Issue 2 2020
 
Polysulphate trials in farmers' fields: changing behaviour through demonstrating the benefits of change
 
Paddy producer (center) with the distributor (right) and an agronomist (left). Photo by L.P. Yeo.
What persuades us to change our behaviour? Being asked? Told? No. Being shown a different way of doing things is most likely to attract our attention, keep us interested enough to remember it and then – when the time comes – to use what we have learned to do a task differently and better.

It’s the same with fertilizer practice. Farmers develop their own practices. They follow their forbears or their peers. They read or listen to experts, advisors or adverts. They do their own ‘look-see’ experiments and notice the difference that doing something differently makes, for better or worse. But few of these channels are as effective as trials that compare, side by side, how a farmer usually nourishes their crop with an alternative strategy.

One of the latest examples we’d like to share with you is from Indonesia, the third largest rice producer in the world. Indonesia has set a target of increasing the national harvest by 38% by 2040, and optimization of fertilizer use is seen a key step to achieving that.

This trial in West Java with two varieties of paddy rice, compared the usual farmer practice of using urea with NPK, with replacing the NPK with polyhalite, the natural multi-nutrient fertilizer that ICL FertilizerpluS supplies to farmers as Polysulphate.

In the control plot, the farmer added 250 kg urea at transplanting and 500 kg NPK (15-15-15) at 10 and 30 days after transplanting. In the Polysulphate-treated plots, 250 kg of urea was applied at transplanting and 150 kg of Polysulphate was applied at 20 and 35 days after transplanting.

The measurements of the rice harvest showed that using Polysulphate increased yields by 20%.
Effect of fertilizer treatments on the rice grain yield in Karawang, Indonesia.
Boosting rice with Polysulphate

The Polysulphate-treated paddy had bigger and stronger panicles compared to the control. The grains were also rounder with a more uniform shape and better filling. Based on three samples containing 100 grains, the average weight of the grains was 9% higher in the plot treated with Polysulphate.
 
Weight of 100 grains in control and polyhalite treated rice. Note 9% higher grain weight in the Polysulphate (polyhalite) treated rice compared to the control. Photos by L.P. Yeo.
In regards to the plant height, the Polysulphate-treated rice was, on average, 8-10 cm higher than the control and appeared less affected by diseases.

The farmer observed that plants in the Polysulphate-treated plot were more resistant to lodging or damage caused by wind. Further, the farmer reported less blast disease (Pyricularia oryzae) and smut compared to the control plot.
 
Control plot on the left and Polysulphate-treated plot on the right, showing the plant height difference; Karawang, Indonesia. Photo by L.P. Yeo.

Bringing Polysulphate into rice nutrition

Polysulphate fertilization has led to a substantial rice yield increase, improved grain characteristics, and taller and healthier plants, indicating that it is a suitable fertilizer, containing essential nutrients for rice crop.

That’s why we chose to feature this work in Indonesia in this Missive. It is another example that demonstrates not only the benefits of Polysulphate but the benefits of research plots in farmers’ fields so the results of balanced and targeted crop nutrition are there for all to see and discuss and learn from in order to improve fertilizer strategies locally, and even much further afield.

Read the full report

 
Mined in the UK, ICL is the first – and only - producer in the world to mine polyhalite, marketed as Polysulphate