Average precipitation: 8 inches (irrigated cropping)
Cropping system: Onions in rotation with corn. They also lease ground to other farmers to grow vegetable crops including potatoes and dry edible beans.
Watch the companion video, Strip-Tillage in Onions, Farmer-to-Farmer Case Study Series, which introduces Grigg and his strip-tillage system.
The farm’s fine sandy soils (Quincy fine sand, NRCS 2016) are highly susceptible to wind erosion. Particularly in the spring and fall, fine windblown dust can create conditions that are a public health and safety concern. In the spring, windblown sand can also destroy young seedlings. When this happens, farmers to have to replant at significant expense, or, if the planting window for the primary crop has passed, convert to another, generally less profitable, crop.
In response to this issue, Grigg and his father developed a strip cover cropping system that reduces wind erosion and protects seedlings during the spring.
Developing Cover Cropping Strategies through Trial and Error
Because almost all of the farm’s 3,000 acres are fine sand, Grigg and his father knew that windblown sand would likely be a concern for slow-growing onion seedlings. Furthermore, onion seed is expensive and small, with demanding requirements for successful stand establishment. The shallow planted seed needs a fine-tilled seedbed for emergence, without crop residues or clods. This leaves the soil, especially sands, even more prone to wind erosion.
The Grigg strip-till system is a response to the exacting needs of onions. Grigg and his father adopted cover cropping the first year they grew onions, in 1993. The system drew on strategies Grigg’s father had used for sugar beets in the 1970’s, as well as a system their neighbor was already using for onions.
Initially, they broadcast the wheat seed for the cover crop across the field in the fall, and then strip-tilled the area that would become the onion beds prior to planting in the spring. However, this left too much residue in the area where the onions were being planted. To address this, they developed an air seeding system that would broadcast the cover crop in strips (Figure 1). In the spring, they strip-till the unplanted area, and then run the planter behind the strip-tiller (Figure 2).