Humic Substances: Prospects for Use in Agriculture and Medicine

*Priya Goel and Madhu Dhingra*

### **Abstract**

Humic substances are the naturally occurring biogenic, heterogeneous organic compounds resulting from the decomposition of plant, animal and microbial residues, over many thousands of years. Research into humic substances have found them to be beneficial not only for crop production, but for human and animal health also. Humic substances influence crop yields by affecting soil texture, water retention, nutrient buffering capacity and microbial diversity. Their stimulatory effects on plant growth and physiology can be ascribed to enhanced nutrient uptake, hormonal activity with root growth and proliferation, activation of antioxidant defense under various abiotic stresses. Furthermore, their potential to remove toxic pollutants from soil as well as aquatic systems might resolve the problem of degrading environment. Positive effects of humic substance on soil as well as crop without harming the environment make humic acid a sustainable solution for crop production. The antioxidant, immunomodulatory, anti-inflammatory, detoxifying and nutritional properties of humic substances opens up new avenues for their medical applications. Still, more research is needed to completely explore their potential. This chapter will summarize and review information about the prospects of using humic substances in agriculture and medicine.

**Keywords:** Humic substances, Fulvic acid, Humic acid, agriculture, medicine

#### **1. Introduction**

Humic substances (HS) are soil-derived substances that form one of the vast reservoirs of organic carbon in nature. HS are primarily produced by physical, chemical and microbial degradation and transformation of plant and animal tissues (humification process) over millions of years. They constitute the bulk of organic matter of the soil – humus, peat, lignites and also brown coal. HSs may also be produced as a by-product of the synthetic oxidation reactions of phenolic compounds.

Humic substances contain carbon, hydrogen, oxygen and nitrogen with small amounts of sulfur and phosphorus. They are a mixture of acids that can be fractionated on the basis of differences in their solubility into humic acid (HA), fulvic acid (FvA) and humin fractions, beside ulmic acid, and some microelements. Humic acid includes aggregates of long chain, high molecular weight compounds, soluble in alkali, while FVA is a mixture of short chain, low molecular weight compounds, soluble in both acidic and alkaline solutions. Humin, in contrast, constitutes the non-soluble fraction of the humate.

Owing to their unique structural and chemical properties, humic substances make an excellent soil amendment. They offer beneficial impacts in terms of overall soil structure, water holding capacity and nutrient availability in the soil along with

#### **Figure 1.**

*Applications of Humic Substances in various fields of agriculture and medicine.*

positive effect on the microbial communities in the soil, hormone like impact on plant growth. Thus, proving their vitality for farmers' economic status. HSs have also been applied in the treatment of various human diseases and maintaining overall vigour and growth of the body. Being rich in minerals which are easily assimilated in our body, their consumption in the form of dietary supplements and addition in cosmetic products is highly recommended. **Figure 1** tabulates various fields of agriculture and medicine where humic substances have shown their applications.
