Rockmin Composts Provides Local Solutions to the Global Soil Crisis

According to the Food and Agriculture Organization of the United Nations: 

Soils are fundamental to life on Earth but human pressures on soil resources are reaching critical limits. Careful soil management is one essential element of sustainable agriculture and also provides a valuable lever for climate regulation and a pathway for safeguarding ecosystem services and biodiversity

In other words, soil degradation is one of humanity’s greatest threats. Fortunately, there are experts like the father-daughter team behind Rockmin Composts who are on a mission to do something about it. The innovative company was founded in 2019 in Queensland, Australia, when Chris Cameron and his daughter Catriona Dale joined forces with two local Geoscientists, Martin I’Ons and Guy Lewington. From the beginning, the company was committed to regenerative agricultural practices and revitalizing the world’s agricultural soils. An inspiration behind their work was to replace standard, environmentally harmful synthetic fertilizers with rock dust-bearing composts that remineralize nutrient-depleted soils while facilitating soil-based carbon sequestration.

Specifically, their composts are designed to use natural mineral-based amendments to mimic the full nutrient profile and microbiological populations of the healthiest and most fertile soils found in nature. The company’s inspiration has led to a suite of site-customized, field-tested compost formulations informed by the latest soil science and microbiological research. 

The mission behind the company has deep roots. A 5th generation Australian primary producer, Chris Cameron has been researching soil nutrition and developing methods of regenerating and sustaining soil health for over 50 years. His respect for the interdependence of soil, plant, and animal health, along with decades of experience working with the ancient, weathered, nutrient-poor soils of his native Queensland, inspired him to develop a method to produce environmentally benevolent composts for soil regeneration. He notes that, at a basic level, soil-health interventions involve variations on three common themes: the shortage of organic matter, unbalanced mineral nutrients, and a lack of necessary soil microbiology. 

Cameron’s experience and passion for regenerative farming culminated in Rockmin Composts, whose products are tailored to address each of his soil-health intervention themes. This team of Cameron, Catriona Dale, and others are making an important impact locally as they provide sustainable, environmentally benevolent rock dust-bearing compost to farmers and graziers in northeastern Australia. Their methodology and approach, however, have much further reaching applicability. They recognize that they are part of a larger regenerative farming movement targeting the global environmental and food security challenges posed by unsustainable farming practices. 

Cameron and Dale’s particular passion is to provide a sustainable alternative to the synthetic fertilizers that contribute to three major environmental crises: soil degradation, climate change, and water pollution. Let’s look at each of these issues in more detail and then examine how Rockmin Composts’ work addresses them. 

Soil Degradation: Loss of Nutrients and Beneficial Microbial Communities

Soil degradation is now recognized as a global crisis. More than 98% of humanity’s food comes directly from our soils, yet every year millions of hectares of cropland are rendered unproductive by unsustainable agricultural practices. The overuse of nitrogen, phosphorus, and potassium salt fertilizers is associated with reduced crop yields and degraded soils. For example, ammonium-based nitrate and phosphate fertilizers have a long-term acidifying effect that negatively impacts crop yields and degrades soil microbiology. Using potassium chloride salt fertilizer contributes to soil degradation in arid regions due to soil salinization. Both soil acidification and salinization destroy beneficial microbial communities responsible for nutrient cycling and bioavailability to roots. The consequences are that plants in soils degraded by the continuous use of synthetic fertilizers are not as healthy and contain lower nutrient levels. 

Greenhouse Gas Emissions

Worse yet, standard farming practices are a major global source of greenhouse gas emissions. For example, if nitrogen levels from fertilizers exceed crop demands, the soil will begin to emit excess nitrogen in the form of nitrogen oxide, a potent greenhouse gas. It has also been reported that the over-application of nitrogen fertilizers can lead to increased carbon dioxide emissions from soils. 

It is estimated that around 5.5% of the world’s greenhouse gas emissions come from agricultural soils. Another 5.8% comes from livestock and manure, 3.5% from crop burning, 2.2% from deforestation, and 1.3% from rice cultivation. So altogether, around 18% of global greenhouse gas emissions come from agricultural sources. A more specific analysis of the carbon footprint of nitrogen fertilizer found that its manufacture, transportation, and use are responsible for 1.13 gigatons of greenhouse emissions. This is around 2% of global emissions. It was found that 2.6% of these emissions were from transportation, 38.8% were from fertilizer production, and 58.6% were from field emissions. Moving away from traditional farming methods to more sustainable practices, such as using organic, rock dust-bearing composts, could invert this emissions trend turning agricultural soils and crop management into a net carbon sink rather than an emissions source.

