Economical Approaches to Minimum Tillage Seeding

Chapter 2 – Systems and Equipment, No. 11, Spring 1988

Roger Veseth

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 winter wheat.

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 amuch 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 equipment.

Research Focus

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 lentils.

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.

Chisel-Planter

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. 1).

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.

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.

Chisel-Plus-Drill

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.

Research Summary

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 or lentils.

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.

General Observations

Based on the comparative field studies of these drills and tillage systems, the researchers have made several
general observations:

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).

1. 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.
2. 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.
3. 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.
4. 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),