Fluorescence excitation-emission matrix (EEM) spectra of soil fulvic acids from the NPK (a) and SM (b) plots and FTIR spectra of the fulvic acids (c) during a long-term (i.e., 22-year) fertilization experiment.

Abstract

<p>Note that peaks A, B and C were located at Ex/Em of 230/410, 250/410, and 330/410, respectively. NPK, chemical nitrogen, phosphorus and potassium; SM, swine manure.</p