Читать книгу Applied Soil Chemistry - Группа авторов - Страница 13

Erfan Sadatshojaei1*, David A. Wood2 and Mohammad Reza Rahimpour3

1Department of Chemical Engineering, Shiraz University, Shiraz, Iran

2DWA Energy Limited, Bassingham, Lincoln, United Kingdom

3Department of Chemical Engineering, Shiraz University, Shiraz, Iran

Abstract

Terrestrial soils, by volume, represent the most significant land-based carbon store on our planet. Over time, soils absorb carbon from a wide range of organisms as they respire during life and decompose after their demise. Carbon currently residing in the upper soil layers constitutes more than the combined quantity of carbon in land-surface vegetation and the atmosphere. Retaining and ideally boosting that carbon store in soils and preventing that carbon entering the atmosphere is of paramount importance in the fight against climate change. Almost 50% of global soils within about 1 m of the surface have been disturbed by agriculture releasing at least some of the carbon they store to the atmosphere. Carbon ideally needs to become mineralized in soils if it is to be stabilized and sequestered in the subsurface over the long term. Unfortunately, a significant portion of carbon in soils has a relative rapid turnover time, or low residence time, and is returned to the atmosphere as carbon dioxide via soil respiration processes. Whereas, it takes much longer for some of the soil carbon to be converted to stable mineralized forms. Soil erosion, as well as tillage, plays a significant role in releasing some soil carbon to the atmosphere. Converting significant areas of croplands and grazing lands to forests, grassland, and wetlands is the best option currently available for increasing the soils uptake of carbon from the atmosphere. Additionally, plant large quantities of perennial deep-rooted, fast growing bioenergy crops, such as switchgrass and miscanthus, can increment the carbon storage potential of grassland soils. The aggressive implementation of such actions has the potential to increase global soil carbon storage by between 0.5 and 2.0 Pg C a⁻¹ for several decades. This could only be achieved in association with large-scale reforestation and robust steps to mitigate anthropogenic soil disturbance and natural erosion.

Keywords: Soil as a carbon store, carbon turnover time, climate change mitigation, soil disturbance, organic matter decomposition, humification and peat formation, carbon mineralization, soil C sequestration potential