Interpretation of soil enzyme activities in a comparison of tillage practices along a topographic and textural gradient

Assessment of the impacts of soil conservation practices requires measureme nt of the resulting changes in soil quality at scales inclusive of soil var iability comparable to that of typical farms. The objective of this study w as to compare changes in six soil enzyme activities (urease, glutaminase, p hosphatase, arylsulfatase, beta-glucosidase and dehydrogenase) and organic carbon (OC) content resulting from implementation of no-till along a topogr aphic and soil textural gradient. Activities of beta-glucosidase, glutamina se, phosphatase and arylsulfatase, and OC content were greater in coarse-te xtured soils at a lower slope-position than in fine-textured soil at an upp er slope-position. Tillage practice influenced activities of urease, glutam inase, beta-glucosidase and dehydrogenase but not OC content. The effect of tillage practice on enzyme activities was influenced by sampling depth and slope-position. Phosphatase and arylsulfatase activities of the Ap horizon behaved as indices of soil organic matter (SOM) content along the topograp hic gradient. Urease and dehydrogenase activities behaved as indices of soi l biochemical activity within the Ap horizon. When interpreted in these ter ms, soil enzyme activities are comparable to other integrative measurements and as such describe system behavior and attributes.