soil toxins

MaryT says...
Thanks for the science, joy but I guess some of us would still be wary about growing food of any kind in contaminated soil. I wonder, if a root crop can absorb contaminants, can a super crop be developed to take out the toxins? What methods do they use now to de-contaminate the soil?

amanda says...
I wonder if there are any scientific papers on the issue? Might be worth a Google..

Xiem says...
I have absolutely no scientific basis for saying this, but I think that if anything helps to detoxify soil it would be bacteria. I saw a program a little while back about India and how the Ganges, which takes the crap and waste from a billion people, cleans itself with bacteria and oxygen. So who knows what the bacteria from buried (organic) waste can do to the soil. PERHAPS if microbic critters can survive the contamination directly, we can survive from the produce.

joy says...
It seems that if unsure it is better to grow treecrops rather than root crops.

Speedy says...
fungi can break down just about anything organic incluting nasties like DDT, dieldrin, petro-chemicals, PAH's , you name it and there'll be a fungi that can biologically tear the molecules apart and turn it into something either benign or even beneficial.

using a blanket of mulch over the soil will provide food for the fungi to grow and a place for them to live while they devour it and anything else that gets in their way.
better still is to get some matured compost (made via aerobic hot-composting method) and dig it into the soil.

Heavy metals (Arsenic, Lead, Mercury, Cadmium, Uranium etc.) cant be broken down in soils and can persist without removal via leaching or physically taking it away.
some fungi and plants are bioacumilators of specific heavy matals and could be used to 'mop up' these elements and through harvesting the plants or fungi and disposing of as toxic waste, thereby detoxifying the soil without total removal.
some heavy metals can be biologically or chemically complexed in soils to form less harmful (less bio-available) substances.
Bringing pH from very low to closer to neutral can also lessen mobility of heavy metals in soils to a point where it is acceptable.
...That all said, unless a site is really badly contaminated, you're likely to inhale/ingest more toxins from fallout of industry if you're anywhere near a city, refinery or powerstation.
soil health, balance and good soil biology is the best buffer against it.

If you're really concerned about it , there are labs that can test for specific toxins.

hot compost , fungi, mulch

amanda says...
Nice one Speedy!? Some good leads there...Must admit - I will be checking out the soil of the next property we buy.

I have always felt so great about mine here...as the land was fallow for maybe 20yrs all up. I also know it's history for the 20yrs previous to that even!?
Very lucky really.

When folk have bought n sold land in the past - this issue was not a blip on the radar really...?

Maybe one day the Soil Test will be as important as the Termite Inspection hey..? ;-)

Speedy says...
yes, when compost is made properly and has a period of maturation after the heat has gone out of it will allow the fungi to develop.
the mycorrhizae in compost is endomycorrhizae, like the type in the Mycoapply Defence.
it will attach to the roots of, and benefit most plants that youd grow in a garden, the exceptions being members of the beet, amaranth and poppy families.
ok for most fruit trees except walnuts.
Blueberries and relatives have Ericoid mycorrhizae.
some other trees eg. pecans will also team up with ectomycorrhizae.

the mycoapply defence also has Trichoderma spp. , fungi that feeds on other fungi and is employed as a defence against pathogenic fungi.

Myco apply Defence ...smallest pkt is 1kg and is about $60 from memory.

I'm guessing that Bokashi in mainly Lactobacilli and simmilar organisms, rather than fungi...still good for dealing with food scraps etc. but different to fungi and could both be used together ok.

Julie says...
Make my own bran? I wouldn't know where to start Mary!

I buy a 3kg bag for $18, and it lasts me about a year. That's around $1.50 a month, which is good value for what it does.

More bulky organic material, like weeds, are just thrown back under the fruit trees. Along with leaves from a couple of deciduous trees, that's my mulch, which turns into compost over winter.

Julie says...
Yes, 3kg can be heavy to carry around. My son picked up the last lot for me and brought it on his motor bike.

He found the backpack a bit heavy for a 30 minute drive - and he is a big, strong lad!

Mary, initially I didn't use enough, and the bucket got a bit stinky. I was advised to use more, but it still lasts me a while. I have started juicing lately (proud new owner of an Oscar Vitamax) which makes even more waste, so I'll see how it goes.

MaryT says...
That is good to know Julie but I guess growing carrots would not be enough to remove some types of toxins? Speedy said "Heavy metals (Arsenic, Lead, Mercury, Cadmium, Uranium etc.) cant be broken down in soils and can persist without removal via leaching or physically taking it away."

MaryT says...
Yes, Julie. I wouldn't know why anyone would want to, though most of us wouldn't know what's in our soil.

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