Enzyme activities and microbial community structure in semiarid agricultural soils

This study investigated the effect of management on b-glucosidase, b-glucosaminidase, alkaline phosphatase, and arylsulfatase activities and the microbial community structure in semiarid soils from West Texas, USA. 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.), rye (Secale cereale) or wheat (Triticum aestivum L.), and had different water management (irrigated or dryland), and tillage (conservation or conventional). The enzyme activities were higher in the loam and sandy clay loam than in the fine sandy loam. Soil pH was not affected by management, but the soil organic C and total N contents were generally affected by the different crop rotations and tillage practices studied. The trends of the enzyme activities as affected by management depended on the soil, but in general crop rotations and conservation tillage increased the enzyme activities in comparison to continuous cotton and conventional tillage. The soil enzyme activities were significantly correlated with the soil organic C (r-values up to 0.90, P