Selecting Adaptable Cover Crops for the Desert Southwest Cropping Systems.

Cover crops can be included in cropping systems to increase soil organic matter, conserve soil moisture, improve soil fertility; and control weeds, diseases and pests. However, the irrigated agriculture in desert southwest presents unique challenges for cover cropping including low water availability and relatively poor soil quality. A study was conducted to evaluate adaptability of selected summer cover crops in a field that had documented incidences of many soil borne pathogens and weeds in southern New Mexico. The objective of this study was to evaluate the performance of selected summer cover crops and their mixtures that will help reduce weed pressures, and provide the vital biomass needed for soil quality improvement in chile pepper rotations. Cover crops tested included, sole sorghum sudan (SS), pearl millet (PM), sesbania, cowpea, lablab, and buckwheat. Results showed that cowpea, lablab and buckwheat were smothered by weeds and infested with several soil borne diseases; and, therefore, could not establish well in early spring. On the other hand, the SS and PM which are grasses, competed effectively and suppressed the early season weeds, were unaffected by any disease organism and produced significant amounts of biomass.  Sesbania also provided good weed suppression and was also unaffected by disease pathogens when planted in mid to late spring. Sorghum-sudan, Sorghum-sudan/Lablab mixture, and Pearl millet were cut and baled at 80 days after planting producing 20, 21, and 11 tons of biomass/acre respectively. When allowed to regrow, SS, SS/L, and PM produced another 10, 12, and 6 tons of biomass/acre as re-growth after the first cut. This could be an attractive economic option for local growers.