Issue 4 2017
Coffee crop research reveals the benefits of Polysulphate use
Coffee robusta plantation in Vietnam. Photo by G. Kalyan.
Catch up over coffee
There’s a saying: “there’s an awful lot of coffee in Brazil”. But there’s also a lot of coffee in the world’s second largest coffee-producing nation: Vietnam. The Vietnamese coffee crop totals in the region of 1.2 million tons of coffee a year. However improving resource utilization has been made a major goal of the industry. Recent research assessing the use of polyhalite to improve yield and quality of coffee has revealed how to optimize fertilizer use.
Reinvigorate robusta
Over a third of the coffee plantations in the Lam Dong region of Vietnam are older Coffea robusta trees. Re-planting with newer, potentially more productive varieties is underway at a rapid pace. But target yields of the new, let alone the potential of the old, are unlikely to be realized without correcting the soil conditions and adopting good fertilizer practice.

Recent research compared current common, or traditional, fertilizer use (urea with a local blend of Ca, Mg and P) with the use of a locally available composite fertilizer (which included S but lacked Ca and Mg) and also with the use of the composite fertilizer plus polyhalite as Polysulphate.  The research was carried out on a reddish brown soil at Bao Lam district and on a grey soil at Di Linh district.

Counting up the coffee
In both the districts of Lam Dong region, the use of composite fertilizer improved profitability. But the biggest improvement was seen in the plots where Polysulphate was used with the composite fertilizer.
Effect of fertilizer treatments on yield in Coffea robusta trees grown at Bao Lam and Di Linh districts, Lam Dong province, Vietnam. Bars indicate LSD at 5%. The treatment with Polysulphate gave rise to a 10-11.5% increase in coffee yield compared to the farmer's practice treatment.
Polysulphate increased productivity of the coffee plants by up to 11.5%, and the farmers’ profits increased by up to 14%. Ca and Mg have a significant influence on coffee crop production; S appears to facilitate N uptake and metabolism by the coffee plants.

Polysulphate demonstrated an ability to supply plant Ca and Mg requirements and maintain soil fertility, whilst supporting greater biomass production, compared to the alternative fertilization programs.

Polysulphate, added to a systematic NPK fertilization program for coffee plants grown on reddish brown soil at Bao Lam or on grey soil at Di Linh, enhanced coffee yields and quality parameters, thus increasing productivity and profits.
Effect of fertilizer treatments on the profit of Coffea robusta grown at Bao Lam and Di Linh districts, Lam Dong province, Vietnam. Polysulphate application gave rise to profit increases of 14% and 10% at Bao Lam and Di Linh, respectively.
Adding to coffee
The research has given a clear steer on what inputs need to be added during coffee production to benefit the crop, build soil fertility and bring greater profitability to coffee farmers.

If you would like to read - over a cup of coffee, of course - more detailed information about the research then you can download the research paper. (
Coffee robusta plantation in Vietnam. Photo by G. Kalyan.
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Mined in the UK, ICL is the first – and only - producer in the world to mine polyhalite, marketed as Polysulphate™