Cover Crops as Killed Mulches, An Alternative in Sustainable Agriculture in Semi-Arid New Mexico.
Sheilla Parr, Plant and Environmental Sciences, New Mexico State University, P.O. Box 30003 MSC 3Q, Las Cruces, NM 88003 and Erin Silva, Dept of Agronomy, Univ of Wisconsin, 1575 Linden Dr., Madison, WI 53706.
Cover crops utilized as killed mulch have shown to decrease evapotranspiration, act as a barrier against weeds, and provide a habitat for beneficial insects, potential significant benefits in semi-arid New Mexico where water use is an ever decreasing commodity. In this study, six annual cover crop varieties were evaluated in killed-mulch cropping systems in order to measure the potential decrease in water-use on chile pepper fields during the growing season. In addition, the effect of the killed mulch on weed and insect populations was determined. The six cover crop cultivars were planted into 40 in. beds in a split-plot design, with whole plot factor being cold-hardiness and cold tolerant, with the sub-plot factor being variety. Each replication consists of three beds, with a total of three replications per cultivar. Three cultivars of cold-sensitive crops were planted in September 2005 and three cultivars of cold-tolerant crops were planted October 2005, with bare ground as the control. Irrigation for each treatment was accomplished through subsurface irrigation and was quantified using water meters. Chile peppers (Capsicum annuum, cv. ‘AZ-20') were transplanted into each bed during April 2006. Data regarding irrigation scheduling, weed densities, insect populations, and vegetable crop yield were taken from the center row of each sub-plot. Irrigation schedules were established with soil moisture measurements obtained using Frequency Domain Reflectrometry (Diviner 2000®) at a 20-40 cm depth. Weed densities were evaluated every two weeks using a quadrat. For both the cold-sensitive and cold-tolerant cover crops, the grass varieties established faster with a greater biomass than the legume cover crop varieties. Additionally, there is a detectable difference in soil moisture retention in the grass cover crops, showing an initial benefit to establishing such a cropping system in New Mexico.