Humic acid fertilizers, also known as compost, are organic fertilizers rich in humic acid and inorganic nutrients, made primarily from peat, lignite, and weathered coal through chemical treatment and the addition of inorganic fertilizers. Their main types include ammonium humate, potassium humate, sodium humate, and compound humic acid fertilizers, which have functions such as improving soil, enhancing fertilizer efficiency, and stimulating crop growth.
Core Functions and Mechanisms of Humic Acid Fertilizers:
Humic acid fertilizers play five main roles in agricultural production, improving soil fertility and crop quality through physical, chemical, and biological mechanisms.
1. Improving Soil Structure: As an organic colloid, humic acid can bind clay minerals to form water-stable aggregates, enhancing the soil’s water and fertilizer retention capacity, regulating pH, and improving both saline-alkali and acidic soils.
2. Improves fertilizer utilization: Its strong adsorption and chelation capabilities reduce nitrogen volatilization and phosphorus and potassium fixation. Experimental data show that nitrogen fertilizer yield can increase by about 10% and phosphorus fertilizer utilization can more than double after application.
3. Stimulates crop growth: Contains physiologically active substances that can promote seed germination 1-3 days earlier, increase root quantity and vitality, and enhance the crop’s ability to absorb water and nutrients.
4. Enhances stress resistance: By regulating crop physiological metabolism, it improves the plant’s resistance to drought, cold, and pests and diseases, reducing the occurrence of soil-borne diseases.
5. Improves agricultural product quality: It helps increase the sugar, starch, and vitamin C content of fruits, reduces nitrate accumulation in vegetables, and improves the taste and color of crops.
Product Classification and Applicable Scenarios
Humic acid fertilizers can be divided into various types according to the source of raw materials, composition, and application method. Farmers need to choose according to their actual needs.
1. Classification by Raw Materials:
– Mineral-derived humic acid: Extracted from weathered coal and lignite, it has high humic acid content and strong activity, suitable for soil improvement and cash crops.
– Biochemical humic acid: Derived from fermented straw and livestock manure, it has high organic matter content and is suitable as a base fertilizer for soil enrichment.
2. Classification by Composition:
– Ammonium humate: Provides nitrogen nutrients, has slow-release properties, suitable as a raw material for base fertilizer or compound fertilizer.
– Potassium humate: Good water solubility, high potassium content, suitable for fertigation, drip irrigation, and foliar spraying.
– Humic acid compound fertilizer: Combines nitrogen, phosphorus, potassium, and trace elements to provide comprehensive nutrition.
3. Classification by Application Method:
– Base fertilizer: Use granular or powdered humic acid organic fertilizer, applied before planting.
– Top dressing: Use water-soluble or liquid fertilizer, applied during the growing season via fertigation or drip irrigation.
– Seed soaking/foliar application: Use sodium humate, potassium humate, or fulvic acid solutions to promote germination or provide rapid fertilization.
Purchase Guide and Application Techniques
Correct selection and scientific application are key to maximizing the effectiveness of humic acid fertilizers.
1. Selection Points:
– Check Raw Materials: Prioritize products from mineral sources labeled “extracted from lignite/weathered coal,” as their activity is more stable.
– Check Indicators: High-quality mineral sources should have a fulvic acid content ≥50% and water-insoluble matter ≤0.5%. Avoid purchasing products with incomplete qualifications or falsely labeled indicators.
– Check Certifications: In organic farming settings, choose products with organic input certification to ensure heavy metal compliance.
2. Application Recommendations:
– Application Timing: Apply base fertilizer early; top dressing should be applied during peak crop nutrient requirements (such as the fruit expansion stage).
– Incompatibilities: Ammonium humate is weakly alkaline; avoid mixing with strongly alkaline fertilizers. Potassium humate is more expensive and is recommended for high-value cash crops. – Dosage control: The dosage of solid compost is generally 100-200 kg per acre, and liquid fertilizer should be diluted according to the instructions before spraying or fertigation.
