Minnesota Crop News > 2001-2008 Archives
Tillage Deserves a New Look
George Rehm, Extension Nutrient Management Specialist
Some of our sky-blue waters
turned brown during the past two growing seasons. Fueled
by heavy rains over much of the southern part of the state,
soil loss has, obviously, been substantial. Most growers
clearly understand the importance of keeping the highly fertile
top soil on the landscape.
Past research has also shown that use of some
type of conservation tillage system will reduce soil loss. Yet, adoption of the systems that have
the greatest potential for reducing soil loss has been, at best, slow. Over
three years, there have been several explanations for the slow adoption rate. Many
are no longer valid and it's time to take a new look at planting systems that
will keep soil loss to a minimum in the corn-soybean rotation.
Although a conservation tillage system can be described as
any practice that leaves a certain percentage of crop residue
on the surface after planting, the three generally accepted
conservation tillage systems used in the northern and western
corn belt are no-till, ridge-till, and strip-till.
Researchers have not ignored these systems. Active research projects
have compared various tillage systems that might be used for corn and soybean
production. Results of research with a silty clay loam in Indiana are
summarized in Table 1. Closer to home, a summary of research conducted
at the Southwest Research and Outreach Center at Lamberton is provided in Table
Table 1. The effect of various tillage systems
on yield of corn and soybeans in Indiana.
*Soil Type = Chalmers silty clay loam.
In this study on a soil with a texture very similar to many soils in southern
Minnesota, yield of both corn and soybean crops was lower when the no-till
planting system was used. Results from several studies which have compared
various tillage systems lead to the general conclusions that yields are reduced
where no-till is used when soils are cold and wet in the early part of the
Table 2. Comparison of three conservation tillage
systems used for the corn-soybean rotation at the Southwest
Research and Outreach Center.
*Average yield for 1999, 2000, and 2001. Source: N. Eash and
The high average yield for the strip-till system is attributed to a high yield
in 2000. In 1999 and 2001, corn yields resulting from the use of these
three systems were nearly equal. Soil at this experimental site is moderately
well drained and probably warms more rapidly than many other fine textured
soils. When the results of several comparisons of tillage systems are
considered, there is a general conclusion that the lowest amount of risk is
associated with the ridge-till and strip-till planting systems.
Thinking About Fertilizer Use
The switch from conventional to conservation tillage planting systems requires
some changes in our thinking about fertilizer use. Recommended rates
of nitrogen needed to achieve the expected yield do not change. However,
broadcast applications that remain on the soil surface are not a good option. Research
has shown that broadcast N (wether fluid or dry) that remains in contact with
crop residue is subject to loss. The mechanism for loss is thought to
be volatilization. Nevertheless, fertilizer N applied in a conservation
tillage planting system should be placed below the crop residue.
of phosphate, potash, and other immobile nutrients our thinking should shift
from broadcast to banded applications. There are several
choices for a banded application. Most ridge-till farmers have adopted
the idea of placing the band in the center of the ridge at a depth of 4 to
6 inches in the fall of the soybean year. This deep band is used effectively
by young corn plants. The yield summarized in Table 3 show the importance
of the deep band. The deep band also eliminates the need for the use
of a starter fertilizer.
The use of deep band has another advantage. Rates
of phosphate and potash needed can be reduced considerably when compared
to broadcast applications
in conventional planting systems.
The placement of the phosphate fertilizer
in a band below the soil surface also reduces the potential
for loss of phosphorus from the landscape thereby
causing an increase in algae populations. The use of the deep land
is evidence that farmers who use conservation tillage planting systems
about the environment.
Table 3. Corn yield in a ridge-till planting
system as affected by fertilizer placement.
|no K2O applied
|110 lb. 7-21-7/acre as a starter
|6-25-100 deep band
|110 lb. 7-21-7/acre plus
|6-25-100 deep band
Economic Comparisons are Positive
The soil conservation positives of conservation tillage planting systems are
widely recognized. The economic advantages of these systems, however
are frequently overlooked. A survey was conducted in the summer of 2001
to document the positive economics of the ridge-till planting system. The
results were convincing.
To complete the survey, several ridge-till farmers were asked via personal
interviews to provide their production costs for corn and soybeans as well
as their yields for each crop. Neighbors who farmed a similar number
of acres with conventional tillage were asked the same questions.
Average corn yields for the conventional and ridge-till planting systems were
144.9 and 149.0 bu. per acre respectively. For soybeans, the average
yield of 41.5 bu. per acre from the conventional system can be compared to
43.7 bu. per acre for the ridge-till planting system. So there was no
reduction in yield for growers who used the ridge-till planting system.
There was, however, a substantial difference in cost of production when the
two planting systems are compared. Those who used the conventional system
had a cost of production of $1.94 per bu. of corn. With the ridge-till
planting system, the cost of producing a bushel of corn was reduced to $1.52
per bu. For soybean production, the cost of production was $4.13 and
$3.69 per bu. for the conventional tillage and ridge-till planting systems
In general, lower production costs in the ridge-till system were associated
with fertilizer, herbicides and fuel. These actual costs and associated
yields reported by farmers illustrate the economic benefits of conservation
tillage planting systems.
Equipment Options Are Not a Concern
In the past, many growers have been reluctant to explore a switch to conservation
tillage planting systems because of a rumor that these systems are best suited
for small equipment. The source of these rumors is not known; but the
Crop producers in Iowa and Minnesota who use the ridge-till
and strip-till planting systems have clearly shown that these
rumors are false. The photo that accompanies this article
shows a 16-row ridge-till planter working in southern Minnesota. The
use of the ridge-till and strip-till planting systems does
not place a limit on the size of equipment. As with conventional
tillage systems, choice of equipment for conservation tillage
is an individual grower decision that is influenced by many
When evaluated from agronomic, environmental, and economical perspectives,
the adoption of conservation tillage planting systems is a win-win situation
for everyone. Results of various research projects conducted by Land
Grant universities, as in the past, continue to document the positive effects
of planting systems.
When viewed from an agronomic perspective, crop yields are not reduced when
the conservation tillage planting systems are used. With the new systems,
care must be taken to place the nitrogen below crop residue and the immobile nutrients
should be applied in a band either in the previous fall or near the seed at
The subsurface banded application of phosphorous has very positive environmental
consequences. This placement provides for the most efficient use of this
nutrient while substantially reducing the loss from the landscape.
Farmer records document the positive economical advantages, with no reduction
in yield and lower costs, the potential for profit increases.