By Jean Caspers-Simmet
IOWA FALLS, Iowa — A new farm energy audit could be a valuable tool for helping farmers reduce their energy consumption, says Heath Ellison, program manager for the Iowa Soybean Association’s Certified Environmental Management Systems for Agriculture, or CEMSA program.
Ellison analyzed data from 51 farmers who completed the farm energy audit with their crop consultants last year. He presented the results of the study at last week’s South Fork Watershed Alliance board meeting in Iowa Falls.
"If we set a goal of helping farmers reduce their energy consumption by at least 10 percent that would be huge," Ellison said. "We often talk about how farmers are producing energy, but conserving energy is an important part of this as well."
The MGT Envirotec crop consultants who developed the energy audit had worked with ISA on a scouting project, and when ISA officials learned about the energy efficiency tool, they saw it as another service they could offer.
The energy audit, which looks at the direct and indirect energy involved with planting, growing and harvesting a crop, was used by nine crop consultants on 51 farms across Iowa. The audit converts all energy sources to gallons of diesel fuel equivalent per acre allowing comparisons across energy sources.
Ellison said the lowest corn production scenario he analyzed used 5.29 gallons of diesel fuel equivalent per acre. The highest used 64.81 gallons of diesel fuel equivalent. The median was 30 to 40 gallons. The range for soybeans was 1.6 gallons of diesel fuel equivalent per acre at the low end to 7.11 gallons on the high end.
Among the case studies Ellison discussed was a dairy operation with a six-year rotation of corn, soybeans, oats and three years of hay. The farmer plowed alfalfa and used manure for nutrients. The operation used just 66.59 units of diesel fuel equivalent over the six years of the rotation.
The same farmer had additional acres with a no-till corn-soybean rotation that used 120 pounds of urea ammonium nitrate, or UAN, for fertility. The total gallons of diesel fuel equivalent per acre for six years of that rotation was 155.28 gallons per acre.
Conventional tilled corn with urea ammonium nitrate plus starter harvested at 17 percent moisture used 33.85 gallons of diesel fuel equivalent compared with a corn system using conservation tillage, with manure plus starter harvested at 16 percent moisture for 8.15 gallons of diesel fuel equivalent.
A soybean operation that used a subsoiler/ripper and spring cultivation consumed 4.33 gallons of diesel fuel equivalent compared with no-till soybeans that used 1.88 gallons of diesel fuel equivalent.
Ellison hopes to obtain data from 200 farms this summer for expanded testing and validation.
"Every farm is different, and I don’t know that there’s a strong general recommendation we can make out of what we learned so far," Ellison said. "Big picture, you can have a huge impact on energy efficiency of growing your crop by looking at nitrogen efficiency and fine-tuning nitrogen rates followed by grain drying and tillage passes."
Ellison said it is possible that down the road the energy audit could be used by farmers to show reductions in carbon and greenhouse gases. This data could potentially give farmers another product to market.