Issue 6 2017
Proving Polysulphate potential in Brazil
Soybean harvest in Brazil. Photo by ICL Brazil.
Evidence is the engine of decision-making
Choice is informed by evidence. Decision is determined by data. Presenting the evidence from research is key to our work with farmers and advisors around the world. The results from the research work we have supported in Brazil is a good example of how to contribute to better understanding of crop nutrition and best fertilizer practice.
From the pot up
Any farmer faced with a choice of fertilizer is going to need proof of how a new alternative compares with an existing option. For some that may involve trials on their own land, or visiting trial plots. However others are reassured by the science of the micro-plot or pot.

In Brazil, at Sao Paulo University, in research carried out with the support of IPI and ICL, the rice crop was taken back to the pot. A low nutrient sandy soil was planted with rice and polyhalite performance was compared with alternative potash fertilizers. Polyhalite, marketed as Polysulphate, performed very well.

Rice plants lacking the macronutrients K, S, Ca, and Mg displayed very poor development (see photo below). Soluble sources of these nutrients and granular or powder polyhalite application, enabled normal plant development.

Both granular and powder polyhalite displayed a similar effectiveness in supplying plants with K, S, Ca, and Mg, when compared to soluble sources. No toxicity or salinity problems occurred following normal or doubled polyhalite application.

These results, collated under greenhouse conditions, demonstrate the principal effectiveness of Polysulphate as a fertilizer, even on low fertility soils.
Development of rice plants applied with polyhalite fertilizer in comparison with plants lacking K, S, Ca and Mg.
Trial high
Scaling up, field trials were also carried out in Brazil with soybean in order to evaluate Polysulphate's nutrient mobility in the soil. The experiment checked the distribution of K, S, Ca, and Mg in the soil profile of a soybean crop, following liming and fertilization treatments with KCl and Polysulphate.

Compared to the KCl applied soil, polyhalite application resulted in a larger increase in Ca and Mg content throughout the soil profile. Sulphate was the most mobile nutrient in the soil in both treatments. While S contents were equal in the top soil layer, polyhalite significantly increased its concentrations in the deeper layers. 
Soybean soil profile contents of Ca, Mg, K, and S following liming and fertilization treatments with KCl or polyhalite on Oxisol soil.
This soybean field trial shows that polyhalite has adequate solubility to reach and promote an active crop rhizosphere when applied to the top soil layer. Thus, polyhalite is a fertilizer with considerable potential to improve production within no-tillage systems, where soils exhibit significant Ca and Mg deficiency in the subsurface layers.

But the findings sign-posted Polysulphate’s important added benefit - the delivery of sulphur, a plant nutrient often overlooked in Brazil and required in significant quantities by every leading crop that Brazil grows. More research to uncover this important evidence has already been commissioned.  

Pots to plots
From pots to fields, from one-to-one conversations to conference presentations to hundreds, our approach is the same: discover the context and crop, share ideas and insights as to how and why polyhalite as Polysulphate fertilizer performs and then offer advice and guidance on application.

With that, and everything else you do, we wish you well.

If you would like to browse the full research description and findings from Brazil then it is available for download.
Overview of the trial plots on soybean in Brazil.
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Mined in the UK, ICL is the first – and only - producer in the world to mine polyhalite, marketed as Polysulphate