Planter size has a significant impact on per acre costs, according to a University of Illinois Extension study examining planter costs with different farm sizes.

"Planting more hours per day could result in a smaller planter size having lower costs," added Gary Schnitkey, U of I Extension farm management specialist who conducted the study.

The study's objective was to determine the planter size that had the lowest cost for a given farm size. Farm sizes from 400 to 4,000 acres in 400-acre increments were evaluated. Planter sizes range from six rows up to 36 rows. Planters were assumed to plant all acres with all acres evenly split between corn and soybeans.

"Two categories of costs were included in the analysis," Schnitkey explained. "These were timeliness and power costs. Timeliness costs account for yield losses from not planting near optimal times. Power costs include depreciation, interest, repairs, housing, insurance, fuel and lubrication, and labor. Power costs were calculated for the planter and the tractor to pull the planter."

According to the study, on the basis of power costs alone, the eight-row planter has the lowest costs for a 400-acre farm. The 12-row planter has the lowest costs for 1,200 and 2,800 acres; and the 16-row has the lowest cost for farm sizes between 3,200 and 4,000 acres.

"However, when timeliness is factored in, costs change," said Schnitkey. "For example, a 36-row planter has the lowest cost for the 3,200 acres and above sizes when timeliness costs are included. When only power costs are included, a 16-row planter has lower costs for 3,200 acres and above farm sizes.

"Timeliness costs are important because least-cost planters differ when timeliness costs are included."

The full report, part of the Farm Economics: Facts and Opinion series, is available on the farmdoc website at: http://www.farmdoc.uiuc.edu/manage/newsletters/fefo04_05/fefo04_05.html.