Impacts of Crop Management Systems on Arid Land Soil Quality.

A study was conducted to investigate the differences in selected soil quality indicators under different long term (≥ 5 years) soil/crop management systems. Four management systems were selected within the same mapping unit having a surface soil texture of clay loam and two other management systems were selected within another mapping unit having a sandy loam surface soil. Management systems within the clay loam soil were conventionally tilled land with varied annual crops (CVT), alfalfa field (ALF), a peach orchard with clover understory (POC) and a permanent grass field with tall fescue (TFG). The two systems chosen in the sandy ground were conventionally tilled soil with varied annual crops (CTS) and young cottonwood tree orchard (CWP). Soil samples were collected in three replicated fields for each of the management systems at depths of 0-0.05 and 5-0.15 m for soil biological measurements and 0-0.15 and 0.15-0.30 m for soil physical and chemical measurements. Results showed that soil/crop management had the major impacts on soil properties compared to measurement depth and the interaction between soil/crop management and depth was not significant expect for soil organic matter (SOM), available water content (AWC), permanganate oxidizable carbon (POXC) and aggregates < 0.25 mm (AGG < 0.25mm). TFG management had significantly higher levels of microbial biomass (4794 ng/g), SOM (2.9%), AWC (0.43%) and water stable aggregates (76%) in the surface soil compared to other management practices irrespective of the soil type. However, the CTS management system had generally less favorable biological and physical soil measurements. This study demonstrates that different soil/crop management systems can significantly impact the quality of arid soils.