Submitted to: Integrated Biological Systems Conference
Publication Type: Abstract Only
Publication Acceptance Date: 4/14/2003
Publication Date: 4/14/2003
Citation: Acosta Martinez, V., Klose, S., Zobeck, T.M. 2003. Soil enzyme activities in semiarid systems: conservation reserve program, native rangeland, and cropland [abstract]. Integrated Biological Systems Conference. p. 45.
Technical Abstract: Over 20 % of the U.S cotton (Gossypium hirsutum) crop is produced in the Texas High Plains mostly under monoculture systems that are economically risky and contribute to wind induced erosion. Recent efforts to protect semiarid soils and enhance environmental quality favor conservation tillage practices and crop rotations. We investigated the effect of management practices on beta-glucosidase, beta-glucosaminidase, arylsulfatase and alkaline phosphatase activities of semiarid soils from West Texas. Surface samples (0-5 cm) were taken from a fine sandy loam, sandy clay loam, and loam that were under continuous cotton (Gossypium hirsutum L.) or in cotton rotated with peanut (Arachis hypogaea L.), sorghum (Sorghum bicolor L.) or wheat (Triticum aestivum L.), and had different water management (irrigated or dryland) and tillage (conservation: reduced or no-tillage, or conventional). Among the enzyme activities investigated, beta-glucosidase activity was studied because it is involved in the final step of cellulose degradation that provides simple sugars for microorganisms in soils. beta-glucosaminidase activity is involved in chitin degradation. Arylsulfatase activity is involved in the mineralization of ester sulfate in soils. Alkaline phosphatase was studied because it catalyzes the hydrolysis of both esters and anhydrides of phosphoric acid, and because semiarid soils have high pH, and thus, this enzyme should play a key role in providing soil P to plants. Soil pH and total nitrogen content in the three surface soils studied were not affected by management. The total C content, however, was affected significantly by the different crop rotations and tillage practices studied, being greatest in soils with crop rotation and conservation tillage practices in comparison to continuous cotton under conventional tillage. In the fine sandy loam, arylsulfatase and alkaline phosphatase activities were significantly (P<0.05) higher in wheat-cotton rotation under no-tillage compared to continuous cotton under conventional tillage. In the sandy clay loam, beta-glucosaminidase, alkaline phosphatase, and arylsulfatase activities were significantly (P<0.05) increased under crop rotations in comparison to continuous cotton. In the loam, the enzyme activities were significantly (P<0.05) increased under crop rotations in comparison to continuous cotton when conservation tillage was used. This study demonstrates the impact of crop rotations and conservation tillage on the important soil biochemical reactions studied in comparison to the typical practice of continuous cotton with conventional tillage.