Humic acid is essentially a naturally occurring mixture, which can play a role in improving the soil condition, enhancing the effect of chemical fertilizers, improving the quality of agricultural products, improving the stress resistance of agricultural products, and promoting rapid growth of crops in agricultural production.
Soil conditioner is an important aspect of soil remediation, which is mainly aimed at the comprehensive improvement of the physicochemical properties and biological properties of degraded soils such as soil salinization, acidification and desertification.
The main role of humic acid in soil conditioners is to improve soil aggregate structure, and fertilizer synergy, maintain acid-base balance and promote soil biological activity.
1. Improvement of soil aggregate structure
After adding humic acid into soil, the loose soil particles are aggregated through flocculation, which reduces the soil bulk density, increases the soil porosity, and forms a granular structure with good water stability.
Our studies have shown that the total number of soil aggregate structures can be increased by 1.5-3 times, and the total number of water-stable aggregate structures can be increased by 8.5%-30%. The water, fertilizer, gas, and heat conditions in the improved soil plough layer were significantly improved.
2. Improve fertilizer use efficiency
Humic acid can control nitrogen, release phosphorus and promote potassium, improve fertilizer use efficiency and increase crop yield.
For Nitrogen: The carboxyl, carbonyl, alcohol hydroxyl, phenolic hydroxyl, and other functional groups in humic acid have strong ion exchange and adsorption capacity. Reduce nitrogen loss and provide nitrogen source, reduce ammonium nitrogen loss. It can effectively slow down the release and decomposition rate of urea and improve the utilization rate of nitrogen fertilizer
For Potassium: Humic acid avoids the fixation of potassium by the soil and reduces the potassium fixation rate of the soil. Humic acid can activate potassium, decompose potassium fertilizer slowly, increase the release of potassium, promote the absorption of potassium by crops, and improve the utilization rate of potassium fertilizer.
3. Maintain soil acid-base balance
Humic acid is a weak acid and an organic macromolecular amphoteric substance. The H+ released by the acidic functional groups of humic acid can neutralize the alkaline substances in the soil to form H2O.
On the one hand, it can generate humate and form a buffer system for the mutual conversion of humic acid and humate. On the other hand, it can combine with various cations in the soil to reduce the soil salt content.
4. Application in heavy metal contaminated soil
Humic acid has a variety of chemical properties and can undergo redox reactions, complexation reactions, and ionic reactions with a variety of substances. It can effectively fix various metal ions through complexation reaction, reduce the absorption of heavy metal ions by crops, and reduce the negative impact of heavy metals on agricultural production and the natural environment.
Optimize the composition of soil structure, enhance the activity of various microorganisms in the soil, and compress the activity space and activity capacity of heavy metal ions. As an organic acid, humic acid can form a certain linkage effect with organic matter, microorganisms and plants in the soil, strengthen the absorption capacity of heavy metals in the soil, and achieve effective restoration of contaminated soil.