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Delineation of Site-Specific management zones Based on Temporal and Spatial Variability of Soil Electrical Conductivity

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Pedosphere 2007年第2期17卷 156-164页

作者： LI Yan SHI Zhou LI Feng Institute of Agricultural Remote Sensing and Information Technology Application Zhejiang University Hangzhou 310029 （China）. Institute of Land Science and Property management College of Southeast Land Management Zhejiang University Hangzhou 310029 （China） Department of Environmental Engineering Zhejiang University Hangzhou 310029 （China）

A coastal saline field of 10.5 ha was selected as the study site and 122 bulk electrical conductivity (ECb) measurements were performed thrice in situ in the topsoil (0-20 cm) across the field using a hand held device to assess the spatial variability and temporal stability of the distribution of soil electrical conductivity (EC), to identify the management zones using cluster analysis based on the spatiotemporal variability of soil EC, and to evaluate the probable potential for site-specific management in coastal regions with conventional statistics and geostatistical techniques. The results indicated high coefficients of variation for topsoil salinity over all the three samplings. The spatial structure of the salinity variability remained relatively stable with time. Kriged contour maps, drawn on the basis of spatial variance structure of the data, showed the spatial trend of the salinity distribution and revealed areas of consistently high or consistently low salinity, while a temporal stability map indicated stable and unstable regions. On the basis of the spatiotemporal characteristics, cluster analysis divided the site into three potential management zones, each with different characteristics that could have an impact on the way the field was managed. On the basis of the clearly defined management zones it was concluded that coastal saline land could be managed in a site-specific way.

关键词： coastal saline field management zone soil electrical conductivity spatial variability temporal variability

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Delineation and Scale Effect of Precision Agriculture management zones Using Yield Monitor Data Over Four Years

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Agricultural Sciences in China 2007年第2期6卷 180-188页

作者： LI Xiang PAN Yu-chun GE Zhong-qiang ZHAO Chun-jiang National Engineering Research Center for Information Technology in Agriculture Beijing 100089 P.R. China Henan Information Industry Department Zhengzhou 450008 P.R.China Resource and Environment College Beijing Forestry University Beijing 100083 P.R.China

In this study, precision agriculture management zones were delineated using yield data over four years from the combine harvester equipped with yield monitor and DGPS receiver. Relative yields measured during each year were interpolated to 4 m2 grid size using ordinary kriging. The resultant interpolated yield maps were averaged across years to create a map of the mean relative yield, which was then used for cluster analysis. The mean yield map of post-classification was processed by applying majority filtering with window sizes that were equivalent to the grid sizes of 12, 20, 28, 36, 44, 52 and 60 m. The scale effect of management zones was evaluated using relative variance reduction, test of significant differences of the means of yield zones, spatial fragmentation, and spatial agreement. The results showed that the post-classification majority filtering （PCMF） eliminated lots of isolated cells or patches caused by random variation while preserving yield means, high variance reduction, general yield patterns, and high spatial agreement. The zoned result can be used as yield goal map for preplant or in-season fertilizer recommendation in precision agriculture.

关键词： precision agriculture management zone PCMF scale effect

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