Nutrient Dynamics Under Cover Crops and the Following Winter Wheat and Sorghum.

Cover crops provide multiple benefits in dryland and limited-irrigated cropping systems. Farmers in the southern Great Plains may benefit from cover cropping because of their potential role in reducing soil erosion, conserving soil water, suppressing weeds, and improving soil quality. The objective of this study is to examine the impacts of Spring planted cover crops on soil quality and subsequent winter wheat and sorghum yields under limited-irrigated winter wheat – sorghum –fallow system. A randomized complete block experiment was established in fall 2015 in a no-tillage field at NMSU Agricultural Science Center near Clovis, NM. Winter wheat was planted in October 2015, and three sole cover crops (pea, oat, canola) and four cover crop mixtures (pea-canola, pea-oat, pea-oat-canola, pea-oat-canola-hairy vetch-barley-forage radish) were planted in February 2016. Cover crops growth, weed population, soil surface temperature, and soil water, soil organic matter, and available nitrogen and phosphorus contents are monitored. First-year results revealed that cover crops used soil moisture and available nutrients, added plant biomass, and improved soil microbial activity. The nutrient utilized by the cover crops is expected to be released during the following crop season. Long-term monitoring will provide more information regarding water use and nutrient dynamics of cover cropping in limited-irrigated cropping systems in the southern High Plains region. With this information, growers will be able to determine the feasibility of utilizing cover crops or mixtures in the limited-irrigated lands. Results from the first year of the experiment will be presented and discussed.