Soil Health Starts With Crop Rotation

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In recent blogs, we’ve talked about the payback growers receive when they intensify their soybean management. Topics we’ve already covered – including optimizing stand counts, fine-tuning fertility and building a strong defense against insects and disease – are all big parts of the yield equation.

When growers ask me what’s the starting point for soybean yield success, I have a simple answer: it all starts with soil health – there are no shortcuts. Over the months ahead we’ll be talking a lot about soil health. One topic on our agenda will be the need for a soil organic matter strategy. Fortunately, most growers are now developing a strategy to bring organic matter up to optimum levels on their farms. In Ontario, sandy soils are typically in the 2% soil organic matter range, but higher is better; silt loam should be at 3.5% or 4%; and clay loam should be 4.5% to 5%.

Short rotations create challenges for soybeans

We’ll also explore how healthy soil can create optimum growing environments for a crop like soybeans, which typically has a shallow and weak root system. But when we talk about soil health and its impact on soybean performance, we really begin the conversation with crop rotation.

Many growers in Ontario have experience with growing soybeans in a tight rotation. Thankfully we see less and less of this practice, including continuous beans. Many years ago, a grower who followed a really tight rotation told me his farm was simply “beaned out.” He was right. After planting continuous soybeans, he had declining organic matter and had created too many challenges for his plant’s roots to overcome, especially when adverse growing conditions arrived during the growing year. His soybean yields were in steady decline – it was a long road back.

When it comes to soil health, the simple truth is strong rotations are a soybean growers’ best friend. It’s well documented how crop diversity plays a key role in helping growers manage the cycle of soil pathogens and root rots that can dash soybean yield hopes.

Soybeans in longer rotations deliver higher yields

I would encourage all soybean growers to check out the long-term rotational studies that research agronomist and associate professor Dr. David Hooker and his team at the University of Guelph-Ridgetown Campus have been managing since 1995. It really demonstrates the powerful impact rotation can have on soybean yield.

In trial data from 2009 to 2012, continuous soybean yields are significantly lower than longer rotations. When corn is added to the rotation, a consistent yield increase is observed and when wheat was added to create a corn-soy-wheat rotation, yields jumped dramatically to produce a six-bushel-per-acre average increase over the corn-soy rotation. Of course, there are many other rotation options that growers can adopt, including forage.

This is just another example of how intensifying your management – in this case, through a stronger commitment to soil health – will help you grow 70-bushel soybeans.