Chapter One - Soil organic carbon dynamics: Impact of land use changes and management practices: A review

Abstract

Global climate change has resulted in changes to the earth's geological, ecological, and biological ecosystems, which pose a severe threat to the existence of human civilization and sustenance of agricultural productivity vis-à-vis food security. In the last several decades, climate change has been linked to erratic rainfall distribution patterns and large variations in diurnal temperatures, because of a rise in atmospheric CO2 concentration. This, in turn, is thought to make world agricultural production systems more prone to failure. Soil organic carbon (SOC) is an important component for the functioning of agro-ecosystems, and its presence is central to the concept of sustainable maintenance of soil health. Soil is the largest terrestrial carbon sink and contains 2- and 3-times more carbon than the carbon in the atmosphere and vegetation, respectively. Therefore, a meager change in soil carbon sequestration will have a drastic impact on the global carbon cycle and climate change. The SOC has different pools and fractions including total organic carbon (TOC), particulate organic carbon (POC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), permanganate oxidizable carbon (KMnO4-C), and mineral associated organic carbon (MOC). Each has a varying degree of decomposition rate and stability. Researchers have identified many ways to offset the effect of climate change through modification of carbon sequestration in the soil. Identification of location-specific, suitable land use and management practices is one of the options to mitigate the impact of the climate change. It can be done by re-balancing different carbon pools and emission fluxes. Labile organic carbon pools including MBC, POC, and KMnO4-C are the most sensitive indicators for assessing soil quality after the adoption of alternate land use and management practices. Information on soil aggregation and SOC stabilization helps for long-term sequestration of carbon in the soil. Here we review the progress of work on SOC dynamics in the major ecosystems of the world. The information should enrich understanding of carbon sequestration and climate change mitigation strategies.