Changes In Tea Performance And Soil Properties After Three Years Of Polyhalite Application

Tea (Camellia sinensis L.) is the world's most widely consumed beverage with high economic and health benefits. Potassium is the second key nutrient for tea plants. Polyhalite is applied in some grain crops as a novel source of K, which also contains Ca, Mg, and S. However, the feasibility of using polyhalite for tea growth is unclear. Consequently, a 3-yr field experiment was conducted to determine effects of polyhalite on soil properties, tea yield, economic benefits, and tea quality in southwest China. There were three treatments: control (CK, without K fertilizer), sulfate of potash (SOP) and polyhalite (POLY4). Compared with CK, SOP and POLY4 application increased soil available K, P, and S contents, as well as tea yields and economic benefits. Compared with SOP, POLY4 increased soil exchangeable Ca and Mg and available S contents, but decreased soil acidification due to high addition of CaSO4 and MgSO4. POLY4 application led to 15.1% higher tea yield than SOP in 2017, while no difference was observed in 2015 and 2016. The POLY4 was economically superior to SOP in 2017 with a greater net benefit by US$1982 ha(-1). Although the two treatments did not differ on tea quality, correlation analysis demonstrated that quality was generally positively and significantly correlated with K, Ca, Mg, P, and S contents in tea leaves. Consequently, POLY4 was suitable as a K source for tea. Given high S and Ca contents in POLY4, it might be better to apply POLY4 together with other K fertilizers in future studies.