Evaluation of Multiple-Use Cover Crops under Rainfed during Two Seasons in Yucatan, Mexico

Abstract

The aim of the study was assessing seven legumes as cover crops during cropping seasons of the years 2000 and 2001 in the central region of the Yucatan. An experimental design of randomized blocks with arrangement of split plots was used; where treatment was the legume, and sub-treatment, was the management of defoliation, 90 days after sowing (DAS) or after harvesting the grain (AHG). Treatments were: short-cycle seed white lima bean ( Phaseolus lunatus ), long-cycle seed white lima bean ( Phaseolus lunatus ), cowpea ( Vigna unguiculata ), dwarf velvet bean ( Mucuna pruriens var. utilis ), ash velvet bean ( Mucuna pruriens var. utilis ), sword bean ( Canavalia ensiformis ) and red rice bean ( Vigna umbellata ). It was collected data on coverage and biomass production, grain, leaf litter and stubble yields, biomass and relative frequency of weeds, pH, total nitrogen, organic matter (OM), potential anaerobic mineralization of nitrogen (MPAN) and soil CO2 evolution. Coverage varied from 70% to 90%; and biomass from 1900 to 2500 kg · DM · ha -1 at 90 DAS in ash velvet bean (AVB) and sword bean (SB). Stubble yielded from 800 to 2200 kg · DM · ha -1 . The SB reached ~3200 kg · DM · ha -1 of grain yield in the first cropping season and it was reduced in the second cropping season. AVB and SB reduced the biomass of weeds from 890 to 780 kg · DM · ha -1 . The OM of soil reached 14.9% in AVB. NH4, pH, and soil CO 2 evolution remained without significant changes by effect of legumes.