Role of humic acid or humic substances in agriculture: A Review
Neeraj Nath Parihar, Dr. VR Shelar
Humic material is very large and complex molecules extracted from organic matter, have been used in many ways for plant and seed production. There are numerous reports of plant response to these materials. This reviews their use in agriculture and points to consider before using humic materials. Since the beginning of Human civilization, the soil organic matter has been used as plant growth promoter or regulator. Indeed, early in plant science history, even before the auxin concept has been established, the term “auximones” was coined to describe plant growth promoting humic acids derived from peat. Despite of this, until the end of the 20th century, humic substances remained as some of the most neglected environment signals in plant physiology research. However, this scenario has changed in last decade with the discovery that the major systems of energy transduction of the plant cell membranes, the proton pumps, can be tightly orchestrated by humic substances just as elicited by a hormonal signaling. Differential activations of both plasma membrane (PM H+-ATPase) and vacuolar pumps (V-ATPase and H+-PPase) are modulated by humic substances triggering ion signatures related to specific patterns of plant growth and development. Phytohormones have been found to be associated with this humus bioactivity. The key role of organic matter in the sustainable agriculture will also be highlighted from a biochemical perspective of the plant cell responses to biofertilization, specially in tropical environments.