2019
Potassium Sidedress on Soybeans
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Contributor/Checkoff:
Delaware Soybean Board
Category:
Sustainable Production
Keywords:
GeneticsGenomicsSeed quality
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Jarrod Miller, University of Delaware
Co-Principal Investigators:
Amy Shober, University of Delaware
Project Code:
Contributing Organization (Checkoff):
Delaware Soybean Board
$5,285
Institution Funded:
University of Delaware
$5,285
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

Comparison of soybean yields using split and pre-plant K applications.

Final Project Results

Updated April 3, 2020:
Soil and tissue samples were analyzed by the University of Delaware Soil Testing Lab and yields were collected from each plot using a plot harvester. Data was statistically analyzed using SAS software as a randomized complete block design. Yields, tissue, and soil results were also analyzed by correlation coefficients. Results were compiled and prepared into a report for the board.

View uploaded report PDF file

When compared to zero K and pre-plant K, a split application did not result in subsequent yield increases; however, this may have been masked by field variability. Plot level soil tests revealed greater soil K in certain parts of the field at optimum K levels. Upon further inspection of soil and tissue test K, there are some trends in K uptake with split applications. Reproductive stage leaf tissue K was greater in plots where sidedress applications were made and correlated to both higher post-harvest soil test levels as well as yield. Where post-harvest K soil test levels were greater, they also correlated to higher yield, even though these soils were at optimum soil test K. The field variability may have masked treatment effects, but correlations between higher soil and tissue K levels with yield indicate promise in K applications during the growing season in sandy soils.

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.