Summary
Manure products fermented underground in cow horns and commonly used as a field spray (preparation 500) in the biodynamic agriculture system were characterized for their molecular composition by solid-state nuclear magnetic resonance spectroscopy [13C cross-polarized NMR (13C-CPMAS-NMR)], gas chromatography, tetramethylammonium hydroxide thermochemolysis and mass spectrometry. Both thermochemolysis and NMR spectroscopy revealed a complex molecular structure, the predominant components of which are aromatic derivatives of lignin, polysaccharides and alkylated compounds. CPMAS-NMR spectra of biodynamic preparations showed a carbon distribution with a low overall hydrophobic character and a significant contribution of lignocellulosic derivatives. The thermochemistry results confirmed the characteristic highlighted by NMR spectroscopy, revealing a molecular composition based on alkyl components of plant and microbial origin and the stable incorporation of lignin derivatives. The presence of of biolabile components and undecomposed lignin compounds in the 500 preparation must be attributed to its particularly slow maturation process, compared to common composting procedures. Our results provide, for the first time, a scientific characterization of an essential product in biodynamic agriculture, and show that biodynamic preparations appear to be enriched with biolabile components and, therefore, potentially conducive to plant growth promotion.
Conclusions
Detailed molecular characterization of three different BD 500 preparations obtained by solid-state NMR spectra and TMAH thermochemolysis reveals a complex molecular composition, identifying a wide range of different molecular structures. Lignin derivatives, plant polysaccharides, and linear and cyclic lipid components of plant and microbial origin were recognized as the main components of biodynamic preparation 500 obtained from cow dung. In particular, the identification of various biomarkers of lignin and lipids by thermochemolysis may become useful in tracing the origin of the products
Both NMR spectroscopy and thermochemolysis indicate that lignocellulosic residues are incorporated to a large extent into the biodynamic 500 preparation, with a significant amount of labile molecules being slightly decomposed. At the same time, the selective retention of recalcitrant alkyl molecules in the BD 500 preparation was also accompanied by retention of less stable alkyl molecules and microbial biomarkers, such that the biochemical recalcitrance of this biodynamic product may be less than that typically observed in mature compost that has undergone complete aerobic fermentation. These molecular properties suggest that preparation 500 may be more biolabile in soil than regular compost and, due to a high content of aromatic lignin derivatives, potentially become more bioactive for plant growth.
Despite skepticism about the rationale for biodynamic agricultural preparations, this system is finding increasing practical applications, primarily as a complementary technique to small-scale organic agriculture, with a proven ability to maintain crop yields and improve soil health. Our results on the molecular composition of three different preparations 500 not only provide the scientific basis for a molecular differentiation between these preparations and other composted materials, but also suggest that these differences may be the cause of the observed bioactivity of this biodynamic product.
Authors: Spaccini R., Mazzei P., Squartini A., Giannattasio M., Piccolo A.
Title: Molecular Properties of a Fermented Manure Preparation Used as Field Spray in Biodynamic Agriculture
Journal: Environmental Science and Pollution Research, 19, P4214-4225, 2012
Link to the original: https://link.springer.com/article/10.1007/s11356-012-1022-x
