Tea production in Vietnam, one of the country’s major exports, has been shown to benefit greatly from the addition of polyhalite in the fertilizer regime.
Alkaline soil mineral levels low
Tea Plantation in Vietnam.
Photo: Nguyen Duy Phuong
Improving tea productivity is a priority in Vietnam; the livelihoods of millions in rural areas rely on it. But gains in yield and quality are limited without adequate nutrients in the soil. Higher yielding varieties tend to deplete available nutrients faster. In addition, heavy rainfall leads to leaching of the nutrients below or away from the root zone. Worryingly, symptoms of deficiency of calcium, potassium and magnesium occur in previously productive plantations.
Partnering polyhalite for an alternative fertilizer regime
Recently introduced compound N-P-K fertilizers are not diverse enough to meet the nutrient need of the tea crop. So tea producers have been experimenting with supplements, but still without success.
Polyhalite, a natural marine sedimentary mineral, is a hydrated sulphate of potassium, calcium and magnesium. Petrovietnam Fertilizer and Chemicals Corporation (PVFCCo) staged an experiment to test polyhalite – marketed as Polysulphate™ – as part of a new fertilizer programme for tea in the Lam Dong district.
Testing polyhalite performance on tea
Seven year old tea plantations at two sites were subjected to three treatments: traditional farmer practice, a newer but conventional fertilizer regime and an alternative where polyhalite was added to the usual N-P-K application.
Reading the results
Three-leaf buds were continuously picked throughout the harvesting season. Bud density, weight and length were all recorded. It was observed that the regime using Polysulphate (polyhalite) so enhanced tea growth that productivity increased by up to 15%. Polysulphate also had a beneficial effect on tea quality, such as dry matter content and the concentrations of important substances such as tannins and caffeine.
Most important of all for tea growers, using Polysulphate contributed to increasing profits by 10% and above.
For further detail on the full analysis and observations of beneficial effects of polyhalite on tea you can read or download the full report from the work done by PVFCCo.
Masthead photo: G. Kalyan
Other photos: Nguyen Duy Phuong