The effects of climate change are being felt on organic vegetable farms in the upper Midwest. Bigger and more frequent rain events cause erosion, delay planting, and hamper weed control. This project will explore using living aisles and no-till planting strips to mitigate the impacts of intense rains linked to climate change. Both practices are known to reduce erosion, improve soil permeability, and increase soil quality, making them logical choices for resilient farming systems. However, concerns about reduced yield, increased labor, and overall weed control mean that neither practice is commonly used on organic vegetable farms. This proposal is designed to address farmers’ concerns and develop no-till techniques that can be incorporated into diversified vegetable systems.
Clover aisles established in fall will improve weed control through two cropping years; winter-killed cover crops in the planting strips will create an in-situ mulch to be planted without tillage (even when the ground is wet); and occultation with black tarps will create a stale planting bed to minimize weeds. This research will use broccoli and peppers and will also inform other transplanted crops. Organic vegetable farmers in southern Wisconsin will cooperate on this research, which will be relevant in the upper Midwest.
- Assess the effectiveness of three planting strip treatments between living clover aisles
- Evaluate yields and management costs of living aisle/planting strip treatments as compared to open ground/conventionally-tilled control
- Share information with growers through a field day (expected attendance 35 to 40)
- Create an illustrated info sheet and video with results and recommendations to be posted on the FairShare website and social media accounts, disseminated through our farmer database (280 contacts), and made available at the annual Organic Vegetable Production Conference (expected attendance over 200)
- Contribute information to the development of longer, multi-year, reduced-tillage vegetable rotations
Trials were established on three cooperating farms in southern WI. All the farms are certified organic and have between 9 and 15 years of experience with vegetables and cover crops. Prior to establishing the trial, all the plots were in the regular tilled vegetable rotation for each farm. Any last vegetable or cover crop residue was tilled under in late August 2018 before seeding the trial.
The living aisles and vegetable planting strips were scheduled to be seeded on 9/1/18. Early September rains delayed the seeding until 9/11/18. Both aisles and planting strips were measured out and sown by hand, and then tilled shallowly to incorporate the seeds and take down any weeds. The 30” aisles were sown to white clover at the rate of 20 lbs/acre with a nurse crop of oats sown at 64 lbs/acre. The 30” vegetable planting strips were sown to a mix of oats (112 lbs/acre) and peas (100 lbs/acre).
Clover, oat, pea, and weed populations were counted 14 days after seeding. Oat and pea population counts were repeated on 10/30/18 and biomass samples were taken at the same time.
Cover Crop Establishment
Visual assessment of the of the clover/oat aisles and oat/pea vegetable planting strips in October 2018 was a bit better than expected given that planting was delayed due to early September rains.
Population counts for the white clover averaged from 54 (Blue Moon), to 65 (Equinox), to 69 (Two Onion) plants per square foot 14 days after seeding. These counts were less than desired based on our previous work with living aisles in 2015 and 2016. In those trials the average population density of the white clover was 120 plants per square foot. If the clover has not fully covered the aisles in the spring, we will consider spreading some additional seed to fill in any open ground.
Fall dry biomass of the oats and peas was also less than desired. This winter-sensitive cover crop will form an in-situ mulch for two of the no-till planting strip treatments in the spring. The more biomass in the fall, the more residue will be in place as a mulch in the spring to exclude weeds. Though we did not expect to produce enough biomass to exclude weeds for the full 2019 growing season, we did hope to at least exclude weeds through pepper planting in late May. It is unlikely that we will meet that goal with the biomass numbers below, which are far less than our goal of 5,000 pounds per acre.
Dry Biomass in lbs/acre on 10/30/18
Individual weed population counts taken 14 and 49 days after cover crop seeding ranged from 0 to 19 weeds per square foot across the three farms and averaged 1.9 weeds per square foot. The vast majority of these weeds were annuals which did not produce seed and will die over the winter. We expect that annual weeds will be suppressed by clover in the aisles and with mulch or tillage in the planting strips in 2019 and 2020 when vegetables are planted. The few perennials in the mix will likely be more problematic and may need to be managed by mowing the aisles and hand-pulling the planting strips.
Educational & Outreach Activities
The cover crops for this trial were planted in September 2018. The vegetable cropping years will be 2019 and 2020. We do not yet have any data or information to share through outreach.
Though cover crops are commonly used on organic vegetable farms, using them as a base for reduced tillage techniques is still an area for experimentation and is far from common. Farmers cooperating on this project are especially interested in living aisles as a way to reduce tillage, prevent erosion, and capture water during the more extreme rainfall events that are becoming more common with climate change. If this project is successful in demonstrating that yield and labor between the living aisle/no-till treatments are similar to the clean cultivated control, we will contribute important information to farmers on how to reduce tillage and increase farm resilience.