Enabling food security through use of local rocks and minerals
David A.C.Manning, Suzi Huff Theodoro
In many developing countries, replacement of the nutrients needed to produce subsistence and cash crops is a major challenge, because of cost and long/complex supply chains. Nutrient audits show that major nutrients are being removed from soils faster than they are being replenished, which is clearly unsustainable. The use of crushed silicate rocks as a source of plant nutrients predates the use of the chemical fertilizers that have revolutionised global agriculture. Such highly soluble fertilizers are not ideal for the deeply leached oxisols wide spread in the global south, and are rapidly leached. In these soils, silica may also need to be added as nutrient. In these circumstances, crushed silicate rocks have great potential to maintain soil health and to support crop production. In Brazil crushed rock remineralizers have been developed, and Brazilian federal law allows these to be used for crop nutrition, with specifications clearly defined by appropriate regulation. This approach provides a model that enables developing countries elsewhere to exploit local geological sources, and reduces dependency on imported chemical fertilizers. It creates opportunities for employment producing crushed rock products for different crops and locally variable soils and conditions, and illustrates renewed academic and practical interest in so-called ‘Development Minerals.