Both pumice stone and volcanic rock ... but certainly do not do/provide the same thing as manure or organic matter.... Pumice, because of the open structure, is supposed to good at aerating and opening up heavy clay soils.
Manures can do this too and provide food for fungi and microbes. That was my point.
Fire, manures cannot do all what pumice and rock dust does though. Manure and organic matter are still my first choice for a soil amendment but cannot do what either pumice (persist) or rock dust (remineralise) does. As I said they are complementary (not equivalent) products.
Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
Both pumice stone and volcanic rock ‘dust’ have their uses in the garden as soil amendments. As far as I’m aware they do and provide different things in the garden but certainly do not do/provide the same thing as manure or organic matter. It would be complementary to the application of that.
Pumice, because of the open structure, is supposed to good at aerating and opening up heavy clay soils, but because it’s essentially silica (glass) and does not break down easily, I’m not sure whether it adds anything to the microbial and fungal health of the soil nor whether the minerals and trace elements it contains are easily available for plant uptake. I have used a very local source of this in my garden (I live close to a volcanic zone) but not for soil health per se..
Basalt rock dust is supposed to be excellent at remineralisation of nutrient deficient or exhausted/overworked soils as the high mineral and trace element content is more immediately available for plant uptake. I suspect it might also be better for overall soil health vis microbial and fungal activity but I have absolutely no evidence to back that. There are UK sources, mined in Scotland (Remin brand) so it does not have to have a high environmental impact, or at least no more than many other garden products.
Is it worth a compare and contrast with the basalt rock dust re purpose/effectiveness, price, application rates etc?
Hello Nollie, Remin is where I get my rock dust from. To answer your question about pumice, it is not expected to contribute any nutrition by yielding its own mass. The purpose of adding it is to enhance the characteristics of the growing medium, the soil. It benefits funghi and bacteria by being a persistent source of air and water retention, that does not need to be topped up over time. As you say, it can complement other natural additives, and in my garden I use it with home made compost, home grown worm castings, rock dust and regular treatments of compost tea. A 360 degree health regime . I have no idea if it works, but I'm enjoying the process.
Hi, many thanks for clarifying that, I think we are in agreement then 😊 There are some erroneous claims about pumice out there which make it sound like it does the remineralising job of rock dust too but I just wasn’t convinced. You will certainly have a very well amended soil!
My initial reason for using pumice was entirely different - I find a ring of pumice gravel around susceptible plants like young dahlias stops snails in their tracks, they hate the dry, rough texture and won’t cross it. It needs renewing every year as it eventually gets mixed in with my clay soil, where I guess it can then adopt the longer term role.
Apologies if this has been said already but what, if any, additional soil amendments are necessary entirely depends on what your soil is like to start with and what you are growing. There is a danger of over-enriching your soil, especially for plants that prefer leaner conditions, or if you go overboard with the rock dust you over-mineralise, which can bring it’s own problems. Not a criticism of what you are doing at all, you’ve clearly done your research, just something to bear in mind generally..
Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
Hi, many thanks for clarifying that, I think we are in agreement then 😊 There are some erroneous claims about pumice out there which make it sound like it does the remineralising job of rock dust too but I just wasn’t convinced. You will certainly have a very well amended soil!
My initial reason for using pumice was entirely different - I find a ring of pumice gravel around susceptible plants like young dahlias stops snails in their tracks, they hate the dry, rough texture and won’t cross it. It needs renewing every year as it eventually gets mixed in with my clay soil, where I guess it can then adopt the longer term role.
Apologies if this has been said already but what, if any, additional soil amendments are necessary entirely depends on what your soil is like to start with and what you are growing. There is a danger of over-enriching your soil, especially for plants that prefer leaner conditions, or if you go overboard with the rock dust you over-mineralise, which can bring it’s own problems. Not a criticism of what you are doing at all, you’ve clearly done your research, just something to bear in mind generally..To be honest, the cost of all these things adds up to do much money, it's difficult to over apply them, because of budget.
I have a bit of a slug problem at the moment, but it's pretty much constrained to my marigolds, that are now dead stumps, basil, which is horribly nibbled at and my hosta, which has suffered mild damage.
I used nemotodes to try and control the slugs and there does seem to have been an effect in reducing the numbers, but I think slugs are quite mobile and travel between gardens, so if your neighbour doesn't use them, you can't be completely successful. I use coffee grounds around the hosta, which may or may not be helping. I will try your idea of the pumice!
