Conservation Tillage

Cooperative Extension Service

Purdue University

West Lafayette, IN 47907

Strip Preparation for No-till Corn
and Soybeans

D.R. Griffith, T.D. West, G.C. Steinhardt, and
P. R. Hill, Department of Agronomy
S.D. Parsons, Department of
Agricultural Engineering

Long-term research and farmer experience in the Midwest show traditional no-till planting (using one no-till coulter in front of each row) usually maintains or improves yield potential on well drained and very low organic matter soils. However in some cases, no-till planting may have a yield disadvantage compared to full-width or ridge-till systems. One or more of the following conditions are usually associated with reduced no-till yields: heavy residue levels, poor soil drainage, northern Corn Belt locations, very early planting, uneven residue distribution, or an uneven soil surface. Such conditions can result in reduced stand, uneven emergence, slow early-season growth, allelopathy, and delayed maturity-all potential yield limiting factors. These negative factors reduce corn yield more than soybean yield, since soybeans have a greater ability to overcome early season stress and to compensate for reduced stand.

To offset some of the limitations of traditional no-till planting, many farmers now use planter attachments to prepare a wider residue-free and/or tilled strip for each row not tilled before planting. One of the more popular "strip preparation" attachments is double disks or spiked wheels for residue removal. Another attachment is a set of two or three staggered, non-powered fluted coulters that loosen soil and partially incorporate residue in a 6- to 8- inch band ahead of planter units. Both types of attachments are often used on the same planter. Some farmers use other methods for improving the in-row area, either at planting or before planting in early spring or the previous fall. One method is planting in the old row middles with a single coulter or other attachments. This method avoids corn stalk stubs and the heaviest residue, often leading to more uniform seed placement. Other methods of loosening soil in the row include cultivator sweeps or powered rotary tillers set for strip tillage, either preplant or with the planter. Anhydrous ammonia applicators with "wings" attached to the knives are sometimes used in the fall to prepare strips for spring planting.

This publication reviews relevant research findings, discusses ongoing Purdue University research, and summarizes the challenges and opportunities with strip preparation practices for corn and soybean production.

Research results

Recent studies in the northern Corn Belt show an advantage for residue-free rows for corn. In Central Iowa, maintaining a 10-inch wide residue-free band for the row regained about 80 percent of the yield loss for no-till compared to a clean-tilled seedbed for continuous corn on silty clay loam soil.

Farther north, Minnesota researchers found that residue removal from the row area was successful for no-till corn in 1989 and 1990, but not in the drier spring of 1988. They concluded that greater than 20 percent in-row surface cover often lowers yield potential. With the longer growing season in western Kentucky, removing residue from the row area increased continuous corn yield in only one year out of four on a moderately well- drained silt loam soil.

Strip tillage for corn and soybeans is not a new idea, but evaluation in research plots is limited. Studies in Indiana (1967-70) and Ontario (1982-84) found that powered rotary tiller strips about 8 inches wide and 4 inches deep improved growth, maturity, and yield of continuous corn compared to traditional no-till planting into the previous year's rows. However, growth, maturity, and yield were still significantly better with full-width tillage, compared to the strip tillage method.

West Central Indiana

More recent comparisons of strip preparation techniques for no-till corn and soybeans in Indiana began in 1991 at the Agronomy Research Center near Lafayette. A conventional fall plow system was compared to no-till with the following planter attachments:

Figure 1. Effect of strip preparation on daily maximum soil temperature, corn after corn, Chalmers silty clay loam, Lafayette, IN, 1991-1993.

With these attachments, both corn and soybeans (in 30-inch rows) were planted into the previous year's rows in plots without any preplant tillage.

When corn followed corn, residue removal significantly increased soil temperature (Figure 1), and improved growth, maturity, and yield (Table 1). However, all these factors improved with fall plowing compared to no-till with residues removed. Corn showed little response to in-row tillage, with or without residue removal. For both corn and soybeans in rotation, there was very limited growth and maturity response, and no significant yield response, to residue removal or strip tillage, compared to traditional no-till planting.

Another study at the Agronomy Research Center compares fall vs. spring strip preparation methods and planting into the "old row" vs. between-row planting. Table 2 shows selected one-year corn following corn data from this study.

Shifting traditional no-till corn to row-middles, instead of planting in rows from the previous year, improved yield, primarily due to a better stand. Using strip preparation with the planter in row middles did not improve yield over traditional no-till. Fall strip preparation improved soil temperature, stand, and maturity, but yield was still significantly lower than fall plowed corn yield and little better than traditional no-till between rows.

In this same study spring strip preparation did not improve traditional no-till stand, growth, or yield when corn followed drilled soybeans.

Table 1. Yield Response to Strip Preparation, Chalmers silty clay loam, Lafayette, IN, 1991-1993.

                     Corn    Corn     Soybeans
                     after   after      after
  Tillage            corn  soybeans    corn

  Fall Plow          171     173        51
  No-till            152     175        50
  No-till + RR       159     177        50
  3-coulters         154     172        51
  3-coulters + RR    161     172        52
  Mini-till          151     176        52
  Mini-till + RR      154     171        50
 RR  Residue removed

Table 2. Continuous Corn Response to Strip Preparation, Toronto silt loam, Lafayette, IN, 1994.

