Humic acid is a natural organic acid widely found in soil, peat, and weathered coal. It improves soil structure and enhances plant nutrient absorption. It cannot be directly absorbed by plant roots and must be properly diluted before application to the soil to effectively regulate pH and activate trace elements.
● Application Scenarios and Methods
▲ Basal Application for Soil Improvement
1. Newly Reclaimed or Compacted Soil: Mix 3-5 kg of humic acid powder (or granules) per acre with fine soil or well-rotted organic fertilizer. Tillage to a depth of 15-20 cm. Continuous use for two seasons can effectively improve soil aggregate structure.
2. Potted Vegetables: When repotting, add 3% humic acid by soil volume (approximately 100 grams for a 5-gallon pot) to significantly improve soil looseness.
▲ Topdressing During the Growing Season
1. Water-soluble Fertilizer Application: During the flowering and fruiting period of cucumbers and tomatoes, it is recommended to dilute 1 catties of humic acid with 200 catties of water and apply it with irrigation. When using a drip irrigation system, ensure proper filtration of residue.
2. Combined with EM bacteria: First dilute humic acid, then add EM bacteria solution and let stand for 2 hours before fertigation. This can significantly improve soil microbial activity.
▲ Foliar Fertilization
1. For nutrient deficiency causing yellowing leaves or during seedling establishment: Liquid humic acid stock solution needs to be diluted 800-1000 times (to a light tea color). Spray both sides of the leaves in the evening or on a cloudy day. Spraying 2-3 times at 10-15 day intervals yields the best results.
2. Use with caution during flowering: To avoid affecting pollination, the effect is more pronounced on leafy green vegetables (such as spinach). Leaves typically turn green and thicken within 5-7 days.
● Precise Dosage Control
▲ Adjustment according to soil type
1. Compacted/infertile soil: Prioritize mineral-derived humic acid (high molecular structure, long-lasting soil improvement). The recommended basal application rate is 3-5 kg per acre.
2. Saline-alkali/acidified soil: Bio-derived humic acid (small molecule, pH regulating + root promotion) is recommended. For saline-alkali soil, it can be combined with desulfurized gypsum (300 kg/mu) for deep plowing and irrigation to lower the pH value.
3. Soil affected by continuous cropping diseases: Humic acid (5 kg/mu) used in conjunction with probiotics (such as Bacillus subtilis) can reduce the incidence of soil-borne diseases by 40%-60%.
▲ Adjustments according to crop stage
1. Field crops (wheat/corn):
Sowing period: Soaking seeds in a 0.1% humic acid solution for 2 hours can promote root development.
Jointing stage: Drip irrigation with 1 L/mu of mineral-derived humic acid solution combined with high-potassium water-soluble fertilizer can increase root density by 40%.
2. Fruit trees: Basal application of mineral-derived humic acid combined with fertigation of potassium humate during the fruit expansion period can effectively increase fruit sugar content and vitamin content.
● Key Precautions
▲ Mixing Contraindications
1. Avoid mixing with strongly alkaline substances (such as lime, wood ash), as this will reduce effectiveness; when mixing with calcium fertilizers (such as calcium nitrate), prepare and use immediately to prevent precipitation.
2. Do not use simultaneously with copper preparations (such as Bordeaux mixture) or strongly alkaline pesticides (such as lime sulfur).
▲ Soil Adaptability
1. Sandy soil: It is recommended to apply in small amounts multiple times to prevent nutrient loss; for clay soils, mineral-derived humic acid should be used for long-term improvement.
2. Infertile soil: Organic fertilizer should be supplemented before using humic acid; its main function is to “enhance” rather than replace fertilizer.
▲ Usage Limits
1. Base application: No more than 200 kg per acre per year to avoid carbon-nitrogen imbalance.
2. Foliar spray: Concentration not exceeding 0.3%; prohibit use during high-temperature periods to prevent leaf burn.
● Special Application Scenarios
▲ Saline-Alkali Land Improvement
1. Core Technology: Deep plowing and irrigation with fulvic acid (5 kg/mu) combined with desulfurized gypsum (300 kg). Fulvic acid chelates sodium ions, and gypsum replaces colloidal sodium in the soil, synergistically lowering the pH value.
▲ Disaster Response
1. After hot, dry winds or floods: Timely application of humic acid water-soluble fertilizer, combined with foliar spraying of 0.15% urea + 0.2% potassium dihydrogen phosphate + brassinolide, can promote rapid new root growth.
▲ Cotton Planting
1. Base Fertilizer Stage: 50 kg/mu of potassium humate to build soil nutrient pools.
2. Budding Stage: Foliar spraying of 0.1% fulvic acid solution to promote flower bud differentiation.
3. Boll Opening Stage: Drip irrigation with fulvic acid chelated zinc fertilizer to enhance fiber strength, achieving a yield exceeding 500 kg/mu.
