Study on abundance-deficiency index of soil readily available potassium and appropriate potassium application rates for grapes in China

Objectives Potassium (K) is an essential nutrient for ensuring high-quality, high-yield, and high-benefit of grape production. We integrated the results of potassium application experiments on grapes from various parts of the country in recent decades, to construct the abundance and deficiency criteria of soil readily available K (SAK), and the appropriate potassium fertilizer amount (APFA) for grapes in China.

Methods We searched the China National Knowledge Infrastructure database (CNKI) and the Web of Sciences, using the keywords “grape”, “fertilization”, and “potassium”, and a total of 52 literatures were obtained, and 80 pairs of data were extracted for the meta analysis. Using the integration method of scattered experimental data, a regression equation was established between the relative yield (RY) of grapes without K fertilizer treatment (KFT) and the SAK content in China. Then the SAK was graded based on the abundance-deficiency criteria, and the potassium fertilizer application amount were proposed based on the SAK, potassium fertilizer use efficiency (KFUE) and grape target yield (GTY).

Results The regression equation between the RY of grapes without KFT and the SAK content in China was: y=13.686 ln(x)+20.225. The SAK in China was classified into 6 grades, ≥340, 164−340, 79−164, 38−79, 19−38, and <19 mg/kg, respectively. At the grape yield (GTY) of 15−60 t/hm² and the KFUE of 40%−60%, the APFA for soils with SAK grade from low to high was 0, 14−83, 28−165, 41−248, 55−330, and 69−413 kg/hm². When the target KFUE was 60%, 55%, 50%, 45%, and 40%, the APFA was 0−275, 0−300, 0−330, 0−367, and 0−413 kg/hm². At the GTY of 15, 22.5, 30, 37.5, 45, 52.5, and 60 t/hm², the APFA was 0−103, 0−155, 0−206, 0−258, 0−309, 0−361, and 0−413 kg/hm².

Conclusions In this study, a recommended potassium application system based on available potassium abundance and deficiency index of grape soil is preliminary established, which could provide scientific basis for soil potassium application of grape in China.