Applying volcanic ash to croplands – The untapped natural solution

Abstract

A nature-based soil security solution is proposed. In countries with active volcanoes, such as Indonesia, volcanic ash could be used to supply nutrients and reduce CO2 from the atmosphere. The weathering can draw CO2 from the atmosphere; in addition, volcanic ash with 0% carbon can turn into soils with around 10% organic carbon. In Indonesia, soils of volcanic origin cover about 31.7 million ha or 17% of its land area. Frequent volcanic eruptions made volcanic ash or tephra readily available. However, tephra is not widely used and has not been adequately investigated as a soil amendment to sequester carbon. This paper calculates the magnitude and opportunity of CO2 drawdown potential from volcanic materials produced annually in Indonesia. In years with significant volcanic eruptions, the subsequent withdrawal will be 100–200 Mt CO2 or 20–40% of the country's fossil fuel emission. The CO2 captured when volcanic materials weather is part of the global carbon cycle and is influenced by land-use decisions. Currently, volcanic ash is often eroded and rapidly transferred to aquatic systems. In relevant landscapes, actively managing this untapped resource is more feasible than external basalt applications as volcanic ashes do not need to be ground, can soak up significant amounts of carbon from the atmosphere, and build fertile soils that supply an abundance of nutrients to achieve food and soil security. Volcanic ash needs to be included in carbon accounting and its management could be part of emission reduction strategies.