An area farmer told University of Nebraska Extension educator Jim Schneider that he recently received an offer to buy his corn residue for as much as $20 a ton or $60 an acre for a 3-ton harvest.
"For a quarter section, he could receive $9,600," Schneider says. "At first glance, it looks like he could get paid for what appears to be waste material — crop residue, but you need to think about the value of that residue.
"First, this residue contains nutrients that feed subsequent crops. We can determine that value by knowing the amount of residue produced, the nutrient concentration of the residue and the current commercial nutrient replacement costs."
The amount of crop residue produced is related to grain production. Approximately 1 ton of crop residue (at 10% moisture) is produced with 40 bushels of corn or grain sorghum (56 pounds per bushel at 15.5%), 30 bushels of soybean and 20 bushels of wheat, says Charles Wortmann, University of Nebraska soil specialist.
"The concentration of nutrients in crop residue varies with the season, management practices, time of harvest and location," Wortmann says. "In addition, crop residue components differ in nutrient concentration, with most elements concentrated more in leaves and husks than in stalks."
The typical nutrient content for corn or sorghum is about 17 pounds nitrogen, 4 pounds phosphorus, 50 pounds potassium and 3 pounds sulfur per ton of dry harvested residue, Wortmann says.
Using current fertilizer prices, he says these nutrients have a value of $36 per ton of residue. The potassium portion of that is $26.
"Since our soils in Nebraska are naturally high in potassium, let’s just say we’d replace only 38% of the potassium for $10, making our nutrient replacement cost $20 per ton," he says. "Assuming 3 tons of residue are removed, the cost of replacing nutrients is $60 per acre."
Research results from Garden City, Kan., show water loss due to evapotranspiration was 4.3 inches greater under irrigated conditions where all residue was removed than in a comparable field that still had its residue, Schneider says.
Variable costs associated with pumping this additional water would be about $17.20 per acre. The trade-off of not pumping this additional water would be a significant loss in yield.
Simon VanDonk, Extension specialist at the West Central Research Station in North Platte, conducted small plot residue removal trials on no-till. He saw a 25-bushel reduction in limited irrigated corn yield when the previous soybean crop residue was removed. Steve Melvin, UNL Extension educator at Curtis, saw a 10-bushel reduction in a similar study when the previous wheat crop residue was removed. These figures can be reduced somewhat if some residue remains.
"If you consider both nutrient loss and moisture loss, the cost to replace the residue now exceeds the benefit of selling it," Schneider says.
In addition, he says residue traps snow for moisture accumulation. On the negative side, residue removal could lead to soil compaction from baling and removal of residue, reduced soil organic matter and soil biological activity, and increased potential for water and wind erosion on unprotected soils.