基于包络线去除和偏最小二乘的土壤参数光谱反演

土壤有机碳的有效评估对全球碳循环和农业可持续发展具有重要作用。可见光-近红外光谱技术已广泛用于土壤有机碳含量的反演研究。然而,基于可见光-近红外光谱的土壤有机碳反演模型通常具有一定的区域局限性。本文基于湖北钟祥市和洪湖市两个区域的土壤光谱和有机碳量测数据(样本数分别为100和96),探究土壤有机碳反演模型在不同区域间的传递性。结果表明,钟祥市或洪湖市区域模型都不能用于另一个区域,但基于钟祥样本全集与洪湖区域30个土壤样本数据建立的模型对洪湖区域土壤有机碳含量有很好的预测效果(R²=0.88, RMSE=2.51 g·kg^-1)。尽管模型在不同区域间的传递性非常有限,但将少量目标区域样本添加到现有区域土壤光谱库中所建立的偏最小二乘回归模型能够估算目标区域土壤有机碳的含量,降低目标区域的采样和量测成本。

Global Soil Characterization with VNIR Diffuse Reflectance Spectroscopy

Assessing soil organic carbon (SOC) effectively is crucial to understand the global carbon cycle and achieve sustainable management of agricultural systems. Visible/near-infrared spectroscopy has been widely used to retrieve SOC content. However, retrieval models with visible/near-infrared spectroscopy generally have regional limitations. The objective of our work was to study the transferability of models between regions using the spectra and SOC measurements of the soil samples collected from Zhongxiang and Honghu(number of samples are 100 and 96 respectively), Hubei province, Peoples Republic of China. Our results show that the regional model calibrated with Zhongxiang or Honghu datasets could not be used in another region. However, the model calibrated with the entire Zhongxiang dataset and 30 samples from Honghu performed well when estimating the SOC contents in Honghu (R²=0.88, RMSE=2.51 g·kg^-1). Although the transferability of this regional model is very limited, nevertheless, this study illustrates that by combining a small set of samples from target region with the regional soil spectral library of anther region can improve the performance when estimating SOC contents in target region, and thus can reduce the cost of sampling,measurement, and determination in a target region.