A new approach to the recording and interpretation of the electronic spectra of humic substances, which can help evaluate their electron-donating properties by the intensity of electron transitions in the ultraviolet region of the spectrum, was proposed. It was found that the electron-donating properties of humus were affected by nitrogen and phosphorus compounds. With a modernized procedure of spectrum recording, it was found that the electron-donating properties of humus changed under the effect of nitrogen compounds mainly because of the increase in mobility of the pi -electron cloud of benzene rings. The effect of phosphates was primarily manifested with respect to the substituents in benzene rings, where free pi -electrons accumulated due to the increased number of C=C bonds.