- Agronomic: annual ryegrass, clovers, rye
- Vegetables: peppers, summer squash
- Crop Production: alley cropping, catch crops, continuous cropping, cover crops, cropping systems, multiple cropping, nutrient cycling
- Education and Training: decision support system
- Soil Management: green manures, organic matter, soil microbiology, soil quality/health
Summary of Problem
The use of plastic mulch is common in warm-season vegetable production in the North Central Region. Excellent in-bed weed control provided by plastic films make it particularly attractive in organic production, though weeds between plastic mulch beds (referred to as “inter-bed” hereafter) remain a challenge. Many organic growers manage inter-bed weeds through cultivation. However, with roughly 50-75% of a field covered with impermeable plastic, sediment loss and associated agrochemical runoff in the inter-bed area can be greatly intensified during rain events (Arnold et al., 2004; Rice et al., 2004; Wan and El-Swaify, 1999; Zhang et al., 2013). Erosion can be mitigated by keeping the inter-bed soil covered with dead plant residues or cover crop living mulches and benefit soil health through organic matter inputs. However, additional management challenges associated with these practices may offset the advantages (Table 1.1). Since the best inter-bed weed management strategy will depend on a grower’s specific management goals, identifying production and soil health tradeoffs associated with various inter-bed weed and soil management practices will aid growers in making management decisions best suited to their agronomic and environmental goals. This research seeks to identify these important tradeoffs of inter-bed weed management practices and equip organic vegetable growers in the North Central Region with the information necessary to optimize inter-bed management strategies for improved crop production and soil health.
Arnold, G. L., Luckenbach, M. W., and Unger, M. A. (2004). Runoff from tomato cultivation in the estuarine environment: biological effects of farm management practices. Journal of Experimental Marine Biology and Ecology,298(2), pp. 323–346. https://doi.org/10.1016/S0022-0981(03)00366-6
Rice, P. J., Harman-Fetcho, J. A., Teasdale, J. R., Sadeghi, A. M., McConnell, L. L., Coffman, C. B., … Hapeman, C. J. (2004). Use of vegetative furrows to mitigate copper loads and soil loss in runoff from polyethylene (plastic) mulch vegetable production systems. Environmental Toxicology and Chemistry, 23(3), pp. 719–725. https://doi.org/10.1897/03-14
Wan, Y., and El-Swaify, S. A. (1999). Runoff and soil erosion as affected by plastic mulch in a Hawaiian pineapple field. Soil and Tillage Research, 52(1–2), pp. 29–35. https://doi.org/10.1016/S0167-1987(99)00055-0
Zhang, G. S., Li, J. C., Hu, X. B., and Zhang, X. X. (2013). On-farm assessment of soil erosion and non-point source pollution in a rain-fed vegetable production system at Dianchi lake’s catchment, southwestern China. Nutrient Cycling in Agroecosystems, 96(1), pp. 67–77. https://doi.org/10.1007/s10705-013-9577-6
The objectives of this research were to 1) determine the influence of different management practices on in-season weed management and future weed pressure, 2) evaluate differences in labor requirements between management strategies, 3) assess the effects of weed management strategies on crop yield and quality, 4) study potential competition factors between living mulches and cash crops, 5) evaluate the nitrogen retention ability of different management strategies, and 6) determine the influence of different inter-bed management practices on soil microbial biomass and functional diversity as an indicator of soil health. A two-year experiment was conducted in southwest Michigan to these objectives. Strategies evaluated included wheel-hoe cultivation, rye (Secale cereale L.) residue dead mulch, mowed weeds, and three living mulch treatments: Italian ryegrass (Lolium multiflorum) monoculture, rye monoculture, and a rye-Dutch white clover (Trifolium repens) mixture. The treatments were implemented between plastic mulch beds planted with green bell peppers (Capsicum annuum cv. Paladin) and yellow summer squash (Cucurbita pepocv. Lioness).
This research was inspired by organic growers’ frustrations with inter-bed weed management in plasticulture production, with specific interest in integrating a cover crop living mulch. In addition to the main trial outlined above a separate cover crop screen was conducted (funded by other sources) to evaluate ease of establishment, weed suppression, and biomass accumulation of various cover crop species. Seed of promising species (namely teff) from this screen were distributed to two growers in 2017 and six growers in 2018. Providing growers with the opportunity to try new practices on their farms helped us evaluate management constraints which can be difficult to identify in a research field. Through our work with grower collaborators we found that the adoption of integrated plasticulture-living mulch systems was primarily limited by labor demands. Poor living mulch establishment was also a constraint in some cases.
Summary of Conclusions
- Cultivation and dead mulch provided greater in-season weed control, with associated reductions in the weed seedbank, than living mulches and mowed weeds.
- Cultivating between the inter-bed area took more than twice as long as mowing weeds and living mulches.
- Squash yields were consistent across all treatments in both years, while pepper yields were reduced in all treatments relative to the cultivated control in 2018
- Pepper yield reductions may be attributed to competition for water.
- Living mulch or weeds in the inter-bed area showed the potential to reduce nitrogen leaching compared to cultivated and dead mulch plots.
- Microbial abundance and functional diversity were not significantly influenced by inter-bed weed management strategy over 2 seasons.
Grower Adoption Actions
Teff seed was distributed to Matt Martin of The Martin Family Farm (Capac, MI) and Mike Yancho of Forgotten Harvest Farm (Fenton, MI) to plant as a living mulch between plastic mulch beds on their farms in 2017 and 2018. Both Matt and Mike were interested in planting cover crops in the inter-bed to manage weeds, reduce soil erosion, and improve harvesting conditions.
Mike was pleased with the weed suppression and soil coverage achieved with teff in 2017. However, these results were not replicated in 2018, likely due to delayed planting of living mulch in that year resulting in weed escapes and poor establishment. Even though Mike experienced mixed results, he has commented that the potential benefits are worth the risks, and plans to continue the practice in the future.
Matt had limited success with teff, primarily because it needed to be mowed multiple times during the season, and labor shortages did not allow for timely management. Matt also experimented with buckwheat between plastic mulch beds and found it was easier to manage than teff because it did not regrow after mowing. Matt was also pleased with the level of weed suppression he was able to achieve with buckwheat. Matt continues to plant buckwheat between plastic mulch beds on his farm.
Teff seed was distributed to an additional four growers in 2018 with limited success. Having to manage the teff throughout the growing season was a major constraint for most of the collaborating growers.
The goal of this project is to evaluate the systems-level effects of different between-bed management strategies for vegetables grown on PM. The results from this study will provide detailed information regarding the functioning of individual parts and the system as a whole which will help farmers make informed inter-bed management decisions in PM systems to improve crop production, soil health, and environmental sustainability.
We anticipate the current study will result in the following outcomes:
- Vegetable farmers will have a greater awareness of alternatives to cultivation for weed and soil management between PM beds.
- Vegetable farmers, extension educators, and researchers will have a better understanding of how different inter- bed management practices in PM production influence system-level functioning.
- Vegetable farmers will be empowered to try alternative inter-bed management strategies and evaluate them in the context of their specific production system.
- Vegetable farmers will make weed management decisions between PM beds which will improve soil health and reduce nutrient leaching.
- Researchers and extension educators will make well-rounded recommendations regarding inter-bed weed management in PM systems.
- Vegetable farmers will have the potential of greater profits as a result of reduced weeding costs, improved fruit quality, greater nutrient retention, and preservation and building of healthy soils.
- Environmental sustainability will be achieved through potential reductions in nutrient leaching and soil runoff.