Strip Tillage and Oat Cover Crops Increase Soil Moisture and Influence N Mineralization Patterns in Cabbage

Abstract

Strip tillage (ST) is a form of conservation tillage in which disturbance is limited to the crop rows while the rest of the soil remains undisturbed. Compared with conventional, full-width tillage (CT), ST may reduce tillage costs, protect soil from erosion, and benefit cool-season crops including cabbage (Brassica oleracea L. var. ‘capitata’) by improving water retention, reducing soil temperatures, and improving the synchrony of inorganic nitrogen (IN) supply with crop demand. Field experiments were conducted in 2010 and 2011 in central Michigan to assess the effects of tillage (CT vs. ST) and a preceding cover crop (none vs. oats, Avena sativa L. var. ‘Ida’) on soil temperature, moisture, N dynamics, and yields in transplanted cabbage. Oats were sown in April and terminated 2 to 3 weeks before cabbage transplanting in early July. In-row (IR) soil moisture, temperature, and IN content were assessed from transplanting until cabbage harvest in October. In 2010, IR soil moisture was higher season-long in ST compared with CT and in oat compared with non-oat treatments, but these effects were not detected in 2011. Tillage and oat residue had little or no effect on IR soil temperature. Shortly after tillage in both years, soil IN availability was greater in CT treatments without oats compared with both ST treatments and CT with oats. However, these differences dissipated after 3 to 4 weeks, and hypothesized improvements in N release patterns under ST were not observed. No differences in cabbage marketable yield were detected in either year, although the proportion of plants that produced a marketable head was lower in cover-cropped plots in 2010. These findings suggest that soil conservation and input savings potentially associated with ST production systems may be attained without a yield penalty. More research is needed to understand and optimize cover crop management in ST systems to realize potential benefits in N use efficiency, moisture retention, and soil temperature moderation.