title: County-scale spatial distribution of soil enzyme activities and enzyme activity indices in agricultural land: implications for soil quality assessment.
abstract: Here the spatial distribution of soil enzymatic properties in agricultural land was evaluated on a county-wide (567 km(2)) scale in Changwu, Shaanxi Province, China. The spatial variations in activities of five hydrolytic enzymes were examined using geostatistical methods. The relationships between soil enzyme activities and other soil properties were evaluated using both an integrated total enzyme activity index (TEI) and the geometric mean of enzyme activities (GME). At the county scale, soil invertase, phosphatase, and catalase activities were moderately spatially correlated, whereas urease and dehydrogenase activities were weakly spatially correlated. Correlation analysis showed that both TEI and GME were better correlated with selected soil physicochemical properties than single enzyme activities. Multivariate regression analysis showed that soil OM content had the strongest positive effect while soil pH had a negative effect on the two enzyme activity indices. In addition, total phosphorous content had a positive effect on TEI and GME in orchard soils, whereas alkali-hydrolyzable nitrogen and available potassium contents, respectively, had negative and positive effects on these two enzyme indices in cropland soils. The results indicate that land use changes strongly affect soil enzyme activities in agricultural land, where TEI provides a sensitive biological indicator for soil quality.
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Xiangping
authors.identifier: 0000-0002-0425-947X
authors.initials: X
authors.lastname: Tan
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Baoni
authors.initials: B
authors.lastname: Xie
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Junxing
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Wenxiang
authors.initials: W
authors.lastname: He
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Life Science, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Gehong
authors.initials: G
authors.lastname: Wei
mesh_terms: D002681:China; D004798:Enzymes / Q000032:analysis*; D051639:Gardening; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D011188:Potassium / Q000032:analysis; D011786:Quality Control; D012987:Soil / Q000737:chemistry* / Q000592:standards
chemical_list: D004798:Enzymes; D012987:Soil; D010758:Phosphorus; D009584:Nitrogen; D011188:Potassium