Farmers' tillage and residue options for spring
This spring presents many challenges for area farmers. Most residues from corn and soybean harvest are still standing, and many corn fields remain ready to combine when conditions allow. The soil under the residue is saturated. In some fields, deep ruts from October and November combining and field traffic remain.
In fields with corn residue and no ruts, there are several options: burning, multiple shallow tillage, spring strip-till, or no-till. No-till would be best suited in medium or lighter-texture soils (loams, sandy loams).
No-till would not be as good an option for clay soils for corn and sugar beets due to the danger of the furrow opening up if the weather turns dry before germination and crop emergence. Although no-till corn and sugar beet yield was better than conventional tillage in a heavy clay soil in 2008, the year was exceedingly wet following emergence, and similar results would not be expected most years.
In drier years, no-till corn and sugar beet yields were significantly reduced compared with strip-till or conventional till. Heavy corn residue may significantly delay soil warming and drying this spring. Burning is therefore a consideration in these unusual conditions. It is important to contact the local authorities before burning to avoid unnecessary responses to bystander 911 calls or possible fines for not obtaining a permit in some areas.
The field will need a tillage pass around the perimeter to deter movement of the fire to neighboring fields. In addition, having a "buddy" nearby to help with containment of the fire may be important. Dry corn leaves may leave the field, and the fire will need to be monitored more than most growers experiences from burning small grain residue fields. Burning will result in a loss of total nitrogen and sulfur from the residue, but may enhance available P and K supplies if the ash does not blow away before tillage. However, nitrogen and sulfur rates will not need to be increased this year due to fire.
The actual nitrogen available for this year's crop may actually increase because of the reduced residue that will be decomposed by microorganisms and the nitrogen they temporarily consume from the soil to accomplish decomposition.
Tillage, whether following burning or without burning should be as shallow as possible. No-till or spring strip-till planting would also be options following burning. An alternative to burning may be baling the residue if there are cattle nearby. However, on soft county roads there may be a logistical problem moving the bales to their destination.
Some type of shallow "vertical tillage" would probably be best under wet soil conditions. It is not necessary in most of our soils to break up traffic "pans." The wetness, future drying and our long winter with occasional thaws will help with that. The tillage will be needed mainly to break up whatever crust develops at the surface and allow better seed/soil contact and seal of the furrow so the furrow does not reopen when drying.
A vertical tillage tool could be spike shanks, coulters set straight with the driving direction, a strip-till unit that does not use a straight deep shank, a heavy rotary harrow, or in lighter soils perhaps even a long, thick-tine harrow. Heavy discs or wide field cultivator shanks will probably do more harm than good in the coming spring, especially on heavy soils.
In fields with ruts, extreme patience will be required. These fields will need to be tilled deeper than fields without ruts to move soil into the ruts and fill them. To promote deeper drying if the fields become crusted, a shallow vertical tillage may be required. Then when the soil dries several inches deep, tilling the field at an angle to the ruts and pulling soil into the ruts first with a heavy disc and then with a field cultivator-type tool once residue is sufficiently cut may be a good option. A combination disc/field cultivator on a second pass might work as well.
It may take several passes to sufficiently fill in some ruts. Try to follow the same tractor tracks in each pass if possible. Tractors with RTK will be able to do this more effectively. Most compaction is made on the first pass, with lesser amounts added to the total compaction in future passes. So limiting and controlling traffic passes is important whenever possible and practical.
No-till soybean into corn residue has been successfully conducted for over 20 years in the cornbelt. Visit with your local equipment dealer to see if you are set up with the appropriate seeder. With the current suite of pesticides (volunteer corn will be a problem in most standing residue fields), no-till soybean is particularly easy to do.
Going into standing stalks the first time without tillage may seem crazy, but the results have been overwhelming by positive over the years. In campus research on no-till in heavy soils, soybeans have been the most resilient to no-till, probably because of their ability to fill in gaps in stand with little yield loss.
No-till corn into soybean residue has also been used successfully, but not as successfully in heavy soils. Some shallow tillage would still be recommended in soybean stubble in heavy soils to prevent furrow reopening.
For more information, contact me at the Polk County Extension office in McIntosh or at the Clearwater County Extension office on Wednesdays. Our toll free number is 800-450-2465, if e-mail is your thing, contact me at firstname.lastname@example.org.
Source: Dave Franzen, North Dakota State University Extension Soil Specialist.