Nutrient Poisoning of Water

Synthetic fertilizers consist of highly soluble salts such as ammonium nitrate, diammonium phosphate, ammonium sulfate, and potassium chloride. Because of their high solubility, they can infiltrate the groundwater or be carried away in surface runoff before being absorbed by plants. Excess nitrogen and phosphorus are carried by field runoff into local streams, rivers, lakes, and eventually oceans. High concentrations of these nutrients cause algal blooms resulting in a thick mat of green slime that blocks sunlight from bottom-dwelling organisms and can release toxins under some conditions. The decomposition of these slime mats depletes local waters in oxygen, leading to fish kills and other ecosystem damage. This process is known as eutrophication. In extreme cases, waters become hypoxic, meaning there is not enough oxygen to sustain life. The resulting “dead zones” can devastate aquatic ecosystems and affect local food and economic security. For example, a large fish kill associated with a single eutrophication event in China led to the loss of approximately 2.5 million U.S. dollars’ worth of finfish revenues. This again points to the urgent need to find alternative fertilizers that are effective at replacing soil nutrients and produced in ways that don’t contribute to climate change or environmental degradation. 

So, this is the global challenge, how do food producers increase production to meet population growth needs in a sustainable way that reverses the potentially devastating problems of soil degradation, climate change, and eutrophication. The solution, as advocated by organizations such as the Rodale Institute and Regeneration International, is adopting regenerative farming practices that mimic natural processes in the restoration of soil, plant, and animal health. 

The central challenge is phasing out the use of synthetic fertilizers. But to do that, we need a sustainable replacement. This is where Rockmin Composts and Chris Cameron’s 50 years of experience play a key role. We will now look at the solution that Cameron and others are rediscovering and perfecting. 

Mimicking Nature’s Soil Regeneration Processes

Rockmin Compost’s principle of looking to natural materials and processes to tackle soil health issues is well-founded. The most fertile soils in the world are formed from fine-grained rock powders such as the “rock flour” produced by the grinding of bedrock beneath glaciers or the windblown silt sediments known as loess. Volcanic ash and alluvial silt deposits in river flood plains also represent natural rock powders that naturally produce highly fertile, nutrient-rich soils. For example, the fertile plains of central North America, eastern Europe, northern China, and the Argentine Pampas that form the backbone of the world’s agricultural production all developed on loess deposits. Loess can consist of glacial rock flour, volcanic ash, or wind-eroded sediments.

Neolithic farmers also took the clue from nature and began adding rock powders and organic material to soils to improve plant health and yield. The moderate use of various fertilizers continued until the industrial revolution, when modern synthetic fertilizer production began.

The birth of modern synthetic fertilizer production, and in particular, the discovery of the Haber–Bosch process that converts nitrogen gas to a nitrate fertilizer salt, led humanity away from traditional agricultural practices and resulted in a dramatic increase in food production. The increase in agricultural output due to synthetic fertilizers led to a dramatic rise in the world population. But the increased production has come with a heavy price. As we have seen, soil degradation, climate change, and water pollution, resulting partly from synthetic fertilizer use, now threaten food and water security worldwide.  

Companies like Rockmin Composts are taking us back to the earlier traditional farming methods but with the benefits of modern scientific insights. The company is part of a growing movement championing the use of rock dust mixed with sustainably produced organic matter as a replacement for synthetic fertilizers. Both laboratory studies and field tests have demonstrated the viability of this remineralization approach.

One of the first things that jumps out of the research is that the successful remineralization of soils with rock dust is not always simple. In a review of 48 crop trials using various silicate rock powders as fertilizers, scientists from the International Centre for Sustainable Development and the Institute of Crop Science and Resource Conservation in Germany identified several interrelated variables that should be accounted for when planning and implementing a rock dust remineralization project. These variables are summarized in the figure below.

This diagram is a simplification, of course. It doesn’t depict the fascinatingly complex interdependencies between the underlying geochemical and biochemical processes. It does, however, capture the central issue for successful soil remineralization: the dissolution rate of the minerals that make up the rock dust. It has been observed that under some conditions, the rate of silicate mineral dissolution is too slow to provide near-term nutrient replenishment. This has led to less-than-optimal results for some trials. Overcoming this potential limitation requires knowledge and experience. This is where Chris Cameron’s decades of research and field experience and Catriona Dale’s passion for sustainable agriculture once again come to the fore. The Rockmin Composts team has demonstrated that the rock-soil-microbial system can be tailored for optimal mineral dissolution rates, microbiological flourishing, and associated nutrient bioavailability.

The Rockmin Compost Process

The magic starts as piles of organic waste materials are heaped into open-air windrows. As microorganisms begin decomposing the organic material, the temperature in the pile increases up to as much as 70^oC. The material remains around this temperature for the entire 4-week composting cycle. Both moisture content and oxygen levels in the pile are monitored and optimized. 

