Humates, Soil Fertility and Organic Farming

Article written by Sam Uffindell

Humates have been around since the dawn of time and are seeing a renaissance in agricultural use. Humates are soft coal deposits that are carbon dense, rich in humic substances, including humic and fulvic acids, and are regarded by agronomists as one of the most important components in building soil fertility. Consumer preferences, government regulations, environmental sustainability and evolving farming practices are all contributing to a shift towards cleaner, more sustainable methods of agricultural production. Humates can play a key role in helping to improve our soil and meet consumer, regulatory and environmental requirements.

There are numerous benefits to your soil from using humates. Number one is that they can significantly increase the amount of soil organic matter, which has numerous key roles in plant growth and development. The benefits for the soil are broad and include increased microbiological activity and additional nutrient holding capacity, leading to healthier plants and deeper root systems. Higher levels of soil organic matter also drive increased oxygen flow and water retention. The soil peds are improved and expanded and soil rich in organic matter is capable of holding up to 170,000 litres of water per hectare, providing farmers with increased protection against drought conditions.

The presence of humic acid in the soil assist in the mobilisation and transportation of metal ions and enhanced cation exchange capacity, bringing more iron, copper, manganese and zinc into the plant. The additional fulvic acid works in the soil to dissolve minerals and trace elements, turning them into readily absorbable bio-available forms. Fulvic acid has the ability to act as a superhighway for nutrients, taking them from the soil into plant roots and enhancing penetration through cell walls.  All of this is great from a growth standpoint. Healthier soils and greater root penetration will assist in producing bigger yields and higher nutrient content, which importantly leads to healthier food for animal and human consumption. Raw humates, with their humic and fulvic extracts, are powerful microbial stimulants. Humic acid feeds and stimulates the fungi component of your soil, while fulvic is a bacterial stimulant. Good quality humates contain a significant humic and fulvic component, so a soil application of humates will feed and stimulate both the fungal and bacterial workforce. 

New Zealand’s nitrogen fertiliser use has increased nearly 600% over the past 30 years. Over the same time, the use of pesticides has increased by around the same rate. This has led to a significant increase in nitrates, phosphorus, soil runoff, leached nutrients and animal by-products in our waterways. The net impact is an increase in algae, which decreases oxygen levels, destroys species, fuels toxic blooms and makes our waterways unsafe for New Zealanders.

Environmental regulations are increasing in New Zealand and this will necessitate an evolution in our farming practices and waterway management. The Green Party, as part of its Farming for the Future Plan, has called for levies to be introduced on nitrogen and phosphorous fertiliser applications. They have called for caps on synthetic nitrogen fertiliser, as well as other measures to protect our freshwater systems. It will be interesting to see what aspects of this plan the Labour government implements through its partnership agreement with Greens. Minister for the Environment, David Parker, has repeatedly signalled he intends to enforce measures to clean up New Zealand’s waterways. With Greens co-leader James Shaw as the Associate Minister for the Environment and Minister for Climate Change, expect efforts to combat leaching and an increased focus on sustainable farming to be common themes of the next three years.

Humates can drive cleaner and more sustainable agricultural practices. They increase chelation, or the holding capacity of the soil, meaning that nitrogen that is not immediately taken up by the plant is more readily retained in the soil for later use, instead of being leached into our waterways. When combined with humates, nitrogen is stored on the humate colloid by the free radicals within the humic and becomes a very stable, slow releasing nitrogen source. All 46 units are retained, and the release pattern is extended by 60-80 days, thus allowing 10-40% less nitrogen to be used. In areas where farmers need to reduce nitrate leaching, humates can play a role in minimising the adverse impacts of nitrogen applications. By using humates, leaching and lockup are dramatically reduced as the plant nutrients are held in the soil and made available to the plant roots upon demand, thus increasing the protein and mineral content of most crops. In addition, inputs will be absorbed and utilised much more effectively, with a 30-50% improved uptake in the presence of humates.

Carbon sequestration is also improved through humates. The number of carbon molecules on earth and in our atmosphere remains constant and carbon takes one of several forms: stored within our soil as humus, contained within plant and animal life forms, or within our atmosphere as CO2. Unfortunately, a significant amount of carbon that was once trapped in our soil as humus has been released into our atmosphere, contributing to climate change. We can use humates to help build up the soil organic matter and effectively work to sequester carbon. Soil rich in organic matter, with high chelation qualities, will work to more actively retain carbon that is brought into the soil through decomposing organic matter or photosynthesis; improved soil conditions means carbon will be more readily sequestered in the soil. We have a great opportunity to use humates to start using our soil as a carbon sink, working to offset the adverse impacts of climate change.

There are several humates products in New Zealand that are BioGro certified. Farmers have the opportunity to move away from heavy chemical fertiliser applications and adopt an approach that is not only environmentally sustainable but provides better crop outputs, reduces costs and improves health outcomes. They should always look for high quality humates, which is not ground up coal but is found in a layer above leonardite or lignite, containing much higher levels of soluble humic and fulvic acids. There are a number of farms that have evolved towards more organic practices and are reaping the numerous benefits such a move can provide. Humates should be a key ingredient in all organic farming practices.

Many thanks to Sam Uffindell from New Zealand HuMates Ltd. for writing this article for the ODPG, which will also be available on our Resources page.

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Cover Photo Credit: Lukas (

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