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Spatial variability of soil available phosphorus in a typical watershed in the source area of the middle Dan River,China |
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| Authors: | Guoce Xu Zhanbin Li Peng Li Tiegang Zhang Shengdong Cheng |
| Institution: | 1. Key Laboratory of Northwest Water Resources and Environment Ecology of Ministry of Education, Xi’an University of Technology, Xi’an, 710048, Shaanxi, People’s Republic of China 2. State Key Laboratory of Soil Erosion and Dry-land Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, 712100, Shaanxi, People’s Republic of China 3. Graduate School of Chinese Academy of Sciences, Beijing, 100039, People’s Republic of China |
| Abstract: | Phosphorus is an essential and common limiting element for plants. Phosphorus losses from agricultural production systems are known to contribute to accelerated eutrophication of natural waters. In this study, soil available phosphorus (SAP) content and SAP density were estimated based on a soil survey of a small watershed in the Dan River, China, and the spatial heterogeneity of SAP distribution and the impacts of land-use types, elevation, slope and aspect on SAP were assessed. Field sampling was carried out based on a 100 m × 100 m grid system overlaid on the topographic map of the study area, and samples were collected in three soil layers to a depth of 40 cm. A total of 190 sites were sampled, and 539 soil samples were collected. The results showed that classical kriging could successfully interpolate SAP content in the watershed. SAP content showed a downward trend with the increase in soil depth and the extent of SAP variability in the three soil layer is moderate. There were significant differences among the three soil layers (P < 0.01). The land use had a great impact on the SAP content. ANOVA indicated that the spatial variation of SAP contents under different land-use types was significant (P < 0.01). The SAP density of different land-use types followed the order of cropland > forestland > grassland. The mean SAP density of cropland, forestland and grassland at a depth of 0–40 cm was 4.28, 3.74 and 2.81 g/m2, respectively. SAP and topographic factors showed that SAP content increased with decreasing altitude and slope gradient. The soil bulk density played a very important role in the assessment of SAP density. In conclusion, the soils in the source area of the middle Dan River would reduce SAP with conversions from cropland to forest or grassland. |
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