[Community_garden] Definitions

[Don Boekelheide]

Not bad, Mike. I get these kind of questions all the time, plus confusing "mulch" with "compost"

A couple additions, edits and suggestions (I know, too late, this is Public Radio...)

Mulch: Not soil or compost (gets confusing - read next graph, too). A mulch is anything you put on top of the ground to cover soil, often to protect it, sometimes to beautify your garden. Organic mulches include pine bark, straw, wood chips, cocoa hulls, chopped autumn leaves - there's a long list (newspaper too, cardboard...). You can also have an inorganic mulch, such as pretty pebbles or white rocks, or those gross plastic sheets with holes punched in them. Mulch wants to stay on top of the soil, not be mixed in with it.

Compost can be used as a mulch - you sprinkle a little layer of compost on top of the soil and don't mix it in. BUT mulch is not necessarily compost, at all. See above. You can mix compost with your soil - don't try that with other mulches.

"Biosolids": Poop. Composted biosolids (Milorganite etc) have a place in the greater scheme of things - we can't just haul it to the landfill. But whether or not they have a place in your organic (or conventional) food garden is a different story. I absolutely avoid them for that purpose.

>>Compost = the rich black soil-like result of decomposed leaves and other 
organic matter. Incredibly high in organic matter content.<<

Confusion - in the UK and Oz, and Canada, other English speaking places, "compost" can be a synonym for what we Merkan gardeners call "potting soil". Example:  John Innes composts.

In the US, "composting" (the activity) has come to mean human-managed decomposition. This ranges from friendly backyard piles (human management = pile it up, maybe wet it sometimes) to very complex  high tech in-vessel composting done at huge facilities. The resulting products, broadly speaking, are similar - stabilized, carbon-rich material similar to the organic fraction of a rich topsoil. Some call it "humus-like", and that's reasonable, though classic ecological studies identify very different types of humus in different ecosystems (what most backyard gardeners want is most like "mull" compost, rich in humates and teaming with microbial life).

Caution: composts are similar, but not the same. Sewage sludge may be "humanure" (laced with heavy metals), but it is considered a compost material by the Composting Council. When purchasing "compost", you need to be careful about both the parent materials and the process. Very careful.

>>Composted manure = decomposed poop, pee and bedding; looks like compost but 
is not. Incredibly high in organic matter content, but often too nitrogen 
rich to use alone. Horse and poultry manure, for instance, are too rich to 
use alone on flowering plants, even after having been composted, during 
which process their nitrogen levels drop.<<

Depends, Mike-o. Dried manures, especially poultry (who pass wastes in a single form), can be very high in N, and can "burn" plants. However, a well composted (and old) ruminant manure - from cows, sheep, etc - can be quite low in N, especially N released quickly. We have forgotten a great deal about manure and its proper storage and use, unfortunately. Anyway, composted manure (remember, human-managed decomposition) is generally what you want. And you do need to be careful about application. BTW, composted properly, there is no reason why manure should lose N unless the pH goes above 7, or if the pile is soaked. You will lose carbon in the form of CO2, but the remainder of the carbon will be stabilized as living cells or more stable molecules. That's also the fate you want for your N, have it become part of the living critters in your pile, who will share it with your plants later, or incorporated into and held by big stable carbon chains like humates.

(Since sufficient N is needed for aerobic composts to heat up, you do have a ready, sterile source of N - HNS, human nitrogenous supplement (aka pee). But I didn't say to go out there and pee on your pile, now, did I?)

>>Soil = What's already there; generally lots of sand or clay with some 
organic matter content; but its very low in un-improved soils and still low 
for improved ones compared to the compost itself.<<

This is a little too blah for me. Soil is magical, and without it, who gardens sustainably? (You can grow anything hydroponically - but what kind of carbon footprint do you get for that hydroponic carrot grown under lights? And what happens when the petro energy runs out?) There are billions of organisms is a tablespoon of good soil. But, again, Mike got the basics right on: You grow veggies in soil. You add compost to enrich soil with organic matter, so your plants will grow better.

>>Topsoil = no legal meaning; could be anything.<<

Topsoil and Civilization (Carter and Dale) is one of my favorite books. That it takes 1000 years to naturally build an inch of topsoil one of my favorite facts. Topsoil is sacred. However, you are absolutely right, Mike, commercially there is no definition. In soil science, it's more-or-less the O and top 15-30 cm of the A horizon - but that won't help you in the garden center. 

Practically speaking, quite often, I think it makes the most sense to look at the soil where you are, test it for heavy metals and other toxins that persist. If it is free of those, build soil with compost rather than try to buy something. Restore our Earth. Hands on. No, it isn't always possible, but if it is, community gardeners can help with that job hands on.

Don
http://urbanministrygarden.wordpress.com

(new post coming soon, by the weekend inch'allah - I'm too busy to blog in the spring!)

Message: 4
Date: Mon, 28 Apr 2008 09:37:04 -0400
From: "Mike McGrath" <MikeMcG at PTD.net>
Subject: [Community_garden] Definitions
To: "Erik Lindberg" <artisan1 at milwpc.com>
Cc: community_garden at list.communitygarden.org
Message-ID: <001c01c8a934$f3eedbd0$3300a8c0 at mikedell4100>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
    reply-type=original

Compost = the rich black soil-like result of decomposed leaves and other 
organic matter. Incredibly high in organic matter content.

Composted manure = decomposed poop, pee and bedding; looks like compost but 
is not. Incredibly high in organic matter content, but often too nitrogen 
rich to use alone. Horse and poultry manure, for instance, are too rich to 
use alone on flowering plants, even after having been composted, during 
which process their nitrogen levels drop.

Soil = What's already there; generally lots of sand or clay with some 
organic matter content; but its very low in un-improved soils and still low 
for improved ones compared to the compost itself.

Topsoil = no legal meaning; could be anything.

Hope this helps (It helped me--I'm using this on the air!)

                                        Best,  McG