Tuning Potassium and Magnesium Fertilization of Potato in the South of West Siberia

Imbalance of nutrients limits crop yields. Although K fertilization receives sufficient attention in research and practice, Mg supply is rather neglected. The effect of Mg fertilization (0, 5 and 10 g Mg/m(2)), combined with two K fertilization rates (10 and 15 g K/m(2)), on potato production and soil exchangeable K and Mg was studied in a three-season microplot field experiment in the Novosibirsk region, Russia. Tuber yield did not respond to the increased K fertilization, but increased at 5 and decreased at 10 g Mg/m(2). Total Mg concentration in tubers increased at 15 g K/m(2), whereas N, P and K were not affected by fertilization. The tuber yield was maximal (3.6 kg/m(2)) at 10 g K/m(2) and 5 g Mg/m(2). Soil exchangeable Mg increased by the year, resulting in preferential development of the aboveground phytomass due to apparently increased Mg availability and K/Mg imbalance. Potato production depended on the year, strongly implicating weather conditions. Therefore, the weather and the chemical nature of K and Mg fertilizers (as pertinent to their release mode from fertilizer in soil), are important for balancing their proportions and amounts while assessing interactions among nutrients in potato production and adjusting regional fertilization strategies.