Visible and near infrared spectroscopy (VNIR) has been successfully used to determine many soil parameters rapidly. However, total phosphorous (P) cannot be well quantified by VNIR, mainly because its absorption spectrum or reflectance spectrum was too weak to be studied. Here, we explored a new way to reveal the reflectance spectrum of total P in soils. Firstly, six types of soil residues were prepared after the original soil was sequentially extracted Ca₂-P, Ca₈-P, Al-P, Fe-P, O-P, and Ca₁₀-P, respectively. Secondly, the reflectance spectra of these P fractions were obtained using these soil residues by QE65000 spectrometer (Ocean Optics). Specifically, if we intended to get the spectrum of a certain P fraction, we would measure the reflectance spectrum of the soil residues without its neighboring former P fraction, using the soil residues after extracting this P fraction as the reference spectrum. Results showed that these P fractions had different characteristics of reflectance spectrum and can be well analyzed qualitatively and quantitatively. After summarizing the diagnostic spectra of these P fractions, the total P diagnostic spectrum was found to be distributed in 250–750 nm. Using these diagnostic bands, the spectral model of total P was established and showed a better result. This study provided an important evidence for understanding the characteristics of total P reflectance spectrum in soils and predicting total P concentrations.

可见光和近红外光谱 (VNIR) 已成功用于快速确定许多土壤参数。然而，VNIR 不能很好地量化总磷 (P)，主要是因为它的吸收光谱或反射光谱太弱而无法研究。在这里，我们探索了一种揭示土壤中全磷反射光谱的新方法。首先将原土依次提取Ca ₂ -P、Ca ₈ -P、Al-P、Fe-P、OP、Ca ₁₀后制备六类土壤残留物-P，分别。其次，通过 QE65000 光谱仪（海洋光学）使用这些土壤残留物获得这些 P 部分的反射光谱。具体来说，如果我们想要获得某个 P 部分的光谱，我们将使用提取该 P 部分后的土壤残留物作为参考光谱，测量没有其相邻前 P 部分的土壤残留物的反射光谱。结果表明，这些磷组分具有不同的反射光谱特征，可以很好地进行定性和定量分析。总结了这些P馏分的诊断光谱后，发现总P诊断光谱分布在250-750 nm之间。利用这些诊断波段，建立了总磷的光谱模型并显示出较好的结果。