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vtown05
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Location: Sihanoukville, Cambodia

Help me make soil

My friend and I are currently living in Cambodia and we want to start growing some veggies in containers on the back patio. We are sort of having a competition.

The problem with the soil here is that most of it is contaminated and polluted. The ground water is not potable because of overflowing septic tanks. I do not wan to just dig soil from the ground and use it. I have unlimited access to cow manure and I live near the beach so unlimited sand also. I took a soil science course online a few years ago but trying to remember some things and my memory isn't all that great.

Does anyone have any advice on how I should make some soil. I thought maybe I cold dig some soil up and sterilize it, but I don't have an oven, just a small gas burner for cooking. Any ideas? My friend says he knows soil, I need to put him to shame! haha!

The picture is my backyard. There is stuff growing here and the locals come by to pick stuff our of here every day but I don't trust the cleanliness of it.

Thanks

Thanks
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imafan26
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Re: Help me make soil

Your sanitary conditions are probably why most Asians almost always cook their vegetables and do not traditionally eat it raw.

If your ground water is polluted, in all likelihood the beaches if frequented by a lot of traffic and if your polluted streams empty nearby they may also be polluted.

Cow manure needs to be composted or aged first otherwise, same problem, the e. coli and other pathogens in the manures may make its way onto the food as well. Manures need to be aged a minimum of 120 days. No fresh manure can be piled on top of an old pile or start the count again.

Sterilizing soil is possible but it really stinks and unless you have a soil sterilizer, it would be hard to do it in quantity.

If you can get commercial potting soil that would be the best thing in pots.

Peat moss and coir are sold in bulk. It is usually mixed 50/50 with something that provides drainage like perlite, sand (clean coarse sand, not fine sand) or cinder. Perlite is the lightest, cinder provides good drainage but it would be hard to grow root crops in it. You can add compost to the mix up to about 20%, but it is hard to put manure in pots without being very careful. You can used fish emulsion or slow release fertilizer. You would have to check around for an agricultural supplier or garden shop.

If you grow vegetables that do not touch the soil and you can test your soil for pollutants it might be worthwhile to plant in ground with aged manure and make your own compost. Beans, squash , cucumbers, tomatoes, bananas, and things that you can trellis to keep of the ground may be better than root crops. If your back yard is not near a factory, septic system, or highly traffic area like roads, there may not be that many heavy metals in it. The heavy metals are more important to sample than the other pathogens as they will accumulate in the body. If you site your garden on high ground, and you test the soil, you may be o.k., as long as you don't add anything that would contaminate it like fresh manures or contaminated water from a pasture. You would still need to wash the veggies and preferably cook them well to kill pathogens.

Phyto remediation is being used to remove toxins from the soil. It is an efficient way to remove known toxins especially heavy metals. It requires testing and selecting the right plants. The plants are pulled and discarded and not eaten but after they have cleaned the soil, (you would have to retest to see if levels have been reduced enough), it should be safe as long as it is not contaminated again.

https://www.resilience.org/stories/2014- ... nated-soil

You have a huge back yard. I am envious.
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applestar
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Re: Help me make soil

It's hot and sunny there? If so solarizing/using solar heat might be the best way to "sterilize" soil in quantity.

Another possible way might be digging a pit like Hawaiian pig roast or New England lobster bake, and burning/steaming a pit sized volume of ground.

Or make an outdoor grill/oven with steel drums that didn't originally contain something toxic.

I admit to not knowing the exact how of any of these methods, though I think for solarizing, I would probably put the dug up soil and sand in a clear container above ground rather than covering with plastic sheeting which would only affect the top layer of the soil and NOT to any kind of depth.

I actually think you could aim for pasteurizing (long period at lower temp) rather than sterilizing (high temp sufficient to kill). In fact pasteurizing is supposed to be safer because some nasties can survive the high heat but succumb to longer exposure to lower heat.

