Author/Authors :
Bremanis، Gunârs نويسنده State Stende Cereals Breeding Institute, “Di?zemes”, p/o Di?stende, Lîbagu pag., Talsu nov., LV-3258, LATVIA , , Klavi??، Mâris نويسنده Department of Environmental Science, University of Latvia, Rai?a bulv. 19, Rîga, LV-1586, LATVIA; , , Purmalis، Oskars نويسنده Department of Environmental Science, University of Latvia, Rai?a bulv. 19, Rîga, LV-1586, LATVIA; , , Ziemelis، Raitis نويسنده Modul House Ltd, Pils iela 28, Ventspils, LATVIA; ,
Abstract :
Extracts for agricultural use were prepared using cavitation method at 45 oC and at 95 oC from
peat and earthworm biohumus. Samples of all studied extracts had similar dry-matter content.
Peat humic substances and earthworm biohumus extracts were analysed using UV-Vis, FT-IR,
and fluorescence spectrometry. Trace element analysis was performed with atomic absorption
spectrometry. Extracts were tested for acidity, conductivity, humic acid concentration, and carboxyl
group concentration. Hydrophobicity was assessed using a water-polyethylene glycol twophase
system and calculation of the partition coefficient. Total nitrogen and phosphorus concentration
was determined. Concentration of the humic substances slightly changed during the heating
process. Significant changes in total phosphorus concentration was observed both in
earthworm humus and peat extract. Thermal treatment caused decrease of hydrophobicity and
lower concentration of organic matter in extracts, while carboxyl group concentrations in isolated
humic substances practically did not change. The calculated ratio from UV-Vis spectra showed
significant difference in humification degree of samples.
