No-Till Soybean Yields

The shift in Ontario to no-till and reduced tillage soybeans has been rapid. More than 60% of Ontario soybeans are now grown under some form of reduced tillage. One of the reasons for the speed of this change can be attributed to the use of glyphosate tolerant varieties. In 2001 approximately 30% of soybeans grown in Ontario were herbicide tolerant. That number increased to approximately 45% this year and may reach 60+% by next year.

Equal Yields

One of the main production fears of those who are considering adopting a no-till system is of having lower yields. This is especially true after years like 2002 when yields varied a tremendous amount. Nevertheless, field experience and research trials have demonstrated almost identical yields on average between tillage systems. From 1997 to 2000 the University of Guelph conducted tillage research, and found that yields for no-till soybeans equaled the fall moldboard plow in row widths of 56 cm (22.5 in.) or less and in twin rows (Table 1).

Least Significant Difference _(P=0.05) = 2.4

Where the difference between 2 treatments exceeds 2.4, there is a less than 1 in 20 chance that it is due to random variation.

1. University of Guelph (1998-2000). Trials were conducted on clay loam, silty-clay loam, silt loam, and Guelph loam soil types.
2. Spring zone-tillage conducted approximately 1 day prior to planting

Soil Types

Heavy textured soil types (clay, silty clay loam or silty clay) are some of the most challenging for no-till systems. Producers have reported reduced no-till soybean yields on these heavier soils during difficult growing seasons. But long-term tillage system research on Brookston clay soil at the University of Guelph's Ridgetown College, showed equal soybean yields for no-till and fall moldboard tillage (see Table 2).

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

Varieties

Not all varieties are suited for a no-till system, however. Soils stay cooler and wetter in the spring, which may result in slower emergence and more soil-borne diseases. This means that varieties selected for no-till need to have excellent vigour and a good tolerance to phytophthora root rot.

Dry & Warm Soil

Also, before planting begins, the soil should have reached an adequate temperature. Planting before the soil reaches 10 ºC (50° F) should be avoided. Reduced germination and lower vigour may result if the newly planted seed absorbs cold water. Planting into wet soils also results in seed slot smearing, which may cause reduced lateral root growth and slower nodulation. Or the seed slot may open up again as the ground dries, resulting in poor seed to soil contact. One of the most important factors in successful no-till planting is to wait until the soil is sufficiently dry and warm. Depending on how well drained the field is, this could mean as little as 3 to 4 days longer than conventional fields.

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