Improving Tea Crops with Polysulphate

The tea industry in Vietnam has a 3,000-year history and plays a vital role in the rural economy. Tea is one of Vietnam’s major exports, and in a recent trial has been shown to benefit greatly from the addition of Polysulphate into the fertilizer regime.

Tea Plantation in Vietnam. Photo: G Kalyan.

Alkaline Soil Mineral Levels Low

In areas like Vietnam, where the livelihoods of millions of people rely on tea, improving productivity is a priority. 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 calcium, potassium, and magnesium deficiency occur in previously productive plantations.

Partnering Polysulphate 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.

Polysulphate® is a natural mineral fertilizer made from polyhalite, a marine sedimentary mineral which is a hydrated sulfate of potassium, calcium, and magnesium. Petrovietnam Fertilizer and Chemicals Corporation (PVFCCo) staged an experiment to test Polysulphate as part of a new fertilizer program for tea in the Lam Dong district.

Testing Polysulphate Performance on Tea

Seven-year-old tea plantations at 2 sites were subjected to 3 treatments: traditional farmer practice, a newer but conventional fertilizer regime, and an alternative where Polysulphate 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 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% or more.

References

The full research Polyhalite Application Improves Tea (Camillia sinensis) Yield and Quality in Vietnam was published in e-ifc No. 46 by the International Potash Institute.