka were used in the study with a pH of 7.3, 6.9, 6.1 and 5.8 and organic matter (g kg^-1) of 12.9, 10.9, 6.4 and 10.4, respectively. The sorption isotherm (n) values were 0.104, 0.101, 0.085 and 0.165 for Kathalagere, Mandya, Mudigere and Mangalore soils, respectively. The sorption isotherm for pyrazosulfuron-ethyl was non-linear in all soils, as explained by the Freundlich equation (n < 1.0), indicating differential distribution of site energies for sorption. In general adsorption isotherms fitted well with Freundlich equation (r^-2 > 0.96), and Freundlich constants 'K', 'Koc' and 'K_c' values were in the range from 5.45 to 9.52, 1099.46 to 1436.12 and 32.24 to 49.07 in different soils and described in the order of Kathalagere > Mandya > Mudigere > Mangalore, which is also in the order of decreasing organic matter content in the soils. The coefficient of determination showed an improvement up to 96 per cent using quadratic functions, suggesting a better goodness of fit in preceding pyrazosulfuron-ethyl sorption compared to the linearised form of the Freundlich equation. The cumulative desorption of five days of pyrazosulfuron-ethyl in these soils were determined and it ranged from 22.3 to 41.1 mg kg^-1 in Kathalagere soil, 25.6 to 49.4 mg kg^-1 in Mandya soil, 37.1 to 51.9 mg kg^-1 in Mudigere soil and 39.9 to 55.7 mg kg^-1 in Mangalore soil. The desorption was also in decreasing order of Mangalore > Mudigere > Mandya > Kathalagere soils. The sorption of pyrazosulfuron-ethyl increased with increasing organic matter content and was significantly correlated with organic matter content of the soils where as clay content did not greatly affect the sorption as indicated by low regression coefficient.

Keywords

Pyrazosulfuron-Ethyl, Sorption, Freundlich Equation, HPLC.

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