Postseason diagnosis of potassium deficiency in soybean using seed potassium concentration

Document Type

Article

Publication Date

10-13-2016

Abstract

Soybean [Glycine max (L.) Merr.] seed nutrient concentrations may be useful for postseason diagnosis of nutrient deficiencies to identify reasons for lower-than-expected yields. Our objective was to determine the relationships between seed-K and soil-K concentrations and relative soybean yield and to develop potential seed-K concentration thresholds for diagnosis of K deficiency as a yield-limiting factor. Soil-test K and seed-K concentrations and yield data were collected from published and unpublished K fertilization research conducted in Arkansas (33 site-years), Indiana (1 site-year), Iowa (34 site-years), Missouri (1 site-year), Tennessee (6 site-years), Virginia (1 site-year), and Canada (24 site-years). Seed-K concentrations accounted for 66% of the variation in relative yield of soybean receiving no fertilizer K for Arkansas, 48% for Iowa, 78% for Canada, and 60% for North America from a database that included 100 site-years. The critical seed-K concentration ranges were 15.6 to 17.0 g K kg-1 for Arkansas, 17.4 to 20.0 g K kg-1 for Iowa, 14.6 to 16.2 g K kg-1 for Canada, and 16.5 to 17.7 g K kg-1 for North America. Seed-K concentrations below the lower threshold for North America accurately predicted positive yield responses to fertilizer K at 77% of the sites classified as deficient. The difference between seed-K concentration of soybean grown with and without fertilizer K decreased linearly as soil-K concentration increased and plateaued when soil-K concentration was ≥87, 139, 73, and 104 mg K kg-1 for Arkansas, Iowa, Canada, and North America, respectively. Results suggest that seed-K concentrations can be used to aid in the diagnosis of K deficiency at maturity.

Publication Source (Journal or Book title)

Soil Science Society of America Journal

First Page

1231

Last Page

1243

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