基于HJ-1卫星的农田土壤有机质含量监测

    Mapping soil organic matter content in field using HJ-1 satellite image

    • 摘要: 土壤状况是决定农田潜在生产力的主要因素,土壤性状及肥力状况信息可以为精准农田管理提供响应依据。利用遥感技术监测土壤养分含量是一种快速、准确、高效、经济的方法。以农田土壤有机质为研究对象,以HJ-1卫星数据为数据源,采用多元线性回归分析方法,构建有机质含量地面监测模型,通过直方图匹配方法求地面监测模型与HJ-1卫星监测模型之间的傅里叶转换函数,将地面监测模型应用到HJ-1卫星数据,并构建有机质含量遥感监测模型。实现了利用HJ-1卫星遥感数据对试验区土壤有机质含量进行监测。该模型监测结果与地面实际养分具有良好的线性关系,其决定系数0.93,标准差0.57%。在保持了较高精度的同时,避免了其他高光谱模型数据过于昂贵的问题,实现了有机质含量快速、经济监测,易于在农业中应用。

       

      Abstract: Abstract: Soil organic matter content is one of the main factors affecting productivity of agricultural soils. Many studies have shown that the remote sensing is a good tool for estimation of soil organic matter (SOM) content. Satellite hyperspectral image or airborne hyperspectral image has been used in the last decade. However, the data derived from these images have a long revisiting period and are expensive in acquisition and processing. To solve this problem, this study aimed to estimate SOM based on HJ-1 satellite multispectral data that had revisiting period of one day and were cost free. SOM content monitoring model was built by remote sensing with the spatial resolution of 30 meters based on HJ satellite CCD's multispectral data and SVC HR-768 spectrometer hyperspectral data. There were four bands for the satellite data and their spatial resolution was 30 meters. In addition, there were 768 bands of hyperspectral data distributed from 350 to 2 500 nm. S-G filter was used to eliminate systematic errors of spectrometer during hyperspectral data-based model fitting. Spectral resolution of resampled hyperspectral data matched that of CCD data from spectral response function (SRF). Then hyperspectral data and SRF were used to analog reflectivity of CCD data at each band. The correlation between SOM and surface spectral characteristics of the samples was analyzed, from which a preliminary SOM monitoring model was established. To further improve the initial monitoring model, initial model histogram was matched to sample's histogram to correct the initial monitoring model. The final monitoring model of SOM was then established. Taking into account spatial difference between the samples and remote sensing images, ten soil samples were used to test the model. The results showed that there was a good linear relationship between estimated and measured SOM values (determination coefficient 0.93, the slope 1.2 and the standard deviation was 0.57%). Based on the model, the distribution of the farmland SOM was mapped with the spatial resolution 30 m and the temporal resolution of one day. The cost-free data of HJ-1 and the model provided an economical tool to estimate SOM in farm field.

       

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