Improving Accuracy of Nutrient Removal Estimates

Accurate estimates of the quantities of nutrients removed when crops are harvested are critical for accurate nutrient recommendations. When estimates are too low, soils are at risk for nutrient depletion and when estimates are too high, there is a risk of nutrient over-application. The goals of this project are to: 1) increase the accuracy of nutrient removal estimates used by farmers, advisers, government agencies, and university scientists, and 2) create a network of partners who contribute to creating and maintaining a set of standard nutrient removal estimates that provide both measures of central tendency and variability. Dr. Manjula Nathan, University of Missouri, has been steadily collecting nutrient removal data for maize, soybean, and wheat from researchers in the U.S.

The means for N, P₂O₅, and K₂O (plus or minus one standard deviation) are 0.63+0.08 lb N/bu; 0.29+0.05 lb P₂O₅/bu; 0.20+0.03 lb K₂O/bu for maize; 3.26+0.27 lb N/bu; 0.67+0.09 lb P₂O₅/bu; 1.12+0.09 lb K₂O/bu for soybean; and 1.19+0.22 lb N/bu; 0.47+0.08 lb P₂O₅/bu; 0.26+0.06 lb K₂O/bu for wheat.

These estimates are for all data collected. Data can also be further subdivided by U.S. state. Future plans are to work with university Extension soil fertility experts in each state and compare the data collected by the University of Missouri to nutrient removal estimates used in state nutrient recommendations.