The cost of drying corn — especially the propane bills — add significant expense at harvest time.
According to a case study conducted by Mark Hanna, agricultural engineer for Iowa State University Extension and Outreach, propane accounts for more than 90% of the energy used in high-temperature corn drying.
"Considering that propane makes up such a large proportion of the energy needed for drying, farmers may want to compare their own propane consumption to the measurements from the case study," Hanna said in a University statement.
Led by Hanna, three ISU Research and Demonstration farm locations collaborated to measure the propane and electricity used for grain drying during the 2013 harvest season. The participating ISU farms included Nashua, Atlantic and Ames locations. Additional support for the project was provided by a grant from the Iowa Energy Center.
On the farms, energy measurements were collected using load cells placed underneath the propane tanks to record weight. Electrical energy was also recorded for drying fans and mixing augers.
Researchers found that though propane was responsible for up to 98% of the energy used in high-temperature systems, initial grain moisture really matters.
"The case study shows that total energy consumption during drying was primarily affected by the initial moisture content of the corn," Hanna said.
Related: 10 Ways To Dry Corn More Efficiently
According to the research paper, it took as much as 210 gallons of propane to dry 1000 bushels of 24-25% moisture corn compared to as much as 100 gallons for corn below 20% moisture.
Though incoming corn was at a higher moisture content at Nashua and required more total energy for drying, it required somewhat less energy than the drier corn (17–19%) harvested at Ames.
According to the study, this could be attributed to a partially filled bin or the added difficulty of extracting moisture as water content continues to decrease inside kernels.
Other variations in energy consumption at these sites may be due to cooler ambient air temperatures that required more preheating for fall drying, the paper said.
"Initial corn moisture content and air temperature will be different this year but we plan to collect additional measurements this fall," Hanna noted.
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