Wednesday, 9 November 2005
21

Effect of Landuse on Selected Soil Parameters and Enzyme Activities.

Abdelmoniem Hassan1, Ramble O. Ankumah1, and Sherwood McIntyre2. (1) Tuskegee University, Dept. of Agricultural & Environmental Sciences, Tuskegee, AL 360, (2) USDA-ARS, 1404 Pinehurst, Edmond, OK 73034

Soil quality has been defined as the capacity of soil to function withiin ecosystem to sustain biological productivity, maintain environmental quality and promote plant health. Cropping practices and land use pattern can affect soil quality. Soil enzymes and microbial community are important contributors to the soil ecosystem functions. In this work our objectives were to determine how land use patterns in 8 watersheds influence soil enzyme activity and microbial diversity and how this can be used to acssess soilecosystem function. Soil samples from watershed in a USDA-ARS research plots under minimum and conventional tillage systems were compared to a control by examining selected soil physico-chemical parameters and enzyme activities. Phosphodiesterase activity was determined using a modification of the assay method of Brownman and Tabatabai (1978). Arylsulfatase activity was determined using a modification of the assay method of Tabatabai and Bremner (1970). Soil pH, Organic carbon, and bulk density were determined using standard methods. Landuse did significantly affect pH and organic matter content in the soils studied. Tillage practices resulted in lowing of organic matter content with concomitant decrease in soil pH. The activity of phosphatase enzyme on soils were significantly affected by landuse patterns. Soil under native grass which received minimum tillage generally had significantly lower phosphatase activity then soil which received conventional tillage. Soil organic carbon content was poistively correlated with the activities of all the phosphatases studied. Phosphodiesterase and alkaline phosphates activities were significantly correlated with both pH and soil organic carbon. No significant relationship was found between arylsulfatase activity and land use. No correlation was also found between arylsulfatase activity, pH, organic carbon and the phosphatases. Tillage activities generally decreased organic carbon content in native control soil, however minimum tillage combined with maintaining soil under native grass increased soil organic matter content.

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