2020
Potassium Sidedress on Soybeans
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Contributor/Checkoff:
Delaware Soybean Board
Category:
Sustainable Production
Keywords:
GeneticsGenomicsSeed quality
Parent Project:
Potassium Sidedress on Soybeans
Lead Principal Investigator:
Jarrod Miller, University of Delaware
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Delaware Soybean Board
$5,625
Institution Funded:
University of Delaware
$5,625
Brief Project Summary:

As an essential plant nutrient, potassium is easier to manage compared to nitrogen or phosphorus. Soils with finer textures and greater CEC can hold more total K. Sandier soils with lower CEC will not retain the same amount of K. While it may not leach from the soil, it could move below the root zone. Split applications of K may improve soybean yields on sandy soils, similar to sidedressing N in corn. If applied during a more rapid uptake period for soybeans, the plants may have access to more K before it moves below the root zone. This project determines if soybean yields and K fertilizer efficiency can be improved with split applications on sandy soils.

Key Benefactors:
farmers, agronomists, Extension agents

Information And Results
Project Deliverables

Soybean yield, soil and tissue K levels associated with it.

Final Project Results

Updated March 25, 2021:
Full report attached.

View uploaded report PDF file

Splitting K applications did not result in subsequent yield increases; however, there are some trends in K uptake with fertilizer applications. Post season soil K levels had a positive relationship with yield, so yield was higher as post-season K was higher. This indicates that maintaining good soil K values can help maintain yield. However, losses of K were greater in treatments receiving fertilizers. These soils were at optimum levels, so that K recommendations are based on plant uptake. It is possible that split applications would perform better on low CEC soils with medium to low fertility index values.

At this time, we would not recommend split application of K in Delaware soils when optimal levels are present. It could also be considered to skip K applications all together.

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.