Recalibration of Phosphorus and Potassium Recommendations for High-Yielding Soybeans in North Carolina
Sustainable Production
GeneticsGenomicsSeed quality
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Luke Gatiboni, North Carolina State University
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

Using best management practices and technology might allow some North Carolina fields to yield more than 70 bu/A. Although soil test phosphorus and potassium levels have been recently confirmed as sufficient, it is unclear if these levels are sufficient for high-yielding soybeans. Recalibration of soil test P and K for high-yielding soybeans is the objective of this research. It investigates the necessity of higher rates of phosphorus and potassium for high-yielding soybeans and optimal levels of P and K in plant tissue compared with regular soybean yields. Efforts also determine the exportation of P and K by grain in high-yielding soybeans, all to help determine if P and K recommendations should be modified based on yield expectations.

Key Benefactors:
farmers, agronomists, extension agents

Information And Results
Project Deliverables

Final Project Results

High-yielding soybeans fields producing more than 60 bu/acre require excellent management and are exporting more nutrients than average-yielding fields. There is uncertainty if the current recommendations of phosphorus (P) and potassium (K) fertilizers for North Carolina are adequate for high-yielding fields. We applied rates of P and K on two on-farm, high-yielding soybean fields and on three long-term trials at Research Stations of North Carolina. We did not observe an increase in crop yields when the P-index and K-index were higher than 50 at any of the trials. This means the current recommendations presented in the “Crop Fertilization Manual” are adequate even for high-yielding fields. The findings of this study show that our producers can keep using the current fertilizer recommendations, even in high-yielding fields, and they will not run short of nutrients. The results of this project will help our farmers to avoid unnecessary application of fertilizers, cut costs, and increase their profit.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.