With harvest finished or wrapping up, focus has shifted to anhydrous applications and managing residue. Corn residue management has been a topic of discussion for years. Research on this topic has included use of tillage, baling, grazing, and use of products like nitrogen.
Iowa State conducted a three year study evaluating the effects of conventional tillage, no-till, and strip-till on residue breakdown on Bt and non-Bt corn residues. They did this by placing bags of residue of Bt and non-Bt hybrids in the three different tillage systems and evaluated decomposition after 3, 6, 9, and 12 months in a corn/soy rotation. The results showed no significant difference between tillage systems or Bt and non-Bt hybrid decomposition. These researchers also studied the impact of nitrogen applications on corn residue breakdown over two years in no-till. Immediately after harvest, three N rates (UAN 32 percent) of 0, 30 and 60 lb N/acre were applied to corn residue. A specific amount of residue was placed in nylon mesh bags and left in the field for 3, 6, 9, and 12 months, after which residue decomposition was evaluated. The different rates of N resulted in no differences in rate of decomposition. In general, the longer the residue remained in the field, the more it decomposed over time, regardless of N rate. Thus the authors shared that applying N after harvest for residue decomposition was not effective nor economical as soil and air temperatures decreased over time after harvest. They shared that in general, decomposition of crop residue is primarily influenced by soil moisture and temperature which allow for microbial activity.
Last year I wrote a series of articles for my news column and shared them in CropWatch regarding cornstalk baling. A team of Extension Specialists/Educators and USDA-ARS also worked together on a workshop at 2018 Husker Harvest Days on this topic. I’ve received various reactions to these efforts, but my desire is to present the research. My perspective is twofold:
- Better serving farmers/landowners in helping answer your residue management questions via the research available and
- With the high winds, dust storms and vehicle accidents last winter/early spring, could we potentially rethink residue management besides so much conventional tillage for this part of the State?
I’m not saying conventional tillage doesn’t have a place, especially as we think of one-time burial of weed seed. I just wonder if we can help reduce soil loss by utilizing other methods of residue management, perhaps including increased use of livestock grazing and cornstalk baling under the right field situations?
Summarizing the research, cornstalk baling is not for every piece of ground or every situation. From the research, our recommendations are that baling of corn residue should only occur on ground with less than 5% slope that yields 180 bu/ac or more, harvesting no more than 2 tons/acre. Retaining at least 2.4 tons of residue allowed for soil carbon maintenance and retaining more residue also reduced erosion. Every 40 bu/ac of corn results in 1 ton of residue at 10% moisture. Baling on fields fitting the above-mentioned criteria should occur a maximum of every other year in continuous corn or once every four years in a corn/soy rotation (due to reduced residue already present after soybean harvest). The research showed no significant impact on soil properties or soil carbon following those guidelines. Other recommendations would be to use a reduced tillage system in the field where baling occurred and consider planting a cover crop and/or adding manure.
In 239 site-years across 36 studies, corn residue baling resulted in 3% average yield increase where moisture was not limited, most likely due to more uniform stands. The average nutrients found in 1 ton of corn or sorghum residue was 17 lbs of Nitrogen, 4 lbs of P2O5, 3 lbs of Sulfur, 34 lbs of K2O (which due to Nebraska soils being high in K, the value may be 0-50% of this depending on soil test results), and cations equivalent to 30 lbs of lime. There’s also research that suggests less nitrogen is needed the following year going into corn due to the change in the C:N ratio and increased mineralization. So corn residue baling, based on the research, can be an effective way of managing residue without significantly impacting soil properties if done using the considerations mentioned above. Many fields I’ve observed cornstalk baling in the area this year look good regarding these criteria and most took less than 50% residue off the fields.
This year we’ve also seen a large increase in soybean residue baling in this part of the State. I realize it’s mostly being used for livestock bedding. In a future column and CropWatch article, the research regarding soybean baling will be shared in addition to an economics comparison of various residue management strategies. I will also share on grazing research for residue management in a future column.
By the time this is printed in newspapers, we’ll be remembering September 11th. Grateful for all the first responders and all who have served our Country to defend our freedom since that day. Grateful for the sacrifices their families have made as well. Thinking of and praying for the families of those who lost their lives in the attacks and in defense of our Country since. May we never forget!
