We found out this spring how important continually adding carbon into our soil is here in western Nebraska. With our somewhat low organic-matter content soil we really need to continually grow high-residue crops a high percentage of the time to keep the soil in good condition.
Hard to Break
We are transitioning our farm on our irrigated acres to a rotation of winter wheat (followed by forages for grazing), dry edible bean, corn, and yellow field pea instead of winter wheat, corn and edible beans. During this transition phase we planted a field that was corn to edible beans the following year. To get this field into our new rotation we planted the field back to corn last year.
This short-term rotation from corn to edible beans, and back to corn, left the field with too little residue and a lot of bare soil exposed for a lengthy period of time. The end result was a soil that was firm and dry on the top layer. The soil was so firm that when it came time to drill our field peas the drill couldn’t penetrate the soil to get the seed to our desired planting depth.
We were left with the option of applying water to the field through our center pivot irrigation, or wait for rain. We had several other fields of dryland to plant to field peas, so we elected to wait and see if it rained, which it did.
These dryland fields have been in a winter wheat/corn/field pea rotation for multiple years. The interesting observation was how ideal these fields were for drilling the field peas. Absolutely no firm layer of soil on top because of high amounts of residues. These fields couldn’t have been in any better condition to drill.
We did have cattle graze the corn on our irrigated field that was so firm and compact. I don’t think the cattle were the problem, since the field was grazed while the ground was frozen for the most part. I really think the problem was the lack of residue grown in the field for multiple years.
Granted there is a lot of residue when growing irrigated corn. The problem with corn residue is it tends to blow up in piles with the winds we get in this area. This leaves a lot of the soil bare to the elements. Over winter these soils tend to get compact and dry.
The biggest problem with this short term corn/bean/corn rotation was the lack of consistent residue in the field. This is another example of why a cereal grain, such as winter wheat, is so important to crop rotation in our area.
Winter wheat has the ability to produce high amounts of consistent residue throughout the field — particularly if a stripper header is used at harvest. Winter wheat residue adds carbon to the soil consistently, which helps soil maintain the properties needed for high performance. Soil tilth and overall soil health are much better when high-carbon residues are grown as a high percentage of the crop rotation.
It will be interesting to see in the future if our new crop rotation will produce enough carbon to keep the soil healthy.
Part of our new rotation will be edible beans, followed by corn and then field peas. The high-carbon part of the rotation will be when we drill winter wheat following the field peas. Immediately following the winter wheat we will plant forages into the winter-wheat stubble for grazing during the winter.
After seeing the results of our short-term, low-carbon-producing rotation this spring, I’m wondering about how this new rotation will affect the ability of the soil to perform at a high level. By using continuous no-till production practices we’ve learned that adding high amounts of residues and carbon back to the soil is very important to maintain soil performance and health.