Rye–vetch spatial arrangement and tillage: Impacts on soil nitrogen and sweet corn roots

Strip-intercropping of functionally diverse cover crops, such as cereal rye (Secale cereal L.; “rye”) and hairy vetch (Vicia villosa Roth; “vetch”), may enhance N use efficiency in reduced-tillage systems by concentrating N-rich vetch residue within the subsequent crop row, thereby increasing root access to pools of organic N. We established a field study in southwestern Michigan between 2011 and 2014 to compare the effects of rye–vetch spatial arrangement and tillage on soil N, soil moisture, sweet corn (Zea mays L.) above- and belowground biomass, and root morphology. The experiment consisted of a 2 × 2 factorial with two levels of rye–vetch spatial arrangement: segregated into strips (SEG) and full-width mixture (MIX), and two levels of tillage: strip-tillage (ST) or full-width tillage (FWT). Strip-tillage reduced soil inorganic N compared to FWT in 2 out of 3 yr, but increased soil moisture and sweet corn shoot biomass in 2 out of 3 yr. Segregating rye and vetch into strips increased inorganic N within the crop row, but had minimal impact on sweet corn biomass or yield. In contrast, sweet corn roots were responsive to relatively small changes in the distribution of soil N or moisture resulting from strip-tillage and segregated plantings. Strip-tillage and strip-intercropping show promise in adapting reduced-till systems for organic production, but future research should evaluate the response of other crops, and adjustments in cover crop species and termination methods to help optimize these practices.