If you’ve ever undertaken a volunteer programme abroad or spent time working on a farm, then you’re likely to have developed an appreciation for the importance of soil. One of the central pillars of WorkingAbroad is nature conservation, and soil – the seemingly dull but yet secretly fascinating substance – lies at the heart of this.
At the recent 22nd World Congress of Soil Science in Glasgow, held between July and August of this year, Brazilian soil professors David A.C. Manning and Suzi Huff Theodorob spoke about a novel method for remineralising soil that involves the use of silicate rock dust. A reminder of the incredibly interconnected nature of our planet, this method implies that that which was once the stuff of stars could in fact solve one of the most common problems faced by farmers around the world today.
The use of rock dust to remineralise soil is not only cheaper than the application of modern fertilisers but also has numerous ecological, social and even political benefits. This technique encourages local resources in farming, combats farming inequality, reduces farmers’ dependency on imported fertilisers and addresses several global sustainable development goals. Although less applicable in the UK where temperate soils dominate, the use of rock dust as a fertiliser has already taken off in several agro-exporting countries in South America, most notably in Brazil.
The science of rock dust
Soil can be defined as a mixture of organic matter, minerals, gases, liquids, and organisms as well as the support system of our modern agricultural societies. The scientific word is ‘pedolith’ and derives from the Greek ‘πέδον’, to literally mean ‘fundamental stone’, or ‘earth’. Agricultural soil must contain essential nutrients, but these are ‘being removed faster than they are being replenished’. Moreover, most fertiliser is imported, and as a result, acquiring it involves complex supply/chain issues as well as high costs. Manning and Theodorob suggest that ‘crushed silicate rocks’ could be a somewhat under-appreciated, but highly viable, alternative option for remineralising soil.
Since the 1990s Brazil has already begun to use this technique, which is especially helpful for local farmers who are unable to access expensive fertilisers. Rock dust has been applied to “upwards of five million hectares of land” in Brazil, which totals almost eight per cent of all arable land in the country.
The geopolitics of fertiliser
This method has geopolitical, as well as economic significance, due to the dependence of Brazil – the world’s largest producer of major cash crops – on fertiliser from Russia and the resulting impact of the war in Ukraine on food production.
Thankfully, careful forward planning and US sanctions permitting the purchase of Russian fertiliser in Brazil have prevented a disastrous outcome. Nevertheless, the technique of using rock dust in place of fertiliser could, in the future, serve as a safety net for food production in similar times of crisis.
Reaching sustainable development goals
In 2015, the United Nations set out 17 Sustainable Development Goals in their agenda for 2030. Of these, the sustainable remineralisation of soil could contribute to achieving a total of eight goals. These include goal one – no poverty; goal two – zero hunger; goal three – good health and wellbeing; goal ten – reduced inequalities; goal eleven – sustainable cities and communities; goal twelve – responsible consumption and production; goal thirteen – climate action and goal fifteen – life on land. The importance of soil in farming for the future of global sustainability and food planning cannot be overstated, and rock dust is beginning to play a starring role.