Abstract

The tea industry in Vietnam has a 3,000 year history and plays a vital role in income improvement and poverty alleviation in rural areas. Improving resource utilization efficiency has recently been determined as the major strategic goal of the industry. Appropriate mineral nutrition practices are pivotal to achieving these goals. However, consequent to the rising productivity of tea plants, the mineral status of soils has been compromised. The availability of alkaline elements, particularly potassium (K), calcium (Ca), and magnesium (Mg), is steadily declining.

Polyhalite, a natural marine sedimentary mineral, consisting of a hydrated sulfate of K, Ca, and Mg, was examined as a potential additive to composite N-P-K fertilizers, as part of an alternative fertilization program for the tea industry in the Lam Dong district. Polyhalite enhances the density, weight and size of tea buds, thus increasing tea productivity by 14-15.5%, and improves tea quality parameters. Overall, Polyhalite gave rise to profit increases of 10 and 12.7%, in the Kim Tuyén and TB14 cultivars, respectively. While no direct effect of S could be observed, yield enhancement may be attributed to facilitated N uptake and metabolism.

Polyhalite demonstrated the ability to supply plant Ca and Mg requirements and maintained soil fertility, whilst supporting greater biomass production, as compared to the alternative fertilization programs.