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Soil health and cover crops

Q & A with an expert

Establishment of a cover crop will reduce evaporation in the spring.

Q: What are the challenges associated with fall cover crops and are the benefits worth the effort? 

A: The simple answer is cover crops will improve your soil health. Cover crops reduce soil erosion, improve nutrient cycling and provide a living biosphere for beneficial soil micro-organisms. The challenging followup questions include: Will cover crops work on my farm? Can I establish a cover crop in low-moisture conditions? Will a cover crop dry out my soil for next year? Do I have enough time in a compressed post-harvest time frame? Those answers will be variable, without a clear one that fits every situation. 

How much moisture do you need to germinate a cover crop? Maybe not as much as you think. Different cover crops will have different moisture requirements (i.e. larger seeds need more moisture than smaller seeds); however, in general, if you can form a ball of soil in your hand without the soil sticking, you have enough soil moisture to germinate most cover crops. 

Will cover crops take soil moisture away from your following crop? Most likely. But cover crops are only temporary, so they don’t use up as much moisture as normal crops. If you do have excellent establishment of a cover crop, you will benefit from the ground cover in the spring, which will reduce evaporation. Even in the best situation though, you are probably going to sacrifice some soil moisture. 

Is there enough time post-harvest for a cover crop? Consider the time of year (early fall versus late fall) and select an appropriate cover crop that will germinate under these seasonal temperatures. You can’t necessarily look at cover crop research from other areas and apply that to your own environment, so you might want to select cool-season crops that are already familiar to use. Crops that germinate at low temperatures include barley, oats and tillage radish. In most situations, one or a combination of these crops should germinate. 

Remember that you aren’t establishing a crop for production, so uniformity and plant counts are less important. If your cover crop germinates, you are starting to benefit. 

Nathan Trowell is a manager of agronomic services for Nutrien Ag Solutions in eastern Saskatchewan.

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