Soil C and N Cycling Under Reduced-Tillage and Cover Crops in the Southern High Plains Agroecosystems.

Cover crops can benefit agroecosystems by reducing soil erosion, improving soil quality, and conserving soil water in dry areas. Influence of cover cropping and other conservation practices has not been much studied in a dry, hot agroecosystem of the southern High Plains. We evaluated soil organic C and N dynamics and CO₂ emissions at Agricultural Science Center near Clovis, NM in a corn-sorghum rotation and a winter wheat-sorghum-fallow. Winter rye cover crop was established in fall 2016 in an ongoing conventional tillage, strip-tillage, and no-tillage study in a dryland corn – sorghum rotation. Similarly, three sole cover crops (pea, oat, canola), four cover crop mixtures (pea-canola, pea-oat, pea-oat-canola, and pea-oat-canola-hairy vetch-barley-forage radish), and fallow plots were established in spring 2016 with no-tillage and limited irrigation management in a winter wheat-sorghum-fallow rotation. Soil organic C, potentially mineralizable C and N, available N, soil moisture and temperature, soil CO₂ emissions were monitored periodically. Results from year 1 and 2 revealed that cover crops contributed to soil organic C and N cycling. Nutrients utilized by the cover crops were gradually released during the following crop season to support crop production. Soil water has been a limiting factor for crop production and cover crops integration in dryland cropping systems. Long-term monitoring will provide more information regarding water use and nutrient dynamics of cover cropping in drylands and limited irrigation cropping systems, and help in improving agricultural sustainability in the southern High Plains region.