Soil compaction is often thought of as a problem associated with perennial berry, grape or tree fruit plantations, in which equipment passes over the same places for many years. However, in reality soil compaction is but one form of damage to soils that is common to all types of agriculture.
Fields under vegetable production can suffer from compaction just as much as those planted in perennial crops, except the compaction can be more widespread.
In native soil (not previously cultivated), particles are arranged randomly, and there are many spaces between these particles that allow for the presence and passage of air, water and living organisms. The wheels on heavy equipment eventually squashes those soil particles closer together, reducing those spaces and therefore reducing the proportion of air and water to solid soil particles. This effect is much worse when equipment is used on the soil in wet conditions, but regardless, tires and cultivation of any sort, in any conditions, will cause soil compaction given the passage of enough time.
Compacted soil is damaged soil and is bad for farm production. In a University of Guelph study that was reported in The Grower magazine in September 2014 researchers examined how air injected into a drip system in field-grown tomatoes, peppers, cucumbers and sweet corn significantly increased yields of between 13 and 18%. By adding air into soils with excess water in the spaces between soil particles, the researchers concluded that root respiration and microbial activity is increased. Obviously, compacted soils will suffer from reduced root respiration and microbial activity.
How do we manage soils that are compacted?
One helpful method that has been used in perennial small fruit plantations is subsoiling. You don’t have to be a berry farmer to benefit from subsoiling. Make sure to perform this task in a dry time of the year, as the fissure left by pulling the subsoiler will stay open through into wetter weather, allowing more air movement and better drainage. Subsoiling in wet weather will not only be more difficult, requiring more tractive power, but the subsoil fissure may close quickly again soon afterwards.
Another way of helping to recover compacted soil is to plant a cover crop of tillage radishes. These are typically daikon radishes that grow a large tuber up to 18 inches or more, with an even longer taproot. An article in Top Crop Manager (West) from December 2013 explains how these radishes break up compacted soil, and plough pans, as their roots grow downwards through the soil.
Planted in the summer, the radishes rot in the spring, leaving natural air pockets that help air and water percolation through the soil. An added bonus is nutrients stored in the tubers, cycled up from the depth of the taproot to the surface layers of the soil where subsequent crops take advantage of it. TerraLink offers Aerifi variety tillage radish under our Richardson Seed brand. A crop of Aerifi tillage radishes also adds valuable organic matter to your soil, giving you several good reasons to try it. For more information on Aerifi or other Richardson Seed products, call and speak to our technical Customer Service Reps at one of our Sales Desks, in Abbotsford (800-661-4559) or in Delta (604-946-8338).
Research project examines drip irrigation on vegetable production. The Grower, September 2014, p.12
Tillage Radishes – A New Option for Improved Soil Health. Top Crop Manager (West), December 2013