The contribution of alkali soluble (humic acid-like) and unhydrolyzed-alkali soluble (core-humic acid-like) fractions extracted from maize plant to the formation of soil humic acid.
Alkali soluble (humic acid-like material) (HA-like) (yield of 132 gkgdm(-1)) and the unhydrolized-alkali soluble (core-humic acid-like material) (core-HA-like) (yield of 33.4 gkgdm(-1)) fractions were extracted from maize plants and characterized by C and N determinations, DRIFT, and 1H and 13C-NMR spectroscopy. Fresh plants were subsequently incubated for 6 months in an artificial mineral soil, and the HA-like and core-HA-like trends were monitored quantitatively (C fraction content) and qualitatively (spectroscopic approach) in order to study their contribution to the formation of soil humic acid. During incubation the HAC-like partially degraded (loss of 320 gkgHAC(-1)) and partially formed new fulvic-like acids (160 gkgHAC(-1)). On the contrary, the stable fraction of HAC, the core-HAC-like, was maintained (loss of 153 kgcore-HAC(-1)), representing, after incubation, 846 gkg(-1) of the initial core-HAC-like content. The core-HA-like fraction is composed of lignin residues, polysaccharides, lipids and proteins, probably structured into a well-defined network, i.e. the plant cell wall.
Adani
Fabrizio
F
Dipartimento di Produzione Vegetale, Sez. di Fisiologia delle Piante Coltivate e Chimica Agraria, Università degli Studi di Milano, Via Celoria 2, 20133 Milan, Italy. fabrizio.adani@unimi.it
Ricca
Giuliana
G
D000468:Alkalies / Q000737:chemistry; D002244:Carbon; D002247:Carbon Isotopes; D006812:Humic Substances; D009682:Magnetic Resonance Spectroscopy; D009584:Nitrogen; D010936:Plant Extracts; D011522:Protons; D012987:Soil / Q000032:analysis*; D003313:Zea mays / Q000737:chemistry*
D000468:Alkalies; D002247:Carbon Isotopes; D006812:Humic Substances; D010936:Plant Extracts; D011522:Protons; D012987:Soil; D002244:Carbon; D009584:Nitrogen