The planters used in this study included both a 16 and 24 row unit. Spring tillage was conducted with a 45 foot field cultivator.

Results from these producer tests showed an average 3.3 percent overlap during planting operations. This overlap was due in part to planting point rows, but also had a significant component of overlap into perpendicular headlands.

This is associated with a delayed response of the driver to lift the planter out of the ground when entering the headland.

For spring tillage, a 7 percent overlap was measured and was mainly associated with pass-to-pass overlap of the outside section of the tillage tool into the previous field pass.

Calculating return on investment of precision ag products

Given these overlap levels, the return on investment of autosteering and swath control products can be directly measured.

For swath control, both the cost of seed production and the loss of yield in double planted headland areas must be considered.

Typical cost for corn seed in central Iowa is $113.80 per acre (Estimated Costs of Crop Production in Iowa– 2012, Duffy).

A conservative estimate for yield loss in double-planted areas is 12 percent based on previous research at Iowa State. For 175 bushel per acre average corn yield with a value of $6 per bushel this results in a production loss of $7.91 per acre.

Based on this analysis, the value of precision ag swath control systems in typical Iowa corn production is $7.91 per acre.

Tillage saving when using a lightbar or autosteer system can be calculated in a similar manner.

A 7 percent reduction in tillage overlap will result in approximately $1 per acre cost savings. The cost savings is less due to a lack of high cost inputs, but still justifies lightbar systems even on the most basic tillage operations.