The EU has a problem with its phosphate fertilizer supplies – cadmium. While the levels of this naturally occurring heavy metal vary, it is toxic for soil, for wildlife, and for people.
For years, Europe has been trying to bring the phosphate fertilizer producers, suppliers, and consumers together to resolve the issue and to set an industry-wide benchmark.
Click to read Cadmium in Phosphate Fertilizer Part 1: The History.
As Andrea Ulrich, PhosAgro’s Head of Government Affairs and Compliance based in Zurich, states in a recent report, “In 1997, the European Commission first suggested phased Cd limit values in mineral fertilizers as a promising approach to reducing Cd content in soils and harmonising national measures.”
But as they soon found out, setting the limit is far from simple. It involves rigorous scientific analysis, economic study, and plenty of politics. All of which are influenced on where in Europe you look.
One of the biggest studies into the problem of cadmium in top soils was conducted by a collaborative team from the European Commission’s Joint Research Centre, the Food and Agricultural Organization of the United Nations, and Hungary’s University of Pannonia. This analysis found that, “Most samples (72.6%) of Europe did not display detectable concentrations of Cd and only 5.5% of the samples have concentrations above the threshold value. However, except for Estonia and Hungary, whose samples did not display any detectable cadmium contamination, soil samples with Cd concentration above the investigation threshold were found throughout the EU.” Adding that, “Regions with some of the highest mean cadmium concentration can be found in Ireland and Greece.”
Much of the regionality of the cadmium in top soils is based on where phosphate fertilizers are sourced. As the study concludes, “Data shows higher concentrations of Cd in the agricultural soils of Western Europe (EU15) compared to those in the new member states (EU12). This may be caused by the phosphorus fertilizers, which are historically of different origins in the western and eastern parts of the continent. While the Russian magmatic Kola phosphate rock, the main source of P fertilizers in Eastern Europe, is practically free of Cd, that from Morocco, the main source of P fertilizer in Western Europe, contains Cd.”
To limit cadmium at a level that restricts use of phosphate raw materials from Morocco would, in the eyes of many fertilizer manufacturers, create an unfair market. As this report from UK based newspaper, the Telegraph, states, “Concerns are mounting that new EU rules to limit the amount of toxin in fertilisers will give Russia an ‘effective monopoly’ over the market and power over European food supplies.
Supporters say the limits – which will ultimately outlaw products with more than 20mg of cadmium per kilogram – will help protect people’s health.
But opponents, including Britain’s National Farmers’ Union (NFU), say evidence does not support the strict EU limits, which they argue go beyond what is necessary to protect human health and will enable Russian suppliers to dominate the market.”
While no one can precisely predict the impact that different cadmium maximum levels would have on phosphate suppliers and the fertilizer market as a whole, a recent report in the UK’s Parliament Magazine, states that, “While a limit of 60 mg/kg would only affect eight per cent of currently available mineral phosphate fertilisers, further reductions to 40 and 20 mg/kg would increase this to 31 per cent and 56 per cent respectively.”
With the EU pushing towards more sustainable industries, no one is ruling out legislators setting the lower 20 mg/kg limit.
As a result, many rock phosphate processors and fertilizer producers are hoping that an answer may lie in technology.
Decadmiation Technology
Even Russian-based PhosAgro’s Ulrich agrees that technology may hold the key to avoid cutting off rock phosphate supplies from non-Russian sources. Noting that, “It is common knowledge that the Cd content in fertilizers can be reduced to desired levels by the use of low-Cd phosphate rock by mixing rocks with different levels of Cd content, by decadmiating phosphate rock or acid, or by substituting rock or finished product with STRUBIAS (recovered P salts, biochar, and ashes) products.”
Adding that, “Implementation of decadmiation technology for fertilizers is clearly a disruptive game changer. As far back as 1984, a research program on Cd removal was started, funded by the World Bank and the EC. Now, processes for the reduction of Cd in phosphoric acid are already being used for food and feed phosphates, but they are [at present] considered uneconomical for fertilizers.”
The research that is being conducted has numerous theoretical routes towards a cadmium removal method; but each has its own drawbacks.
“The most common method”, as outlined by the Brussels based European phosphate and NPK fertilizer industry trade body, the Alliance Européene des Engrais Phosphatés, “is calcination.” A process that requires heating the phosphate to more than 767°C, at which point the cadmium will evaporate from the rock.
Much of the downside with this method is not only the environmental and economic costs of the extreme temperatures required, but also that the process, “… will change the structure of the rock which will become harder and less reactive. Under high temperature, the fine grinds in the rock will aggregate and the porosity will reduce, which will induce a smaller contact area and ultimately drastically reduce the reactivity of the rock. This means the rock will lose its agronomic value and will not be usable as such in fertilisers.”
Other methods listed apply only for cadmium removal from phosphoric acid and are therefore “not relevant” for fertilizers derived from rock phosphate and single superphosphate. These include the use of solvents, ionic exchanges, and gypsum, as well as “organic sulphides to precipitate cadmium”.
The alliance also notes that a process called ‘micro-waiving’ has a similar approach to calcination (the use of intense heat), and therefore has similar drawbacks (changes in rock structure, loss of reactivity and restricted agronomic properties).
Liquid membrane technology is also being tested but is a long way from being proven as an effective agro-industry tool.
In fact, at present, the alliance is clear that, “At an industrial scale, there are no methods for removing cadmium from the rock.”
This technological situation is grim reading for the phosphate fertilizer industry, which remains caught between a rock and a hard place. On one hand is the protection of European top soils from contamination with heavy metals that could lead to an increase in phosphate fertilizer prices and a dependency on Russian agribusiness feedstocks. On the other, the continued use of rock phosphate supplies that are high in cadmium that could damage agricultural land in a way that lasts for generations.
This series of articles has attempted to explain something of the past, the present, and the future of phosphate fertilizers in the EU. Three parts of the fertilizer industry that are tied into one Gordian-knot; a situation that EU legislators certainly have their work cut out to unravel.
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At a November 2018 summit the EU agreed on a 60mg per kilo limit in order to 'promote organic fertilizer'.
The effects of this decision will be felt by us all.
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