I don't remember if they have it available on-line, but see if Fungi Perfecti (fungi.com) has the method for pasteurizing mushroom growing substrate posted there. It's meant for large scale and the one I remember from one of Paul Stamets' books involved boiling a steel drum of water and soaking a straw bale in it for a period of time at a certain temperature range. You may find similar instructions on line for mushroom farms in Southeast Asia (I remember coming across them before)

I think imafan has a good idea with phyto remediation for removing hazardous comtaminants. There is also myco remediation which uses mushrooms.
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rainbowgardener
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Re: Help me make soil

But in the meantime we don't recommend actual soil in containers. All of the above is options for if you want to make your ground better and grow in the ground. If that is possible, it is always preferable. But if you really just want to grow in containers, what you are looking for is some kind of soil-less potting mix that will be light and well draining. I have no idea what ingredients are available to you for that. Your beach sand, washed, could be one part. The mushroom compost, applestar mentioned could be one part. Peat moss or coconut coir could be one part. If you have fall leaves there, crushed up fall leaves could go in it. I use rice hulls in mine.

Your basic recipe would be something hard and loose that will keep the mix from packing down, i.e. sand, rice hulls, crushed pumice, perlite, crushed eggshells etc; something organic for nutrients, i.e. mushroom compost, very well aged and composted manure, crushed pine bark; something that holds some moisture but stays loose and keeps air pockets, i.e. peat moss, coconut coir, crushed fall leaves. So you can think about what you have available that would meet those requirements.

Then you can play around to find what proportions work best for you, which will depend somewhat on what the ingredients are and how available they are. Start with thirds as a rough guideline and play around.

Keep us updated how it goes for you!
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imafan26
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Re: Help me make soil

In most tropical countries, there aren't many fall leaves as most trees are not deciduous unless they are non natives. There are some leaves around though as even evergreen trees and shrubs do shed some leaves and you can cut the vegetation and compost it.

Coconut coir would probably be the easiest to get, but here shredding the coconut takes a chipper and several passes and that is by hand pulling as much of coir out as possible. Most chippers will break if you try to put a whole coconut in it.

If you can get bagged potting mix it would be the best. It all depends on what is locally available.
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applestar
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Re: Help me make soil

I don't know, I'm a bit resentful of the notion that you have to buy potting mix already when we are surrounded by dirt. It's one thing if you live in an apartment or an urban local with no access to dirt you can call your own -- yeah I've been there -- but just look at that lush landscape! (have you found out what the local people are harvesting from there? Are they just wild foraging or did this land used to be a farm or something?)

If I lived there and was told to have growing medium bagged and shipped to me from who knows where -- even overseas? -- I would think it would be awfully extravagant. Then, too, how reliable would the mix be? What is the horticultural market like over there? If you actually bought something shipped all the way from more urban consumer oriented areas, how well would they ship in the local climate?

I agree you need the ratio of the mix to be correct for container growing. But I suspect you can use locally sourced materials. It would be kind of fun to find out what WOULD be good local materials there since I suspect they would be VASTLY different from what I could get around here 8) Actual ratio and material would depend on what you are growing.
Learning never ends because we can share what we've learned. And in sharing our collective experiences, we gain deeper understanding of what we learned.

imafan26
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Location: hawaii, zone 12a 587 ft elev.

Re: Help me make soil

In ground the plants would probably be a lot happier, but as you know dirt is not a good medium for pots, in the long run it packs down, contracts and water ends up flowing around the outside of the pot leaving the core hard and dry. Besides, if the concern is soil contamination, there still needs to be some testing or sterilizing which would also destroy any good microbes too. I like Rainbow's idea of cooking the soil. If you do build an imu it would steam the soil. It would get rid of most microbes but not the heavy metals.

I did find this article about how to make your own soil mix with materials available in Cambodia.

https://www.phnompenhpost.com/real-estat ... round-home
Happy gardening in Hawaii. Gardens are where people grow.

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