What Produce Growers Should Know About Humic and Fulvic Acids

As growers strive to produce more food on fewer acres, many are rediscovering nature-based tools to address yield-limiting factors. Rising production costs — driven by advanced genetics, expensive chemistries, and precision technologies — have shown that “new school” inputs do not always guarantee a return on investment. As a result, progressive growers are reintroducing affordable “old school” solutions to complement modern practices. Identifying yield-limiting factors and matching them with the right tools is critical. One major limiting factor is nutrient use efficiency (NUE). Nature’s original solution for improving nutrient efficiency is humic substances — humic and fulvic acids — naturally found in soil organic matter.

Humic acid (long-chain) improves soil properties, such as water-holding capacity, aggregate stability, and nutrient retention. Fulvic acid (short-chain) enhances plant functions, including root activity, nutrient transport, and stress tolerance.

However, high soil organic matter does not guarantee adequate levels of plant-active humic substances. Modern farming practices rapidly deplete these fractions; research shows more than 50% of the most active components can be lost within three years if not replenished. In perennial systems, limited organic matter incorporation further reduces soluble humus production.

Rather than attempting to rebuild the entire soil profile — which is cost-prohibitive — growers are “spoon-feeding” small, affordable doses of humic and fulvic acids through existing fertigation, nitrogen applications or foliar and broadcast nutrient passes. This targeted approach improves NUE where it matters most: the root zone.

Crops typically utilize only a fraction of applied nutrients due to losses such as leaching, fixation, volatilization, and precipitation. Humic substances help mitigate these losses across all major nutrients.

• Phosphorus is often only ~30% efficient due to tie-up with calcium, iron, and aluminum. Numerous studies show humic and fulvic acids significantly improve phosphorus availability by binding antagonistic cations and keeping phosphate soluble. This effect is especially valuable in low organic matter soils.
• Nitrogen efficiency averages about 70%. While split applications and stabilizers reduce losses, stabilizers can suppress beneficial soil biology. Adding humic acids improves nitrogen “hang time” by reducing ammonium volatility and stimulates microbial activity in the rhizosphere, helping offset the negative impacts of synthetic fertilizers and salt accumulation.
• Potassium is essential for water movement, nutrient transport, and carbohydrate translocation. Humic substances improve soil structure, release fixed potassium, and enhance root uptake. Research has documented potassium uptake increases of up to 34% with humic and fulvic acid applications.
• Micronutrients such as zinc, iron, manganese, and copper are far more available in chelated forms, although much of the benefit lies in formulation stability rather than plant uptake. Fulvic acid acts as a natural transporter for micronutrients, improving uptake efficiency by 50% to 200% in field studies. This allows growers to use lower-cost micronutrient sources while improving efficiency and crop quality.

By integrating humic and fulvic acids into existing fertility programs, growers can reduce nutrient losses, lower input costs, and improve yield and quality — using the same biological systems nature designed to optimize plant nutrition.