My latest batch of soil preparation is underway now. I have two pear and two apple trees being delivered in January, and I want to make sure they go into the healthiest possible growing medium, to act as a precaution against disease. I plan to not reading once the trees are in. In the end I bought 20 litres of fine pumice and 20 litres of fine zeolite. To answer my own question, I found zeolite to be £5 cheaper per 10L and to have much the same properties as pumice. I'll also add organic compost, shredded dried seaweed and some insect frass. I'll use a treatment of Rootgrow, which is a funghi inoculation product. The trees will be bare root, so that will go straight on them. I'll also be doing monthly treatments of compost tea, using a mix of home made worm castings & compost, seaweed, frass and some natural debris from my local woods.
I messed up my comment there, but what I meant to say is that once the trees are in, that's my last chance to modify the structure, so I need to add lots of persisting air bubbles. I'll also get a batch of worms, and forgot to mention a serving of rock dust . Then I can treat it regularly by adding organic matter over the top, which will feed my nice habitat that is working for me under ground
I really wouldn't worry about adding minerals to clay ... clay is some of the most mineral rich and potentially fertile soil types there is ... what is needed is to improve the structure (which you're doing) in order for the minerals in the clay to be accessible to the roots of your plants.
This was proved by the farmers on the heavy clay of High Suffolk ... improved drainage and the addition of copious quantities of farmyard manure has made what was, a generation ago, almost worthless land, into some of the most productive and valuable in the country.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
I messed up my comment there, but what I meant to say is that once the trees are in, that's my last chance to modify the structure, so I need to add lots of persisting air bubbles. I'll also get a batch of worms, and forgot to mention a serving of rock dust . Then I can treat it regularly by adding organic matter over the top, which will feed my nice habitat that is working for me under ground
Tree roots will themselves help to improve your soil; their root growth physically breaks up the soil, and (something I hadn't appreciated until recently) their fine roots go through a continuous cycle of death and renewal. This adds organic matter to the soil, improving the structure of it and promoting beneficial fungi etc. I think that a tree's roots contribute more to the organic matter of the soil than fallen leaves.
Re pumice, I could see an advantage for using it in a targeted way for specific plants, but I think chunky organic matter is going to give better bang for your buck on a garden-wide basis. The organic matter will degrade over time as you say, but the soil will remain 'alive' due to the roots that are continually penetrating it and going through death/renewal cycles, and the addition of organic matter at the surface, and the action of worms and fungi etc.
"What is hateful to you, do not do to your neighbour".
I messed up my comment there, but what I meant to say is that once the trees are in, that's my last chance to modify the structure, so I need to add lots of persisting air bubbles. I'll also get a batch of worms, and forgot to mention a serving of rock dust . Then I can treat it regularly by adding organic matter over the top, which will feed my nice habitat that is working for me under ground
Tree roots will themselves help to improve your soil; their root growth physically breaks up the soil, and (something I hadn't appreciated until recently) their fine roots go through a continuous cycle of death and renewal. This adds organic matter to the soil, improving the structure of it and promoting beneficial fungi etc. I think that a tree's roots contribute more to the organic matter of the soil than fallen leaves.
Re pumice, I could see an advantage for using it in a targeted way for specific plants, but I think chunky organic matter is going to give better bang for your buck on a garden-wide basis. The organic matter will degrade over time as you say, but the soil will remain 'alive' due to the roots that are continually penetrating it and going through death/renewal cycles, and the addition of organic matter at the surface, and the action of worms and fungi etc.
What would you use? Fine bark? Leaf mould? I will be using a lot of organic compost. Is that enough or should I use more?
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My initial reason for using pumice was entirely different - I find a ring of pumice gravel around susceptible plants like young dahlias stops snails in their tracks, they hate the dry, rough texture and won’t cross it. It needs renewing every year as it eventually gets mixed in with my clay soil, where I guess it can then adopt the longer term role.
Apologies if this has been said already but what, if any, additional soil amendments are necessary entirely depends on what your soil is like to start with and what you are growing. There is a danger of over-enriching your soil, especially for plants that prefer leaner conditions, or if you go overboard with the rock dust you over-mineralise, which can bring it’s own problems. Not a criticism of what you are doing at all, you’ve clearly done your research, just something to bear in mind generally..
This was proved by the farmers on the heavy clay of High Suffolk ... improved drainage and the addition of copious quantities of farmyard manure has made what was, a generation ago, almost worthless land, into some of the most productive and valuable in the country.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
https://www.rhs.org.uk/soil-composts-mulches/clay-soils
Good Luck with your experiment.
I'll be interested to see how things go for you
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
Re pumice, I could see an advantage for using it in a targeted way for specific plants, but I think chunky organic matter is going to give better bang for your buck on a garden-wide basis. The organic matter will degrade over time as you say, but the soil will remain 'alive' due to the roots that are continually penetrating it and going through death/renewal cycles, and the addition of organic matter at the surface, and the action of worms and fungi etc.