Crop Protection
Zone Tillage Systems for Corn and Soybeans in Ontario

by Ken Hough, OCPA Director of Research and Market Development

This report summarizes the final results of a 4-year project, conducted from April 1997 to March 2001, which examined corn and soybean response to zone tillage and other conservation-till systems such as no-till and fall disk, on Ontario's medium to fine textured soils. Conservation-till soybean response to various methods of potassium (K) fertilizer application were also evaluated. This project consisted of a total of 43 site-years of experiments conducted on public research stations and private farms throughout southwestern Ontario in the counties of Essex, Kent, Lambton, Middlesex, Perth, Oxford and Brant. All sites had been in at least 5 years of continuous no-till prior to treatment initiation.

The research was initiated under the supervision of Dr. Tony Vyn, University of Guelph: following his departure to accept a faculty position at Purdue University, oversight was shared by Greg Stewart, Ken Janovicek and Bill Deen. Portions of the project were conducted in direct collaboration with Dr. Craig Drury, Agriculture and Agri-Food Canada (AAFC), Greenhouse and Processing Crops Research Centre, Harrow, Ontario, and Dr. Doug Young, University of Guelph, Ridgetown Campus.

OCPA provided $150,000 in cash funding for the project over the four-year term of the research ($130,000 of this came from Round I of the Safety Net R&D program), with cash support of $98,000 coming from the Ontario Soybean Growers (OSG). In-kind contributions through donation of tillage implement usage throughout the project from Till-Tech Systems, John Deere and Becker Farm Equipment amounted to $89,000 with some minor in-kind support for administration, coordination, reporting and dissemination of results provided by OCPA, OSG, U. of G. and AAFC. The industry-matching contributions of $147,000 of Matching Investment Initiative (MII) funds for the portion of the research conducted through Harrow, and the research grant of $316,900 provided to the project through the AAFC-supported CanAdapt program are gratefully acknowledged and were invaluable in accomplishing the research at the required scale within the 4-year time frame.

Project highlights and recommendations are as follows:

• Zone tillage to 30 cm (12") depth produced the highest and most stable conservation-till corn yields following both soybeans and wheat. Deep fall zone-till yields did not differ from those obtained in fall moldboard systems and often were higher than no-till. It is not clear from this study if this was due to the depth of tillage, or the more favourable near-surface conditions (i.e., mounds which persisted into the spring and/or width of the zone) associated with the deep fall zone-till system.

• Underseeded red clover increased conservation-till, especially fall zone-till, corn yield following wheat; an effect which was due to greater yield stability and/or faster wheat straw decomposition.

• Spring disking or zone tillage did not result in corn yields greater than those obtained with similar tillage operations conducted in the fall or with no-till. Fall conservation-tillage generally was associated with more uniform emergence and soil conditions which would allow for spring field operations 2-3 days earlier than where fall tillage did not occur.

• Corn yields in side-by-side experiments following wheat were usually greater than following soybeans; the effect was especially large when corn was produced in no-till and zone-till systems. This indicates that including wheat in conservation-till corn production systems increases yield potential.

• Soybeans planted in twin-rows (two 19 cm rows on 76 cm centres) had yields in no-till and zone-till systems which were similar to those obtained in 38 cm (15") and 19 cm (7.5") row widths.

• Potassium fertilizer applied to previous corn (at a rate between 100-150 kg-K2O/ha) was available to subsequent no- till soybeans and did, on occasion, increase yield. On fields with low soil-test K levels, soybean growers are advised not to rely exclusively on K applied only when corn is in the rotation, but rather apply K fertilizer prior to soybeans as well.

• Near-surface placed soil K, because of either stratification or fall broadcast application, was available to conservation-till soybeans for uptake and did on occasion affect yield.

• Banded K fertilizer did occasionally increase soybean yield, but not significantly more than when a similar quantity was fall broadcast-applied. On the other hand, K fertilizer applied in the spring just prior to soybean planting in bands beneath the soybean rows was more available, and produced higher yields, than when spring broadcast-applied.

• Soybeans planted in zone-tilled strips (even when depth was 30 cm deep or when K fertilizer was band-applied) did not produce yields which exceeded those obtained with no-till planted in 38 cm rows. Soybean growers are advised not to consider switching back to wide-row (single 76 cm row) soybean production to facilitate the use of fall zone-till systems or banding of K fertilizer.
Summaries of the individual components of the overall project, listed below, are available on request to OCPA (and will be posted to the research page on OCPA’s website once this is inaugurated later this year).

• Zone Tillage For Corn On Medium And Fine Textured Soils

• ZoneTillage And Red Clover Impact On Soil Quality And Corn Yield

• Zone Tillage And Row Width Effects On Soybean Yield In Ontario

• No-till Soybean Response to Tillage and Potassium Applied to Previous Year Corn

• Tillage, Row Spacing and Potassium Placement Effects on Conservation-till Soybeans

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