Best Management Practice for Potassium Application in Potato in Northwest China

IPNI-2012-CHN-NM3

02 Apr 2013

2012 Annual Interpretive Summary


Fifteen on-farm trials with two treatments including an optimum (OPT) and OPT-K, were conducted in randomly selected rainfed and irrigated potato fields in Inner Mongolia and Gansu. The effect of K source and time of application on potato tuber yield and quality were also studied in the two provinces.

In Inner Mongolia, K application increased tuber yield by an average of 12 and 8%, starch content by 7.6 and 4.5%, and decreased the reducing sugar content by 25 and 17% for rainfed and irrigated potato, respectively. In Gansu, K application again increased tuber yield by 7.7 and 8% and decreased the reducing sugar content for rainfed and irrigated potato, respectively. However, it increased the starch content of rainfed potato, while decreased the starch content of irrigated potato. The average agronomic efficiency (AE) of K was 28 kg tuber/kg K2O for rainfed potato and 14 kg tuber/kg K2O for irrigated potato in Inner Mongolia, while in Gansu, the corresponding values were 19 kg tuber/kg K2O and 28 kg tuber/kg K2O, respectively.

Potassium rate was recommended to farmers based on agronomic efficiency, target yield, and soil indigenous productivity. For target yields of 17 t/ha for rainfed potato and 25 t/ha for irrigated potato crop, 71 kg K2O/ha and 147 kg K2O/ha were recommended in Inner Mongolia. In Gansu, 106 kg K2O/ha and 180 kg K2O/ha were recommended for target yields of 23 t/ha and 32 t/ha in rainfed and irrigated conditions, respectively.

Potassium nitrate (KNO3) produced similar or more tubers than potassium chloride (KCl) or potassium sulfate (K2SO4) in Inner Mongolia, but showed no such effect in Gansu. Basal K application or 50% basal plus 50% top-dressing of recommended K at the flowering stage both resulted in significantly more tuber yield than 100% top-dressing at flowering in Inner Mongolia, but there was no such effect in Gansu. However, at both locations, application of KCl or KNO3 via basal or basal plus top-dressing at flowering resulted in greater agronomic efficiency (AE) than 100% top-dressing at flowering under both rainfed and irrigated conditions. Potassium source did not significantly affect tuber quality. Thus, the best management practice for K application in potato is to apply KCl or KNO3 as basal or basal plus top-dressing in both rainfed and irrigated conditions. NW Potato K