Moving from uniform to variable fertilizer rates on Iowa corn: Effects on rates and returns

This study develops a model based on the yield potential of various soil ty pes in 12 Iowa counties to estimate the potential value of switching from u niform to variable fertilizer rates. Results indicate modest increases in t he grass returns over fertilizer costs, ranging from $7.43 to $1.52 per acr e. The net profitability of variable-rate technology (VRT) is sensitive to the per acre costs of moving to a VRT program. Under the assumptions of the model, applying variable rates would increase yield by 0.05 to 0.50 bushel s per acre, and would reduce fertilizer costs by $1.19 to $6.83 per acre.