Chapter4 2 4. Plant Growth Biostimulants from By-Products of Anaerobic Digestion of Organic Substances

Abstract The by-products of anaerobic fermentation of agricultural wastes as a result of methanogenic microorganism activity are various bioactive substances, including humic-like substances (HLS). The contents of HLS formed are changed during fermentation process. The degree of humification significantly ranges on different fermentation stages reflecting the biosynthetic activity of microbial consortium in the processes of maturing and transformation of humic compounds. Characteristics of HLS isolated on various fermentation stages and bioactivity assessment present much interest for future applications as plant growth biostimulants, organic-mineral fertilizers, and phytohormones.