Establishment And Applications Of Soil Database Of Zhejiang Province

Soil is one of the most fundamental natural resources, which supports varied forms of life on the Earth surface. With the increasing challenges from global food shortage, environment degradation, ecology deterioration, etc., there is an ever urgent demand on managing soil resource in a systematical, efficient, and accurate way. Building digital soils is an inevitable task for integrating traditional soil science, modern earth science, and information technology. At current stage, establishing soil database has the highest priority.Initiated in1979, China conducted the Second Nation Soil Survey, from which, mega quantity of data and substantial achievements have been obtained. To make better use of the results and also to keep abreast of the development in science and technology, soil database construction emerged as an urgent task. This dissertation reported the establishment of a soil database for Zhejiang Province, which was built on the materials and relative data from the Second National Soil Survey. Then, to improve the quality of database and to extend its applications, this dissertation studied the practice of updating soil map from the Second National Soil Survey and constructing a referencing system between the Genetic Soil Classification of China (GSCC) and Chinese Soil Taxonomy (CST). In the arena of soil database applications, this study evaluated and analyzed the pedo-taxa abundance, soil erodibility and the impact of urbanization on soil resources. Main results are as follows:(1) Establishment of soil database, Zhejiang Province The soil database of Zhejiang includes two main parts:spatial database and attribute database. Spatial database is comprised of small scale (1:1000000,1:500000), medium scale (1:250000) and large scale (1:50000) soil geographic databases. Attribute database contains2677soil profiles, including typical profiles, statistical profiles and nutrient data of surface layers. The established soil database of Zhejiang generated a seamless provincial-wide digital soil map well-linked to various soil attributes, which to a certain extent lays a solid foundation for the construction of Zhejiang digital soil.(2) Soil map quality Improvement The Second National Soil Survey was conducted in1980’s. Since then, three decades has been passed, substantial science and technology development has been made. By applying remote sensing and geographic information techniques, attempts were made to improve the quality of soil map, which consisted of four aspects,1) mathematic base update, which is used essentially for filling the vacancy of geodetic coordinate system. This further updated the geographic reference of soil map from the Beijing54coordinate system to the National Xi’an80coordinate system or Geodetic Coordinate System2000;2) map unit refinement, which is mainly aimed at problems of vagued feature, missing drawing and unreasonable compilation;3) symbol update, which is used to resolve the problem of outdated map symbol;4) administrative divisions update, which is to update the traditional soil maps with the latest administrative divisions to meet the needs of the regional soil resource management.(3) Reference system between the Genetic Soil Classification of China and Chinese Soil Taxonomy Based on the soil database of Zhejiang, associations between Soil Species in GSCC and Soil Subgroups in CST were set up, and the distribution of CST Soil Subgroup was compilated. Results showed that at the basic taxon level of GSCC, the reference relationship was relatively clear and certain, but at higher levels, the relationship became complicated. There were a total of99Soil Genus and277Soil Species in GSCC, among which,62Genus and252Species could be uniquely referenced to Soil Subgroup in CST. Therefore, it is feasible to transform the large-scaled soil map of Soil Species under GSCC from the Second National Soil Survey into the Soil Subgroup map of CST at1:100000. With this reference system, the soils of Zhejiang could be sorted into8Soil Orders, of which Cambosols was in dominance, accounting for31.3%, Anthrosols for23.4%, and Histosols had the least percentage in area. At the Order level in CST, soil distribution presented a clear spatial pattern. These findings are of values to soil classification with CST, and they provide examples for CST soil mapping of Zhejiang Province.(4) Pedodiversity analysis Using the1:50000soil database of Zhejiang, pedodiversity analytical theory was employed to analyze soil landscape pattern, the rarity and representativeness of Soil Species. At Soil Species level, the diversity values of11cities in Zhejiang follow the sequence as Shaoxing> Taizhou> Ningbo> Hangzhou> Jinhua> Huzhou> Zhoushan> Wenzhou> Quzhou> Lishui> Jiaxing. Among the10Soil Groups, Red soils have the largest area, Paddy soils have the maximum number of map units, and Yellow soils show the maximum average size delineation. According to the area, number of map units, spatial distribution diversity of each Species, the representative and rare Species were identified from the277Species, respectively.(5) Assessment of soil erodibility Soil erodibility is an important indicator for assessing the soil susceptibility to erosion and serves as a major parameter for soil erosion prediction and land use planning. With the attributes from the soil database, the soil erodibility (K) values of277Soil Species, Zhejiang Province were computed with the formula of EPIC (Erosion Productivity Impact Calculator), and the map of K value of Zhejiang was generated. Results showed that the K values ranged from0.116to0.425, which correspond to the Salt flate and Fluvio-sand ridge soil, respectively. By using the method of area weighting factor, K value for each Soil Group was estimated from all affiliated Species. The K value of10Soil Groups follows the sequence as: Coastal saline soil> Fluvio-aquic soil> Purple soil> Paddy soil> Limestone soil> Basic rock soil> Mountain meadow soil> Red soil> Yellow soil> Skel soil. Both the soil texture and soil organic carbon had great influence on the Soil erodibility. The K value of Red soil showed significant negative correlation with soil organic carbon and sand content, while a significant positive correlation with silt content. In the whole area of Zhejiang Province, moderate-low erodible soils covered64.2%, and moderate erodible soils were26.4%.(6) Urban Sprawl and soil resources dynamic With a case study in the Northern Zhejiang Plain, the impact of urban sprawl on soil resources was evaluated. Using satellite images acquired during1969-2009and the soil database, the urban area of the20cites in the Northern Zhejiang Plain in1969,1987,1995,1999,2005,2007,2009was derived respectively, and soil types occupied by urbanization were identified. Results showed that urban area in the Northern Plain expanded enormously around the initial urban boundary in the past40years, and the urban area of20cities increased1005km2, from165km2in1969to1171km2in2009with an annual increment rate of17%(about25.8km2/year). The increment rate in different periods varied somewhat. From1995to1999, it showed the minimum rate, while from1999to2005it presented the maximum rate, accounting for42.7%of the total expansion area. During the past30+years (1987-2009), urban sprawl occupied835.6km2soil areas, of which Paddy soils accounted for about73.6%and Fluvio-aquic soil19.3%. A total of113Soil Species were utilized by the urbanization process, while Eutric fluvio-aquic soil, Eutric fluvio-marine friable loamy soil, and Yellow-red soil were completely sealed in the region.With the completion of Zhejiang soil batabase and some examples of application, it demonstrated the great values and application potentials of the database. However, this database is still imperfect. Constrained by the time, a lot of work needs to be done, such as the update of soil database, especially the update of the contents of map units, so that it could provide up-to-date soil information. This study only showed its applications in soil diversity, soil erodbility, and monitoring of soil resources dynamic. It is expected that this database has vast application potentials in agriculture, land resources management, soil and water conservations, and environment etc.