Cover crops used as killed mulch have been shown to decrease
evapotranspiration, in addition to acting as a barrier against weeds, and providing
a habitat for beneficial insects. Using
cover crops could be especially beneficial 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. Additionally, the effect
of the killed mulch on weed and insect populations was determined. Six cover crop cultivars were planted into 101.6
cm beds in a split-plot design, with crop cold-hardiness as the whole plot factor
and cover crop variety as the sub-plot factor.
Each replication consists of three beds (60.39cm2), with a
total of three replications per cultivars. Three cold-sensitive cultivars crops
were planted in September 2005 and three cold-tolerant cultivars 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 at 20cm and 30cm
depth using Frequency Domain Reflectrometry (Diviner 2000®). Weed densities were evaluated every two weeks
using a quadrat. Insect populations were
monitored weekly by pit-fall traps and sticky traps. Both the cold-sensitive and cold-tolerant
cover crops, the grass varieties established faster, at a greater density, and
with less water applied than the legume cover crop varieties. This illustrates a greater potential benefit
of grass cover crops as part of a killed mulch system for water conservation
purposes.