Pedosphere 27(1): 147--154, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Non-algorithmically integrating land use type with spatial interpolation of surface soil nutrients in an urbanizing watershed
WU Qian1, LI Qing-Liang1,2, GAO Jin-Bo1,3, LIN Qiao-Ying1,3, XU Qiu-Fang2, P. M. GROFFMAN4 and YU Shen1
1Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China)
2Zhejiang A&F University, Lin’an 311300 (China)
3 3University of Chinese Academy of Sciences, Beijing 100049 (China)
4Cary Institute of Ecosystem Studies, Millbrook NY 12545 (USA)
      Integrating land use type and other geographic information within spatial interpolation has been proposed as a solution to improve the performance and accuracy of soil nutrient mapping at the regional scale. This study developed a non-algorithm approach, i.e., applying inverse distance weighting (IDW) and ordinary kriging (OK), to individual land use types rather than to the whole watershed, to determine if this improved the performance in mapping soil total C (TC), total N (TN), and total P (TP) in a 200-km2 urbanizing watershed in Southeast China. Four land use types were identified by visual interpretation as forest land, agricultural land, green land, and urban land. One hundred and fifty soil samples (0–10 cm) were taken according to land use type and patch size. Results showed that the non-algorithm approach, interpolation based on individual land use types, substantially improved the performance of IDW and OK for mapping TC, TN, and TP in the watershed. Root mean square errors were reduced by 3.9% for TC, 10.7% for TN, and 25.9% for TP by the application of IDW, while the improvements by OK were slightly lower as 0.9% for TC, 7.7% for TN, and 18.1% for TP. Interpolations based on individual land use types visually improved depiction of spatial patterns for TC, TN, and TP in the watershed relative to interpolations by the whole watershed. Substantial improvements might be expected with denser sampling points. We suggest that this non-algorithm approach might provide an alternative to algorithm-based approaches to depict watershed-scale nutrient patterns.
Key Words:  geographic information system, inverse distance weighting, non-algorithm approach, ordinary kriging, spatial pattern
Citation: Wu, Q., Li, Q. L., Gao, J. B., Lin, Q. Y., Xu, Q. F., Groffman, P. M. and Yu, S. 2017. Non-algorithmically integrating land use type with spatial interpolation of surface soil nutrients in an urbanizing watershed. Pedosphere. 27(1): 147-154.
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