Compound-Specific Stable Isotope Techniquesfor Improving Soil Conservation Strategies:An Overview of the Lessons Learned from anFAO/IAEA Coordinated Research Project

摘要

This paper summarises key findings from a five-year (2009-2013) coordinated research project (CRP) on "Integrated Isotopic Approaches for Area-wide Precision Conservation to Control the Impacts of Agricultural Practices on Land Degradation and Soil Erosion", organized and funded by the International Atomic Energy Agency through the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. The project brought together fifteen participants, from Australia, Belgium, Canada, Chile, China, Germany, Morocco, New Zealand, Poland, the Russian Federation, the Syrian Arab Republic, the United Kingdom and Vietnam. The project involved the use of isotopic and nuclear techniques to assess soil erosion and developsoil conservation strategies at a landscape level. The overall objective of this CRP was to develop integrated isotopic approaches using not only fallout radionuclides (FRN) but also compound-specific stable isotope (CSSI) techniques to identify criticalareas of land degradation in agricultural catchments so that effective soil conservation measures can be implemented. Compound-specific stable isotope (CSSI) techniques are based on the measurement of carbon-13 (~(13)Cs) natural abundance signatures ofspecific organic compounds (e.g. fatty acids of plant and animal origins) in the soil profile. A harmonized protocol for the application of CSSI techniques measuring ~(13)Cs of fatty acids extracted from soils was developed to identify critical sedimentsource areas and erosion hotspots at the catchment scale in a range of environments and land-use systems. The results obtained show that FRN and CSSI based techniques are complementary as fingerprints and tracers of sediment redistribution within agricultural catchments. The CCSI technique provides information on sources while FRN techniques can provide information on the extent of soil losses so that effective soil conservation measures can be targeted to criticallly degraded areas in agricultural landscape.