Summer cover crop and management system affect lettuce and cantaloupe production system
Cover crops are widely used in both conventional and organic systems to protect and improve the soil. This study evaluated the effect of summer cover crop and management system on the production of fall romaine lettuce (Lactuca sativa L.) and spring cantaloupe (Cucumis melo L.) from 1999 to 2003. Cover crop treatments included cowpea [Vigna unguiculata (L.) Walp.] incorporated (CPI), cowpea used as mulch (CPM), sudangrass [Sorghum bicolor (L.) Moench] incorporated (SGI), and a bare ground control (BG). The management system treatments included conventional (CON), integrated crop management (ICM), and organic (ORG). The CPM and SGI increased soil organic matter content and changed the soil N profile. Soil organic matter was higher and nitrate leaching was lower in the ORG system. The CPM plots had less weed growth during the lettuce crop, but higher weed biomass during the cantaloupe crop in the first year. During the cantaloupe season, weed biomass in the ORG increased over years relative to the CON system. The CPI plots had the highest lettuce yield in the first 2 yr, while SGI and CPI had higher cantaloupe yield. Lettuce yield in the ORG system increased over years relative to the CON system, but cantaloupe yield in the ORG system was lower in all four seasons. This study showed that cover crops could be used to improve cropping systems and that the soil and plants previously under long-term conventional system changed significantly during organic transition.