The Economic Research Service staff found the Cornbelt and Northern Plains dominate in terms of cropland not meeting the best management practices, which they readily acknowledge are the major corn growing areas of the US. They say in terms of nitrogen application in excess of the criterion rate, the Cornbelt and Lake States receive the greatest amounts of excess nitrogen. When viewed in a positive light of acreage treated with best management practices, 35% of all cropland met all three criteria. Corn acreage met all three criteria on 30% of acreage. Only 4% of all treated acres did not meet any of the criteria.
The economists say small changes on some of the acres would mean a significant turnaround in the data. “For example, about 14% of corn acres receive applications of 10% or less over the criterion rate. Reducing application rates on these acres so that the rate criterion is met would mean that nearly 80% of all corn acres would meet the rate criterion and that 35% of corn acres would meet all three criteria.”
The survey data indicate that in 2006, all of the nitrogen management criteria were met on an estimated 35% of the crop acres treated with commercial and/or manure nitrogen. In addition, a high percentage of treated acres met at least some of the nitrogen management criteria. Among all crops, corn met the criteria the least, and corn accounts for 50% of the treated acres upon which one or more improvements to management could be made to improve nitrogen use efficiency. Improvements in rate, timing, and/or method might be needed on 67% of corn acres.