Progress report for FNE24-075
Project Information
The objective of this project is to find the ideal time to plant an oat/pea cover crop before no-till planting garlic into it. The ideal planting time maximizes biomass production up to the point of cover crop residue makes mechanical cultivation of weeds unfeasible. To determine the ideal planting time we will plant 4 successions (spaced 3 weeks apart) of oat-pea cover crop and a bare-earth control. Then we will document the differences in erosion control, weed suppression, feasibility of mechanical weed control, and yield.
The goal of this study is to develop a cost effective way to grow garlic, avoiding plastic mulch. While growing garlic in plastic mulch is a proven and cost effective system, it is wasteful and has potential negative environmental effects from micro plastics.
Another method of weed suppression in garlic is straw mulch, which is effective, but costly. In addition to the cost of the straw itself, small-scale garlic growers often do not have the equipment to efficiently spread straw mulch on garlic beds. Therefore, labor costs associated with this method are also high.
No till planting into rolled cover crops is a widely used method in herbicide based growing systems providing soil health benefits and weed suppression. When weeds grow through the mulch however, hand weeding is the only option for organic farmers, without herbicides in their toolbox.
For all the reasons stated above we have adopted the bare earth method on our farm which reliably produces good garlic yields with no or minimal hand weeding. It is more profitable for us than the other growing methods, because mechanical cultivation takes very little time. We are noticing that the soil is taking a toll. We avoid bare earth going into the winter wherever we can because we have seen soil washout, loss of soil structure and a higher rate of compaction in beds that skipped the cover cropping cycle. To close this cover cropping gap in garlic production and protect the soil through the winter, we want to find out if there is a way to have some benefits of a cover crop, while still being able to use conventional mechanical weed control tools in the following year.
This trial proposes to plant an oat and pea cover-crop at different intervals, successively closer to the first frost date. This will ensure that, at each successive interval, the cover crop would be smaller. Thus we will be able to determine the point at which the cover crop is still effective at controlling erosion, while also being manageable enough to not interfere with the mechanical cultivator. Although the cover crop would be insufficient at suppressing weed growth, as long as the mechanical cultivator is able to pass through the garlic rows unobstructed by leftover debris, this does not pose an issue. We will determine if the cover crop, at that stage, is still able to control erosion and preserve soil structure.
Cooperators
- - Technical Advisor
Research
This trial took place in 5 adjacent 500-foot by 5-foot beds. We used three successive planting dates for the oat/pea cover crop mixture, as well as a bare-earth control. Weather would not permit a fourth cover crop succession. Five 500-foot beds were tilled using a Forigo G-35 stone burier. Oat/pea cover crop was seeded at a rate of 150lb/acre using an APV air seeder. Each bed was planted with 2 rows of garlic 30” apart at a 6-inch in row spacing. The beds were prepared and cover-crop was seeded on the following dates: 8/10, 8/28, 9/28. These beds were mowed on 11/14, and our bare-earth control bed was tilled on the same day. On November 14th, the cover crops were at the following growth stages:
First planting (8/10): Peas were flowering, oats in boot stage, 3ft
Second planting (8/28): Peas not yet flowering, oats in beginning of flag leaf stage, 1.5ft
Third Planting(9/28): Peas beginning to vine, oats in the tillering stage, no stem yet for the most part, 6 inches tall.
They were flail mown directly prior to planting. The no-till transplanter available through the local conservation district was a drop-tube style planter that did not allow for upright planting of the garlic cloves. Thus, we decided to lay drip tape with our drip tape layer, which created a furrow like a no-till planter would have. We then planted by hand in the furrows at a 6-inch in-row spacing, and closed the furrows by driving a tracked mini skid-steer over them.
Deviation from original method:
Due to reliance on rainfall for cover crop germination, precise timing of cover crop seeding is challenging. We were therefore only able to plant three out of four planned cover crop plantings.
We were planning to use a no-till transplanter, but we realized that the design of the transplanter did not allow us to place every garlic bulb upright, which is required for growing hard-neck garlic successfully. The work-around we used using our drip-tape layer to create a furrow and using our mini skid steer tracks to close the furrow simulated a no-till transplanter that could be used for this method of growing garlic.
We noticed a significant amount of mustard growing to viable seed stage in the cover crops, which may pose an issue next year. Depending on the local seed bank, oats and peas alone may not be sufficient to eliminate all weed pressure during the growing season.