TILLAGE HANDBOOK SERIES
Chapter 2 - Systems and Equipment, No. 11, Spring 1988
Approaches to Minimum Tillage Seeding
The development of
effective, economical equipment for minimum tillage seeding to control
soil erosion has been an important research focus of a number of scientists
at the Agricultural Engineering Department of the University of Idaho
in Moscow, Their efforts on equipment design and modification for conservation
farming have been part of the STEEP Conservation Research Program since
it began in the Northwest in 1975. The research has been a cooperative
effort by agricultural engineers Chuck Peterson and Ed Dowding and research
assistants Kyle Hawley and John Whitcraft. Primary emphasis has been on
developing inexpensive equipment options for minimum tillage seeding of
Economics an Important Factor
To help put their work in perspective, the researchers point out that
low commodity prices, high interest rates and the drop in farm values
make it difficult to obtain credit for operating costs, and especially
to purchase new equipment. In addition, production costs continue to increase,
although at a much lower rate than several years ago. Crop production
costs increased nearly 2 percent in 1985 and about 3 percent in each of
the prior 3 years. They stress that to survive these difficult economic
times, producers must give careful consideration to farming practices
which reduce production costs. Based on their 13 years of research, they
feel that one important option is minimum tillage, utilizing low-cost
A majority of the cropland soil erosion in the Inland Northwest occurs
on conventionally-seeded winter cereals, where little or no crop residue
remains on a relatively fine, smooth seedbed. This is why the researchers
have focused their efforts on developing minimum tillage equipment for
seeding winter wheat, primarily after low residue crops such as peas and
In addition, the minimum tillage equipment they have developed has also
been used successfully for seeding of winter wheat after other crops and
for spring seeding. Their research indicates that the minimum tillage
methods reduced surface runoff overwinter by about 80 percent and soil
erosion by 75 percent compared to conventional tillage.
The minimum tillage practices combine field operations to reduce trips
over the field and leave a rougher seedbed with higher surface residue
levels than conventional seeding. They have also documented a significant
reduction in the loss of nitrogen and phosphorus in the runoff water with
minimum tillage, In addition to reducing soil, water and nutrients losses,
minimum tillage seeding also has the advantage of potentially saving field
time and fuel.
Through comparative field studies, the researchers have found that by
combining the tillage, fertilizer injection and seeding operations into
a one-pass, minimum tillage implement, field time was reduced by 18 to
47 percent and diesel fuel consumption by 50 to 70 percent. They also
point out that since the tractor operates on previously undisturbed soil
with the one-pass equipment, the field operation can begin sooner after
a rain and earlier in the spring than would be possible with similar size
equipment operating on tilled soil.
One approach the researchers have taken on minimum tillage systems
is the 'Chisel-Planter, " beginning in 1975. It combines three successful
practices common to the Palouse: (1) use of the chisel plow for runoff
control, (2) fall-applied fertilizer deep-banded in the seedbed and (3)
use of a fluted-feed, end-wheel drill. The Chisel-Planter was built from
modified or redesigned components of two International Harvester implements,
a Model 645 Vibra Chisel and a Model510 double-disk, end-wheel drill,
with the addition of fertilizer tanks, pumps and distribution system (Fig.
They point out that the Chistel-Planter is a one-pass, till-plant system
and not a "no-till" drill because the chisels do a considerable
amount of tillage ahead of seeding. The chisels leave small ridges and
furrows in the field, which the researchers call "mini-terraces."
They attributed the effective soil erosion control with the Chisel-Planter
system to this mini-terracing effect, in conjunction with adequate surface
residue retention and rough soil surface.
Chisels are on a 12-inch spacing, 24 inches apart, staggered in two ranks.
Liquid fertilizer is injected at the bottom of each chisel point at a
depth of 4 to 5 inches. The double-disk seed openers and rubber packer
wheels follow directly behind each chisel in a single staggered-row at
the back of the chisel. This arrangement allows the fertilizer to be banded
about 2 inches below each seed row. A more detailed description of the
early model of Chisel Planter is available in CIS 476, "The Chisel-Planter:
A Minimum Tillage System for Winter Wheat, " a 1979 publication available
through the University of Idaho Cooperative Extension Service.
Fig. 1. University of Idaho Chisel-Planter: a one-pass tillage, fertilizer
injection and seeding implement (Peterson, Dowding, Hawley and Whitcraft,
Fig. 2. Original 24 inch wide Vibra-Chisels with packer wheel additions
(top) and narrow shanks used beginning In 1984 (bottom) on the University
of Idaho Chisel Planter (Peterson, Dawdling, Hawley and Whitcraft, Ul)
The current Chisel-Planter model includes several modifications of
the earlier version. The original Chisel Planter had standard 2-inch wide
chisel points. Specially designed packer wheels were attached directly
to the chisel shanks to compact the soil between the fertilizer band and
the seed (Fig, 2, top). The packer wheels were removed in 1984 when the
2-inch chisel points and shanks were replaced with narrow shanks (Fig.
