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.

Strip-intercropping of functionally diverse cover crop mixtures including cereal rye (Secale cerealeL.) and hairy vetch (Vicia villosaRoth) is one mechanism by which nitrogen (N) banding can be applied to an organic, strip-tilled system to increase crop competitiveness over weeds. We hypothesized that by targeting hairy vetch, a low C:N legume, to the tilled strip directly in row with future crop establishment, and cereal rye, a high C:N grass, to the untilled strip directly between future crop rows, that N would be preferentially available to the crop. We conducted a field study between 2011 to 2013 in southwest Michigan to examine the effects of rye–vetch mixture spatial arrangement (strip intercropping vs. full-width mixture) on (1) soil inorganic N; (2) weed biomass; and (3) sweet corn (Zea maysL.) biomass, yield, and competitiveness against weeds. We found that as the proportion of vetch biomass in the crop row (in-row, IR) increased, we also saw increasing levels of IR soil inorganic N and greater early sweet corn N uptake and growth relative to weeds. However, sweet corn yield and final biomass were more responsive to vetch biomass across the whole plot (WP) and did not respond to rye and vetch segregation into strips. Increasing vetch WP biomass increased sweet corn final biomass across both years, but only increased corn competitiveness against weeds in 1 out of 2 years and decreased sweet corn competitiveness in the other year. Strip-intercropping of cereal rye and hairy vetch has potential to increase soil N availability to the crop, thereby increasing early crop competitiveness, which may lower weed management costs.

A common critique of organic farming is that it is very tillage intensive, and therefore deleterious to soil quality. However, little information is available on the tillage practices currently employed by organic farmers, as well as organic farmers’ attitudes toward reduced tillage (RT). To address these knowledge gaps, a detailed written survey of Michigan organic field crop and vegetable farmers was conducted to investigate their current tillage practices, as well as their perceptions of the barriers and benefits to adoption of RT. Respondents reported a wide range in tillage frequency and intensity, both across and within production of specific crops, with operations split evenly between field preparation and cultivation. Compared with field crop growers, vegetable growers were generally smaller scale and relied more heavily on a limited set of tillage (e.g., rototiller) and cultivation tools. Interest in adoption of RT practices among respondents was low to moderate with median Likert scale ratings (0–7 scale with 0 representing no interest and 7 extreme interest) of 4 or less for all forms of RT. Vegetable growers were most interested in permanent beds, rotational tillage and strip tillage, whereas field crop growers were most interested in rotational tillage and strip tillage. The greatest perceived benefits to adoption of RT were improved soil quality and fuel savings. Both groups ranked weeds, impacts on yields, residue management and crop establishment as high barriers to RT adoption. Vegetable growers also cited lack of scale appropriate equipment as a major barrier. Survey results suggest that future research efforts should focus on overcoming key barriers to adoption, such as weed management and access to low-cost adaptable RT equipment rather than reiterating relatively well-known soil quality benefits. Our results also suggest that promotion of incremental reductions in the frequency and intensity of tillage operations on organic farms may be more realistic and equally valuable compared with promotion of more extreme forms of RT such as no-till.

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