In the third week of the cycle, a customized blend of rock dust is incorporated into the still-steaming pile of almost-compost. In the final week of the process, organic acids produced during composting extract macro and micronutrients from the rock powders. The extracted nutrients are maintained in plant-absorbable forms within the pile. These nutrients will be bioavailable to plant roots soon after compost application. 

Cameron also discovered that adding a unique mix of minerals and trace elements at the start of the composting process significantly reduced both ammonia volatilization and emission levels of the greenhouse gasses methane and nitrous oxide. This procedure maximizes the amount of carbon and nitrogen in the compost, which means more for the soil and less in the atmosphere. 

Their process is entirely natural, and their products are certified for organic production by the National Association for Sustainable Agriculture Australia (NASAA) and the U.S. Department of Agriculture National Organic Program (NOP). 

The Rockmin Compost process addresses four of the key variables from our “key factors” diagram above. They customize their product by mixing rock dust of a specific mineralogy and particle size with compost and selected microbes. The customization process optimizes the product for the site-specific factors: weather, plant species, and soil type. Adding rock dust to the steaming pile of organic material successfully addresses the challenge posed by the otherwise slow dissolution rates of silicate minerals. Having the nutrients pre-extracted by organic acids allows the composts to replenish soils and fortify plants over short periods. However, not all nutrients will be consumed in one growing cycle. The rock dust will likely remain in the soil as a slow-release fertilizer for several seasons. 

The specific composition of the rock dust added to the compost is based on a comprehensive, integrated mineral amendment program. Tests are performed to determine the mineral deficiencies in the target soil, and the rock dust additives are then formulated to address these needs. The rock dust additives are chosen not only to restore the macro and micronutrients needed for plant health but also for the trace elements that are increasingly recognized as essential for human health. 

They also have leveraged research on how bioavailable silicon in soils improves plant disease resistance and acts as a natural defense against animal and insect pests. This suggests that incorporating silica into the rock dust/compost mixture will allow farmers to minimize the use of chemical pesticides, thus eliminating another important source of environmental contamination.

Successful Applications

Rockmin Composts have been used for various applications throughout Queensland and beyond. The company has produced products for sugar cane production, intensive horticultural production, cattle grazing, and broadacre cropping. In 2021 their compost was compared with 57 other fertilizer and soil amendment products at Australia’s Grains Research and Development Corporation Tosari research farm. Rockmin Compost’s rock dust-bearing product resulted in the second-highest wheat yield and produced the greatest increase in beneficial soil microbial populations. The wheat yields and microbial populations for Rockmin Compost’s mineralized product versus standard synthetic fertilizer and untreated soil are shown in the graphs below.

They have also provided compost to Australia Zoo’s eucalyptus plantation to boost the soil fertility and enhance the quality of leaves for the koalas. By addressing nutrient deficiencies in the soil, they hope to address nutrient deficiencies in eucalyptus which means healthier, happier koalas.

The Future

 As Catriona Dale says on Rockmin Composts’ website: 

To be truly sustainable, we must seek to restore the full mineral profile of truly healthy and fertile soils, capture the nutrients that are removed from our paddocks, and return them to our soils.

Rock dust-bearing compost is the key to restoring this cycle. The decades of research and experience of Cameron have led to one of the leading examples of how rock dust and organic compost can successfully and sustainably remineralize degraded soils. Rockmin Composts has shown how the nexus of science and field experience can lead to innovative sustainable practices and products that offer a superior replacement for synthetic fertilizers. To summarize, the demonstrated benefits of their customized mineralized, organic composts are numerous. For the farmer:  reduced costs, reduced fertilizer and pesticide use, increased yield and increased quality. For the environment: increased carbon sequestering capability, healthier waterways, decreased erosion due to improved soil structure, greatly reduced reliance on chemicals and toxins. For the consumer: nutrient-dense produce grown without the use of toxic chemicals.

We’ll close with a quote that embodies the Rockmin Compost team’s outlook and approach (from their company’s Facebook page):  

“The health of soil, plant, animal, human and planet as one and indivisible…Hopefully, the wider farming community is coming to understand this and the utmost importance of creating and sustaining healthy soils.”

To learn more about Rockmin Composts, visit their Facebook page.

James Jerden is an environmental scientist and science writer focused on researching and promoting sustainable solutions to urgent environmental problems. He holds a Ph.D. in geochemistry from Virginia Tech and a Master’s degree in geology from Boston College. Over the past 20 years, James has worked as a research geochemist and science educator. He joined Remineralize the Earth because of their effective advocacy, research, and partnership projects that support sustainable solutions to urgent environmental issues such as soil degradation (food security), water pollution from chemical fertilizers (water security), deforestation, and climate change. As a science writer for RTE, his goal is to bring the science and promise of soil remineralization to a broad, non-technical audience. When not writing, he can be found at his drum set.