Synthesis, characterisation and evaluation of slow nitrogen release organic soil conditioners from South African technical lignins

[摘要] ENGLISH ABSTRACT: Today there is renewed interest in using technical lignins and similar ligneous materialsas soil fertilising materials as they are available in large quantities from the pulping andagricultural industries. In addition, excessive application of inorganic fertilisers resultsin ground water pollution, especially in sandy soils through leaching of nitrogen.Lignin is an important precursor of humic material in soils and with modification, canbe used as a raw material to produce slow nitrogen release fertilisers (N-lignins). Thiscan be done using a reaction process called oxidative ammonolysis. This process hasbeen developed over the years by the Institute of Plant and Wood Chemistry of theTechnical University of Dresden in Germany, and a patent has been obtained for anambient pressure based, oxidative ammonolysis. The patented product obtained fromthis process which is prepared from low-grade brown coal (due to its similarity tolignin) is trade named NOVIHUM™. It is a slow nitrogen release and long lastingorgano-mineral fertiliser which has similar properties as natural humic substances.This project focussed on the characterisation and use of industrial residues such astechnical lignins and similar ligneous materials which are produced by the SouthAfrican pulping and agricultural industries, and on the production of N-ligninsaccording to the patented NOVIHUM™ technology. Three technical lignins, onederived from the sulphite pulping process (a calcium lignosulphonate), the second fromsugar cane bagasse (Sucrolin), and a third a, partially stripped sugar cane bagasse (alignocellulosic residue with a low lignin content) were subjected to oxidativeammonolysis. A Kraft lignin, lndulin AT, from Westvaco, USA was used forcomparison. The N-lignin products obtained were characterised and evaluated in plantgrowth trials.

[发布机构] Stellenbosch University