Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/17/2011
Publication Date: 7/21/2011
Citation: Cotton, J.E., Moore-Kucera, J., Acosta Martinez, V., Burow, G.B. 2011. Responses of Enzyme Activities in Sandy Soils to Cropping System Changes in a Semiarid Region[abstract]. Enzymes in the Environment. July 17-21, 2011, Bad Nauheim, Germany.
Technical Abstract: Sandy soils under agricultural production found in the Southern High Plains of the United States are typically low in organic matter (<1%) due to the low organic inputs of intensively-tilled continuous cotton (Gossypium hirsutum) monoculture cropping over the last 50 years. This has resulted in soils that are less productive due to reduced fertility and water holding capacity and that are prone to erosion, especially aeolian. Although alternative cropping options are limited due to a semiarid climate and the limited irrigation capacity of the depleted Ogallala aquifer, drought tolerant crops such as sorghum (Sorghum bicolor) offer viable alternative cropping systems that are both economically and environmentally beneficial. In order to better understand short-term changes in soil functioning related to a transition from cotton to sorghum cropping systems, this study evaluated the effects of 2 high-tonnage yield forage sorghum cultivars with different cell wall composition (typical and reduced lignin content) under 2 deficit irrigation levels (rain-fed non irrigated and supplemental irrigation at 2.88 mm day-1) and 2 biomass removal rates (100% and 50% removal). After 2 years, soil (0-10 cm) under sorghum cropping systems had higher enzyme activities (ß-Glucosidase, ß-Glucosaminidase, Alkaline Phosphatase, Phosphodiesterase, Arylsulfatase) and microbial biomass (C and N) compared to continuous cotton. Certain enzyme activities (ß-Glucosidase, Alkaline Phosphatase, Phosphodiesterase) were higher under irrigated sorghum than non-irrigated. However, no differences were detected due to sorghum cultivar or the amount of biomass removed. This study demonstrated that over a short time period soil enzyme activities were more sensitive to changes in cropping systems than to differences in biomass incorporation to soil, sorghum cultivars, and water irrigation levels.