Abstract:In order to balance the accuracy and cost of soil surveys in territorial comprehensive remediation and optimizing the sampling density of soil nutrient indicators for base surveys, taking three natural villages (773.8 hm2) in a certain project area in Shanghai as the study area, 263 sampling points have been layed , and 5 indicators (including organic matter) have been measured. Based on geostatistics and GIS spatial analysis, spatial variation characteristics of soil attributes under different sampling densities (10~40 points/km2) have been analyzed, and the sampling plan has been optimized through cross validation. The variation coefficients for each indicator range from 33.66% to 76.58%, with organic matter and total nitrogen primarily exhibiting structural variation (nugget effect<10%), while effective phosphorus and other indicators are significantly influenced by anthropogenic factors (nugget effect is 10.06%~23.34%). It is indicated that at a sampling density of 20 points/km2, the spatial distribution patterns of key nutrient indicators are effectively maintained, with the spacing between sampling points closely matching the range heights of each indicator. This approach can reduce the sampling volume by 50% compared to 40 points/km2. Therefore, for areas with homogeneous parent material and flat terrain, a density of 20 points/km2 can serve as a recommended option that balances accuracy and efficiency. This study will provide practical references for optimizing soil nutrient indicator sampling plans in territorial comprehensive remediation base surveys at the township scale in the Yangtze River Delta region.