Encouragement: The wet weather has created challenges with harvest, making silage, increasing ear/stalk rots, kernel germination, and dampening spirits. So seeking to encourage: grateful for the soil moisture profile recharge the rain has provided and how it’s allowing pastures to recover and cover crops to grow! It’s really special to live in a State where our State Fair is now so ag and family focused! It was wonderful seeing so many farm families during the fair and I look forward to seeing many during Husker Harvest Days too! Thankfully harvest will be here soon and we’ll appreciate the sunshine that much more when we see it again!
Sprouted Kernels: I’m seeing and hearing of kernel sprouting in hail damaged and drought stressed corn in addition to corn hybrids that have tighter husks and upright ears. Sprouting is also occurring in soybean. So why are we seeing this?
Prior to full maturity it comes down to a hormonal imbalance within the kernels between gibberellin and abscisic acid (ABA). According to a study by White, et. al (2000), Gibberellin production with the lack of ABA allowed for kernel germination while less Gibberellin and more ABA deterred kernel germination. At full maturity, very little ABA is left in the kernel (in both corn and soybeans) which allows them to germinate in correct conditions after harvest.
These conditions include temperatures above 50ºF and moisture. Thus the continuous drizzle and rain we’ve experienced can allow for sprouting within soybean pods. In corn, sprouting under those conditions typically occurs at the base of the ear first but we’re also seeing it in exposed ear tips. We’ve also seen Fusarium and Gibberella ear rot fungi occurring in ears that have been damaged by hail and/or insects in ears. These fungi also produce gibberellins which can aid in the hormonal imbalance and stimulate kernel germination.
If you’re seeing kernel sprouting in your field, make sure your crop insurance adjuster is aware of the situation and submit samples for kernel damage due to mold and sprouting. Also check for mycotoxins prior to harvest if ear molds are a problem in your field. The local co-op will decide whether to accept the load based on percent damage and the standards they need to follow. If the load is rejected, contact your crop insurance agent to determine your next step.
Sprouted kernels lead to higher kernel damage and more fines in a load. Keys for harvest will include
- harvesting early,
- drying it to 14%, potentially drying at a high temperature to kill the sprout,
- screening out fines, and
- monitoring stored grain closely for hot spots, mold, and additional sprouting grain.
With the moisture continuing to exacerbate corn ear molds,particularly in hail damaged fields, you may also decide to take the grain for silage instead. More information regarding correctly making silage can be found at: https://cropwatch.unl.edu/2018/silage-hailed-corn.
Husker Harvest Days Cornstalk Baling Workshop: Baling of cornstalk residue has been an increasing topic of interest among growers. Reasons are many including residue management when cattle don’t graze a field, use of residue as a feedstuff, and as was the case in 2017, to bale up much of the downed ears with the cornstalks. With this interest, we’ve had individuals contact us about custom baling residue as an additional income source. With the topic of residue baling comes many questions. These include:
- What is the nutrient value of the residue removed from the field?
- What are the impacts of residual removal on subsequent yields and field soil properties?
- What is the feed value of that residue?
- How do I best set my current equipment to bale corn residue?
- Is my current equipment the best to bale corn residue?
This year, Nebraska Extension, Farm Progress, and several forage equipment manufacturers are partnering in a Corn Residue Baling Workshop at Husker Harvest Days (September 11-13). The workshop will be from 1:30-2:00 p.m. daily in the fields adjacent to the haying demonstrations, which begin at 2 p.m. Equipment manufacturers who have committed to the demonstration include: CNH, AGCO, Rowse Rakes, Vermeer, and John Deere.
Some of the manufacturers will be showcasing the same equipment in this workshop and in the haying demos. Each manufacturer will talk briefly about their equipment and specific settings that might be needed to make their machinery work better on residue. Because of the high moisture content of the corn residue during the Husker Harvest Days Show, equipment demonstrations of baling residue are not a possibility; however, videos of the manufacturers’ equipment in action can be viewed in the University of Nebraska Institute of Ag and Natural Resources building.