From 1998 to 2000, yields from different tillage treatments were tracked at the Ag Engineering Research Center near Boone. The purpose was to research differences in yield in a side-by-side comparison.
The tillage treatments studied included three different full-width tillage practices: a moldboard plow, a subsoiler, and a chisel plow; strip-till (without fertilizer deep-placed at the time of tillage); and no-till. Yields were measured in both corn and soybean (Table 1). The approximate individual plot size was 20 rows by 90 feet in length on a slope of 0 to 3 percent. All the plots were treated equally; for example, all plots were planted on the same day, and if one plot was cultivated, all were cultivated (including strip-till and no-till). Fertilizer was broadcast applied for all tillage treatments (the fertilizer was not incorporated for strip-till). Although fertilizer is ordinarily deep-banded at the time of strip tillage, it was desired to see whether tillage alone in the row made a significant difference without the addition of fertilizer. The research returned some interesting data and the following observations were made.
First, there was a trend during the 3 years for some full-width tillage to increase corn yield at this location. Individual tillage treatments failed to consistently rank high or low within different field locations in the experiment, however, so statistics did not suggest with a high degree of certainty overall differences between tillage systems.
Second, the yield performance of any one tillage system tended to vary between years. For example, soybean that had been treated with the subsoiler went from lowest yield in 1999 to highest in 2000. Several factors may have been important in that result. Dry soil conditions early in the season may have forced roots to go deeper for moisture. Then, in August, with the hot weather, the root systems were better developed, allowing the plant to withstand a dry period in late summer. Conversely, soybean performed better with strip-till in the row in 1999 and not as well in 2000.
So what do the data prove? The numbers vary from year to year and averages tend to converge with time. Although 3 years of data give some perspective, tillage systems probably will respond somewhat differently as weather and soil conditions vary in the future. In addition, long-term effects on soil productivity must be taken into account if a full-width tillage system produces erosion on unprotected soil.
Although the yield response of specific tillage systems varies with soil and weather conditions, reducing input costs to maintain profitability is an important factor under the producer's control. Every tillage pass costs something. For example, an average primary tillage pass (plowing, chisel plowing, or subsoiling) costs around $7-10 per acre, whereas an average secondary tillage pass costs somewhere between $5-8 per acre.
Here's an example: the input costs of chisel plowing, following by disking and a pass with a field cultivator adds up fast--as much as $26 per acre in input costs over no-till before any crop is planted. Consider closely added input costs and time requirements versus potential yield benefits of extra tillage trips.
Precise records of activities (and their input costs) and returns can mean more money in the bank. Think about managing for profit rather than simply yield.
It's a sure bet that weather and soil conditions next year will differ somewhat from those experienced by these tillage plots the previous 3 years. Research will continue in an attempt to discern longer term trends. Regardless, the data indicate yields from tillage systems vary with that year's weather conditions. Because of the impact of input costs on slim profit margins, managers should have a clear-cut objective for tillage before taking the implement out to the field.
Table 1. Yields from tillage treatments at Ag Engineering Research Center (Boone) in 1998, 1999, and 2000.
|Strip-till (w/o fert.)||142||139||134||138||47||59||32||46|
NS, not significant.
This article originally appeared on page 199 of the IC-484(25) -- December 18, 2000 issue.