ABSTRACT
Humic materials are categorized into three main classes: humic acids (alkaline soluble), fulvic acids (acid and alkaline soluble), and insoluble humin. The use of humic products is increasing among farmers due to their ability to considerably improve soil health and alter soil characteristics. Besides being used as soil amendments, humic products can also be used to formulate a variety of synthetic and organic fertilizers. Most likely, humic acids appear to improve the cation exchange capacity (CEC) of soil, which may contribute to an improvement in mineral nutrients retention in soil. The term “Alkamides” denotes a group of secondary metabolites consisting of nearly 200 compounds, and all of them have a special structure that results from the condensation of an unsaturated fatty acid and an amine group. The Alkamides (N-iso-propyldecanamide) in the macro-molecular structure of humic acids is linked to hormonal changes, including auxin and nitric oxide, that presumably regulate root growth. The resistance of humic materials to microbial actions helps in maintaining soil structural stability. The humic acids may alter the cellular electrical environment via modulation of the plasma membrane proton pump (PM-ATPase). Intensified proton (H+) extrusion to apoplast and enhanced root growth both reflect an extension in root absorption capacity that modulates the plant nutrition. This chapter illustrates the possible effects of humic acids and Alkamides on root development, nutrients uptake efficiency, nutrients cycling, and crop yield.
