I did a search for this subject and the threads I found were rather old. After time has gone by, would those who have used expanded shale give me their opinion as to whether it was worth the cost or not? Did it really perform in the way you wanted?
Our dense red clay is so deep that amending it is worthless because you could amend it 10 feet deep and still have nothing but a huge clay pot. So have elevated beds with good soil mix that have performed great since planted September 2008. Installed Netafim drip irrigation in June 2009 and love it except some of the lower outer portions of the beds receive too much water because it runs down from the higher part of the elevated bed.
Wondering if expanded shale would help the upper portions retain more moisture and also help the lower portions that are getting too wet to have more oxygen available to roots. Always have chlorosis in areas where plants have any contact with the clay soil.
Would appreciate any feedback from members who have used expanded shale.
Thanks.
Expanded shale
I think expanded shale is great for breaking up heavy soils and helping with drainage, I don't think it does much for water retention or soil nutrition, but where you want to break up the soil it works great because it doesn't decompose like compost and mulch do and it lasts a long time.
Josephine.
Thanks, Josephine. That's the kind of input I need because reading the advertising on the internet when it was first being promoted, supposedly would absorb water and then release it slowly and also hold oxygen to help deal with too wet areas. That's not the exact phrasing but "my take" on it. Sounded almost too good to be true, so wanted to hear from actual gardeners and see what their experience had been.
In my situation, I don't try to amend or break up the clay because doing that next to foundation caused many dollars of damage from water retention causing clay to swell and heave the foundation, causing sheetrock cracks inside home. Have to leave that clay pan intact at the proper level and fall for drainage and elevate beds on top of it. I've had to become almost a drainage expert dealing with our difficult situation but have it conquored now except for tweaking it in a few areas.
Glenna
We use it at the greenhouse as part of our potting soil, and I have done tests to see if it retains water
by pouring the same amount of water in a pot soil with shale and one without.
The same amount of water came out of both, so no extra water retention, but the water passed through the pot with shale in it twice as fast, so it does help with drainage.
Josephine.