Spatial variations of soil organic carbon and available microelement contents in interlaced area of vegetable lands and grain lands----A case study in Shouguang City, Shangdong Province

Taking Shouguang City as an example, the spatial variation characteristics and the influence factors of soil organic carbon (SOC) in the top 0-20 cm soil layer under greenhouse vegetables lands and wheat-maize rotation land were analyzed based on GIS and geostatistics methods, and the correlations between the contents of SOC and available trace elements were calculated. The result show that the average content of SOC in the greenhouse vegetable fields is higher than that of wheat-maize rotation fields in the studied area and the variations of SOC in the two fields are moderate and significantly influenced by fertilization, temperature, irrigation, tillage, etc. The variation range of SOC in vegetable fields (749 m) is less than that in farmlands (1460 m), indicating that the spatial variation of SOC in vegetable fields correlates stronger to fertilizer management than in vegetable fields. The simulation results of the SOC are higher in the middle, lower in the middle east and west in the grain fields, higher in the northeast, northwest and southeast, and lower in the northern part of Midwest in vegetable fields. The SOC storage is positively correlated with available Fe, Cu and B contents in the wheat\|maize rotation fields and negatively correlated with available Mn, but there is no such a significant correlation in the vegetable fields.