Quantitative effects of potassium application on potato tuber yield, quality, and potassium uptake in China: A meta-analysis

Context Potato is a potassium (K)-sensitive staple crop with an essential role in ensuring food security in China. However, there have been no previous systematic quantitative analyses of the effects of K application on the potato tuber yield, quality, and K uptake. Objective and methods Thus, we conducted a meta-analysis based on 2165 observations from 192 publications to quantify the effects of K application on the potato tuber yield, quality, and K uptake, and to analyze the key related factors. Results K application could significantly increase the yield (19.2 %), starch content (6.7 %), crude protein content (7.9 %), vitamin C content (9.6 %), and K uptake (40.5 %), and significantly decrease the reducing sugar content (16.1 %) compared with no K application. Climatic conditions with mean annual precipitation > 800 mm and mean annual temperature > 12°C facilitated optimal increases in the tuber yield and K uptake, but were not conducive to increasing quality. KNO 3 application was more effective for improving the yield than K 2 SO 4 and KCl. Furthermore, split application of 150–200 kg ha –1 K 2 SO 4 was beneficial for increasing the tuber quality (starch and vitamin C) and K uptake at a planting density of 6–7 × 10 4 plants ha –1 under mulching conditions, and the effect was most pronounced in soils with soil organic matter > 30 g kg –1 , total nitrogen > 1.5 g kg –1 , exchangeable K < 100 mg kg –1 , and available phosphorus = 10–20 mg kg –1 . Based on the sustainable potassium application program, the optimal K application rates for the northeast, northwest, southwest, north, and southeast regions of China were determined as 76.1 kg ha –1 , 170.3 kg ha –1 , 168.7 kg ha –1 , 225.8 kg ha –1 , and 146.6 kg ha –1 , respectively, which can simultaneously achieve the optimal potato tuber yield, environmental benefits, and quality. Conclusion and implications This study provides an important reference for formulating appropriate K fertilizer management strategies to achieve sustainable potato production in different regions of China.