POET-DSM Advanced Biofuel’s Project LIBERTY in Emmetsburg, Iowa, will process about 770 tons of crop residue (corn cobs, leaves, husk, some stalk) per day into cellulosic ethanol once the biorefinery is operational. Most of that material will be stored for some time on farmers’ fields before going to the facility. So what impact does storage have on those farmers’ fields?
Since the storage work with biomass started about 5 years ago, Project LIBERTY personnel have monitored and researched the effect that both corn cob piles and crop-residue bale stacks have had on soil and the following year’s crop. The effect was more pronounced with loose cob piles in affecting crop development, especially with corn. The switch to bales has had a much lower effect, but some impacts still exist that can affect the following growing season crop.
The most notable impact on plant growth is related to the amount of loose corn cob-residue mixture left on the soil’s surface. In general, most baled cob-residue leaves very minimal amounts on soil surface after bales are removed from the field. Issues are generally caused when bales break during the stacking and loading phases of handling the bales in the field. If such cob-residue mix is left accumulated on the soil’s surface, it might cause difficulties for raising a crop the following year.
Primarily, leaving piles of broken bales on the soil surface can slow the rate at which the soil warms. This ultimately will slow seed germination and offsets the advantage of removing some residue. Second, the excess biomass left can cause planting challenges. To manage such a condition and reduce its effect on plant germination, planters can be equipped with residue cleaners (residue wipers) to remove the excess residue from the seedbed and create a residue-free zone.
Corn cobs that accumulate on soil surface in a concentrated area for an extended period of time can cause a nitrogen deficiency at that area, resulting in poor plant development. Some ways of addressing this include spreading the loose corn cob-residue evenly across a larger area in the field, re-baling the excess corn cob-residue mixture and sufficient nitrogen application.
The other issue that can result is soil compaction from the increased wheel traffic. The bales themselves do not result in significant compaction, but the traffic bringing the bales to the storage location and then loading those bales increases the chances of compaction in the field. This is very dependent upon the soil moisture conditions. Wet soil is more prone to soil compaction, which limits root development in next year’s crop. It is recommended that removal of bales from the field should be done in the driest conditions possible and that tillage be applied in the storage area where bales are being handled and loaded.
By following proper practices in managing corn cob-residue bales, you can greatly reduce your chances of seeing an effect due to storing your bales in the field. By managing the amount of corn cob-residue left at the storage area, minimizing traffic in wet conditions, and applying a proper nutrient program using soil testing for proper N, P and K applications, effect on crop production can be successfully managed.
Adam Wirt, POET Biomass Logistics director, has been with the company since 2003 and works on creating and establishing feedstock supply chains. He is actively working on the feedstock roll out plan for Project LIBERTY, a cellulosic plant that will be built in Emmetsburg, Iowa, through a joint venture between POET and DSM, www.poetdsm.com. His roles in this arena consist of feedstock research, supply-chain development and program implementation. Prior to Wirt’s time on the Feedstock Team, he worked in various POET biorefineries managing plant operations. Wirt has a bachelor’s degree in Agricultural Systems Technology from South Dakota State University and recently graduated from the South Dakota Agriculture and Rural Leadership (SDARL) program. You may contact him by e-mailing firstname.lastname@example.org.