Tropical Cover Crop Mulch Systems for Low-external-input Reduced-tillage Vegetable Production

Tropical smallholder farmers that operate within the confines of low-external-input agroecosystems must often rely exclusively on farm derived resources for soil fertility management and pest solutions. Cover crops (CC) have been shown to provide many agroecosystem benefits that include soil quality improvement and weed suppression. This experiment compares three cover crops terminated with a roller-crimper and tests the resulting surface sheet mulch as a weed suppressor in Jalapeno pepper (Capsicum annuum L.) production in the tropics. Four randomized treatments with three replications consisting of a weedy fallow control (WF) treatment with no CC and three CC treatments were evaluated. Cover crops tested included pigeon pea [(Cajanus cajan cv. BRS Mandarim) PP], sunn hemp [(Crotalaria juncea cv. IAC-1) SH], and sun flower [(Helianthus annuus cv. Black Oil) SF]. Cover crops were established as rainy season covers and terminated with a roller-crimper at maturity. Jalapeno peppers (JP) were transplanted into WF treatments (conventional full-tillage) and into CC treatments with residual surface sheet mulch (conservation tillage) seven days after CC termination. Weed biomass was determined for two weeding frequencies (standard weekly weeding vs. reduced weeding at three-week intervals) at 3, 6, 9, and 12 weeks after pepper transplant. Jalapeno fruit was harvested to evaluate treatment effects on pepper yield. Sunn hemp yielded the highest amount of CC shoot biomass at termination. Sunn hemp provided the greatest level of weed control and suppressed both grass and broad leaf weeds during the CC rotation. Plant tissue nitrogen content and SH shoot biomass contributed to greater potentially available nitrogen content from SH biomass compared to that from PP and SF. Both SH and SF provided weed control by reducing weed development following pepper transplant compared to the WF and PP treatments. Sun flower did not exhibit any regrowth following termination and was effectively killed with the roller-crimper. Jalapeno yields were greatest in SH and SF treatments. Results indicate that the use of SH and SF as CCs terminated with a roller-crimper in tropical conservation tillage cropping systems can reduce weeds and support equitable yields of JPs compared to JPs produced by conventional full-tillage cropping systems.