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Ameding clay soil

S Hill
9 years ago

I am getting ready to install a drought resistant landscape. I need to amend my heavy clay soil. What is the best way to do this? I have heard some say gypsum... but others say gypum doesn't work that well. A local materials supplier sells a rice hull blend for $27 a cubic yard.
Is it ok to till in the amendment while the soil is fairly wet (we finally had rain in S. Cal, yay!!!)?

Comments (7)

  • calistoga_al ca 15 usda 9
    9 years ago

    Are you sure your soil is not appropriate for drought tolerant plants? Here in California, much of our native soil, could be described as "clay". Our native plants are normally what we think of when thinking "drought tolerant". They do quite well in the native "clay" soil. Garden soil which is usually clay/loam contains up to 5% vegetative matter which can be obtained with the addition of compost dug in when preparing the garden, then maintained with regular applications of vegetative mulch. Al

  • lgteacher
    9 years ago

    Gypsum is helpful for sodic soil - soil that has a salt crust or buildup of minerals. Otherwise, you are better off just adding a lot of mulch on top when you plant. Native plants grow in less than ideal soil. A think layer of mulch will not only keep moisture in, it will encourage the growth of natural flora and fauna in the soil, including mycorrhizae.
    Don't work on soggy soil. Soil should be about 25% air, and you may end up compacting the soil. If you just had a light rain, it shouldn't be a problem. Pea gravel? I'm skeptical.

  • toyon
    9 years ago

    Rocks or gravel will not break up clay soil. Over time the clay particles will move between the rocks or gravel and you will have a really hard time with the soil. Someone did that here and had to replace the soil...after chipping it out.

    Don't till the soil when it is wet. Work the soil when you can crumble it by hand. If you work it while wet you will end up with compacted clods of clay.

    Amend the soil with anything organic. I know someone who has numerous pines on their property. The pine duff is about two feet thick in places and partially decomposed to the point that it is like a coarse peat moss with some pieces of bark in it. I have found that to work the best for my soil. I also save leaves during the fall. Now is the time to collect leaves and start a compost pile while leaves are still plentiful. You can probably get leaves from the neighbors.

    There are also varying degrees of clay. Most people have clay-like soils that are clay-loam or silt that is compacted. Loosening the soil down to at least 12 inches and amending the first 8 inches will help, then even the soil with a rake. Don't compact it. Water it, then let it settle.

  • hoovb zone 9 sunset 23
    9 years ago

    Amending soil is recommended only for certain natives. Use plants that can thrive in the soil you have.

    Here is a link that might be useful: soil for CA native plants

  • toyon
    9 years ago

    The question was for drought tolerant plants in general, not necessarily natives.

    And there is a limited selection of plants tolerant of heavy clay. The idea behind the amendment is to increase permeabiity.

  • hoovb zone 9 sunset 23
    9 years ago

    My answer is the same. Been to Greece and seen the soil ancient olives grow in? Or Mexico and seen what in-habitat Agaves grow in?