2, bottom). The narrow shanks were fabricated by making a right angle
twist in the original chisel shank. Chisel width is now 0.75 inch.
Hardened narrow shovels were added on the chisel tips, and the fertilizer
tubes were reinstalled. The narrow shanks reduced total draft requirements
by approximately 25 percent compared to the standard chisel. They provide
a more even seeding depth and uniform' 'mini-terraces." This corrected
emergence problems formerly encountered when some of the seed rows were
planted too deeply in ridges created by the standard chisels. No significant
changes in yield, soil disturbance, surface residue retention or soil
erosion have been documented after conversion to the narrower shanks.
The "Chisel-Plus-Drill" approach to one-pass tillage/fertilizer
injection/seeding was first used by the UI researchers in 1982 to address
two producer-needs in minimum tillage drills: (1) low cost and (2) a system
easily duplicated-with existing equipment for on-farm use. It consists
of two implements pulled in tandem, combining more than three field operations
into one (Fig. 3). The researchers used a John Deere chisel adapted for
injecting liquid fertilizer with a tillage operation, and attached an
IH end wheel double-disk drill behind the chisel. Chisel/fertilizer band
spacing is 12 inches and the seed row spacing is 6 inches. The chisel
is operated at a depth of 4 to 6 inches.
The Chisel-Plus-Drill generally retains about 65 to 75 percent of the
surface residue and creates a rough seedbed, providing effective soil
erosion control. It has often resulted in one of the highest yields in
comparative field studies with other drills. Other options the researchers
have used with the Chisel-Plus-Drill are 14-inch wide sweeps instead of
the chisel points, and a rod weeder attachment between the chisel and
drill. The sweeps have provided effective weed control, and the seedbed
is not as sharply ridged as where the chisel points are used. The rod
weeder attachment levels the ridges, and the researchers do not recommend
its use on steep slopes. In excessive residue, e.g. after a high yielding
pea crop with long vines, the rod weeder may bunch up the residue and
cause seeding problems.
Most growers already own a chisel plow, What is needed to develop their
own 'Chisel-Plus-Drill" is fabrication of the fertilizer application
system and drill hitch attachment. In areas of higher precipitation, similar
results have been obtained with surface broadcasting of fertilizer and
using a starter fertilizer in the seed row through the drill.
The UI researchers made 40 dryland drill/tillage system comparisons
which included the Chisel-Planter and/or Chisel-Plus-Drill in northern
Idaho and eastern Washington from 1978 through 1986. Various no-till drills
were included in 10 of the 40 comparisons. Comparisons were made with
conventional tillage systems on adjoining test plots on similar landscape
positions. Test sites usually ranged from 5 to 15 acres. Most sites were
within 100 miles of Moscow in areas receiving about 18 to 25 inches or
more of annual precipitation. Almost all were previously cropped to peas
Fig. 3. University of Idaho Chisel-Plus-Drill: a chisel and drill pulled
in tandem for one-pass tillage, fertilizer injection and seeding
(Peterson, Dowding, Hewley and Whitcraft, Ul).
Yields were determined from 8 to 10 hand-harvested subplots within
each main plot. Winter wheat yields with the three conservation tillage
systems averaged 93 to 95 percent of yields with conventional tillage
(Table 1). A wide range of yields was encountered between sites and years
with all drills and tillage systems.
Soil loss by water erosion was determined from rill widths and depths
measured on contour transects. The three conservation tillage systems
reduced soil loss from about 26 to 56 percent of the loss under conventional
tillage (Table 2), Soil losses from the different treatments were also
quite variable between sites and years.
Based on the comparative field studies of these drills and tillage
systems, the researchers have made several
Table 1. Summary of winter wheat yields shown as a percent of yields
under conventional tillage from field comparisons of drills and tillage
systems in northern Idaho and eastern Washington, 1978-1986 (Peterson,
Dowding, Hawley and Whitcraft, Ul).
no-till drills in use on the particular farm sites were included in the
are shown as a percent of yields with conventional tillage.
- A considerable
amount of variability in yield and soil loss occurs between site locations
and years; the reasons for the variability are often unknown or obscure.
- The appearance
of winter wheat plots in the spring is not necessarily correlated to
yield at harvest. Consequently, spring plot tours can often lead to
misleading conclusions as to which tillage system is the most productive.
- Management and
experience can probably make any one of a number of tillage systems
work if the manager believes in the system. Conversely, nothing will
work if the manager does not believe in the system.
- Major changes
in equipment are not necessary to develop conservation farming systems
which are effective, productive and affordable. The Chisel-Plus-Drill
is one example of a low-cost minimum tillage option which reduces erosion
and production costs and maintains yields.
Table 2. Summary of soil losses shown as a percent of soil losses under
conventional tillage from field comparisons of drills and tillage systems
in northern Idaho and eastern Washington, 1976-66 (Peterson, Dowding,
Hawley and Whitcraft, Ul),