Field-Scale Variation in Microbial Activity and Soil Properties in Relation to Mineralization and Sorption of Pesticides in a Sandy Soil

• Published in: Journal of environmental quality Vol. 37; no. 5; pp. 1710 - 1718
• Main Authors: Vinther, F.P, Brinch, U.C, Elsgaard, L, Fredslund, L, Iversen, B.V, Torp, S, Jacobsen, C.S
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy, Crop Science Society of America, Soil Science Society 01.09.2008; American Society of Agronomy
• Subjects: Adsorption; Agricultural land; Agrochemicals; analogs & derivatives; analysis; Aquatic habitats; arylsulfatase; Biomass; Carbon; carbon dioxide; chemistry; clay fraction; Denmark; environmental fate; field experimentation; Glycine; Glycine - analogs & derivatives; Glycine - chemistry; Glyphosate; groundwater contamination; Groundwater reservoirs; Herbicides; Herbicides - chemistry; Leaching; metabolism; metribuzin; Microbial activity; Microbiology; Mineralization; nitrophenols; Organic carbon; Pesticide Residues; Pesticides; Pesticides - chemistry; Sandy soils; Silicon Dioxide; Silicon Dioxide - chemistry; Soil; Soil - analysis; soil depth; soil enzymes; Soil Microbiology; soil microorganisms; soil organic carbon; Soil Pollutants; Soil Pollutants - chemistry; soil pollution; Soil properties; Soils; Sorption; spatial variation; Surface water; Triazines; Triazines - chemistry; Denmark
• ISSN: 0047-2425; 1537-2537; 1537-2537
• DOI: 10.2134/jeq2006.0201

Pesticides applied to agricultural soils are subject to environmental concerns because leaching to groundwater reservoirs and aquatic habitats may occur. Knowledge of field variation of pesticide-related parameters is required to evaluate the vulnerability of pesticide leaching. The mineralization and sorption of the pesticides glyphosate and metribuzin and the pesticide degradation product triazinamin in a field were measured and compared with the field-scale variation of geochemical and microbiological parameters. We focused on the soil parameters clay and organic carbon (C) content and on soil respiratory and enzymatic processes and microbial biomass. These parameters were measured in soil samples taken at two depths (Ap and Bs horizon) in 51 sampling points from a 4-ha agricultural fine sandy soil field. The results indicated that the spatial variation of the soil parameters, and in particular the content of organic C, had a major influence on the variability of the microbial parameters and on sorption and pesticide mineralization in the soil. For glyphosate, with a co-metabolic pathway for degradation, the mineralization was increased in soils with high microbial activity. The spatial variability, expressed as the CV, was about five times higher in the Bs horizon than in the Ap horizon, and the local-scale variation within 100 m2 areas were two to three times lower than the field-scale variation within the entire field of about 4 ha.