                    Position   Soil   50%       Stand at  Height  50%  
                          b      c
                    of rows    Temp.  Emergence   4 wk     8 wk Tassel  Yield
  No-till	       in      62.5   21        21,500     38     84    163
  No-till              bet.    61.5   19        24,958     42     82    184
  Spring strip-prep a  bet.    62.2   19        22,958     43     82    177
  Fall strip-prep      bet.    63.4   17        25,708     43     80    189
  Fall plow            --      65.8   15        25,667     57     78    223
 a Strip-preparation included row cleaners plus 3 fluted coulters per row.
 b In or between last year's corn rows.
 c  Average daily soil temperature for first 5 weeks.

Table 3. Corn After Drilled Soybean Response to Strip Preparation on Blount Silt Loam, NEPAC, 1992-94.

                 Stand,    Height, Harvest
  Tillage        4 wks     8 wks   moist     Yield
                 plants/a. in.      %         bu/a.

  Spring chisel 23,125     57.8     26.2       156
  No-till       24,667     57.1     26.5       153
  Row cleaners  22,972     55.1     26.6       151
  3 coulters    24,694     55.9     26.3       155
  Mini-till a   23,875     56.8     26.1       157
  a Loosens a 4-inch strip of soil 4 inches deep, leaving residue

Northeastern Indiana

Strip preparation studies are also being conducted on two soil types at the Northeast Purdue Agricultural Center (NEPAC) near Columbia City, IN. Three- year data from Blount silt loam (Table 3) show no significant difference in yield among spring chisel, no-ftll, and strip preparation for corn following drilled soybeans.

In continuous corn on Rawson sandy loam at this same location, the spring chisel system produced the highest yield (Table 4), but planting between the old rows improved traditional no-till yield. Residue removal and strip tillage did not increase yield compared to traditional no-till planting between the old rows.

Fall fertilizer bands

Some Indiana farmers apply anhydrous ammonia (and sometimes other nutrients) where the corn rows will be next spring, often using disks to form a small ridge of soil over the fertilizer band. They then no-till plant corn into these fall- prepared strips. One year's data at Lafayette, IN, planting into a 2 inch fall ridge, showed soil temperature, growth, and maturity advantages similar to other strip-preparation techniques.

Studies throughout the Corn Belt show planting into a 5- to 7- inch ridge made the previous year provides growth and yield almost equal to fall plowing, even in poorly drained, high- residue fields. It appears the success of this method of strip preparation depends on the ridge height, amount of seed zone elevation, and the resulting increase in soil temperature.

An advantage for this system could be the omission of starter fertilizer, since roots of young seedlings should have access to the fall-fertilized bands. However, fall applied nitrogen (N) often needs a nitrification inhibitor to minimize losses. Even with an inhibitor, fall applied N is usually less efficient than side- dressed N in the Eastern Corn Belt.

Soil erosion and strip preparation

Moving residue from the row and/or loosening soil can cause serious water erosion problems if rows run up and down slope. Residue measurements in corn stubble have shown that fluted coulters and soil lifters usually leave enough soil cover for adequate erosion control and compliance with Food Security Act regulations. Use of attachments to provide residue removal in corn stubble, or any strip preparation in soybean stubble, may not leave soil with adequate protection from soil erosion. Consider the following suggestions for residue removal or strip tillage on highly erodible land:

Table 4. Corn After Corn Response to Strip Preparation on Rawson Sandy Loam, NEPAC, 1993-94.

                       Stand,   Height, Harvest
 Tillage               4 wk     8 wk    moist     Yield
                     plants/a.  in.      %         bu/a.

 Spring chisel        25,375    69      21.0       157
 No-till in row       23,500    62      21.1       142
 No-till between rows 25,590    63      21.1       148


Experience shows that both strip preparation techniques and traditional no-till planting have limitations in certain situations. Where soils stay wet under heavy residue, soil engaging tools throw soil from the row and form clods when the soil dries. When residues are removed from wet soil, the soil often sticks to planter depth gauge wheels causing variable seed depth. Spiked wheels may throw some wet soil from the row area, leaving a slight furrow in the seed zone.

The operating depth of both residue removal and strip tillage attachments can change as soil conditions change across a field. On-the-go adjustment of these attachments would be desirable.

In heavy cover crops or sod not killed several weeks prior to planting, non-powered strip tillage attachments may not perform satisfactorily. The vigorous root system of these crops holds soil firmly in place.

Wind often blows residues back into the row area lessening the desired warming/drying effects.

Summary and conclusions

Where reduced stands or uneven seedling emergence limit traditional no-till yields, either planting beside/between last year's rows (in corn after corn) or using strip preparation should improve yield potential. In uneven crop residue or surface-applied manure, row cleaners should provide a more uniform seeding depth. Where previous wheel tracks create a non-uniform soil surface, zone tillage may also improve seeding depth uniformity.

If lower early season soil temperature and/or allelopathy cause slow growth and delayed maturity, row cleaners should improve yield potential. However, yields may not equal those with full-width tillage on dark, silty clay loam soils.

Since both erratic seedling emergence and slow early growth affect corn more negatively than soybeans, strip preparation is likely to improve corn yield more than soybean yield.

While response to strip preparation depends on soil type, previous crop, and latitude, both research and farmer experience support the following conclusions.

New 12/94

Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U.S. Department of Agriculture Cooperating. H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the Acts of May 8 and June 30, 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to our programs and facilities.