Published online January 24, 2019 RESEARCH Cover Crop Biomass Production Is More Important than Diversity for Weed Suppression Chloe MacLaren,* Pieter Swanepoel, James Bennett, Julia Wright, and Katharina Dehnen-Schmutz C. MacLaren, J. Bennett, J. Wright, and K. Dehnen-Schmutz, Centre ABSTRACT for Agroecology, Water & Resilience, Coventry Univ., Ryton Gardens, Biotic resistance theory suggests that diverse Wolston Lane, Coventry CV8 3LG, UK; C. MacLaren, current address, cover crop mixes may be more effective at Rothamsted Research, West Common, Harpenden AL5 2JQ, UK; weed suppression than a cover crop monocul- P. Swanepoel, Dep. of Agronomy, Stellenbosch Univ., Welgevallen ture. However, evidence for this has so far been Experimental Farm, Suidwal St, Stellenbosch, South Africa. Received inconsistent. To investigate, we designed a trial 19 May 2018. Accepted 22 Nov. 2018. *Corresponding author (chloe. to explicitly test the role of cover crop diversity
[email protected]). Assigned to Associate Editor David in weed suppression by comparing eight cover Stoltenberg. crop mixes that varied in species diversity, Abbreviations: DAE, days after emergence; 4C, four-cereal mix; 4D, functional diversity, and composition. Mixes four-species diverse mix; 4L, four-legume mix; HC, high-richness contained either one, four, or eight species, in cereal mix; HD, high-richness diverse mix; HL, high-richness legume equal proportions. Three mixes contained only mix; 1C, single cereal monoculture; 1L, single legume monoculture. cereal species, three contained only legumes, and two contained a mix of cereals, legumes, over crops, defined as crops planted for a purpose other and brassicas. Research was conducted on Cthan harvest, are integrated into cropping systems to achieve two farms in South Africa’s winter rainfall region, a variety of goals.