This analysis works out the economic implications for variable rate seeding of the corn population response curves estimated by Pioneer Hi-Bred agronomists. Examples are developed for various mixes of low, medium and high yield potential soil, as well as for a range of seed costs and variable rate equipment costs. The strategies analyzed were: variable rate planting using agronomic recommendations for each yield potential zone, variable rate planting using an economic decision rule for each yield potential zone, an information strategy which sets the uniform planting rate at the highest population indicated by agronomic recommendations for any part of the field and a second information strategy which uses an economic decision rule for the whole field based on potential in each yield zone. The economic decision rule sets the value of additional yield produced by adding a few more plants equal to the cost of planting a few extra seeds. Major assumptions of the analysis include: only corn is considered for variable rate planting, 1000 acres of corn are planted annually, the yield potential zones are small, irregularly shaped and interspersed so that changing population by field is ineffective, the zones are accurately mapped and corn price at harvest is $3/bu. The analysis does not include risk, alternative uses for low yield potential soil or the benefits of variable rate planting other than seed cost savings and matching population to the yield potential of the soil. The general conclusion is that variable rate seeding has profit potential only for farmers with some low yield potential land (<100 bu./a). Farmers with mix of medium and high potential land are better off with uniform rate seeding. The surprise is that variable rate seeding is potentially profitable when the proportion of low yield land is small. In the example, the farm with 10% low yield potential soil shows positive returns to variable rate planting. The results are not particularly sensitive to seed cost or variable rate investment cost.


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