Fall Tillage Options

By Greg Stewart, OMAFRA Corn Specialist

Selecting the most suitable tillage system for your farm can have a significant impact on input costs, crop productivity and soil protection. Most corn producers have a sense of the type of tillage that best suits their farm; however, on-farm and public research can help to fine-tune the systems. The following information summarizes results from years of research in an effort to give some insight into the ongoing process of improving corn-growing efficiencies.

Table 1 - The Impact of Fall Tillage Systems on Grain Corn Yield All tillage plots received secondary tillage in the spring prior to corn planting. (Trials conducted following various previous crops in the period 1979-1996).
Location(County)	Soil	PreviousCrop	# of Years	Fall Tillage SystemsCrop Corn Yield (bu/ac)
Location(County)	Soil	PreviousCrop	# of Years	Moldboard	Chisel	Offset Disc
Milton (Halton)	Clay loam	Corn	3	117	109	109
Elora (Wellington)	Silt loam	Corn	7	123	117	121
Elora (Wellington)	Silt loam	Soybeans	2	118	118	124
Comber (Essex)	Clay loam	Soybeans	3	124	117	124
Morpeth (Kent)	Clay	Soybeans	2	108	98	110
Average				118	112	118

Data from T. Vyn, K. Janovicek and D. Young, University of Guelph.

Fall Mulch Tillage
The chisel plow has been the most widely adopted fall mulch tillage tool in Ontario, with tandem and offset discs also being used extensively in some areas of the province. Tillage research trials conducted across Ontario over the past 20 years generally have shown that discing often results in more favorable soil conditions and higher corn yields than chisel plowing. Table 1 summarizes the corn yield data from these sites.

Chisel plowing with twisted shovel teeth may leave the soil quite ridged. This can lead to extra costs in secondary tillage (more passes), uneven seed beds and, occasionally, excessive soil drying. Using sweep teeth on all or part of the chisel plow overcomes some of these problems, as does adding a leveling bar or harrows to the rear of the chisel plow, or timely secondary tillage in the spring.

Table 2 - The Impact of Fall Tillage Systems on Grain Corn Yield Moldboard and Chisel plots received spring secondary tillage; Fall Tandem Disc Only plots were planted directly in the spring without any secondary tillage.
				Tillage Systems Corn Yield (bu/ac)
Location(County)	Soil	PreviousCrop	# ofYears	Moldboard	Chisel	Fall Tandom Disc Only
Alvinston (Lambton)	Clay	Soybeans	3	95	86	91
Fingal (Elgin)	Silt clay loam	Soybeans	3	159	154	154
Centralia (Huron)	Silt loam	Wheat(straw baled)	3	146	139	141
Wyoming (Lambton)	Silt clay loam	Wheat(straw baled)	3	159	155	157
Average				140	134	136

Data from T.Vyn, K. Janovicek, D. Hooker and G. Opuku, University of Guelph.

Tandem Disc Only
Some of the earlier success with offset discing inspired a series of experiments where the tandem disc was used in the fall. When fall discing is done in such a way as to leave the soil level in the fall, single-pass corn planting (no secondary tillage) becomes a viable option in the spring and is a good method for reducing tillage costs. Table 2 outlines research conducted in Ontario where this approach was taken. On average, using only the tandem disc yielded within five bushel of the conventional tillage system. In some years, growers could improve upon these results by doing some light spring tillage prior to corn planting.

Table 3 - Tillage system effects on grain corn yield following soybeans at Fingal (silty clay loam) and Alvinston (clay), 1994 - 1996 average.
	Fingal	Alvinston
	Grain corn yields @ 15.5 % ------------- bu/ac -------------
Fall Moldboard + Spring Tillage	159	96
Spring Tillage Only	156	96
No Tillage	154	90

(T. Vyn, D. Hooker and C. Swanton, U. of Guelph)

The Disc and Compaction
We have been referring to fall discing where the risk of soil compaction is less than if you disced in the spring. If you believe you have a compaction problem, then you may be tempted to try more aggressive implements which allow you to run deeper than any disc will be able to. Three suggestions as you move towards deeper tillage: 1) Have you identified where the compaction is? How deep is it? Is it restricted to the headlands and some poor draining areas? 2) If your soils are compacted, what can you do to eliminate wheel traffic concerns? Lower axle weights? Lower inflation pressures? Control the traffic patterns? 3) If you do some deep tillage this fall, leave some check strips of shallower tillage to evaluate the return for your equipment and diesel fuel.

No Fall Tillage
The best practice for reducing erosion and input costs is to eliminate fall tillage. Producers working on heavy soils, where crop residues are high following corn, wheat or other crops, may be apprehensive about leaving soils untouched in the fall. However, following soybeans, there is little justification for doing fall tillage on most fields in Ontario. Table 3 illustrates that even on finely textured soils, spring tillage alone (field cultivator, 2 passes) was generally sufficient when corn followed soybeans in the rotation. Other demonstration trials established on medium and coarse-textured soils have arrived at the same conclusion.

Grower experience with spring mulch tillage systems has indicated that, when working undisturbed soils in the spring, better results are obtained when using high clearance tines, narrow teeth, and/or packers or rollers in conjunction with the field cultivator.

Conclusions
Fall discing using an offset disc resulted in yields that were often better than chisel plowing when both systems received secondary tillage in the spring. Both systems allowed for reasonable levels of surface residue cover following cereal crops.

When corn follows soybeans, systems that involve more tillage than spring cultivation only, often do not produce enough extra corn to pay for the fall tillage operation.

Following winter wheat, if fall discing (tandem or offset) can be accomplished while leaving the field level with uniform residue cover, corn can often be successfully planted in the spring with little or no spring tillage.