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
100
75
50
25
0500 5 10 15 20 25 30 35 40 45
% o
f sul
phat
e re
leas
ed
Ammonium sulphateSulphate of potashKieseritePolysulphate
Prolonged availability
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
TRIASSIC
PERMIAN
CARBONIFEROUS
JURASSIC
Depth belowsurface in metres
1000
1100
1200
1300
1400
1500
Potash Mine level
Polysulphate Mine level
1100
1250
190 million years
225 million years
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
