toxcrusadr
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Location: MO

The Best Quality Compost: Yours!

Just a note as the spring gardening season takes off. Lots of people have questions about compost and many are just starting out.

Two years ago I did a study on locally available compost products here in Columbia, Missouri. Tested NPK, trace elements, pH, moisture, and organic matter. The results were not perfectly consistent, but...

:x Cheap products generally had less organic matter and NPK.
8) Very expensive products were generally pretty good, but probably not worth the extra cost.
:P The midrange was a good value. The product I recommended was a Cotton Burr compost, which you may not be able to get in your area.
:-() Finally, the winner in nearly every category was my own backyard compost, made from yard trimmings, kitchen scraps, leaves and grass clippings.

Commercial operations don't necessarily use the best ingredients, and sometimes a lot of useless material gets in. Many of the low cost composts and manures actually have very little organic matter in them, and are mostly soil. I've seen bags labelled Compost that are clearly just topsoil. If you need that, to fill a hole or a raised bed, fine, but know what you're getting.

If you're buying, find a torn bag to look at. Do you see clumps or grains of soil? Does it smell bad? Fill of wood chips? Then judge whether it's worth the price.

Store bought compost is OK, but keep in mind all the reasons to make your own.

Happy gardening!
Tox

toxcrusadr
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Posts: 969
Joined: Thu Sep 09, 2010 8:50 pm
Location: MO

Re: The Best Quality Compost: Yours!

I looked back at my compost analysis study data from a couple years ago. Out of 11 samples (10 store bought plus one batch of my homemade compost), mine ranked as follows for minerals (1 being highest):

Ca 2
Mg 6
Zn 2
Fe 10
Mn 7
Cu 3

Not sure what happened on the iron there, I'll have to add more nails to the bin. :-p But for the most part, the homemade compost ranked average to very high in minerals compared to commercial compost.
Tox

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ElizabethB
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Re: The Best Quality Compost: Yours!

Tox - good idea. I have soil test done on my garden after the compost has been worked in but never on the compost itself. I depleted my compost from last spring and I am starting over. Will have a soil test done before adding to the garden - just to satisfy my curiosity.

Good point - thanks
Elizabeth - or Your Majesty

Living and growing in Lafayette, La.

When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant. ~Author Unknown

rot
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Joined: Wed Sep 24, 2008 5:15 am
Location: Ventura County, CA, Sunset 23

Re: The Best Quality Compost: Yours!

..
Thanks Tox. All good info. Thanks for taking the trouble to gather all that information and thanks for sharing.

One more reason I find mine better than store bought: when mine is done I can take a handful and see the life in it. I can see the bugs crawling and smell that earth smell of the living as opposed to the desiccated dirt out here not far from the Mojave.

The store bought stuff sometimes looks like it was living once but mine is very much alive. Adding life itself to the garden.

Thanks again
..

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