Humic acids are primarily used as an addition to liquid fertiliser foliar applications.
The main benefit of adding them is that plants will be able to uptake and utilize the other nutrients in the solution many times more effectively than without the humic acids.
Humic acids also increase the water infiltration and water-holding capacity of the soil. They greatly improve the soil, increase plant root growth and metabolism, enhance seed germination, and help plants deal with environmental stresses.
In the soil, humic and fulvic acids are important chelators, combining minerals into organic compounds that are more available to plants. They also tie up toxins, making them less available to plants.
Humic Acids Application
Humic acid powder can be applied dry, but it is more commonly mixed with water in a watering can, sprayer, or irrigation system. Liquid humic acids are ready to use after dilution. Although the application rates are very low, they are optimal, so applying more is not better.
Whenever the powder is used in water, pre-mix the desired amount of powder with warm water in a separate container in order to dissolve it thoroughly before adding it to the final liquid tank. Work slowly, and preferably outdoors – it’s messy.
Powder product: For foliar spraying, mix 1 teaspoon of powder into one gallon of water and spray leaves until wet. For soil application, mix 2 tablespoons of powder into one gallon of water to cover 1,000 sq ft.
Liquid product: Dilute at rates between 1:10 (100mL per 1L of water) for soil application, and 1:50 (20mL per 1L) or weaker for foliar spraying. Shake well before diluting. If leaves get stained, dilute more.
More detailed instructions:
- To make a 6% concentrated solution from powder – Mix the dry powder with water at 65g of powder (5 tbsp or 1/3 cup) per liter of water. Or buy the ready to use liquid.
- For direct soil application, apply 50 mL (3.5 tbsp) of this solution per 1,000 sq, diluted with water at a rate of 1:10 (50mL in 500mL). For best results, apply to moist soil at planting or prior to germination and irrigate after. Applications may be made every 4-6 weeks during the growing season.
- For seed treatment, dilute 1:20 (50mL per 1L). For a transplanting soak, dilute 1:30 (35mL per 1L).
- For foliar spraying, dilute the solution 1:50 with water (20ml or 4 tsp per 1L of water) and spray on plant foliage until the leaves are fully wet. At this dilution, one liter covers some 2000 sq ft. If stains appear, dilute more.
- In daily irrigation systems and for hydroponics, you can dilute down to 1:100 or weaker (just a few drops per liter).
- Compost Tea – Add 15 g (1 tbsp) of dry humic acid powder or about 150mL of the 6% solution into your 5-gallon brewer at the start of the brew. No more.