No Till Notes - "Cover Crops" 12-19-12

By Mark Watson, Panhandle No-Till Educator

In the past couple of articles I’ve talked about how we have added diversity into our cropping rotations to diversify markets and improve soil health. We have added field peas into our dry land cropping rotation which has allowed us to diversify our herbicide rotations, improve and diversify our soil microbial populations, and add a legume in our crop rotation for nitrogen fixation. Our crop rotation is now winter wheat, followed by corn, then field peas and back to winter wheat.

I also talked about the possibility of adding forages as part of a crop rotation for grazing. I think this is a very viable alternative to grain production in our cropping rotation. This would allow us to include livestock in our operation which would also diversify our markets. I also think this may be a hedge against drought provided we receive enough moisture to grow forages in the future.

The other practice we tried this year was to plant a cover crop following irrigated winter wheat harvest. We planted a cover crop mixture of field peas, flax, radish, and sunflower. We decided on this diverse mixture to help achieve specific goals we had in mind for the cover crop.

We planted 80 pounds of field peas per acre, 2 pounds of nitro radish per acre, 5 pounds of flax per acre, and 2 pounds of sunflower per acre. The mixture was chosen to include all broadleaf crops so we could control the volunteer winter wheat. We did spray the cover crops with a grass herbicide after the crops had emerged to control the volunteer wheat and allow the cover crops to get off to a good start without competition.

A goal we had for the cover crop was to plant field peas and inoculate them to help produce nitrogen for the corn crop that we will plant in the field next year. We also chose the peas because of their high nitrogen to low carbon ratio in the pea stubble. Winter wheat has a high carbon to low nitrogen makeup in the stubble and we were trying to reverse this ratio with the peas so more nitrogen will be available for the corn next year. 

We also chose the peas to diversify the diet and populations of our soil microbes. Different soil microbes prefer different crops that are grown in the field. If we have only crops planted that are high in carbon those microbes that prefer those types of crops will thrive. In order to balance the populations and diversity of the microbes in our soil, we chose a legume to help balance the diet available to our soil microbes.

We planted the flax and sunflower in the cover crop mixture to add some vertical structure to the cover crop. When we drill the cover crop we lose a lot of vertical structure provided by the winter wheat. Adding the flax and sunflower helped us to grow some of this vertical structure back into the field. These taller plants will help us catch the snowfall that we receive during the winter months. Hopefully we will see a change in the weather pattern before spring and will capture significant moisture from winter snowfall in the field.

The radishes were planted to help capture any nitrogen in the soil and prevent it from leaching away if we do receive good moisture. The radishes also provided a good root to help break up any soil compaction and will leave a good hole in the ground for water infiltration next year.

All of these crops will help capture and store nutrients for us. As these cover crop residues are broken down next year by the soil microbes some of these nutrients will be released for the following corn crop. This helps us to keep the nutrients in the plant cycle.

We did a plant biomass sampling of these cover crops and I have received the results of this sample. Next week we’ll take a look at how these cover crops performed and what we can expect for nutrients being available for next year’s corn crop.

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