By Sjoerd Duiker, Soil Scientist
Residue distribution is important in both high and low-residue crops. Uniform distribution is important for planter and drill performance, uniform spreading of residual nutrients, soil temperature and moisture consistency, and as a food source for soil organisms.
If you have swaths of heavy residue alternating 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 both the front and the back of the combine to improve residue distribution. Some important principles are:
- Limit the amount of residue that is taken into the combine, and
- 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 planter or drill parts and chains. 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, they may include crushing knife roll,s which crush corn stalks to speed up decomposition.
There are also chopping corn heads that chop up stalks for faster decomposition. Made by several different manufacturers, 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. So if you have a 15-foot combine head you need to distribute the residue uniformly over that width behind the combine. Larger heads will necessitate more aggressive residue spreading. There are bat spreaders and chaff spreaders, as well as rotary choppers.
I would like to call attention to the need to spread chaff 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 in addition to 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.