Rockdust, Glacial Milk, and Plant Nutrition

I’ve been using rockdust as part of my soil balancing strategy, as well as an ingredient in my potting mixes. In addition I’ve been mixing rockdust into my poutry food, adding it to my wormeries, and compost heaps, but over the last couple of weeks I’ve been using the rockdust in a liquid suspension, to water my plants, and as a foliar spray.

Glacial Milk

One of the many books that have influenced me is ‘The Healthy Hunza‘ by J. I Rodale. In it he describes the milky coloured glacial meltwater, full of minute mineral particles, ground from rock by glacial action. (The particles are also known as Rock Flour)

agricultural terraces

Hunza Agriculture

This was described by Howard in ‘An Agricultural Testament’, and is the reason that Howard gives for the health of the crops, and of the people. The crops are irrigated using this mineral rich water, and the people drink the water, and eat the crops.

The glacial milk contains clay sized particles of rock, which give a massive amount of surface area on which soil microbes can eventually work to dissolve these minerals to use in their own bodies. This helps to make the minerals available to plants in an organic form.

Hunza Valley

Hunza Valley

 Replicating Glacial Milk using Rockdust

I don’t have any glaciers nearby, but the rockdust that I buy contains a really wide range of particle sizes. I added a small amount of rockdust to a jug of water and stirred it hard. Whilst the larger particles settled almost instantly, the water stayed cloudy for a long time, showing that the rockdust contained a lot of tiny particles. I was able to use this liquid to water plants, and as a foliar spray. Whilst using this rockdust ‘suspension’ to water plants may not offer any additional benefits compared with using the dust in a potting mix, the foliar spray can’t really be replicated by throwing dust at plants. The rockdust contains high levels of silica, which is used by plants in building cell walls, and to fight disease. (If you want to read more about silica, try an internet search of ‘silica fo.liar spray’)

Rockdust ‘Milk’ and Compost Tea

To provide a full range of minerals when making Actively Aerated Compost Tea, I usually add liquid kelp. The kelp provides a good range of minerals, as well as a number of other useful compounds. but it’s quite expensive. As the rockdust that I use also contains a wide range of minerals, I may be able to reduce the kelp content, and replace it with my rockdust ‘milk’. The microbes in the compost tea should be able to start digesting the tiny particles of rockdust  in the solution, helping to lock them up in their bodies. It also gives surfaces for the microbes to attach themselves to.

Mineral Rich Soil

When I read books like ‘The Healthy Hunza’, or articles suggesting that pests and diseases are the result of unhealthy soil, I wonder what it would be like to grow my food on ‘gritty’, mineral rich soils with far less organic matter than I have now. Would the lower levels of organic matter be so critical if the full spectrum of minerals were available to plants? Would lower levels of Soil Organic Matter create more dependence on Nitrogen fixing bacteria, and would that create a healthier environment? Sadly, I have no way of knowing. What I can do is some simple experiments to look at plants grown in pots with a high level of minerals, and low levels of Organic Matter, to see how they differ from plants grown inconventional potting mixes, and my own mix, which is already more mineral rich than most.

3 thoughts on “Rockdust, Glacial Milk, and Plant Nutrition

  1. Andy P

    After reading about the importance of Phosphorus, and how important it is and how the microorganisms convert it to a soluble form for it to be used I think it depends on how much “very little organic matter” you mean. Plants need a readily available amount of this through their whole life cycle.

    The microorganisms obviously need food to do this conversion. They also need phosphorus to convert nitrogen gas into a usable form.

    There may be a lot of surface area for the microbes but too little organic matter and in theory that won’t help without food. As far as I can remember most of the usable phosphor is in the organic matter. The young plants may be able to find enough in the mixture but in a small pot they should use it up and need more.

    Interesting to see if the effects match what I have read. A good test to try. I’m very interested.

    Are you going to grow the plants to fruiting stage and not feed during their life cycle?

    PS, I’ve just been informed that the permaculture course I am on is taking us to you later in the year 🙂

    1. Deano Martin Post author

      Hi Andy
      Microbe food is also produced by plant roots secreting sugars to feed them, which gives them the energy to find and accumulate minerals. Mycorrhizal fungi are pretty key in the case of Phosphorus, but plants are less likely to make the connections if Phosphorus is abundantly avaialable to them.
      Not sure about the feeding. For now I’m concentrating on observing, to see how the plants react. Adding a feed/not feed strand may just make it too complicated for simple observations, but I haven’t decided yet.
      I guess that means that you’re studying with Neckie and Joe. Introduce yourself at the visit, and perhaps tell the rest of the course that it’s worth a visit. Sometimes people drop out, particularly if the weather forecast is grotty.
      See you soon

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