Mechanical management strategies improve corn production in organically managed living mulch systems

Reducing tillage in organic grains offers a path toward sustainable soil management. Living mulches provide a strategy for tillage reductions in organic corn (Zea mays L.) that suppresses weeds and increases system biodiversity. Yet, organically approved management strategies need to be identified that minimize living mulch competition with commodity crops. An experiment conducted at the University of Wisconsin's Arlington Agricultural Research Station from 2021 to 2022 examined both pre- and post-corn planting management strategies of a red clover (Trifolium pratense L.) living mulch on clover growth, weed biomass, corn plant population, and grain yield. A 2 × 2 × 3 factorial experiment explored (1) pre-plant tillage strategy comparing undercutting of clover versus no-till management, (2) post-plant flaming of clover versus no flaming, and (3) in-season mechanical clover suppression strategies examining post-plant use of inter-row roller crimping and high-residue cultivation used either alone or in combination. While corn yields remained relatively low across the experiment, averaging 4.61 Mg ha⁻¹, both flaming and undercutting showed promise as mechanical management strategies to improve corn yield. Undercutting increased corn yields over no-tilling by 3.15 Mg ha⁻¹ in 2021, while inadequate clover suppression resulted in no statistical differences in 2022. Inter-row roller crimping reduced early-season clover heights but did not affect end of season clover biomass. Clover biomass between rows was reduced using high-residue cultivation; however, neither in-season clover suppression strategy influenced corn yield. While yield gaps remain, mechanical management strategies suggest viability in improving corn yields in organic living mulch systems but require further exploration.