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Soil 101 - Making soil - Please Help

16 years ago

Please help - I am a first year gardener, and I have 4 very specific questions about soil I can't get answered. I would be thrilled if I could get some specific answers. First -

1.) Sterile soil mix - I saw a bag of potting soil labeled as "Sterile - Organics rich". I don't think I understand what soil being sterile means. The garden center guy told me I needed to use it to start indoor seedlings, to prevent mildew. I thought being sterile meant that it wouldn't have any food for the plants. But then why would a sterile potting mix be labeled as organics rich? My husband thought being sterile meant it had been irradiated against micro-organisms, but that it would still have nutrients for the plants. The reason I need to know is that I don't know if my seedlings that just came up are getting any food from their soil or not? Do they require fertilizer?

2.) I live in an area with high levels of lead contamination in the soil. As a result, it is possible I will not be able to use any of the soil in my yard for my garden. What does someone in my position do? I know I need to bring in new soil. But am I going to be going to the garden supply store and buying a bag marked "soil"? Or am I supposed to create my own using humus, vermiculite and peat moss? Would those three items mixed together constitute "soil", or does there need to be something else? The gardening books I've read talk about using those substances to amend soil, not to replace it altogether.

3.) Raised beds - are they supposed to have a bottom? My husband says no, but how are you supposed to isolate the roots from the lead if they grow through the new soil into the old? But wouldn't putting bottoms on mean my garden would actually be more like a container garden?

4.) Last question - manure versus humus. I know humus is decomposed organic material, largely plant. Manure is - well "processed" material - if from a cow than probably mostly plant also. Are these two substances used interchangeably?

Sorry for such an involved post, but I would really appreciate any help people can give with this.


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