Polyhalite: a New Multi Nutrient Fertilizer with Sulphur, Potassium, Magnesium and Calcium

2019 IFS AGRONOMIC CONFERENCE Cambridge (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: 4 nutrients in one single fertilizer • 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 48% SO 14% K O 6% MgO 17% CaO nutrient. However, nowadays the S emissions had declined sharply and the 3 2 need for S fertilizer is recognized and applied by many growers. (19.2% S) (11.6% K) (3.6% Mg) (12.2% Ca) • 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 ® Polyhalite from Boulby mine: Polysulphate 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).

Boulby Mine Polyhalite has prolonged nutrient availability

100

Prolonged availability

50 Ammonium sulphate Sulphate of potash Kieserite

% of sulphate released 25 Polysulphate

0 0 5 10 15 20 25 30 35 40 45 50 Days/Pore volumes Granular Mini Granular Premium Standard 2-3 mm 1-2 mm Figure 1. Release of sulphate in Polysulphate (granular grade), versus other S sources (Jiang et al., 2016)

JURASSIC 0 • Polyhalite has the additional benefit of three other essential nutrients – K, 1000 100 1100 Mg and Ca – is thus a useful fertilizer for many soil and crops with these 200

300 requirements (Vale, 2016; Yermiyahu et al., 2017). 190 million years 400 Potash Mine level 1100 500 • High quality forage: In a leguminous crop, a Lucerne trial in Scotland, the N:S TRIASSIC 600 ratio in the Polysulphate® treatment was improved to the 12:1 target value 700 required for optimal digestibility, while at the same time the crude protein 800 1200 900 content improved by about 10%.

PERMIAN 1000 ® 225 million years 1100 Polysulphate • Baking quality: In wheat trials in USA, application of Polysulphate resulted in 1200 Mine level 1300 smaller N:S ratios in grains inferring better baking quality for optimum dough 1300 and bread making properties. 1400 1250 CARBONIFEROUS 1500 • Nutritional value: S deficiency or an N surplus may lead to asparagine and 1400 glutamine accumulations. During the baking process, free asparagine may promote acrylamide synthesis, a compound considered to be a neurotoxin and ® Depth below potential carcinogen. Thus, Polysulphate not only increases wheat yield but surface in metres 1500 also promotes a more nutritional processed product.

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). • Vale F. 2016. Calcium and magnesium movement in soil profile with polyhalite as potassium fertilizer for soybean crop. Proceedings of FERTBIO 2016, Goiana, Brazil, October 16–20, 2016. www.polysulphate.com • 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.