Ten Reference Materials for Available Nutrients of Agricultural Soils

Six nutrient-doped soil samples, used as reference materials, were prepared in 1998 but have been used up in the past 10 years. They played an important role in evaluation of soil productivity and ecological geochemistry. To satisfy surveys and evaluations in multi-purpose regional geochemistry and agricultural soil productivity, a series of ten new reference materials (GBW07412a-GBW07417a,GBW07458-GBW07461) were collected from the main agricultural regions of China and prepared by the Institute of Geophysical and Geochemical Exploration(IGGE) at in 2009. Six of the ten samples were collected from the same sites as the six samples prepared in 1998, while the others four were collected from western China and calcareous. 50 indices, including nutritious and heavy metal elements, have been certified for all ten materials. These reference materials are more comprehensive and have been more widely distributed than the materials prepared in 1998. Furthermore, to eliminate the influence of analytical method differences in some indices between agricultural and forestry departments, methods of analysis and pretreatment were comprehensively discussed and unified by 13 laboratories from Ministry of Agriculture, Ministry of Land and Resources and Chinese Academy of Sciences.