Short-season cover cropping can be an important weed management tool. To optimize the use of mustard [Sinapis alba L. and Brassica juncea (L.) Czern.] in the Great Lakes region, we assessed planting time eff ects, mustard biomass production, and weed suppression during mustard growth and aft er incorporation. Th e study was conducted in Illinois, Michigan, and New York for spring and fall from 2010 to 2012. Mustard was sown every ~10 d from mid-March to early June for spring plantings and from early August to mid-September for fall plantings. Spring mustard biomass, weed density, community composition, and dry biomass were collected at mustard fl owering. Fall mustard biomass, weed density, and dry biomass were collected at season end. Spring mustard biomass ranged from <0.5 to 4 t ha -1 . Early fall biomass ranged from 3 to 5.5 t ha -1 , and was related to growing degree days (GDD) according to a logistic function. Weed biomass during mustard growth was reduced by at least 50% in 9 of 10 site-years (90%) for fall-planted mustard but only 15 of 31 site-years (48%) in spring plantings. Weed suppression was independent of mustard biomass. Th e total number of weed seedlings emerging aft er mustard incorporation was not signifi cantly reduced, but there was a species-specifi c response, with a decrease in common lambsquarters (Chenopodium album L.) and grass emergence. Th e results permit a location-specifi c recommendation to plant mustard cover crops 13 to 23 August in the southern Great Lakes Region, and no later than 1 to 10 September for adequate biomass production.

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Altering the spatial arrangement of cover crop mixtures with strip‐intercropping is an under‐explored strategy that may enhance cover crop performance and provisioning of ecosystem services. We hypothesized that strip‐intercropping of a cereal rye (Secale cereale L.; “rye”) and hairy vetch (Vicia villosa Roth; “vetch”) mixture would increase cover crop productivity and concentrate low C/N vetch residue within the future crop zone, thereby increasing the potential for improved N use efficiency. We conducted a field study in southwestern Michigan to examine how strip‐intercropping of rye–vetch mixtures influences: (i) total cover crop productivity, and (ii) the spatial distribution and C/N ratio of rye–vetch residues. Spatial arrangements included the standard full‐width mixture (MIX) in which rye and vetch were sown together in the same rows; and segregated mixtures with either two rows of rye alternated with two rows of vetch (SEG2) or three rows of rye alternated with one row of vetch (SEG1). Benefits of strip‐intercropping for reducing interspecific competition appear to have been offset by the costs of increased intraspecific competition and/or reduced facilitation. Over 5 site‐years, strip‐intercropping either had no effect or reduced total rye–vetch biomass or the biomass of component species relative to MIX. However, SEG2 resulted in greater concentration of N‐rich vetch tissue and a lower C/N ratio of both aboveground and belowground rye–vetch biomass in the crop‐planting zone. Strip‐intercropping may be a promising strategy to increase future crop access to mineralized N, and improve N use efficiency in agroecosystems. Strip‐intercropping of rye and vetch either had no effect or reduced cover crop biomass. Strip‐intercropping of rye and vetch concentrated N‐rich vetch residue in the future crop row. By reducing the C/N ratio of rye–vetch within the crop row, strip‐intercropping may increase crop N.

Core Ideas Strip‐tillage decreased soil inorganic N within a rye–vetch organic system, but had minimal effect on sweet corn yield. Strip‐intercropping rye–vetch increased N availability within the crop row of strip‐tillage. Strip‐intercropping rye–vetch decreased root mass within the row, but had no effect on yield or shoot biomass. 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.