RUSANDICA STOICA, FLORIN OANCEA, IULIAN MINCA, SANDA MARIA DONCEA, RODICA GANEA, LUIZA CAPRA, RALUCA SENIN, MARIANA MATEESCU, IRINA CIOBANU, GEORGETA IVAN, MIHAELA MANOLACHE SPECTROSCOPIC, TEXTURAL AND THERMAL CHARACTERIZATION METHODS OF BIOSTIMULANTS BASED ON SODIUM HUMATE Plant biostimulants, an emerging class of agricultural inputs, are complex products. The reproducibility of their specific action on plant metabolism and plant physiology, which lead to an enhanced nutrient use efficiency, stress tolerance and edible yield quality, is still a challenge. Development of quality insurance systems for plant biostimulants need complex investigation based on adapted analytical, physico-chemical and chemical methods. The objective of this work was to characterize commercial humate biostimulants through different analytical techniques (Fourier transform infrared spectroscopy - FTIR, thermogravimetric analysis- TGA) and to evaluate their textural and chemical (pH, C, N, humic acids, inorganic components) parameters. The first derivative curve from TG analysis showed decomposition of different compounds, classified according to the results obtained by FTIR. The humic substances determined by TGA method was comparable with the results obtained by gravimetric reference method. The inductively coupled plasma-optical emission spectrometry (ICP-OES) technique was applied to determine the inorganic elements either from the production process of humate or from raw materials, as well as for the control of humate in terms of requirements for safety and quality. Their complementary properties obtaining through different analytical techniques provide essential information on the chemical characteristics of the humate plant biostimulant formulations.
Keywords: sodium humate; humic acids, FTIR, TGA, BET, ICP-OES, biostimulant