You only get one chance to give a crop the right start, so it’s important to understand how previous tillage and crops impact seed’s access to soil. While crop residue breaks down to provide additional nutrients, it can also impede seed success if not managed correctly.
“There are four key risks we identified associated with residue at planting: reduced seed-to-soil contact, physical impedance of emergence, nutrient tie up and slower soil warm up,” says Pauley Bradley, John Deere product manager.
1. Residue can prevent seed-to-soil contact. Managing residue starts at harvest—did your combine evenly spread residue this past fall? If so, you’re off to a good start. If not, know uneven residue might keep some seeds from coming into contact with the soil.
“Planter mounted residue managers can be an effective way to move residue out of the way,” says Chris Lursen, Case IH tillage marketing manager. “In no-till or minimum till, use a ‘no-till style’ planter-mounted residue manager to move residue out of the way and use finger-style options in conventional tillage.”
Adjust row cleaners to provide adequate seed-to-soil contact for each field and specific areas of fields.
2. Residue can physically block seedlings from emerging. Corn is more sensitive to residue impeding emergence than soybeans. Heavy residue can block access to sunlight, and the weight of residue can stop seedlings from breaking through the ground.
“Improvements in corn hybrids over time leads to higher yields and more residue to deal with than in our history,” says Mahdi Al-Kaisi, Iowa State University (ISU) professor and Extension specialist in soil management.
Be mindful of areas of the field where residue is gathered, such as low spots where water moved residue over the winter. Those areas are at a higher risk of impeding seedling emergence.
3. Avoid making seedling roots and microbes compete for the same nutrients. “Microbes begin to ramp up as soil temperature approaches 50°F, which means they could compete with roots for nitrogen,” Bradley says. “Microbes need nitrogen to digest residue. Think of it as a diet where the nitrogen is protein and the cellulose and lignin in the residue are carbs.”
The nitrogen you apply helps feed microbes, and a spring or at-plant banded application near the row can help ensure both microbes and seedling roots have what they need. Particularly in fields with heavier residue, consider spring application or banding near the row.
4. Residue impacts soil temperature. Residue insulates the soil, so fields with more residue will take longer to hit the optimal 50°F mark for planting. This could mean you need to delay planting for a few days to avoid emergence issues.
While too much insulation can be harmful in the spring, it could be beneficial in hot summer months. Residue interrupts sunlight, which could help slow water evaporation and keep the soil around the roots cool. Because corn roots don’t like excessive heat this could help reduce stress and keep the plant focused on grain production.
Residue breaks down at approximately the same rate, regardless of the tillage system or whether it’s buried or left on the soil surface, according to Al-Kaisi and ISU research.
“No matter what, when residue decomposes about 70% of its carbon will be lost as CO2 and only 30% added to the soil organic matter,” he says.
This spring, evaluate your fields’ residue cover and make a game plan to use residue to benefit your crop.