Crop fallow cropping system with spring wheat after no-till fallow.
Before variable-rate fertilizer application:
Producer had fertilized for ten years.
In 2003, applied 177 pounds of 55-25-5-5 on re-crop acres and applied 140 pounds of 55-25-5-5 on fallow acres which cost $13.65 per acre.
In 2004, applied 110 pounds of 25-25-5-5 dry fertilizer for a cost of $12.50 per acre plus $4.50 per acre for liquid fertilizer for a cost of $17.00 per acre.
a. 2004 was a dry year and averaged 26.4 bushels per acre.
b. Producer did not have a yield monitor on the combine.
With variable-rate fertilization application:
In 2006, zone development was $6.00 per acre by a Technical Service Provider (TSP).
Soil tests were $30.00 per test.
Five zones were developed and designing the zones cost $235 or $.47 per acre.
Producer applied 73 pounds of 20-20-0 with the drill at a cost of $11.28 per acre; also applied variable-rate liquid of 28-0-0 for a cost of $3.50 per acre application cost plus $14.82 for fertilizer for a cost of $29.60 per acre.
a. Zone application variable rate varied from 0 pounds to 100 pounds.
b. Average yield was 40 bushels – was a good crop year.
Looking for a 20 percent increase in average yield in future years due to evened-out yield across the field.
Producer spent more on fertilizer in 2006 because dry fertilizer prices increased 30 percent and wanted to even up the yield across the field.
Producer wants to use the yield maps obtained when harvesting the grain to develop the fertilizer rates to variable-rate apply the fertilizer.
Areas where no nitrogen was applied produced better yields than in the past. In the past, the areas would have good straw, but not a good yield. The south-end of the field would be ten to 12 bushels less due to over-fertilizing.
The yield across the field evened out.
Producer spent $12.60 per acre more on fertilizer.
Producer needs a Global Positioning System (GPS) guidance system for combine for yield monitor.
Develop a realistic yield goal based on a yield within ten percent of the average yield