Investigating tarps to facilitate organic no-till cabbage production with high-residue cover crops

Abstract

High-residue cover crops can facilitate organic no-till vegetable production when cover crop biomass production is sufficient to suppress weeds (>8000 kg ha−1), and cash crop growth is not limited by soil temperature, nutrient availability, or cover crop regrowth. In cool climates, however, both cover crop biomass production and soil temperature can be limiting for organic no-till. In addition, successful termination of cover crops can be a challenge, particularly when cover crops are grown as mixtures. We tested whether reusable plastic tarps, an increasingly popular tool for small-scale vegetable farmers, could be used to augment organic no-till cover crop termination and weed suppression. We no-till transplanted cabbage into a winter rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth) cover crop mulch that was terminated with either a roller-crimper alone or a roller-crimper plus black or clear tarps. Tarps were applied for durations of 2, 4 and 5 weeks. Across tarp durations, black tarps increased the mean cabbage head weight by 58% compared with the no tarp treatment. This was likely due to a combination of improved weed suppression and nutrient availability. Although soil nutrients and biological activity were not directly measured, remaining cover crop mulch in the black tarp treatments was reduced by more than 1100 kg ha−1 when tarps were removed compared with clear and no tarp treatments. We interpret this as an indirect measurement of biological activity perhaps accelerated by lower daily soil temperature fluctuations and more constant volumetric water content under black tarps. The edges of both tarp types were held down, rather than buried, but moisture losses from the clear tarps were greater and this may have affected the efficacy of clear tarps. Plastic tarps effectively killed the vetch cover crop, whereas it readily regrew in the crimped but uncovered plots. However, emergence of large and smooth crabgrass (Digitaria spp.) appeared to be enhanced in the clear tarp treatment. Although this experiment was limited to a single site-year in New Hampshire, it shows that use of black tarps can overcome some of the obstacles to implementing cover crop-based no-till vegetable productions in northern climates.

Strip Intercropping of Rye–Vetch Mixtures: Effects on Weed Growth and Competition in Strip-tilled Sweet Corn

“…Most importantly, roller-crimping is not as effective at fully terminating cover crops as flail mowing (Creamer and Dabney 2002) and therefore increases the risk of cover crop regrowth suppressing the cash crop. Plastic tarps placed over cover crops after roller-crimping can effectively terminate a rye–vetch cover crop and could eliminate this regrowth risk within vegetable systems (Lounsbury et al 2018) but are not practical in larger agronomic systems. The effectiveness of strip intercropping might also be enhanced through integration of a “cut and carry” system, in which residue is moved from the BR to the IR zone for suppression of IR weeds and to facilitate mechanical cultivation within the BR (Rostampour 2011).…”

Legume species not spatial arrangement influence cover crop mixture effects in strip‐tilled organic cabbage

“…For example, a recent survey of organic growers in Michigan revealed that weed management was the most cited obstacle to adoption of RT, and these concerns were higher among vegetable growers compared to field crop growers (Lowry & Brainard, 2019b). Weed management challenges in organic RT vegetables have stimulated renewed interest in combining cover crop-based strategies with tarping (Lounsbury et al, 2018;Rylander et al, 2020aRylander et al, , 2020b, however these are currently more practical on a small scale (Fortier, 2014;Mefferd, 2019).…”

Trials Evaluating Solarization and Tarping for Improved Stale Seedbed Preparation in the Northeast USA

“…Research comparing these practices over a wider range of soil, weather, and seedbank conditions could aid in the development of guidelines to help growers select practices that align with their situations and goals. We advocate as well that further studies follow Lounsbury et al [26] in examining the utility of solarization and tarping for terminating cover crops prior to organic no-till or strip-till plantings. Recent work on 'biosolarization' [57] and anaerobic soil disinfestation indicates that incorporation of crop residues [58] and other organic amendments [42,59] prior to treatment can increase the weed control efficacy of solarization and tarping.…”

“…However, in one study conducted during the fall in Israel, tarping outperformed solarization [25] perhaps because soil temperature during this relatively cool season was insufficient for weed control via solarization. In the Northeast USA, a single-year study found that tarping outperformed solarization as a method of cover crop termination [26], but we are aware of no prior studies comparing solarization and tarping for stale seedbed establishment in our region. The primary objective of this study was to test whether solarization combined with flaming could improve the efficacy of stale seedbed establishment in the Northeast USA.…”