Biocompost from sugar distillery effluent: effect on metribuzin degradation, sorption and mobility.
BACKGROUND
Metribuzin (4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one) is weakly sorbed in soils and therefore leaches easily to lower soil profiles and results in loss of activity. Soil amendments play an important role in the management of runoff and leaching losses of pesticides from agricultural fields. Therefore, the effect of biocompost from sugarcane distillery effluent on metribuzin degradation and mobility was studied in a sandy loam soil.


RESULTS
Metribuzin was more persistent in biocompost-unamended (T-0) flooded soil (t(1/2)-41.2 days) than in non-flooded (t(1/2) - 33.4 days) soil. Biocompost application at the rate of 2.5 and 5.0% (T-1 and T-2) in non-flooded soils increased metribuzin persistence, but no significant effect was observed on persistence in flooded soils. Freundlich adsorption constants (K(f)) for treatments T-0, T-1 and T-2 were 0.43, 0.64 and 1.13 respectively, suggesting that biocompost application caused increased metribuzin sorption. Leaching studies in packed soil columns indicated that biocompost application affected both metribuzin breakthrough time and maximum concentration in the leachate. Leaching losses of metribuzin were drastically reduced from 93% in control soil (T-0) to 65% (T-1) and 31% (T-2) in biocompost-amended soils.


CONCLUSIONS
Biocompost from sugarcane distillery effluent can be used effectively to reduce downward mobility of metribuzin in low-organic-matter sandy loam soil.
Singh
Neera
N
Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi 110 012, India. drneerasingh@yahoo.com
D001673:Biodegradation, Environmental; D019649:Food Industry; D006540:Herbicides / Q000378:metabolism*; D007220:Industrial Waste; D007700:Kinetics; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D014227:Triazines / Q000378:metabolism*; D014873:Water Pollutants / Q000378:metabolism*
D006540:Herbicides; D007220:Industrial Waste; D012987:Soil; D012989:Soil Pollutants; D014227:Triazines; D014873:Water Pollutants; C009235:metribuzin