Issue 9 2018
Pepping up pepper production with Polysulphate
The Polysulphate experiment on black pepper located in ChưSê district, Gia Lai province of the Central
Highlands of Vietnam.
Breakfast, lunch or dinner, our premium crop nutrition products can contribute to just about every food ingredient you enjoy. Even to that sprinkling of black pepper that adds a little spice to many a meal.

Pepper consumption worldwide has risen fast in the last ten years. Vietnam has emerged as a major pepper producer. However, many Vietnamese farmers are struggling to maintain quality. Disease and precise crop nutrition and are becoming major limiting factors. That’s where we come in: the part that precise and balanced crop nutrition can make to yields and livelihoods.

With the support of the International Potash Institute (IPI), a research team from the Soils and Fertilizer Research Institute and the Central Highland Soils and Fertilizers Research Centre in Vietnam investigated how a better fertilizer strategy could help. They found that a regular and precise application of our Polysulphate fertilizer makes a remarkable difference.

The results show that black pepper yields of the unfertilized control in 2016 and 2017 were poor, and significantly lower than in the other treatments. The combination of 120/120 kg K2O ha-1 of MOP/Polysulphate, respectively, gave rise to the best crop performance and to the highest yield, produce quality and profit. This treatment increased yields by 147% in 2016 and by 128% in 2017, as compared to the control.

When compared to the farmers’ practice, the advantage of Polysulphate becomes obvious: a smaller K input of 240 kg K2O ha-1, 50% of which originated from Polysulphate, resulted in 8-14% more yield than obtained at 270 kg K2O ha-1 applied with MOP.
Effect of Polysulphate and KCl (MOP) applications on black pepper yield. The experiment was conducted over two successive years, 2016 and 2017, in the Central Highlands of Vietnam. Note: FP = farmers’ practice. Bars indicate LSD0.05.
Bi-monthly applications of Polysulphate greatly improved the supply of potassium to the pepper vines. The accompanying calcium, magnesium and sulphur also contained in this natural mineral fertilizer also proved to have significant beneficial effects.

The balanced supply of essential nutrients in Polysulphate resulted in multiple benefits for the crop:
  • Fruit weight, volume and density were increased by Polysulphate application combined with MOP, while fruit shedding rates were reduced.
  • Elongation of primary branches and number of secondary branches were increased by Polysulphate application combined with MOP, while premature fruit abscission was dramatically reduced.
  • The combined MOP and Polysulphate applications significantly reduced mealybug infestation.
  • Plants supplied with combined MOP and Polysulphate showed increased levels of leaf K, S, Ca, and Mg as compared with the unfertilized control.
The combined MOP and Polysulphate applications resulted in higher profits for the farmers. Economic analyses showed that K application doses above 240 kg K2O ha-1 provide maximum absolute and relative profits. Lower K doses yielded significantly poor profits, while lack of K supply led to loss of money. The combined MOP and Polysulphate at 240 kg K2O ha-1 was more profitable than the farmers’ practice, at 270 kg K2O ha-1. These results confirm recent results obtained with other crops grown on acid soils in Vietnam and in Brazil that have demonstrated the agricultural and economic advantages of using Polysulphate as a source of K, Ca, Mg, and S.
Effect of Polysulphate and KCl (MOP) and applications on the relative profit from black pepper grown on an acid soil in the Central Highlands of Vietnam, in 2017. Note: FP = farmers’ practice.
So - this spicy story from the central highlands of Vietnam is another example of the important part that balanced and precise crop nutrition, and the fertilizer we supply, can play. It’s a story of the important role we have in sustainable farming and supply of food that, thanks to pepper, tastes fantastic.

More information is available in the full research paper available from the International Potash Institute.
Ca and Mg deficiency in black pepper leaf.
Mined in the UK, ICL is the first – and only - producer in the world to mine polyhalite, marketed as Polysulphate