Soybeans: Tillage Options

Excerpt from Agronomy Guide for Field Crops (Chapter 4)

Order OMAFRA Publication 811: Agronomy Guide for Field Crops

Table of Contents

1. Introduction
2. Tillage Options
   • No-Till and Minimum Tillage
   • Soybean Yield Response Under Various Tillage Systems - Table 4-1
   • Soybean Yields for Ridgetown College 1992-2000 - Table 4-2
   • Effect of Tillage and Wheat Residue Management on Soybean Yields - Table 4-3
     • Crop Rotation Considerations
     • Soybean Yield Response Under Various Crop Rotations - Table 4-4
3. Winter Wheat Following Soybeans
   • Soybean Maturity Dates for 2950, 3050 and 3150 Heat Unit Varieties -Table 4-5
4. Updates on Soybeans:Tillage Options
5. Related links...

Introduction

Soybean acreage in Ontario has doubled in the past 10 years to over 809,000 ha (2 million ac). This represents more than a 2,000% increase over the past 50 years. The development of earlier maturity varieties, a wider selection of herbicides, improved yield stability, adaptability to no-till production and the relative low cost of production have contributed to this increase.

Expansion in the demand for specialty soybeans with identity preservation (e.g., food-grade, non-GMO, organic, etc.) has created new marketing opportunities for Ontario beyond the traditional end use of soybeans for oil production (i.e., crush) and livestock feed.

Tillage Options

The wide adaptation of soybeans to various tillage systems, particularly no-till, has contributed to rapid expansion in soybean acreage. Approximately 40% of the soybean crop is no-tilled, and 30% is planted with reduced tillage. Field experience and research trials have shown nearly identical yields between tillage systems. Management of the tillage system used is as important as the actual system selected.

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No-Till and Minimum Tillage

Ontario tillage research from 1997 to 2000 found that no-till soybean yields equalled the fall moldboard plow in twin rows and row widths 56 cm (22.5 in.) or less (see Table 4-1, Soybean Yield Response Under Various Tillage Systems). Although the yields are similar between the two tillage systems, no-till input costs are often lower and profit higher. Where single 76-cm (30-in.) rows were used, moldboard plowing produced the highest yields. When soybeans are planted in twin rows, soybean yields improve over 76-cm (30-in.) rows for all tillage systems. In this study, zone tillage has shown no significant yield improvement over no-till. Twin rows should be used in the spring zone-till system.

Least Significant Difference (P = 0.05) = 2.4²

¹Average of nine sites per year. University of Guelph (1998-2000). Trials were conducted on clay loam, silty-clay loam, silt loam and Guelph loam soil types. Spring zone-tillage conducted approximately 1 day prior to planting.
²Where the difference between two treatments exceeds 2.4, there is a less than 1 in 20 chance that it is due to random variation.

The greatest challenge in the adoption of minimum/no-till tillage is on heavy texture (clay, silty clay loam or silty clay) soil types. In some years, growers have reported reduced no-till soybean yields on these soil types compared to conventional tillage. Long-term tillage system research on Brookston clay soil at Ridgetown College, University of Guelph, resulted in equal soybean yields for no-till and fall moldboard tillage (see Table 4-2, Soybean Yields for Ridgetown College 1992-2000).

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Values followed by the same letter are not significantly different at the 5% level.

When soybeans follow a cereal crop, special attention must be paid to the management of cereal residue beginning at harvest to avoid problems with soybean establishment. The best action is to remove the straw and spread the chaff evenly. In research trials done by University of Guelph, removal of wheat straw improved seedbed conditions, stand establishment, growth and yield for no-till soybeans (see Table 4-3, Effect of Tillage and Wheat Residue Management on Soybean Yields). Cereal residue can form a mat that slows soil warming and drying in the spring. This can delay soybean planting, reduce soybean emergence and early growth, and lead to increased pressure from slugs. Minimum tillage in the fall or spring without the need for secondary tillage improves seedbed conditions and creates looser, finer soil to improve early soybean growth, while maintaining adequate residue to reduce erosion.

Tillage is best avoided along highly erodable knolls and slopes. In these situations, it may be prudent to use tillage only where the soil routinely remains cooler or wetter in the spring.

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Average 1994-96, Centralia & Wyoming

Note: Stubble heights were approximately 20-30 cm (10-12 in.) except for plots where stubble was cut and removed. Soil types: Centralia: loam, clay loam. Wyoming: silty clay, silty clay-loam. Soybeans were seeded with JD 700 conservation planter equipped with a single 1.25 in. coulter. No-till planter was equipped with tine row cleaners.

Source: T. Vyn, G. Opuku and C. Swanton, University of Guelph

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Crop Rotation Considerations

Soybeans are very responsive to crop rotation. Table 4-4, Soybean Yield Response Under Various Crop Rotations, presents the results of rotation studies conducted at Ridgetown College, University of Guelph. A rotation of soybeans, winter wheat and corn provided the greatest yield response. The continuous soybean rotation had the lowest yield. A short rotation leads to a build-up of disease and other long-term problems. Soybean cyst nematode (SCN) populations can increase rapidly, further reducing yields (see Soybean Cyst Nematode). To reduce the incidence of white mould, maintain a 3-4 year rotation with other non-host crops. In fields with a history of Phytophthora root rot, a short rotation contributes to an increase in severity and number of races of the disease. The repeated use of Group 2 Herbicides-ALS inhibitors will encourage the spread of Group 2-resistant weeds.

Ridgetown College/University of Guelph, 1997-2000.

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Winter Wheat Following Soybeans

For more information on soybean crop rotations and precautions under different tillage systems, refer to the section Crop Rotation.

Source: Ablett, Ridgetown College, University of Guelph.

¹For 1990-99.
²These dates are for physiological maturity. Combining would be 3-10 days after these dates.

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Updates on Soybeans: Tillage Options

No updates available at this time.

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Related links...

• Soybeans
• Tillage

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