Physical Effects of Humic Acid on Soil
Humic acid can increase soil organic matter and organic carbon content.
The high-quality soil shows characteristic dark brown and black brown, which absorbs solar radiation better and can increase the soil temperature. The temperature of dryland soil with high humus content is 2-3℃ higher than that of barren soil. Humus substance also reduces soil heat conductivity and acts as a buffer against sudden fluctuations in temperature to protect soil organisms from attack.
Humus substance is the bridge and binder of soil aggregates.
Soil application of humic acid can form a clay-humic acid complex. The acidic functional groups of humic acid exist in the internal structure and react with calcium and magnesium ions in the soil to form an aggregate structure, while the hydrophobic part of humic acid is in the outer layer of the aggregate structure, thus preventing the infiltration of water and the decomposition of soil aggregates.
Humic acid can reduce soil capacity and increase porosity and water-holding capacity.
The improved soil with humic acid can maintain a loose, porous, and small particle state, to improve soil air permeability, permeability, and water holding capacity, which is more conducive to root growth and seed germination.