In the past 100 years, decoupling of crop-livestock systems has posed detrimental environmental effects through intensive agriculture. Reintegration of these systems can mitigate environmental effects and provide a means of sustainable intensification. In the upper Midwest there is an opportunity after wheat harvest in a wheat-corn rotation to plant quick growing annual cover crops. In this study, based in Central Michigan, we assessed the impact of grazing annual cover crops on soil fertility, soil carbon, soil compaction, weed population dynamics, and corn yield and quality. In this 2x4 factorial strip block design we planted two cover crop mixtures as our main plot: 1) a pure brassica mixture (PURE), and 2) a complex mixture containing brassicas, warm season grasses, cool season grasses, and legumes (MIX). Our sub-plot factor was the date of grazing: October (Oct), November (Nov), December (Dec), and a non-grazed control (NG). Cover crops were strip-grazed with lambs in the fall of 2019, 2020, and 2021. Soil measurements were collected the following spring, and then silage corn was planted. Silage corn was harvested in fall 2020, 2021, and 2022 when the crop reached 65% moisture content, and yield and forage quality were assessed. Grazing annual cover crops had no detectable impact on soil organic matter, permanganate oxidizable carbon, soil C/N ratio and soil penetration resistance. Plots grazed in Oct and Nov contained greater frequency of spring weeds when compared to the NG control which contained less spring weeds and greater frequency of live cover crop. There was also no effect of grazing on corn yield and forage quality. Spatial heterogeneity in site soil conditions resulted in high variance in summer weed biomass, particularly during the 2021 site-year. Overall, grazing annual cover crops with lambs had no negative impacts on soil health or silage corn yield and quality. This system can provide a means of sustainable intensification without reducing the productivity of corn silage rotations.
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