Mulches Reduce Weeds, Maintain Yield, and Promote Soil Quality in a Continental-Climate Vineyard

Abstract

Weeds reduce vineyard productivity by competing with grapevines for water and nutrients. To manage weeds, growers commonly apply herbicides and/or cultivate, which compromise soil quality. With the expansion of continental-climate viticulture, such as in the Midwest, there is a need for sustainable weed management strategies that maintain grapevine productivity, fruit quality, and soil quality. Our objective was to evaluate four weed management strategies in a Midwestern vineyard. Data were collected from an established vineyard in Iowa planted with Maréchal Foch grapevines (an interspecific hybrid). Treatments were established in a randomized complete block design. Treatments were replicated four times and included: (1) cultivation, (2) herbicide application, (3) straw mulch, and (4) a living mulch of creeping red fescue (Festuca rubra L. Pennlawn). Weed control, grapevine productivity, fruit quality, and soil quality were measured from 2004 to 2010. Straw and living mulches provided greater weed control than cultivation and herbicides. Grapevine yield was unaffected by the treatments, although pruning weights were reduced in cultivated and living mulch plots. Excluding titratable acidity and pH, no differences in fruit quality were detected. Straw mulch plots tended to have more phosphorus and potassium in analyzed soil samples. Water-filled pore space and water content were also higher in plots mulched with straw. Both types of mulched plots had higher organic matter, total organic carbon, and stable aggregate content. Biological activity, measured as soil enzymatic activity and earthworm counts, was enhanced in mulched plots. Our results demonstrate that straw and living mulch reduce weed populations, maintain grapevine productivity, improve several indicators of soil quality, and are viable weed management strategies for continental-climate viticulture.