Ministry of Agriculture and Rural Affairs: Special investigations on saline-alkali soil are specifically arranged in the Third National Soil Survey.
On December 5th, the Ministry of Agriculture and Rural Affairs held a press conference to introduce the progress and achievements of the third national soil survey.
Wu Wenbin, the deputy head of the expert technical guidance group for the third national soil survey and the director of the Institute of Agricultural Resources and Regional Planning at the Chinese Academy of Agricultural Sciences, stated that since the founding of the People’s Republic of China, two national soil surveys have been conducted. The first survey took place from 1958 to 1960, focusing on understanding the distribution of arable soil resources and farmers’ experiences in soil improvement and usage, with limited survey content. The second survey was conducted from 1979 to 1984, clarifying the types, quantities, and distribution of soil resources in the country at that time, with a focus on soil fertility.
Regarding the characteristics of the third national soil survey, Wu Wenbin explained that first, the design is innovative. The third survey adheres to the principles of comprehensiveness and scientific rigor, fully drawing on and utilizing existing methods and results, while innovating the overall design. It maintains six combinations: integrating soil quality assessment with soil type improvement, combining current soil surveys with soil usage investigations, merging field observations with laboratory testing and analysis, combining surface soil sampling with profile collection, and integrating government leadership with professional teams. Additionally, it implements six unifications: a unified survey work platform, unified survey technical procedures, a unified base map for the survey, unified planning for field sampling points, unified standards for selecting testing and analysis institutions, and unified quality control throughout the process. Compared to the previous two soil surveys, the design of the third survey is scientifically advanced, ensuring the uniformity, comparability, and accuracy of the survey results.
Second, the point placement is precise. The soil survey does not investigate every inch of surface soil but uses the characteristics of a sampling point to represent a similar area. Generally, the more sampling points there are, the more accurate the survey results, but this also increases the time and cost, making point placement a significant challenge. In the first two surveys, limited by the conditions at the time, point selection relied mainly on expert experience. In contrast, the third soil survey was based on the comprehensive inheritance of historical survey results, with the national level unifying the construction of an electronic base map that integrates soil types, topography, and land use status. By combining the spatial distribution patterns of soil, sampling points were accurately placed on the base map, which were then verified and confirmed by various provinces, ultimately completing the establishment of 2.872 million sampling points, including 2.793 million surface points and 79,000 typical profile points. Among these, the density of points in arable and garden land is greater than that in forest and grassland, with arable land sampling points accounting for 74.5%.
Third, the survey is comprehensive. In the first two surveys, the information from field investigations and laboratory testing indicators was relatively limited. For example, the second soil survey mainly focused on indicators related to soil fertility. In contrast, the third survey conducts a comprehensive examination, covering various indicators such as soil physics, soil chemistry, soil biology, soil fertility, and soil environment, investigating nearly a hundred items of information regarding the soil formation environment, surface characteristics, and soil types at the sampling points. Among the tested surface points, there are 29 indicators for arable and garden land and 11 indicators for forest and grassland. For profile points, there are 43 indicators for arable and garden land and 17 indicators for forest and grassland. Additionally, the third survey has specifically arranged thematic investigations on saline-alkali soils, specialty product area soils, and soil biology. In saline-alkali regions and areas with specialty products, some physicochemical analysis indicators related to saline-alkali conditions and potential impacts on specialty product quality have been conducted, with some soil samples requiring testing of 34 biological indicators.
