Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 10, 2002
Publication Date: November 14, 2002
Citation: Acosta Martinez, V., Zobeck, T.M., Gill, T.E., Kennedy, A.C. 2002. Microbial community structure and enzyme activities in semi-arid agricultural soils[abstract]. ASA-CSSA-SSSA Joint Annual Meeting. Indianapolis, Indiana. November 10-14, 2002. Technical Abstract: The role of microorganisms in crop production and quality of semiarid soils has been underestimated. This study investigated the effect of agricultural practices on the microbial community structure using Fatty Acid Methyl Ester (FAME) profiles and enzyme activities. Three semiarid soils in the Southern High Plains of Texas were used in this study. Soil surface samples (0-2 in) were collected from a fine sandy loam, sandy clay loam and loam soil. The soil was collected from fields that were under continuous cotton or in rotations with wheat, peanut or sorghum, and had different water management (irrigated or dryland) and tillage practices (conservation: minimum, reduced, no-tillage, or conventional). Significant differences in the fatty acid composition (type and amounts of seventy fatty acids) were found among the three soils. Common fatty acids to all samples were: 16:0, 14:0, a15:0, i15:0, i16:0, 16:1w5c, 16:1w7c, i17:0, a17:0, 18:0, 18:1w9c, 18:2w6c. The activity of b-glucosidase, b-glucosaminidase, alkaline phosphatase, and arylsulfatase were significantly (P<0.05) increased in the three soils when cotton was rotated with sorghum or wheat in comparison to continuous cotton. This was also true under conservation practices when compared to the corresponding rotation under conventional tillage. Results demonstrated FAME profiles and enzyme activities are sensitive indicators of changes in soil properties induced by agricultural practices, and thus are useful for selecting agricultural practices that enhance soil properties and sustain productivity. The results demonstrate the benefits of conservation practices and crop rotations, and suggest that such practices will enhance soil properties compared to conventional practices with continuous cotton.