干旱区生态环境知识资源中心

A study was conducted to evaluate selected soil quality indicators in lands that have been in Conservation Reserve Program (CRP), which is a federal program in the United States offering annual rental payments and cost-share assistance to farmers who establish long-term vegetation covers on their erosion prone lands. The study site has semi-arid climate, and soils with grass vegetation covers for 15 years were compared with adjacent cultivated croplands that have never been in the CRP. Field measurements were performed and surface soil samples (0-0.15m) were collected from multiple sites having either coarse textured or fine textured soils. Soil measurements assessed included bulk density (BD), penetration resistance (PR), wet aggregate stability (WAS), dry aggregate size distribution (DASD), soil organic matter (SOM), permanganate oxidizable carbon, nitrate nitrogen, extractable potassium and phosphorus, electrical conductivity, pH, sodium adsorption ratio, and soil micronutrients (copper, iron, manganese, and zinc). Results showed a significant effect of CRP management compared to the cropped fields for BD, WAS, and PR only, with the CRP fields being less compacted and having higher WAS than the cropped lands. CRP land did not significantly differ from cropped lands in SOM and for many other measurements. The effect of soil texture was significant for DASD, SOM, copper, and manganese, with the fine textured soils having more favorable measurements than the coarse textured soils. CRP management did not produce significant increase in topsoil SOM compared to cropped lands of the study area.