November 12, 2017
Nutrient Value of Corn Stover: With an option of downed corn ears being baled up with corn residue, I’ve received questions on residue removal. These questions include the nutrient value of the residue (stover), yield effects to the successive crop, and any research on planting cover crops after baling. I will address these three topics in the next three week’s columns.
Corn residue can be looked at from many perspectives…from being a source of feed or bedding for livestock, protection of the soil surface for wind/water erosion and evaporative losses, cellulosic biofuel production, made into pelleted feeds for livestock, food for microbes resulting in nutrient source for future crops, and considered a challenge in achieving uniform emergence and plant stands particularly in no-till continuous corn situations.
How does one estimate the total residue produced by a corn crop? Grain yield is related to residue production. For every 40 bu/ac of corn produced (56 lbs at 15.5% moisture), 1 ton of residue (at 10% moisture) is produced. For example, a 240 bu/ac field will produce approximately 6 tons of residue while a 120 bu/ac field will produce approximately 3 tons of residue.
This week I’ll share research regarding the nutrient value of the corn stover. Our Extension nutrient management specialists share that nutrient value can depend on the season, management practice, time of harvest, location, and what part of the plant is being removed. For example, more nutrients are concentrated in leaves and husks than in the stalks. Per ton of dry harvested corn or sorghum residue, average nutrient concentrations include 17 lbs of Nitrogen, 4 lbs of P2O5, 34 lbs of K2O, and 3 lbs of Sulfur. Taking these nutrient values in pounds per ton and multiplying by current fertilizer prices in dollars per pound give the value of nutrients in the residue based on dollars per ton of residue removed. Of note, this formula takes into account the full fertilizer value of the nutrients removed. However, if the soil has adequate capacity to supply some nutrients (such as potassium in Nebraska), the value of removed nutrients may be less (from 0-50% of fertilizer value).
Another consideration includes the fact that positively charged ions removed with residue harvest such as calcium, magnesium, and potassium removes their contribution to neutralizing soil acidity implying lime will eventually be needed. Harvesting 1 ton of corn residue removes the equivalent cations contained in 35 lbs of lime. So for example, if lime is worth $40/ton, $0.70 should be added to the value of crop residue.
Additional values to the residue come from potential soil loss due to wind and/or water erosion, any potential yield loss (which I will share next week to be minimal and primarily observed in water-limiting environments), any increased irrigation due to evaporative losses, and the cost of raking/baling/transporting residue.
Research has shown a minimum of 2.4 tons/acre of residue is necessary to maintain soil organic carbon in no-till systems. With increased tillage, greater residue amounts are necessary because tillage increases decomposition rates of residues and soil organic matter.
Regarding soil losses due to water erosion, additional studies in Gage, Sherman, and Chase counties in Nebraska looked at tillage, soil type, and terrace effects on the amount of residue that could be removed to maintain less than 5 tons/acre/year water erosion for silt loam and silty clay loam soils. The research found that no residue could be removed if the land is tilled by disking unless the field is terraced, had 2% slope (but not 5% or greater), and yielded greater than 150 bu/ac. Fields that were no-tilled and terraced even up to 10% slope could have residue removed and still maintain less than 5 tons/acre/year water erosion. Regarding wind erosion in another study, ground covers of 30 and 60% were estimated to be sufficient to reduce wind erosion by 70 and 90% respectively compared to bare soil.
Totaling up the various factors for consideration can provide an estimate of the cost of crop residue harvest in dollars per ton. These factors again include: nutrients removed, lime equivalent value, yield loss, soil loss from wind and water erosion, any increased irrigation, and raking/baling/transportation.
Maintaining Cattle with Limited Perennial Pasture Meeting: Kansas and Nebraska Extension are hosting a 3-meeting series to address some possible options to help maintain cattle inventory with limited perennial pastures. Topics at these meeting will include confined cow feeding and management, usage of corn residue, cover crops and annual forages systems. The first meeting will be held on December 12, 2017 at the Helvering Center (111 S. 8th St, Marysville, KS) with a start time of 6:30 p.m.; please RSVP to Anastasia Johnson at email@example.com or 785-562-3531. The second meeting will be held December 13, 2017 at the Blue Hill Community Center (555 W. Gage St. Blue Hill, NE) with a start time of 6:30 pm.; please RSVP to Brad Schick, firstname.lastname@example.org or 402-746-3417. The final meeting of the series will be December 14, 2017 at the Gateway Civic Center (1 Morgan Dr. Oberlin, KS) with a start time of 6:30 p.m.; please RSVP to Alyssa Rippe, email@example.com or 785-475-8121. Dinner will be provided and there is no cost to attend. Speakers include Dr. Mary Drewnoski and Dr. Karla Jenkins, UNL Beef Specialists and Dr. Jaymelynn Farney, KSU Beef Systems Specialist.
Nebraska Soybean Day and Machinery Expo December 14: Dicamba issues and recommendations for achieving more precise herbicide applications are among the timely pest management and production topics slated for this year's Nebraska Soybean Day and Machinery Expo. The event, which includes equipment and exhibitor displays, will be from 8:30 a.m. to 2:15 December 14 in the pavilion at the Saunders County Fairgrounds in Wahoo. Dr. Jason Norsworthy from University of Arkansas is the featured speaker and will focus on dicamba. Additional speakers include Chris Proctor, Weed Science Educator and Michael Swanson, Wells Fargo Chief Ag Economist. The expo also will include an update on the Nebraska Soybean Checkoff and association information. While the event and noon lunch are free, the Saunders County Soybean Growers Organization asks that each attendee donate one or more cans of nonperishable food to the food pantry. Registration is available at the door. For more information call (800) 529-8030 or e-mail firstname.lastname@example.org. This program is sponsored by Nebraska Extension, the Nebraska Soybean Board, Saunders County Soybean Growers Organization and private industry.