Spatial variability of glyphosate mineralization and soil microbial characteristics in two Norwegian sandy loam soils as affected by surface topographical features

• Published in: Soil biology & biochemistry 2006-05, Vol.38 (5), p.962-971
• Main Authors: Stenrød, Marianne, Charnay, Marie-Paule, Benoit, Pierre, Eklo, Ole Martin
• Format: Article
• Language: English
• Subjects: Agricultural sciences; Agronomy. Soil science and plant productions; Biochemistry and biology; Biolog EcoPlate; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Glyphosate degradation; Grues; Life Sciences; Microbiology; Organic C mineralization; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil microbial biomass; Soil science; Soil study; Surface topography
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2005.08.014

The aim of this study was to investigate the possible influence of surface topographical features on the spatial variability of glyphosate degradation and some microbial characteristics in sandy loam soil. Soil samples were taken from the ploughed layer across an agricultural field after seedbed preparation for grain (Grue site), and down to 1 m depth under a ridge tilled field (Målselv site), both sites having similar soil textural characteristics (sandy loam soil). Laboratory experiments were performed looking at glyphosate mineralization and soil microbial activity at the Grue site, as well as microbial biomass, activity and substrate utilization patterns at the Målselv site. Microbial biomass and activity decreased, and substrate utilization patterns changed with increasing soil depth, reflecting naturally occurring changes in quantity and quality of soil organic carbon. Further, our results show that considerable spatial heterogeneity in the degradation rate of glyphosate and general carbon utilization exists even across small areas within a single agricultural field. This horizontal variability was observed over several spatial scales, and could not be clearly explained. It evidently arose from differences in environmental factors affecting microbial activity and growth, and topographical features controlling redistribution of water and matter flow patterns were correlated to the investigated soil microbial variables.