AEN-129

Are Your Fields Ready for No-Till?

AEN-129
Authors: Dr. Greg Brenneman, ISU Extension Field Specialist -
Agricultural Engineering, and Mr. Jim Fawcett, ISU Extension Field Specialist - Crop Production
Revised January 1992
Content reviewed 4/95 by Dr. Mark Hanna, Department of
Agricultural and Biosystems Enginering

Welcome to No-till Notes, a four issue newsletter to help you be successful with no-till planting. The topics to be covered are:

Are Your Fields Ready For No-till?
No-till Soybeans - The Explosion
No-till Corn Can Work
Equipment Tune-Up for No-till

In this first issue of No-till Notes , we are going to look at what needs to be done to be sure your fields are ready for no-till. Areas to consider include compaction, drainage, fertility, and residue management.

Compaction

One of the most important reasons that poor results have sometimes occurred with no-till is because of soil compaction and poor soil structure. In many cases, this is a result of past tillage operations being conducted when the soil is too wet. This compaction, and associated poor soil structure, is often located at depths of 2-6 inches. If the soil has been disked early in the spring to "dry out the ground", there may well be a zone of compaction being created at the depth of disking that can cause problems for several years to come. Repeated tillage passes in the spring results in a high percentage of the field being covered by wheel traffic. This reconsolidates much of the soil loosened previously by the tillage. Also, repeated tillage passes break down the structure of the soil making it more susceptible to recompaction and allowing it to run together when subjected to rainfall.

When tillage is done year after year, enough of this soil is loosened to allow decent crops to be produced. If tillage ceases, this zone of poor soil structure and compaction can restrict root growth and decrease yields.

The best way to determine if compaction is a problem is to dig some test holes to a depth below any previous tillage in early summer. Examine corn roots for direction of growth and density. If compaction is a problem, dense layers of soil with few pores will be altering root growth. Root density in these zones will be decreased and often roots will be growing horizontally above the compaction zone. Other clues of compaction problems are uneven corn growth and frequent ponding of water following rains.

If it appears that compaction is a problem or the soil seems to have poor soil structure, a deep loosening of the soil prior to starting to no-till is often beneficial. A Paratill or similar tool that fractures and loosens the soil while leaving much of the crop residue undisturbed and a level surface is ideal for this. Another option is to use a chisel plow and pull a harrow or other leveling device to leave the field even enough for no-till planting the following spring. Ideally, these operations should be done under dry conditions in the fall following corn. Once this loosening tillage is done, it is
important to minimize traffic and do no further tillage that would recompact the soil that has been loosened.

Drainage

In the upper Midwest, best results with no-till have usually been obtained on soils that are well to excessively well drained. With good management, favorable results have also been obtained on moderately well and somewhat poorly drained soils.

Crop residues left on the surface by no-till can slow soil warming in the spring. Usually, this only presents a problem on wet soils where the excess water is already causing problems with soil warm-up. Therefore, in marginal drainage situations, adequate tile and surface drainage are important for successful no-till production.

In a corn-soybean rotation, problems with soil drainage are less than in continuous corn production. This is because the lighter soybean residue does not slow soil warm up as much as corn residue does. Soybeans are planted later than corn, so early warming of the soil is less critical.

Fertility

Before going into a no-till system, it is desirable to have phosphorous and potassium levels in the medium range or above. Also, soil pH should be above 6.0. If soil tests show levels below this, ideally, some fertilizer or lime should be incorporated prior to starting with no-till. This could be done in the fall in conjunction with tillage being done to correct compaction problems.

If large amounts of lime are needed to correct a pH in the low 5 range, it should be incorporated with a chisel plow or other tillage operation. Otherwise, if a heavy application of lime is made without incorporation, a very high pH level can occur right at the soil surface. Incorporation of P or K is less critical than lime. Also, on low testing soils, P and K can be "deep banded" into the soil with the planter or in a separate operation. In fact, applying a complete fertilizer with the planter is desirable in many no-till situations. On higher testing soils, if maintenance fertilizer is desired, it can be applied this way. On low testing soils, row applied fertilizer is most likely to give a yield response.

Residue Management

No-till planting actually starts the fall before. It is important to get last years crop residue evenly spread during harvest. This not only provides better erosion protection but also reduces problems with equipment operation and early crop growth.

Proper spreading of residues includes both the straw and stalks as well as the fines. This is especially true with soybeans where large amounts of hulls and chaff can be concentrated behind the combine. For combines with headers 15' or wider, consider adding a chaff spreader in addition to the normal straw spreader.

In most cases, chopping or shredding of cornstalks after harvest is not needed. In fact, this can be a detriment by making a mat of the residue that slows the drying and warm-up of the soil. Finely shredding the stalks can also allow residue to blow or be washed off the field.

Getting Ready For This Spring

To get ready for no-tilling this spring, evaluate the following items for each field:

What are the P and K soil test levels and what is the pH level of the fields you want to no-till? Will any special fertilization need to be done?
Have you observed any past compaction problems? Is there reason to think there might be compaction or poor soil structure problems? (worked or harvested on wet soils, repeated tillage operations)
Are your soils well suited to no-till? Many soils that are subject to soil erosion problems often have good natural drainage where no-till works the best.
Is last year's crop residue well distributed? Is there a heavy windrow of soybean chaff that could cause problems? If so, row cleaning disks may be very helpful.

Just because you don't have the "ideal" field for no-till, it doesn't mean you will be unsuccessful with no-till. Just be aware and carefully manage around potential problems.