Soil carbon sequestration and land‐use change: processes and potential

TLDR

Reverting agricultural land to natural or perennial vegetation can lead to soil organic carbon accumulation, but the rate and duration vary widely depending on vegetation productivity, soil conditions, and prior land use. The paper reviews key soil organic matter dynamics that can enhance carbon sequestration following land‑use change and management. The authors synthesize literature on soil organic carbon changes following land‑use shifts that promote accumulation. The review estimates sequestration rates of roughly 30–35 g C m⁻² yr⁻¹ for forest or grassland establishment, with early‑stage rates below 100 g C m⁻² yr⁻¹, and concludes that such gains are too small to explain the global carbon deficit.

Abstract

Summary When agricultural land is no longer used for cultivation and allowed to revert to natural vegetation or replanted to perennial vegetation, soil organic carbon can accumulate. This accumulation process essentially reverses some of the effects responsible for soil organic carbon losses from when the land was converted from perennial vegetation. We discuss the essential elements of what is known about soil organic matter dynamics that may result in enhanced soil carbon sequestration with changes in land‐use and soil management. We review literature that reports changes in soil organic carbon after changes in land‐use that favour carbon accumulation. This data summary provides a guide to approximate rates of SOC sequestration that are possible with management, and indicates the relative importance of some factors that influence the rates of organic carbon sequestration in soil. There is a large variation in the length of time for and the rate at which carbon may accumulate in soil, related to the productivity of the recovering vegetation, physical and biological conditions in the soil, and the past history of soil organic carbon inputs and physical disturbance. Maximum rates of C accumulation during the early aggrading stage of perennial vegetation growth, while substantial, are usually much less than 100 g C m −2 y −1. Average rates of accumulation are similar for forest or grassland establishment: 33.8 g C m −2 y −1 and 33.2 g C m −2 y −1 , respectively. These observed rates of soil organic C accumulation, when combined with the small amount of land area involved, are insufficient to account for a significant fraction of the missing C in the global carbon cycle as accumulating in the soils of formerly agricultural land.