With harvest already out of the way for some corn and soybean producers, there may be ample time this fall to repair compaction-damaged fields. Randall Reeder, an Ohio State University Extension agricultural engineer, encourages growers to explore cover crops like legumes or grasses as a way of alleviating compaction issues.
“Subsoiling is an obvious and common technique to break up soil and smooth out rutted fields,” Reeder says. “But cover crops are a natural biological plow and may be an attractive option to solve some compaction issues, while getting the added soil and environmental benefits that cover crops bring to ag production management.”
Ohio State University Extension research has found that cover crops incorporated into a continuous no-till field crop rotation can produce enough nitrogen to complement, or in some cases, replace corn nitrogen fertilizer applications. In addition, cover crops improve the soil structure, support microbial diversity, facilitate drainage, reduce soil erosion, reduce nutrient leaching, store carbon, suppress weeds, enhance wildlife and serve as a forage product.
In order for no-tillers to make the most of all that cover crops have to offer, they need to plant as early as possible, preferably by mid-October, Reeder says. The early harvest of corn and soybeans this fall provides a good window for experimenting with a cover crop.
“Cereal rye and oats are the two best fall cover crops,” Reeder says. “They are both deep-rooting and if planted by mid-October, should grow well in Ohio.”
If producers are planting cereal rye and plan to follow with corn in the spring, they should plan to kill the crop 3 to 4 weeks prior to spring planting, Reeder says.
“If planting soybeans, growers can let the cereal rye continue to grow and then plant no-till soybeans into the standing cover crop,” he says. “Most drills will flatten the rye. The cereal rye can then be sprayed either before or after soybean emergence.”
Reeder says that oats is another good choice because the crop will winter kill. For growers living in southern Ohio, oilseed radish is also an option.
“The radish will not reach the size it would have if planted in August, but should produce roots 1 to 2 feet deep,” Reeder says.
Research has shown that compaction affects crop yields. Years of Ohio State research on Hoytville silty clay loam showed that through compaction, 10% to 15% of the potential crop yield was being left in the field.
Subsoiling can help, Reeder says, but recent research shows that continuous no-till can be more effective at minimizing compaction losses. Continuous no-till soil resists compaction from heavy loads better than soil that is subsoiled every 3 years, resulting in higher yields.