Manage high-yielding corn residue with vertical tillage
Vertical tillage may help solve problems of uneven germination and emergence caused by heavy residue from high-yielding corn
How to manage residue from high-yielding corn in conservation tillage systems is a hot topic among corn and soybean growers. Excessive corn residue causes a problem because it is slow to decompose and can interfere with drill and planter performance in the following crop. Problems at planting can lead to poor and uneven germination and emergence, delayed dry down, and reduced yield and profitability.
Growers are saying that the corn stalks with many of the current varieties are larger, remain green longer, and break down slower than in the past. Some suspect the Bt varieties are more resistant to microbial breakdown but that link is not clear. Differences may simply be due to healthier plants and less insect damage. Stalk breakage and boring by European corn borer opens plants and ears up to drying, while rootworm damage impedes water uptake. This leads to plants that dry sooner and are more susceptible to decay with more insect damage.
High residue fields typically have cooler, wetter soil at planting so delayed soil warm-up is an ongoing problem in poorly drained soils. Zone-tillage with multiple coulters and/or row cleaners to sweep residue from the row are generally effective for loosening, drying and warming the soil for planting in high-residue conditions. No-till drills are not as well equipped as planters to manage heavy residue. Drills tend to plug and push residue into piles that persist throughout the season and interfere with the combine at harvest.
The specific demands of no-till cropping have led to a new generation of tillage equipment that use coulters or narrowly spaced, shallowly concave disks rather than conventional tillage shanks. These ‘vertical’ tillage tools fracture and loosen the top 2 to 3 inches of soil, level wheel tracks, improve infiltration and reduce runoff. They do not bury crop residue, but they cut and shatter it into smaller pieces for even distribution and better contact with the soil. These are generally high-speed tillage tools that run at 8 to10 miles per hour when conditions allow it. Ownership and operating costs for these tillage tools are typically $8 to $10 per acre per pass across the field.