2019
Assessment of Potassium and Phosphorus Mining in Soybean Fields in ND
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Contributor/Checkoff:
North Dakota Soybean Council
Category:
Sustainable Production
Keywords:
GeneticsGenomicsSeed quality
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Jasper M. Teboh, North Dakota State University, Carrington Research Extension Center
Co-Principal Investigators:
Project Code:
QSSB
Contributing Organization (Checkoff):
North Dakota Soybean Council
$12,922
Institution Funded:
North Dakota State University
$12,922
Brief Project Summary:

Potassium’s role in soybean production is essential in the crop’s photosynthesis and metabolism. Even though it plays a vital role, many producers don’t apply K fertilizers to their fields. But K and P removal without supplementation in soybean fields have brought up concerns that crops may be producing below their potential. Sampling methods for K in the soil can reduce the reliability of test results. Objectives in this project include: determining how much potassium and phosphorus are being removed in soybean fields without replacement; determining the effects of soil handling and analysis on testing values; and determining the effects of potash application on soybean performance.

Key Benefactors:
farmers, agronomists, applicators, extension specialists

Information And Results
Final Project Results

Update:

View uploaded report Word file

Research Conducted
This trial estimated the removal of K from soil by soybeans following harvest at Hettinger, Minot, and Williston. At Carrington, (CREC) K and P removed by soybeans estimated from a trial that either received 50 lbs K or did not, across plots that had received the same N treatments applied in over three years on conventional till (CT), and no-till (NT). Soil samples from the top six inches of each plot before planting, mid-season, and at harvest, were divided into two groups, one group refrigerated and the other air-dried. The samples were analyzed by wet analysis at AgSource Laboratories, Ellsworth (IA).

Why the research is important to ND soybean farmers
There are some concerns about potassium (K) and P mining (removal without supplementation) in soybean fields, and as a result, yields of subsequent crops could be impacted if production continues without K fertilization. Also, reliability soil tests for K, and predictability of yield response when soil samples are stored by refrigeration or air-dried. This is important because only when a good soil available nutrient estimate is made from analysis that K fertilizer recommendations can be effective.

Final findings of the research
Application of 50 lbs K at CREC did not improve yields, protein or oil concentration. Aboveground biomass was significantly increased by K application under NT but not under CT. Test weight was significantly greater under NT. Yields were low due to drought conditions in 2018. At CREC yield average was 34 bu/ac, and a bushel removed 1.2 lbs K and 0.54 lbs P on average, which is relatively low compared to 0.65 lbs P/bu for a 69-bushel crop in a previous trial at CREC. Available soil K was greater at mid-season than before planting and after harvest (Figure 1), and was not necessarily less following harvest at the other sites. Soil analysis of refrigerated samples showed higher K values than air-dried samples. Available soil P after harvest was not less than before planting. More research is needed to assess the need for P fertilization of soybeans to improve yields. Potassium fertilization is likely to enhance yield for soils that the North Dakota state recommendations have clearly defined. Response depends strongly on type of clay.

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.