Potato response to potassium fertilizer combined with different P sources in Inner Mongolia, China

The objectives of this study were to compare the effects of potassium chloride (KCl) and potassium sulfate (K₂SO₄), along with their combinations with diammonium phosphate (DAP) and MESZ (12-40-0-10S-1Zn), a new P fertilizer containing sulfur and zinc), on potato tuber yield and economic returns. A field trial was conducted in Inner Mongolia (the Northwest region) in 2016 with five treatment: 1) DAP with no K, 2) all K by K₂SO₄ with DAP, 3) half K by KCl and half K by K₂SO₄ with DAP, 4) all K by KCl with DAP, 5) all K by KCl with MESZ. The nutrient application rate to potato in this experiment was 225-120-150 kg N-P₂O₅-K₂O/ha.

The results indicated that the application of K produced 9 to 13% more tuber yield than the control (no K fertilization). It also increased the commercial size of potato tuber and weight of a single tuber, but there was no significant yield difference between the K treatments. Economic analysis indicated that KCl with DAP resulted in the largest benefit, followed by KCl with MESZ at US$674 and US$557/ha more than that of the K omission plots respectively, and US$278 and US$161/ha more than the treatment of K₂SO₄ with DAP, respectively. Therefore, KCl applied with DAP or MESZ is the right source for potato production in Inner Mongolia in Northwest China.