Saving Millions of Tons of Agricultural Topsoil in China and Enhancing Livelihoods and Water Quality
China is one of the countries suffering from the most serious soil erosion in the world. IAEA-funded projects conducted in the Loess Plateau (Nianzhuang watershed), Northern China (Fengning site) and North Eastern China (Baiquan site), have shown substantial soil erosion rates from cultivated land as measured by the fallout radionuclide method (137Cs), ranging from 16-20 t ha-1 yr-1 for the Northern China site to 24-36 t ha-1 yr-1 for the North Eastern China site and 40-70 t ha-1 yr-1 for the Loess Plateau. In the Loess Plateau and North Eastern China sites, severe water erosion was the major cause, resulting from intensive tillage operations, downslope cultivation and inappropriate crop rotation. At the Northern China site, wind erosion was the major factor, resulting from conventional tillage operations without surface cover.
Soil erosion rates, as measured by the fallout radionuclide method, declined by 16 to 80% depending on the type of conservation measures employed (terracing hillslopes, vegetated hillslopes, contour cultivation and no tillage) highlighting the importance of tracers in targeting appropriate soil conservation measures.
Information gained from IAEA-funded projects has been adopted by the World Bank Project in Baota district, Yan'an for selecting effective soil conservation measures to control soil erosion. The project area covered 800 km2 (80000 ha) in the Yanhe River watershed of the Loess Plateau. Through the use of cash forests, fruit tree crops and the planting of shrubs and grass in a structured framework, annual sediment delivery after a 6-year period (1998-2004) was reduced by 77% compared to that annually produced (8.32 million tons) before the project was implemented (1998). Enlargement of the forest area (17625 hectares) by 88% compared with that of 9340 ha at the beginning of the project and the addition of 10 key check dams and 50 silt dams over a 6-year period (1998-2004) has increased the net income per farmer from 446 Yuan in 1998 to 1754 Yuan in 2004 and grain production per capita from 347 kg to 570 kg.