2017
Potassium Soil Test Study
Category:
Sustainable Production
Keywords:
GeneticsGenomicsSeed quality
Parent Project:
Lead Principal Investigator:
David Hardy, North Carolina State University
Co-Principal Investigators:
Project Code:
P16-013
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

Two decades have passed since soybean potassium needs were researched in NC. Since this time, soybean varieties and production practices have improved. This project evaluates the current soil test K recommendations using replicated, small plot studies across the state. These trials characterize the yield response of soybean, both full-season and double-cropped, to soil test K in different soil types under no-till and conventional tillage practices, correlate the relative yield and trifoliate leaf K concentration at V5 to R2 with soil test levels, determine the accuracy of existing soil test K recommendations to maximize yields and revise as necessary and identify the critical trifoliate leaf K concentrations used to identify K deficiency at V3, V5, R2, R5 stages.

Key Benefactors:
farmers, agronomists, extension agents

Information And Results
Final Project Results

Weather played a major role in the outcome of this study in 2018. Heavy rains in the early fall from Hurricane Florence hurt yields of early planted and/or early maturing soybeans, particularly in Robeson, Pitt, and Northampton counties. Less than ideal growing conditions in April were not conducive to producing the high yields that were seen with early maturing varieties in the Tidewater region in 2017. Abnormally high rainfall in June hurt stands of late planted beans in Beaufort, causing some bean plots to be abandoned. This two-year study suggests that over all locations and environments the ideal combination is a Late IV or Early V planted from Mid-April to Mid-May. While most seasons have a “sweet spot” with the most potential for outstanding yields, finding it can be a difficult proposition unless you spread your risk as a producer. For instance, averaged across all locations, the cost of making the wrong decision in variety and planting date could have been as much as 35 bu/A. Of course there is no way to predict the weather, but this research shows how critical it is to manage risk by paying attention to weather forecasts at planting time, multi-year/multi-location variety trial data when selecting varieties, and planting multiple varieties of varying maturities in order to avoid significant weather events.

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.