Greenhouse gas emissions and carbon sequestration associated with Integrated Crop-Livestock-Forestry (ICLF) systems

Greenhouse gas (GHG) emissions from the Agriculture, Forest, and Other Land Use sector account for 23% of net global anthropogenic emissions. However, effective conservation agriculture practices can sequester carbon (C) up to 1 m in soil depth and vegetation biomass. Integrated Crop-Livestock-Forestry (ICLF) systems attempt to ensure sustainable agricultural production by combining various agricultural, livestock, and forestry production systems. This bibliographic review aims to present and discuss ICLF systems and their advantages and disadvantages compared with conventional systems, achieving a better understanding of the sources and sinks of GHGs (CH4, N2O, and CO2). Integrated systems exist in tropical and temperate climates with different practices, arrangements, designs, and modalities. Intercropping species with different root structures provides more ecological interactions that enhance biodiversity, soil quality, and C sequestration while reducing GHG emissions. Yet, ICLF systems are complex and require technical assistance and support for being implemented, besides an extensive initial investment that increases the cost of operation. A relevant carbon sink in ICLF systems is carbon from tree biomass, where the wood can be used for various purposes. Timber for sawmills and general construction has a longer C immobilization time. Methane from enteric fermentation is the greatest contributor to GHG emissions in livestock and ICLF systems. Nitrous oxide is released primarily from synthetic fertilizers (when applied), manure deposited on pastures, and the decomposition of plant residues. Carbon dioxide is emitted to a lesser extent from the application of lime and urea. Many studies do not include all compartments in the C balance and often focus on only one GHG or compartment of C. Accordingly, more studies on the sources and sinks of C and their potential to offset GHG emissions in terms of CO2 equivalent are urged.