Pursuing robust agroecosystem functioning through effective soil organic carbon management

Soil organic matter is a key indicator of many ecosystem functions, particularly in agricultural systems. With carbon as its majority constituent (∼58%), soil organic matter is a key variable relating production and environmental responses. However, it is argued that depth distribution of soil organic carbon (SOC) may be more important in understanding how agriculture affects ecosystem services derived from soil than the total quantity of SOC. Conservation agricultural systems lead to highly stratified SOC, which helps to protect soil from erosion and prevent runoff loss of nutrients (i.e., water quality improvement), creates a concentrated organic habitat for nutrient storage and soil biological diversity (i.e., soil quality improvement) and promotes a structurally stable pore network connecting surface and subsurface to avoid negative impacts on soil aeration and GHG emissions (i.e., air quality improvement). A protocol is described to calculate the stratification ratio of soil organic matter fractions from a diversity of sampling procedures, which may be relevant in different ecoregions and conditions of the soil.