Rock Dust Can Revolutionize Soil Health

By Alanna Moore

Rock dust, also known as blue metal, cracker dust, or crusher dust, is a byproduct of the quarrying industry. Initially used by landscapers for filling holes, bedding paving stones, and mixing with cement, its applications have expanded as its true importance becomes apparent. In this article, we will explore the incredible benefits of rock dust for soil health and plant growth.

Remineralization: Restoring Life to the Soil

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Over a century ago, Julius Hensel introduced the concept of using crushed rock to improve soil fertility in his book “Bread from Stones.” Decades later, in the early 1980s, John Hamaker and Don Weaver emphasized the impending climate change and the need for massive-scale soil remineralization combined with reforestation. Their book, “Survival of Civilization,” was groundbreaking as it warned of climate instability, a prediction that has since proven true.

Intensively farmed and tropical soils suffer from rapid demineralization. However, rock dust can reverse this process by adding a rich array of minerals to nourish microorganisms and, with sufficient organic matter, rapidly rebuild topsoil. According to John Hamaker, remineralization is crucial for the soil’s ecosystem to obtain the nutrients necessary for the thriving growth of plants, animals, and humans.

Scientific Evidence: Trials and Research

Since 1997, the Australian construction company Boral has been scientifically documenting the benefits of rock dust. Their comprehensive studies demonstrate the positive effects of applying rock dusts alone or in combination with other soil preparations and fertilizers. The results have shown improvements in soil pH, water retention capacity, microbial activity, plant health, seed germination rates, and more.

Remarkably, Boral’s trials also revealed a paramagnetic effect of rock dust. Even without physical contact between plant roots and rock dust, control plants showed inexplicable lush growth when located near treated plants. Pot trials conducted by the Men of the Trees group in Western Australia further confirmed this phenomenon.

The Right Rock Dust: Choosing the Best Blend

While basalt rock dust is rich in trace elements, it may lack essential macronutrients such as nitrogen, phosphorus, and potassium. Boral suggests blending different types of rock dust, such as granites and river gravel, along with added minerals to address any deficiencies. However, it’s essential to evaluate your soil’s individual requirements, as poorly selected rock dusts can be toxic or create imbalances.

For example, soils with high iron levels may suffer from excess iron if basalt rock dust or lava scoria is applied without caution. On the other hand, the right amount of iron is crucial for photosynthesis, with 10 to 50 parts per million considered sufficient in fertile soils.

The Benefits of Rock Dust: Enhancing Soil and Crop Yield

The use of rock dusts has been proven to provide several benefits in agriculture:

  • Increase in crop yields
  • Lower mortality rates
  • Pest deterrent
  • Fungal protection
  • Weed suppression
  • Improved crop quality and flavor
  • Increased brix levels

Additionally, rock dust is particularly effective in acidic soils, as it helps raise pH levels and reduce acidity. Acidic soils tend to lock away essential nutrients like calcium and phosphates, while also releasing aluminum, which can cause free-radical damage in our tissues and be linked to health issues like repetitive strain injury and Alzheimer’s disease.

Application Rates and Regimes: Finding the Perfect Balance

When applying rock dust, it’s important to consider optimum application rates and regimes. Boral’s research recommends 5 to 10 tons per hectare (2 to 4 tons per acre) as the ideal rate. However, beyond the maximum rate, the effects level off, making it unnecessary to exceed the recommended amount.

To reduce costs associated with transportation and spreading, it’s more economical to apply larger quantities less frequently. For example, instead of spreading 2 to 4 tons per acre every two or three years, spreading 4 tons per acre every five or so years can be a better option. Even smaller amounts, like 1 to 2 tons per hectare (1/2 to 1 ton per acre), when applied more often, can yield positive results.

Austrian farmers have found that applying rock dust around the time of cutting the cover crop creates a more aerobic environment, facilitating the decomposition of the green manure crop.

One Final Note: Safety First!

While rock dusts offer numerous benefits, it’s crucial to prioritize safety. Fine particles of rock dust can pose a hazard if inhaled, resembling the dangers of asbestos to the lungs. Always wear dust masks when handling rock dust and ensure that it is properly covered or wetted down during transportation to prevent it from blowing away.

In conclusion, rock dust has the power to revolutionize soil health and plant growth. With its rich mineral content and remarkable effects on soil pH, water retention, microbial activity, and crop yield, it’s no wonder that its applications are expanding. Embrace the power of rock dust and unleash the true potential of your soil and plants!

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