SOIL ORGANIC MATTER AND NUTRIENT CYCLING TO SUSTAIN AGRICULTURE IN THE SOUTHEASTERN USA
Location: Athens, Georgia
Title: Carbon sequestration and land degradation
Submitted to: Springer Verlag
Publication Type: Book / Chapter
Publication Acceptance Date: July 6, 2007
Publication Date: September 14, 2007
Citation: Franzluebbers, A.J., Doraiswamy, P.C. 2007. Carbon sequestration and land degradation. In: Sivakumar, M.V.K., Ndiangui, N. (eds). Climate and Land Degradation, Springer Verlag, Berlin, Germany. p. 343-358.
Interpretive Summary: Land degradation is a serious concern around the world. Conservation management practices offer an opportunity for landowners to build soil organic matter (i.e., sequester carbon in soil), while halting or reversing the effects of land degradation. Researchers with the USDA-Agricultural Research Service in Watkinsville, Georgia and Beltsville, Maryland reviewed the literature to (1) describe carbon sequestration concepts and rationale, (2) expound on relevant management approaches to avoid land degradation and foster carbon sequestration, and (3) summarize research quantifying soil carbon sequestration. The three primary agricultural greenhouse gases (CO2, CH4, and N2O) have increased dramatically during the past century. Management practices to sequester carbon and counter land degradation include: tree planting, conservation-tillage cropping, animal manure application, green-manure cropping systems, improved grassland management, cropland-grazingland rotations, and optimal fertilization. Strategies to sequester soil carbon are urgently needed so that degraded land can be restored and further land degradation can be avoided on the 13.3 billion acres of drylands in the world.
Storing carbon (C) in soil as organic matter is not only a viable strategy to sequester CO2 from the atmosphere, but is vital for improving the quality of soil. This presentation describes (1) C sequestration concepts and rationale, (2) relevant management approaches to avoid land degradation and foster C sequestration, and (3) a summary of research quantifying soil C sequestration. The three primary greenhouse gases (CO2, CH4, and N2O) derived from agriculture have increased dramatically during the past century. Conservation management practices can be employed to sequester C in soil, counter land degradation, and contribute to economic livelihoods on farms. Trees can accumulate C in perennial biomass of above-ground and below-ground growth, as well as in the deposition of soil organic matter. Minimal disturbance of the soil surface with conservation tillage is critical in avoiding soil organic C loss from erosion and microbial decomposition. Animal manures contain 40-60% C, and therefore, application to land promotes soil organic C sequestration and provides readily-available, recycled nutrients to crops. Green manures can be used to build soil fertility, often with leguminous plant species having symbiotic root associations with nitrogen-fixing bacteria. Grasslands have great potential to sequester soil organic C when managed properly, but can also be degraded due to overgrazing, careless management, and drought leading to accelerated soil erosion and undesirable species composition. Opportunities exist to capture and retain greater quantity of C from crop and grazing systems when the two systems are integrated. Fertilization is needed to achieve production goals, but when applied excessively it can lead to environmental pollution, especially when considering the energy and C cost of manufacture and transport. Agricultural conservation management strategies to sequester CO2 from the atmosphere into soil organic matter will also likely restore degraded land and/or avoid further land degradation.