no-till, ridge-till, or strip-till planting systems are used,
it’s a tradition in Minnesota to use major tillage
on the top 8 to 10 inches of the root zone. Except for sandy
and highly erosive soils, most major tillage is completed
in the fall. Recently, however, growers are asking about
the effect of zone tillage on crop production. This type
of tillage has also been referred to as the Rawson system.
All deep tillage systems are not the same. In previous years
in Minnesota, deep tillage was thought to be random and not
necessarily parallel to the rows. With a zone till system,
the deep tillage is parallel to existing rows and the intended
crop is planted directly into the deep tilled zone.
of deep tillage has been evaluated in Minnesota. Trials with
corn were conducted at the Southern Research and Outreach
Center, Waseca and in Olmsted County. The yields from a Port
Byron silt loam at the Olmsted County site measured from
1997 through 2000 are summarized in the following table.
The Rawson system uses deep tillage. The “one-pass” system
for planting corn can be considered, many times, as a conservation
tillage practice. In this system, there is no fall tillage
and the corn crop is planted following a previous crop of
soybean with seed bed preparation by use of a field cultivator.
effect of four tillage systems on corn yield (1997-2000). Olmsted
were lower when corn was planted following corn in a no-till
planting system. Otherwise, tillage system had no significant
effect on yield regardless of the previous crop. There was
no advantage to the use of the Rawson system for corn production.
study was conducted on a Webster/Nicollet clay loam soil
to measure the effect of tillage systems on yield of corn
following soybeans. Those grain yields are summarized in
the following table.
of the rip-strip treatment is needed. This tillage system
involves the use of in-row subsoiling/ripping using the implement
shown in Figure 1. The depth of tillage is 14 inches on 30
inch centers. This deep tillage is completed in the fall
followed by planting directly on the ripped strip zone the
following spring without any secondary tillage. The strip
till treatment was similar except that a mole knife (much
like an anhydrous knife) was pulled to a depth of 8 inches
to create the tilled zone.
effect of tillage system on yield of corn following soybean.
2000-2002. Southern Research and Outreach Center.
were slightly lower when the no-till and one pass planting
systems were used. The rip-strip system tilled to 14 in.
did not produce yields higher than those produced by the
use of the strip-till system where tillage was at a depth
of 8 inches. In other words, the use of the extra deep tillage
had no positive effect on corn yield.
also a risk associated with the use of deep tillage. The
field shown in Figure 2 is one example. Deep tillage had
not been used where the corn is green. A deep tillage implement
had been used where the corn is yellow. The cause of the
yellow corn is related to denitrification and probably reduced
deep tillage is thought to alleviate subsoil compaction,
there may be an increase in resistance to root growth when
deep tillage is used where the subsoil has a high clay content.
When a knife or shank is passed through soil that is wet
with a high clay content, the soil separates and is compressed.
This can result in sidewall compaction and reduced size of
the air-filled pores in the soil. These two factors can have
a large negative effect on root growth, nutrient availability
and nutrient uptake especially under drier or wetter-than-normal
conditions. When the soil comes together again, the point
at which the separated soil joins together is frequently
more resistant to root growth than the original soil. In
this situation the “soil strength” has been increased
rather than decreased by the use of deep tillage.
nothing new about the concept of deep tillage. This management
practice has been used successfully on soils in the Eastern
and Southeastern part of the United States. Those soils,
however, are quite different from those in the northern and
western Corn Belt.
modifications of the deep tillage concept have been evaluated
by several universities in the region. The results, as illustrated
by those from the Southern Research ad Outreach Center, have
not been positive.
information is being collected this summer. That information
will be summarized after fall harvest.
that are interested, the zone tillage practice is being evaluated
at the John Illiss farm east of Elrosa (more
information). The zone tillage was completed in the fall
of 2002. The Field Demonstration will be featured at the
farm located ½ mile east of Elrosa on County Road
13. Corn growth as well as root growth can be viewed on August
28 starting at 1:00.
1. Deep tillage implement used at Waseca.
2. Impact of deep tillage on corn growth in the Red River