Are your cover crops taking a beating this winter?
Here’s what to do about it this spring
This La Niña winter has brought wildly different weather patterns to the US and if you’re a typical farmer, you’re already calculating what these conditions will mean to your 2022 production potential. However, if cover crops have not typically been part of your production practices, you may not have considered the implications for managing them in the coming spring.
Your management agenda will depend on the specific conditions you’re facing. We’re seeing cold, dry conditions in some regions and warm, wet conditions in others. Here’s the rundown of what to expect as you get back in the field in the next few months.
Cold and dry
If you’re in the prairie states (Kansas to Minnesota), which are seeing extreme cold temperatures and dryness, watch for frost penetrating deeper than normal. Among other things, that means water lines used to supply livestock could freeze.
Winter wheat, whether cash crop or cover crop, could experience crown damage due to the lack of snow cover, particularly in cases where the crop was late to sprout. Normally as little as 1 inch of snow is enough to insulate a crop, but many places haven’t even retained that much. Unfortunately, you may get a sense of déja vu as there is potential to see the same high rate of winter kill as last year which could mean your intended winter wheat cash crop becomes a cover crop even if that’s not what you intended.
Given these challenging growing conditions, your cover crops may produce a lot less biomass than you expected. This means you can be more intentional about how much biomass you leave on the field for planting.
Warm and wet
Meanwhile, warm and wet weather brings its own set of challenges and opportunities. When there is too much precipitation, low spots will see ponding and plants will die. But the real concern for most farms in this zone is around soil nutrients, primarily nitrogen.
The wet conditions began last fall, delaying harvest and preventing some farms from applying fall N. Compounding the issue, wet soil is at risk for further N loss over the winter. It means you may have to adapt your N fertilization strategy. You can mitigate N losses by implementing split application or by using a N stabilizer, but check out your state or local university for recommendations for your area.
Invest in pre-plant or in-season soil testing. Not only will you find the moisture has affected nutrient levels, but so will growing a cover crop which will have taken up some of the previous year’s nutrients. Soil tests can help you create more precise N applications, meaning you can save money by not overapplying.
Chances are your cover crop has grown quite a bit. This means you need a workable termination plan – and a backup plan to be safe. I recommend you terminate about two weeks before planting if you want to control biomass and the carbon to nitrogen ratio. But termination date can also be influenced by your other goals such as weed suppression. If that’s the case it can be worth it to delay termination until planting.
The watchout is that when cool, wet conditions remain at planting, termination that happens too early will leave a layer of mulch on top and prevent drying. So make sure you’re not terminating just to terminate. Be intentional about what you’re trying to accomplish. Waiting until planting to terminate has its own set of risks and I do not recommend it for first time cover crop growers who are planting corn.
We also know that due to field conditions, so many farmers missed out on fall work, including tillage and fertilizer application. The lack of fall tillage means you have an opportunity to experiment with reduced tillage planting this spring, especially with soybeans or well-draining fields for corn.
The reality is that the cost of fertilizer is sky high. Because many farmers couldn’t put it down last fall they’ll need to put it down this spring. If you’ve had good growing conditions for cover crops, they will continue to take up nutrients as long as they’re alive. Again, this is where I stress that soil sampling can help you dial in your N application needs. Of course, spring work is all about time management, and that can be the trickiest part.