No Till Notes

I hope everyone is able to spend the holidays with friends and family spreading good cheer throughout our region.

We have the results of our cover crop biomass sampling back and the cover crops performed about like we thought they would. I think we could justify the cost of planting the cover crops with the benefits we’ll see from producing them, but I do have some concerns with producing cover crops.

Our sampling from the cover crop field showed some interesting results. We sampled a square yard of the field that we felt was pretty consistent with the overall field. We removed all the above ground vegetative growth from the field peas, sunflower, flax, radish, and volunteer winter wheat within the square yard of sampling area. We also removed all the previous crop’s residues from this same square yard which consisted of winter wheat stubble, corn, and edible beans.

We sent this biomass sample in to Ward Labs for testing. The results showed we have 6,722 lbs./acre of Carbon, 171 lbs./acre of Nitrogen, 28.5 lbs./acre of Phosphorous, and .285 of a lb./acre of Zinc. Other micronutrients were also shown in varying amounts in the sample.

Our carbon to nitrogen ratio for the sample was 39 parts carbon to one part nitrogen. This is a significant ratio as it will determine the amount of nitrogen we can expect to be available for next year’s corn crop. The winter wheat stubble that we planted the cover crop in has a C:N ratio of around 80 parts C to 1 part N. In order for a more rapid release of nitrogen for next year’s corn crop, this ratio needs to be around 20 parts C to 1 part N.

We were able to lower the ratio to 39 to 1 from what the wheat stubble contained, but not low enough to get maximum nitrogen release. Looking back we could have included more field peas in our mixture. Anyhow, we will utilize a portion of the 171 lbs./acre of N from the sampling. Given the C:N ratio of 39 to 1, Ward Labs estimates we can plan on using approximately 50 lbs. of the N available in the sampling for corn production next year.

We plan to graze this cover crop later this winter so we’ll get some value out of the cover crop for grazing. We will also reduce our nitrogen commercial fertilizer requirements for corn next year by 50 lbs./acre. The benefits we don’t know for sure are if we will see a boost in corn yield next year by planting the corn into the cover crop stubble. I also don’t know how to put a value on soil health benefits we may have from producing this cover crop. A side benefit to the cover crops has been the pheasant hunting these cover crops have provided. The pheasants really utilize these cover crops during the day and for roosting at night.

Economically I felt we could justify the planting of the cover crops. My concerns are the amount of irrigation water we pumped to produce these cover crops. We pumped five inches of water per acre this year to produce these cover crops. This was a dry summer and we received very little rain during the growing season for these cover crops so our water use was probably the maximum we would ever need to produce cover crops.

With our limited groundwater resources I don’t think I can justify this amount of water use for the growing of cover crops. Our groundwater resource is very valuable and I don’t think it makes sense to trade our groundwater resource as a means to improve our soil health resource. If we have a normal precipitation pattern during the summer and there is moisture in the soil following winter wheat harvest I would consider planting cover crops following our irrigated winter wheat harvest.

The idea of planting cover crops to improve soil health and provide additional forage for grazing makes a lot of sense to me provided you don’t have to use our groundwater resource to grow the cover crops. If you have the moisture available I think planting cover crops is a good management tool to utilize.