No Till Notes - “Cover Crops pt. 2”

By Mark Watson, Panhandle No-Till Educator
The cover crops we planted on our irrigated wheat stubble have emerged. I think the idea of planting a cover crop to manage residue and improve soil health is an interesting concept.
 For years prior to adopting no till crop production on our farm we always used tillage to manage residue. The idea of using cover crops to manage the residue while at the same time producing nitrogen, improving organic matter, feeding soil microbes and improving the overall health of the soil is more appealing than dragging a disc over the field.
I wanted to visit with you about the cover crops we planted and why we included these crops in our mixture. Let’s start first with the goal of managing the winter wheat stubble residue. Research has shown than brassica crops such as radishes and turnips really reduce residues in the field. Care must be taken to not include so much of these brassicas in your mix that you wind up with fewer residues than you intended. We settled on 2 pounds of nitro radishes per acre in our mix. Our idea is to reduce the amount of high carbon wheat stubble and replace it with high nitrogen residues such as the field peas. Our goal is to have residue covering the soil next spring that is easier to plant corn into.
We also wanted to produce nitrogen for next year’s corn crop with our mixture. We used 80 pounds per acre of field peas to accomplish this nitrogen production with our cover crop mix. We inoculated the field peas at planting time to insure they produce nitrogen as they grow.
We’re not sure how much nitrogen these cover crops will supply. Preliminary research has suggested you may be able to reduce the commercial nitrogen rates significantly in the corn crop following these cover crops.
I’m also wondering if the increase in soil microbe populations and diversity doesn’t contribute to this nitrogen reduction as much as the legume supplying the nitrogen for the corn crop. Regardless of where this nitrogen benefit is coming from, if these cover crops allow us to reduce nitrogen fertilizer expense for the corn crop that will have a significant impact on our production costs for producing irrigated corn.
We also included 2 pounds of sunflower and 5 pounds of flax in our cover crop mix. We included the sunflower to give us good vertical growth for the remainder of the summer months. The flax will grow well into the fall and provide us with a good vertical stem as well. Our idea is to replace some of the vertical structure to catch snow that we lost by drilling these cover crops into our irrigated wheat stubble. There is still wheat stubble standing, but not as much as we had prior to seeding.
With the exception of the sunflower, the cover crops we planted are all cool season and will give us good growth until really cold temperatures set in. My guess is the field will stay green until the middle of November.
The downside to these cover crops is any irrigation they may require. After our wheat harvest we applied an inch of water to give us some moisture to plant into since we have been so dry. We applied an additional half inch of water after seeding to insure we had good moisture to get the cover crops started. I’m really hoping we’ll get enough rainfall this late summer and fall that we won’t need any additional irrigation to produce these cover crops. This is the main reason I have not grown cover crops recently. I don’t like the idea of trading groundwater for soil health benefits but we decided to try it this year and see what type of results we find with these cover crops in our environment.