Detailed soil spatial and attribute information are now basic parameters for environmental modeling and land management applications.The accuracy and efficiency of conventional soil surveys,based on the polygon model and the manual mapping practice,are quite low.A geographical information system(GIS) and expert knowledge based-fuzzy soil inference scheme(soil-land inference model,SoLIM) was developed to overcome the problems faced by the conventional soil survey.The scheme consists of three major components:(i) a model employing a similarity representation of soils,(ii) a set of inference techniques for deriving similarity representation,and (iii) application of the similarity representation.According to case studies conducted in Wisconsin,U.S.A,SoLIM improves the accuracy and efficiency of soil survey.Soil type and properties maps based on SoLIM are better than these based on conventional techniques in term of both spatial detail and attribute accuracy.The accuracy of the soil series maps based on SoLIM is about 80%.Moreover,soil mapping by means of SoLIM is about ten times faster than by conventional ones and saves about 2/3 in cost.However,how the SoLIM works highly depends on the availability and quality of environmental data and the quality of soil,environmental relationship model for the study area.The Second Soil Survey in China was conducted 20 years ago.Recent intensive land use activities may have greatly impacted the soil conditions.It's quite necessary to update the soil data in China for agricultural purposes.The SoL.IM framework can provide great assistance in updating soil resource inventory.At the same time,the availability of spatial data,spatial information proceasing technology and human resources related to GPS,GIS and RS also make it possible to apply the SoL.IM approach in the Chinese soil survey.However,the degree of success of the SoL.IM highly depends on the quality of knowledge on soil environmental relationships in the study area.The knowledge about soil-environmental relationships used for the SoLIM in USA comes mainly from local soil survey experts.Although experts in soil taxonomy can provide much help for soil survey in China,the number of experts who focus on soil mapping in local areas is small,which will pose a major problem in using the SoL.IM approach in China due to its reliance on human expertise for soil-environmental relationships.If we try to discern the soil-environmental relationships by field sampling,we will need a large amount of samples,which is too expensive and too slow.Thus,we must develop new approaches for extraction of knowledge on soil-environmental relationships.These new approaches could include new sampling methods,such as purposive sampling to reduce fieldwork and data mining for extracting knowledge from existing soil maps.