J-WAFS in action: Rocks for Crops – Delivering affordable potassium fertilizer across Africa

Antoine Allanore, Assistant Professor in the Department of Materials Science and Engineering at MIT, is leading one of seven research projects recently awarded J-WAFS funding.  Antoine aims to develop a new kind of potassium fertilizer derived from K feldspar, a widely available mineral that can be produced locally, rather than relying on expensive supplies of imported potassium chloride.

Opening Doors spoke to Professor Allanore about the project and its aims.

What is the title of your research project?

The project is called ‘Affordable Potassium Fertilizer from K Feldspar for Africa’.

What issue are you seeking to address?

The United Nations forecasts a global population of 8.5 billion by 2030 – increasing 1.2 billion in just 15 years from 2015 – and hitting 9.7 billion by 2050[1].  These growth rates are already startling, but even more so when you consider much of this is expected in the parts of the world already struggling to meet the food and water needs of their current population today.  The UN Food & Agriculture Organization (FAO) predicts that, with 33% more mouths to feed by 2050, food production will have to increase by 70%[2] – so we need to look at ways to grow more food, more efficiently.  Fertilizer is one way to increase yield, but in countries where there is most need, imported solutions are very expensive.

Today, Canada, Russia and Belarus account for more than 85% of the world’s production of potassium chloride (KCI), which is the most widely used compound for potassium fertilization in agriculture.  While supplies are cheap and easily available for countries in the northern hemisphere, transportation logistics ensure KCI is expensive and scarce in the southern hemisphere.  At the same time, soils in the southern hemisphere and the tropics have a different make-up to soils in the north.  This means that KCI is not as effective for fertilization in these areas.  So, we are aiming to develop a new potassium fertilizer derived by hydrothermal processing of potassium feldspar – a widely available mineral across the globe, including Africa – in the presence of calcium oxide.  This could be particularly useful to tropical agriculture across North Africa, where 1) potassium chloride transportation costs are prohibitively high, 2) the soils are not so well suited to potassium chloride fertilizer and 3) potassium feldspar (K feldspar) is readily available.

Why has potassium chloride traditionally been the most widely used compound for potassium fertilization?

By the end of the 19th century, agronomists had discovered a link between soil types and certain elements in the ground.  But until the discovery of salt mines in Germany, nobody really had access to high-potency potassium chloride.  Suddenly Germany had easy access to potassium chloride – you didn’t have to go very deep, it was almost at ground level.  Then, at the turn of the 20th century, these mines were discovered all over Europe, Russia and North America, so potassium chloride became the main option for soil fertilization.

Can you briefly describe the benefits of your proposed solution?

Our proposal does not rely on the complex and costly supply chain of potassium chloride.  Instead, we are using K feldspar, which is widely available almost anywhere.  So rather than importing potassium chloride from Canada, Russia or Germany, we can use local resources and develop the local industry.  At the same time, because it is being produced locally, it should be possible to tweak the process to ensure that the end-product is more suitable for local soil conditions.

Feldspars (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth’s continental crust by weight. The salmon-pink color is typical of K-spar. Fragments of pure feldspar crystals tend to form rectangular blocks with irregular ends.

This creates a double benefit: you’re helping farmers with a more effective fertilizer, and you’re helping the economy by developing local industry.  There’s also a third potential benefit, in that countries in Africa with readily accessible reserves of K feldspar could become producers and exporters of fertilizer, like Russia, Germany or Canada are today.  So it could open up new opportunities for mining, as well as production.

What are the key challenges you need to address?

We have to consider the complexity of soil science and agronomy[3].  We are still at the beginning of understanding how our product will interact with other nutrients in the soil and crops.  These farming complexities are what we hope to tackle, particularly in understudied regions.

The first thing we need to do is understand the type of soil in which we are going to use the product. Soils differ greatly around the world due to a range of reasons, from the amount of water they hold through to their different geological origins and, sometimes, previous use of the soil.

Africa, obviously, is a huge area, with different soils in each region. The crop being grown is another factor we must consider.  Once we know the soil type and the crop, we will be able to tweak and design our material to ensure it is going to be able to perform according to the needs of the farmers.

[1] http://www.un.org/en/development/desa/news/population/2015-report.html
[2] http://www.fao.org/news/story/en/item/35571/icode/
[3] the science of soil management and crop production

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