2019 IFS AGRONOMIC CONFERENCECambridge (UK), 12-13 December 2019

Polyhalite: a new multi nutrient fertilizer with sulphur, potassium, magnesium and calcium - for better nitrogen use efficiency Imas, P., ICL Fertilizers, Israel, Morell, F.J., ICL Fertilizers Europe

Polyhalite from Boulby mine: Polysulphate®

• Balanced supply of available N and S is essential for the synthesis of proteins from the precursor amino acids.

• A lack of S limits the production of two of the amino acids which are required

constituents of all proteins – cysteine and methionine. • The deposition of S from industry to agricultural land was historically well in

excess of crop and animal requirements. Thus, S was not discussed as a crop nutrient. However, nowadays the S emissions had declined sharply and the need for S fertilizer is recognized and applied by many growers.

• Most of the fertilizer S requirement to date has been met using ammonium

sulphate. Containing both N and S, this is a useful product for use on crops which require both nutrients, but ammonia volatilisation may be a concern in soils with pH > 7 (Powlson, 2019). On the other hand crops like legumes which, because of their Rhizobial associations, do not need any N fertilizer. Polyhalite can effectively supply S, with a performance equivalent to well-stablished S fertilizers (Dugast, 2015).

Polyhalite has prolonged nutrient availability

48% SO3(19.2% S)

6% MgO(3.6% Mg)

14% K2O(11.6% K)

17% CaO(12.2% Ca)

Polyhalite: 4 nutrients in one single fertilizer

Days/Pore volumes

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Ammonium sulphateSulphate of potashKieseritePolysulphate

Prolonged availability

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Depth belowsurface in metres

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Potash Mine level

Polysulphate Mine level

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190 million years

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Granular2-3 mm

Mini Granular1-2 mm

Premium Standard

References• Dugast P. 2015. Use of polyhalite as a source of sulfur for oilseed rape and winter wheat in France. International Potash Institute (e-ifc) 43:21-26.• Jiang, L., S.D. Young, M.R. Broadley, E.H. Bailey, N.S. Graham, and S.P. McGrath. 2016. Dissolution Rate of Selected Sulphur Fertilizers; Understanding Selenate - Sulphate Competition. In: Royal Society of Chemistry,

16. London, UK: University of Nottingham.• Powlson, D.S. 2019. Ammonium sulphate and emissions of ammonia: a review. 2019 IFS Agronomic Conference, Cambridge (UK).• ValeF.2016.Calciumandmagnesiummovementinsoilprofilewithpolyhaliteaspotassiumfertilizerforsoybeancrop.ProceedingsofFERTBIO2016,Goiana,Brazil,October16–20,2016.• Yermiyahu U., Zipori I., Faingold I., Yusopov L., Faust N., Bar-Tal A. 2017. Polyhalite as a multi nutrient fertilizer – potassium, magnesium, calcium and sulfate. Israel Journal of Plant Sciences, 64: 145-156.

Figure 1. Release of sulphate in Polysulphate (granular grade), versus other S sources (Jiang et al., 2016) • Polyhalitehastheadditionalbenefitofthreeotheressentialnutrients–K,

Mg and Ca – is thus a useful fertilizer for many soil and crops with these requirements (Vale, 2016; Yermiyahu et al., 2017).

• High quality forage: In a leguminous crop, a Lucerne trial in Scotland, the N:S

ratio in the Polysulphate® treatment was improved to the 12:1 target value required for optimal digestibility, while at the same time the crude protein content improved by about 10%.

• Baking quality: In wheat trials in USA, application of Polysulphate® resulted in

smaller N:S ratios in grains inferring better baking quality for optimum dough and bread making properties.

• Nutritional value: S deficiency or an N surplus may lead to asparagine and

glutamine accumulations. During the baking process, free asparagine may promote acrylamide synthesis, a compound considered to be a neurotoxin and potential carcinogen. Thus, Polysulphate® not only increases wheat yield but also promotes a more nutritional processed product.

www.polysulphate.com

Boulby Mine