Structure of humic acids as influenced by plough tillage and minimum | Vplyv orby a minimalizácie na štruktúru huminových kyselín
Pospíšilová, L., Mendel Univ., Brno (Czech Republic) | Jandák, J. | Živna, T.
Objective of this study was to show the effect of different soil tillage systems on humic substances content and quality. Furthermore, chemical composition and structural differences in humic acids molecules in selected tillage systems were assessed. Long-term experiments were carried out on Luvi-haplic Chernozem (locality Unčovice,Olomouc region) during the period 2008 - 2011. Two types of tillage systems were studied: first, plough till 0.35 - 0.40 m; second, minimum tillage till 0.15 m. Humic acids were isolated from the plough and minimum tillage horizons (0 - 0.30 m) according to the international standard method and characterized by elemental composition and 13C NMR spectroscopy. The results showed differences in quality of humic substances and higher content of fulvic acids in fractional composition under minimum tillage system (3.5 g/kg). Analysis of chemical composition and structure of humic acids indicated higher relative intensity of aliphatic groups signal in HA molecule due to minimum tillage (at 106 - 15 ppm about 50). On the other hand, humic acids isolated from ploughed soil were more aromatic. 13C NMR spectroscopy could be a useful tool to assess changes in structural composition of humic acids isolated from the different eco-systems.
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