Despite an improvement over the last five years, Iowa has a substantially high percentage of soils testing below the critical level for K and P, in large part due to a tremendous decline in nutrient balance trends.
The eKonomics nutrient balance analysis is the industry’s first to annually assess state-by-state nutrient removal records, fertilizer consumption information and manure data. Findings reveal that a large percentage of soils are becoming depleted of nutrients at an alarming rate, causing many areas to fall below the critical level for K and P. Is your farm among them?
|Balance||-7.1 lb/acre to -22.9 lb/acre|
|Balance||1.3 lb/acre to -23.2 lb/acre|
1.) USDA-NASS: P2O5 and K2O nutrient removal obtained from harvested tonnage of crops from each state. Manure applied nutrients subtracted from harvest removal.
2.) AAPFCO: Fertilizer consumption data subtracted from the removal information to obtain a mass balance of nutrient levels for each year for each state. “Commercial Fertilizers 2014” is available; all earlier versions are still available. National fertilizer use data are available in a hard-copy publication, “Commercial Fertilizers 2014”, which is available from The Fertilizer Institute (TFI). The Association of American Plant Food Control Officials (AAPFCO), in partnership with TFI, has published the 2014 edition of the Commercial Fertilizer Report.
PERCENTAGE OF SOILS BELOW THE CRITICAL LEVEL SOURCES:
International Plant Nutrition Institute: Data presented is based upon percent of samples testing below established critical levels for P and K for major crops in 2015. This includes results of P and K analysis performed on approximately 4.4 million soil samples. Critical Bray P1 equivalent levels for the soils and crops of the Great Plains and Corn Belt are usually around 20 ppm and increase to 25 to 50 ppm for the eastern U.S. Critical ammonium acetate K equivalent levels are generally in the 120 to 200 ppm range. Some crops may require substantially higher soil test levels than the critical level used in this analysis (consult your local university/agronomist for more information).
Important to Note: Soil testing is statewide and can differ within regions of every state and province. Nutrient management should occur on a site-specific basis where management objectives and the needs of individual fields and, in many cases, areas within fields, are recognized. Therefore, a general soil test summary like this one cannot reflect the specific needs of individual farms. Its value lies in calling attention to broad nutrient needs, trends, and challenges, and in motivating educational and action programs that are in turn relevant to growers and their advisers.