2023
On-farm Evaluation of Soybean Potassium Fertilizer Recommendations in South Carolina
Contributor/Checkoff:
Category:
Sustainable Production
Keywords:
DiseaseField management Pest
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Bhupinder Farmaha, Clemson University
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:
Soybean yields have increased substantially due to better management of improved varieties. One question is, “Are Clemson’s current potassium fertilizer recommendations good enough to sustain high soybean yields?” Previous research conducted in-depth work on evaluating K recommendations and plant analysis to optimize yield. This project expands that work to on-farm trials and verifies if results obtained at on-station trials are aligned with the results of on-farm trials. This helps create more robust datasets testing K fertility recommendations across production environments. The research will generate new information by evaluating the response of soybean yield across four application rates, determining K removal values for soybean and correlating the trifoliate leaf K concentration with soil test levels.
Key Beneficiaries:
#agronomists, #extension agents, #farmers
Unique Keywords:
#agronomy, #fertility, #fertilizer, #k, #potassium, #potassium fertilizer
Information And Results
Project Summary

For soybean producers, K fertilizer is the costliest input; while under-fertilization can decrease seed yields, over-fertilization may not result in a yield increase. Our recent work at Edisto REC showed that over-fertilization of K can reduce soybean seed yields. Hence, from a producer’s perspective, finding the optimum K fertilizer application rates is vital. Moreover, despite being an immobile nutrient in the soils, K still leaches out of the root zone in sandy, low organic matter soils. These factors together make K of greater concern for South Carolina soybean producers. Hence, this project aims to determine optimum K fertilizer rates to maximize soybean yields and farm profits.

Project Objectives

1. Evaluate the soybean yield response across five fertilizer-K application rates (0, 30, 60, 90, and 120 pounds K2O per acre) through on-farm trials.
2. Correlate the trifoliate leaf K concentration with soil test levels.

Project Deliverables

Outputs will be a better understanding of soybean potassium management and improve soybean profitability. The results from this study will be presented to extension agents and producers in field days and winter meetings. This will be the third and last year of the study. At the end of 2023, results will be compiled into an extension article made available for stakeholders and a short (< 5 minutes) YouTube video.

The ability of the potassium fertilizer applications to enhance growth and soybean yield will be quantified and analyzed at the end of the field trial. Economic cost/return sheets can be developed to determine how profitable the treatments are.

Progress Of Work

Final Project Results

Benefit To Soybean Farmers

Soybean yields have increased substantially in recent decades due to better management of improved varieties. The question being asked is, “Are Clemson’s current potassium (K) fertilizer recommendations good enough to sustain high soybean yields?” In phase one, we conducted in-depth work at Edisto REC on evaluating K recommendations and plant analysis to optimize yield. In the second phase, we expanded this work in 2021 and 2022 to on-farm trials to verify if the results obtained at on-station trials are aligned with the results of on-farm trials. We want to continue on-farm trials with five more sites in 2023. This will help us create more robust datasets testing K fertility recommendations across production environments. The proposed research will generate new information to make Soybean production in South Carolina more productive and profitable.

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.