Expanding cover crop use through interseeding into established vegetable plantings

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2019: $8,947.00
Projected End Date: 02/28/2021
Grant Recipient: Sogn Valley Farm
Region: North Central
State: Minnesota
Project Coordinator:
Dana Jokela
Sogn Valley Farm

Information Products


  • Vegetables: peppers


  • Crop Production: cover crops, cropping systems, intercropping, relay cropping
  • Education and Training: on-farm/ranch research
  • Production Systems: organic agriculture
  • Soil Management: soil quality/health


    Peppers are a high-value and widely grown crop among vegetable growers in the Midwest. Many growers, myself included, plant peppers on plastic mulch because of its soil warming, moisture retention, and weed suppression benefits. While an effective tool for us, the waste generated through its disposal doesn’t align with our sustainability goals.

    A major factor preventing us from discontinuing use of plasticulture is controlling weeds once plants become too large for mechanical cultivation, which can be more than a 2-month period for this long-season crop. For both plasticulture and bare ground systems, harvest is typically not completed until mid-October, at which point cover crop options are limited and unlikely to produce meaningful growth.

    This project evaluated interseeding of cover crops at various dates into an established pepper crop using both plasticulture and bare ground systems. We did this through field-scale plots set up within our production field. The treatments were not replicated, as our goal was for this to be assessed within a production environment to evaluate ease-of-implementation for commercial farmers. Consequently, some plot-to-plot variability could have contributed to differences among treatments, so this should be kept in mind when drawing conclusions.

    We found some reduction in yield when an interseeded cover crop was present, around 10-12% in the bare ground system and 13-22% in the plasticulture system. However, overall yields were still quite good compared to historical averages. Given the other benefits from the cover crop, we feel the system has promise and plan to continue experimenting with interseeded cover crops in pepper fields in future seasons. We also found that, while plastic mulch did lead to earlier harvest, the overall yields were actually lower than those in the bare ground plots. We did find a reduction in soil temperature where an interseeded cover crop was present, but the insulative properties of the surface vegetation actually maintained warmer temperatures during cool temperatures in the fall. We saw improvements in biological soil health indicators when cover crops were present in bare ground plots, but no improvement in aggregate stability. The poorest biological soil health was observed in the plasticulture path, with and without a cover crop, likely because topsoil was moved into raised beds during bedshaping.

    As commercial organic vegetable farmers, we were keenly interested in the potential for interseeded cover crops to extend our cover cropped acreage into long-season crops like peppers, and feel excited about continuing to experiment with this system. We will likely continue using Dutch white or medium red clover, but seek out a different grass species to mix with it given the rapid seedhead production observed with annual ryegrass. The establishment and maintenance of the cover crop did not feel onerous, and we appreciated the presence of the cover crop keeping our plants clean from soil splash and allowing us to harvest after heavy rain events without going ankles deep in mud.

    Project objectives:

    1. Compare plasticulture and bare ground production systems in terms of yield, ease of management, and suitability for cover crop interseeding.
    2. Determine which cover crop sowing date optimizes both cover crop growth and cash crop yield.
    3. Monitor environmental co-variables (soil temperature and moisture), crop nutrients, and cover crop biomass to help explain treatment effects on cash and cover crop growth. 
    4. Quantify soil health benefits of cover crop interseeding through the multifaceted Cornell CASH (Comprehensive Assessment of Soil Health) test.
    5. Provide a production-scale demonstration of cover crop interseeding for farmers through a field day and photos.
    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.