M.E. Crownover, T.L. Roberts, W.J. Ross, N.A. Slaton

Edamame is a specialty soybean (Glycine max L. Merrill), that is harvested as a vegetable crop when the seeds are immature. Edamame, also known as a vegetable soybean, is a relatively new crop for Arkansas. This study was done to establish the importance of potassium (K) fertilizer rates and type on edamame yield and quality. Since edamame does not require nitrogen (N) because it can fix N, K is the next most limiting nutrient. Potassium is used to produce nodes on soybean plants to help with N fixation and growth. For this study we are looking at two sources of fertilizer; Muriate of Potash (KCL) and Sulfate of Potash (K₂SO₄). These sources are similar in analysis, but vary greatly in composition due to the difference in anions. Although the chloride anion could inhibit growth of the plant, the sulfate anion would not influence growth to the same degree. Traditionally sulfate of potash has been more expensive, but has now become more comparable in price due to the recent increases in muriate price. This has made the two more competitive in use among growers.

  Three field studies were conducted to evaluate the influence of K rate and source on edamame yield and quality during 2012. The field studies were conducted at Newport Research Station (Newport, AR), Vegetable Research Station (Kibler, AR), and at Pine Tree Branch Station (Pine Tree, AR). The two types of K fertilizer were applied KCL and K₂SO₄. They were applied by hand at rates of 0lb, 60lb, and 120lb K₂O equivalent. The two commonly grown varieties of edamame, the JYC-2 and the Kirksey were used. They were grown on slit loams to more accurately predict the growth since most silt loam soils require K applications. Once they were harvested they were weighed and graded. The amount of fertilizer applied showed an increase in yield, but not a significant amount of change in pod size.