Response of Medium Maturity Russet Potato to Source and Time of Potassium Fertilizer Application.

Potassium (K) fertilizer is comparable to nitrogen in the quantity needed for a successful potato crop production. Earlier studies conducted indicate that the source of potassium fertilizer applied can influence potato tuber yield and quality. A new potassium-based fertilizer, known as Bio-K^Ⓡ has been introduced. According to the Bio-K website, this fertilizer “is a combination of an inorganic salt reacted with an organic acid to form potassium acetate fertilizer”. A study was conducted at the Colorado State University San Luis Valley Research Center to evaluate the effect of source and time of K fertilizer application on the performance of Mesa Russet (a medium maturity Russet potato). Bio-K and  Potassium Chloride (KCl) were used as sources of K fertilizer. Treatments included (i) preplant application of Bio-K; (ii) pre-plant application of Bio-K, followed by foliar application of Bio-K; (iii) foliar application of Bio-K; (iv) preplant application of KCl; and (v) preplant application of KCl,  followed by foliar application of Bio-K.  The study also included a control treatment where no K fertilizer was applied. Using Bio-K as the source of K fertilizer and applying it preplant increased marketable and premium size tuber yield by 20 and 118%, respectively, compared to the control treatment. When compared to KCl as the source of K fertilizer, Bio-K applied pre-plant, and as a combination of pre-plant and foliar application, increased premium size tuber yield by 71 and 29%, respectively. Data from this study indicate proper timing of application of the appropriate source of K fertilizer can improve tuber performance of Mesa Russet.