Desertification is one of the world's most alarming processes of environmental degradation. The current desertification rate of more than 50.000 km2per year is not only jeopardizing the global food supply, but also current developments towards biorefinery-based chemicals, biofuels, and biomaterials, due to the available area of farm land permanently decreasing.Re-establishment of vegetation on highly eroded, barren soils requires the application of a sufficient amount of organic matter, next to nutrients and water. Ammoxidation has been developed over the past decades into a powerful technique for converting ligneous raw materials into value-added, artificial humic substances. These synthetic humins additionally feature a slow release of nitrogen which can last for several growth periods due to different mineralization rates of the various types of nitrogenous moieties introduced upon ammoxidation. Considering the huge global demand for high-grade humus substitutes, a considerable fraction of technical lignins accumulating at the pulp mills could be cycled out and commercialized as N-modified lignins. This would be beneficial in many ways as it allowed for increasing the pulp production and closing natural cycles by returning a valuable organic carbon source back to the soil. Here, it would serve as soil improving material in particular after enrichment with nitrogen which, in turn, could be beneficial with regard to shortening the rotation period of tree plantations and biomass yield.The present paper summarizes the state of research in the field of N-modification of ligneous materials, presents new results about the fate of mono- and polysaccharide �impurities� under ammoxidative conditions, the formation of bioactive compounds thereof, the types of nitrogen moieties present in N-lignins, the occurrence of (substituted) 2,5-diamino-[1,4]benzoquinones in the ammoxidation mixture, a finding which supports the polyphenol theory of formation of natural humic substances.

N-modified lignins as artificial humic substances: Application potential and unresolved issues

247th National Meeting (2014)

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