Should I use rock dust in desert soil

I am a newbie who had a disaster for my first years garden so I don't want a repeat. I live in the desert which I have heard has alkaline soil. There seems to be controversy on whether rock dust is beneficial. First some say the calcium in rock dust will break down more quickly then the other nutrients which will make the soil more alkaline. Others say that the rock dust takes 100 years to break down so it is useless. Still others say the plants uptake it and it helps repel disease and helps make a bigger yield by giving minerals that are depleted.

I also wonder about the heavy metals in rock dust and do the plants convert them or would I be adding toxins to my food. I have been using Happy Frog and Ocean Forest as a base because I need time for compost to break down, yet my plants didn't do well for several reasons, many of which I have been learning on this journey.

So, do I use the rock dust?


  • Megan Venturella
    Megan Venturella Posts: 678 ✭✭✭✭

    I don’t have an answer for you! But a few considerations- have you had your soil tested? It’s probably the only way to know for sure what you need to add. As for the rock dust, what kind? Azomite powder? I’m assuming that’s the info you need to really answer your question.

    In the meantime, I’d start building a massive compost pile for next year! Find a friend with livestock and you’ll be set! Even without doing soil tests, maybe you could skip all of the above and plant in the compost next year.

  • Acequiamadre
    Acequiamadre Posts: 269 ✭✭✭

    Steve Solomon has a few opinions on this. His book "Gardening When It Counts" discusses this--and he has adapted his organic fertilizer mix to high- alkaline desert soils. He recommends amendments based on a $25 dollar soil test--you can use the results to figure out what you need. It on my to-do list! Like you, I like in the desert with that soil profile. For the record, I use Azomite in my kitchen garden soil and nothing has imploded--yet. However, I build a compost pile and make my garden bed soils almost purely from that.

    This year I am putting more "in ground" row beds, so will know more--learning the hard way.

  • Debra
    Debra Posts: 7

    Thank you! Yes, I have started a compost pile and am waiting to build it big when the leaves come. I have been blending the food and adding it to keep away pest problems and I bought Cascade Minerals on the advice of a long time desert youtube gardener, but became reluctant because I don't want to be eating heavy metals. The soil test is definitely worth the $25.

  • Torey
    Torey Posts: 5,396 admin

    Hi @Debra Welcome to TGN! Have you checked out the Academy? In particular, the Nutrient Dense Soil course? Lots of great information on how to build healthy, life-giving soil. There is also one on Bio-intensive Gardening which is based on nutrient dense soil.

    Best idea is always a soil test kit so you know what you are starting with. If you do have alkaline soil, adding some peat moss along with the compost will help sweeten the soil. If it is like desert soil that I know (won't hold much water), the peat will help retain water as well.

  • Debra
    Debra Posts: 7

    Thank you!

  • Gil Montano
    Gil Montano Posts: 39 ✭✭✭

    A good idea to achieve a better quality substrate is to add the food waste that the ants leave outside the anthill. It is made up of seed hulls or other wastes that contain some of the secretions produced by the ants during the processing of their food.

  • Thomas
    Thomas Posts: 81 ✭✭✭

    @Debra I have read, but don't have the link anymore, that plants that are healthy and getting the nutrients they need do not readily absorb those things that they don't need - for example Arsenic or Lead in Azomite.

  • Gil Montano
    Gil Montano Posts: 39 ✭✭✭

    I don't know what you mean by rock dust, but everything you do to improve the substrate for your plants is a good thing, with the understanding that you are going to enrich the substrate where you are going to put your vegetables or what you are going to sow for your consumption. Otherwise you would be altering the substrate of the native desert plants.

  • Hassena
    Hassena Posts: 345 ✭✭✭

    Hi @Debra

    Desert soils and water tend to be very alkaline, upwards to a pH of 8/9.

    Heavy clay soil tends to have small pore spaces making it difficult for roots to grow deep. If there's any compaction, then water can shed right off the surface.

    When we began our first garden in central phoenix. We added a layer of thick fresh wood chips with gypsum.

    Then placed a sprinkler. Watered for a few months and walah! The soil was alive again.

    I buried a lot of compost. Digging out some small basins to harvest rainwater. I heavily mulched the basins too.

    Do you have access to fresh chips?

    Soil tests are always a good idea. Perhaps your local county extension office offers free testing.