By Sjoerd Willem Duiker, Soil Scientist
Corn and soybean grain harvest is just around the corner, and it’s time to emphasize the importance of residue distribution for no-till success. Uniform distribution is important for planter and drill performance, but also because the residue contains nutrients that you want to spread evenly over the field and because it affects soil temperature and moisture, and is the source of food for soil organisms.
If you have swaths of heavy residue alternating with strips with little residue in the field, you will have areas that will be cooler and wetter alternating with areas that are warmer and drier — causing unevenness in germination and early growth of the next crop. In addition, you have piled up the nutrients in the residue swaths, which can cause nutrient variations.
There are things that can be done at the front and back of the combine to improve residue distribution. Some important principles are (1) limit the amount of residue that is taken into the combine and (2) distribute whatever comes out at the back evenly over the entire harvest width. The combine head can be set up to limit crop residue intake. Any residue that does not enter the combine does not need to be distributed, so it is better to leave it where it stands. In addition, it improves harvest efficiency and reduces fuel consumption.
Raising the head is one option to avoid taking in too much residue. However, remember that some of those tall stalks can cause problems when they get stuck in the planter or drill chains and other parts. Some corn heads strip the cobs off the plant, leaving most of the corn plant before it enters the combine. There are trash reduction kits available that allow you to modify your head to accomplish this objective. Besides helping with residue distribution, these kits also help to improve combine performance and allow for faster harvesting speed. In addition, these kits may include crushing knife rolls to crush corn stalks to speed up decomposition.
There are also chopping corn heads that chop up stalks for faster decomposition. There are a couple of manufacturers making these. They come at a price and require extra power — estimated at 1.5-7 hp per row. They leave the residue in a uniform blanket on the soil. Personally, I prefer to leave as much of the stalks standing as possible and limit the amount of residue that is loose on the soil surface because it can easily be blown around by wind or carried away with water.
At the back of the combine, chaff, stalks, leaves and cobs or empty pods need to be distributed over the entire width of the combine head. Larger heads will necessitate more aggressive residue spreading. There are bat spreaders and chaff spreaders, as well as rotary choppers. Remember that chaff needs to be distributed besides straw. Usually, the chaff exits the back of the combine at a different location than the stalks. Therefore a chaff spreader needs to be on the combine besides a stalk spreader.
Residue distribution is extremely important to have success with your no-till seedings this fall and next year. A video about crop residue distribution and other no-till issues is available here.