Optimizing No-Till Methods for a Direct-to-Market Organic Vegetable Farm

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Commodities

Practices

• Crop Production: no-till
• Soil Management: soil microbiology, soil quality/health

It is that tillage disrupts the soil microbiome and, while it leads to short-term gains, ultimately reduces soil health, increases compaction, and propagates weeds. By comparison, no-till methods, or practices which limit or eliminate mechanical turnover of soil layers, stimulate the growth of natural microorganisms which help to make soil nutrients more biologically available, increase organic matter content, and can reduce overall labor while yielding successful harvests.

No-till farming methods are increasingly part of the dialogue in conventional crop farming, but the techniques employed at large scales are not practical or accessible for small vegetable growers. Multiple recent references (Mefford 2022, 2019; Mays 2020; O’Hara 2020) offer no-till recommendations, but there is little practical guidance for small-scale, organic vegetable farming. Especially in the Midwest, these farms are highly diversified and require flexibility in approach. On our farm, we see little improvement from year to year by tilling our fields, which have highly variable soil, significant compaction, and weed pressure from foxtail and Canada thistle. The primary goal of this study is to test recommended methods of no-till vegetable growing to identify the most sustainable approach in terms of soil health, labor investment, and crop health and yield.

plot layout_20221129We propose to compare three distinct no-till treatment methods with a traditional (tilling) approach to identify the most sustainable. The results will help us plan for and modify no-till methods on our farm and will provide valuable, practical results to share with other vegetable growers.

After review of the most recent literature, we have selected the following no-till treatment methods to study:

• Treatment A: Occultation of cover crop with weed fabric; residue topped with 6 inches of compost. Plant transplants into compost. Maintenance would include hand weeding and hoeing of annual and perennial weeds. This method is being used by several farms switching to no-till methods.
• Treatment B: Flail mow cover crop with a walk-behind-tractor flail mower. Plant transplants into mowed residue and mulch with 6 inches of chopped hay or straw. Maintenance would include hand weeding only. A version of this method has been promoted by Jan-Hendrik Cropp, a German farmer.
• Treatment C: Flail mow cover crop with walk-behind-tractor flail mower. No-till seed clover into residue to grow a living mulch. Plant transplants into seeded residue. Maintenance would include hand weeding only. This method builds upon a SARE grant study by Dana Jokela of Sogn Valley Farm (FNC19-1171), taking his approach one step further by not tilling the bed and monitoring the biological and nutrient activity in the soil.
• Treatment X: Our control method will be a traditional tilling approach including tilling in the cover crop and transplanting directly into prepared soil. Maintenance would include hand weeding and hoeing.

If awarded, we will test these three methods in a plot on our farm in southeastern Minnesota over two growing seasons (2023 and 2024). The plot (see attached diagram) will have a total area of 6,250 square feet (about 1/6 acre) arranged in 12 beds. Each bed will be 2.5 feet wide by 100 feet long, with 2.5-foot pathways between beds. Our planned arrangement allows for randomization of each method, including the control, in each of the three replicates, which will reduce the impact of confounding variables and allow us to correct for natural variation across the plot.

Initial preparation will consist of tilling the entire block and forming beds with a tractor-drawn bed shaper raised to approximately 6 inches. All beds will begin with an initial cover crop of a mix of oats, field peas, and buckwheat . Over the 23-month project duration, we will plant two cycles of spring and fall cover crops in addition to a cash crop (cauliflower in 2023 and peppers in 2024) throughout the plot. The no-till treatments will be applied separately to each row.

To identify the most sustainable no-till approach, we will collect soil samples and make routine observations throughout the plot as described in the “measuring results” section. Observations will be recorded using a monthly log for each of the 12 beds. Data will be entered into spreadsheets for statistical analysis. We will cease data collection by December 31, 2024, to allow time for statistical analysis and reporting.

The objectives of this project include:

1. Evaluate which of the three treatment methods provides the largest gains in soil health over the project duration by comparing soil sample data and quantitative observations.
2. Establish a practical, sustainable balance between labor investment and ecological benefit of three no-till treatments by comparing return on labor with measured soil and crop health
3. Share study progress, results, and practical implementation techniques with other small vegetable growers through farm field days and publication or conference presentations.