Soil compaction can adversely affect vegetable production by hindering your plant’s root growth and development.
Soil compaction occurs when soil particles are pressed together, reducing the space between them, and limiting the rate of water flow and drainage from the compacted layers. Compaction reduces the exchange of gases in the soil, decreasing aeration, and it also reduces the roots’ ability to penetrate into the compacted layers of soil.
Mark Hutton, Extension Vegetable Specialist at the University of Maine, provides insight on how you can discover what practices on your farm may be leading to compaction and how to get back on the path to improved soil health and plant vigor.
Minimizing Traffic in the Field
One of the primary practices that leads to soil compaction is traffic in the field, according to Hutton, whether it be from vehicles or feet.
“Vehicle traffic and foot traffic can eliminate the air pockets, or the spaces between soil particles, and that’s what holds the moisture and air plants need,” Hutton explains.
To solve this problem, many growers Hutton is working with are using permanent bed systems, which enable the wheels on their tractors to always be in the same spot.
“So we’ll have a heavily compacted area there, but the bed in which they’re growing the crop never has foot traffic or has vehicle traffic on it; we tend not to see compaction issues in that area other than what we might get from a plow pan,” he says.
Hutton also has seen larger-scale growers using floating tires and generally minimizing the number of times they pass through the field to further reduce compaction.
Benefits of Reduced Tillage
Conventional tillage is one of the main production practices that leads to soil compaction, he explains.
“If you’re taking a rototiller through the field, for example, you always go to roughly the same depth. Whether that’s 6 inches or 12 inches, you’re loosening that soil profile, but below that you are packing the soil down and creating what we call a plow pan. The roots grow down to that plow pan and stop, hindering plant growth,” he says.
Furthermore, conventional tillage affects the soil structure negatively by breaking up the soil into finer and finer particles that eventually clump together again and become compacted.
As an alternative to rototilling, moldboard plowing, or other forms of conventional tillage, Hutton suggests using tools such as rippers, chisel plows, or employing deep-zone tillage to help minimize compaction.
“Deep-zone tillage units are essentially single shanks on a tool bar, and the spacing between them varies for different operations. The shank may go between 18 inches and 22 inches into the soil and it rips through the soil to break up the plow pan and fracture the soil to eliminate compaction,” he explains.
Behind the shank, there is typically a rolling basket that creates a seedbed growers can plant directly into.
Through this particular method, roots are able to find the fissures in the soil and grow through them, and water is able to penetrate deeper into the soil after heavy rainfall.
Because deep-zone tillage systems utilize approximately 40 horsepower equipment to pull each shank, some growers may not have the proper scale of equipment for the job.
“To help, we are looking at different intensities of tillage scaled for smaller growers who may not have large enough equipment. We are researching different combinations of intensities, depths, and frequencies of tillage,” he says.
Advantages of No-Till
Hutton says that no-till is the direction many growers are headed, and that row crops such as corn and soybeans are already being planted no-till.
“These growers will lightly disk up the field, drill the seed in, and use herbicides to manage the weeds. They will occasionally go through with a ripper to open up the channels through the field so water can infiltrate instead of running off,” he explains.
This technique is slowly being adopted for use in vegetable crops, Hutton says. Bare ground crops such as squash, pumpkin, sweet corn, and beans have been some of the first to utilize no-till practices.
Hutton also suggests using tillage radish as a way to break up plow pans, especially for those who may not be able to use deep-zone tillage.
“The tillage radishes form a very long taproot that goes down through the soil and can fracture and break down the plow pan. The radish forms a very dense canopy, it winter kills, and as the roots rot, they leave an inch to 2-inch diameter hole down through the soil.
In addition to helping reduce soil compaction, tillage radish also can help suppress weeds.
Make Sure Reduced Tillage or No-Till Is Right for You
Before deciding to implement reduced tillage, Hutton suggests asking yourself a few basic questions about your motivations.
“Growers need to develop a clear idea about their reasons for implementing reduced tillage or no-till. What are they hoping to achieve from it? How is it going to integrate with their choice and use of cover crops and cash crops?” he says.
While he explains that reduced tillage and no-till may not be for everybody, the reasons for this have more to do with grower temperament or level of management than anything else.
“It’s a different way to look at how you’re farming,” Hutton says. “One of the best things to do is to talk to other growers who are doing reduced tillage. Find out their reasons for doing it, see how it fits into their system, and think about how you can make those changes in your own operation. I don’t think these methods are harder or easier than anything else — they’re just different.”