NPK Survey of Field Crops 2014-2017
Data set is a survey of nitrogen (N), phosphorous (P), and potassium (K) percentages in grains of corn, soybean, and wheat samples collected around the state of Illinois from 2014 to 2017. The survey was funded by the Illinois Nutrient Research and Education Council (NREC) Award# 2014-02377 to improve the accuracy of P and K removal values for corn, soybean, and wheat. We solicited grain samples from producers each fall using online bulletins and through appropriate producers associations and radio. Additional information included field location (Illinois county) and yield level (bushels per acre) of the field from which samples were taken. Due to the lack of measured association between crop yields and nutrient extraction levels, we removed the requirement of yield reporting for sample submission starting on the second year to improve participation. Samples were sent to a commercial laboratory (Brookside laboratories, Inc., New Bremen, OH) for the determination of N, P, and K in grain samples, reported as percentages.