Agrogeology: An interdisciplinary approach to serve agricultural development

Agrogeology is a relatively new applied, problem-solving, interdisciplinary earth and agricultural science that aims at improving agricultural production using agromineral resources. There are two aspects of agrogeology: 1. The influence of parent material on soil development and soil fertility, and 2. The beneficial application of rocks and minerals to enhance soil fertility and crop productivity (‘rocks for crops’). New research on the influence of parent material on soil development and soil fertility will be presented from geochemical and geophysical research in NE Brazil. Integrated geophysical survey techniques are introduced that support soil fertility assessments, in this case soil fertility over different granites. The second aspect of agrogeology is the beneficial use of locally available geological materials to enhance the productivity of agricultural crops and contribute to better management of agricultural, horticultural and forestry systems. Locally available rock resources are tested to enhance soil fertility of low nutrient soils. Physically, chemically and biologically accelerated nutrient release from ‘fertile’ rock and mineral phases is seen as an additional, pragmatic and inexpensive option to contribute to soil fertility improvement. Examples will be provided on the use of phosphate rock resources in sub-Saharan Africa. A number of modification techniques are known to enhance the nutrient use efficiencies of agrominerals and rocks, including mechanical, biological and chemical modification. Biological/chemical modification techniques include acidification and complexation using organic acids e.g. oxalic and citric acids. An example of enhanced biosolubilization of igneous phosphate rocks illustrates the potential of using organic acids produced from cassava waste citric acid production enhancing P release. In Indonesia, biologically modified phosphate fertilizers are produced on a commercial basis. Another area of research and development focusses on the use of K-silicate rock as alternative to soluble K-fertilizers. Locally available K-rich kamafugites in Uganda are target of research to improve soil productivity for banana and coffee production. In addition, recovery techniques of biotite K from granite quarry fines, and initiatives to enhance biosolubilization from K silicates will be presented. In many countries with semi-arid and arid climates, water is the limiting factor for crop production. Examples of rock mulching with pumice and volcanic scoria to reduce evaporation will be presented from research in the Canary Island, Spain and Ethiopia.