I must be missing something here!!

Kinda. ;) You are leaving out what all happens to the waste during the decomposting process. The end result isn't anything like what went INTO the compost pile in terms of beneficial fungi and bacteria. It is like one of those "junk in, treasure out" situations.

I won't deny that composting diseased garden plants is debated. It is. But in addition to the many years of experience with composting diseased plants, there is also much new research on the question. Over on the Soil & Compost forum you'll find several recent discussions on this issue and links to studies that show how properly managed composting not only destroys any harmful ingredients but also appears to create "antibodies" that can act to prevent future infections. So no, you are not automatically infecting your soil by composting diseased plants.

Likely the 2 schools of thought on this question will never agree so ultimately it is your choice. ;)

Further, there is also the point that many of the chronic garden problems are now proven to be airborne, not soil-borne or at least equally airborne and soil-borne.

Also, search out some of the past discussions here on "crop rotation". You'll find that it is primarily a tool used by large scale commercial growers, not possible for or relevant to the average home gardener. ;)

Hope this helps clarify it for you a bit.

Dave

Lori, the theory behind composting is that, in a properly done compost pile, the heat generated by the various microbes rises to such a level, about 160 degrees, that it pasteurizes the compost, killing the disease organisms in the process.

However, in practice, that doesn't always happen. You may not have enough material, the right mix of materials, or pile it or turn it properly, etc.

What I do with things that I think are diseased or infested are either: 1) put it in garbage cans for the curbside yard waste pickup, or 2) compost it, but put that particular compost back on some totally unrelated plant where it isn't sas likely to be a problem -- for example, if I were composting old tomato vines, I shred them all up with the lawnmower, then put the compost generated from that around the base of my walnut and apple trees for mulch, far away from my vegetable gardens.

PS -- you can add a high-nitrogen fertilizer, like urea or ammonium nitrate, to your compost to really help heat things up.

Dennis
SE Michigan

Thanks for the very informative posts!! They do raise some more questions for me, though =)

Dave,
I will look up those posts on crop rotation, but quickly, what is your opinion? And if it isn't really helpful for preventing disease, do you think it is useful for replenishing nutrients to soil (for example, growing beans one year, greens the next)? Or does adding compost every year accomplish the same thing? It really would be helpful for me to NOT have to rotate crops, since I have weird sun/shade patterns from spring to fall--only a few beds are in full sun over the entire growing season. So of course it would be nice to grow tomatoes and peppers in those, rather than lettuce!

Dennis,
I am thinking that all the coffee grounds I added to my compost (from generous local coffee shops) must have been what turned several cubic feet of sod, leaves, and kitchen scraps into beautiful compost over last winter. I know they are not HIGH-nitrogen, but they do provide some, and I had a lot of them! Is that a good indicator that my compost is "heating up" enough, do you think? (Or, how DO I know?)

Thanks for your input!
Lori

Stick your arm into the pile to check the temp. If it is too hot to stay in there it's doing well. Wear a long glove if you want :)

There are special long probed thermometers you can buy especially for compost piles....but observing heat and steam while turning it, reaching into it and feeling the heat, or using a kitchen thermometer that you wash afterwards :), seems fine to me.

Or just let it do it's thing. Don't let worries over heat keep you from composting.

but quickly, what is your opinion?

As I have posted in the other discussions, I have no dirt here unless it is trucked in. We are rocks and glacier scrub otherwise. So all my gardens are raised beds of off-site soil - about 1 to 1 1/2 acre total in several locations around the farm here. In some 40+ years I have never rotated crops except for succession planting with different crops. Tomatoes have gone in the same beds in the spring for years, so has most everything else with no problems.

But I am a big advocate of both fall and spring tilling, heavy mulching, and of home composting so no, I don't rotate.

Not to turn this into a long discussion on composting which best belongs on the other forum, but we have the space and components to do heavy composting and we don't restrict our compost to only healthy ingredients - if it is organic it goes on the compost piles. Wife and I come from long line of farmers and grew up composting that way.

All our gardens get several inches of fresh compost each spring and more as it becomes available for mulching and mixing in between crops and another layer in the fall. I do not have chronic disease problems except during the rare soupy spring we may get and in that case the compost isn't the cause - the airborne fungi and humidity is. No nutrient problems and never have.

That said, I recognize that many cannot compost in the amounts we can nor as effectively as we can but I still maintain that if they make the effort to compost properly (get it to 'cook' even 1x) OR allow it to cold compost for at least 1 year, the compost will not be the cause of any disease problems they may have. How to tell if it is hot? Easy - it steams and you can't stick your hand in it. You can feel heat radiating off the pile.

As Dennis said, proper composting takes some learning. While coffee grounds are ok, they sure shouldn't be your primary source of nitrogen for a hot pile. If you don't have the resources to hot compost or don't what to invest in or use any of the many high N kickers, then go with long-term cold composting or elect to not compost diseased materials. Either way, crop rotation is not required IMO.

Dave

Hmm... well, my compost heap was hot enough to keep the snow melted on it last winter, I guess that's something... (Not that we have blizzards here, but we did have snow.) I haven't tried sticking my arm in there just yet ;) I would definitely want a glove, I know what's in there!

If "hot" compost will save me from needing to rotate crops, I'll make sure mine gets hot enough! And maybe it will give me a chance to try a heated cold frame this winter, built on top of the compost heap... always wanted to try that...

Lori

Digdirt is in Arizona, a place with minimal disease pressure.
In the moist, warm Midwest (at least in summer) things are different. I do have early blight in some of my beds, and not in other beds. I take away all diseased plants, and typically I mow them into the lawn about 100-200 yds away ( I have a very long, narrow property). The rest of vegetable refuse I happily compost. In practice, I remove tomatoes, squash, cucumbers, peppers, potatoes, and peas, and reuse the rest.

No, glib, I am in AR - Arkansas. ;) On the shores of Bull Shoals Lake and all its associated humidity.

Dave

Nitrogen kickers need not be expensive. I produce my own for free, and it does miracles for heating up a pile. Some call it recycled beer, but I don't drink beer. Simply collect your own in a jug... It's easy to collect a few gallons by the time you're ready to turn your pile again. Add it along with some water to get your pile properly moistened and it will heat up marvelously!

I agree steelshepherd. I like the $3.00 bags of alfalfa pellets they sell as rabbit food or a $2.00 box of blood meal now and then. But grass clippings, some cow, sheep, or horse manure, a bale of hay goes along way, or a couple of heads of tossed lettuce from the grocery produce manager work well too. ;)

I think there are some good reasons for rotation other than disease control. So I would say that composting is not at all a substitute for rotation.

Rotation goes hand-in-hand with crop diversity. A high level of diversity, IME, is the key to avoiding soil and disease problems. A common scenario is the weekend gardener who grows tomatoes, peppers, eggplant (all closely related) and summer squash in high concentration in the same little plot year after year. No amount of compost or "rotation" is going to avoid the eventual severe insect infestations and disease problems that occur in situations like that.

True, there are many reasons to rotate crops, yet somehow many people manage to grow some things in the same spot every year without incurring those problems. Tomatoes seem to be one of those things that don't necessarily suffer from staying put.

Just because a veggie is an annual doesn't mean it needs to be moved. Perennials stay put fine, as do trees and shrubs.

Some shrubs like hybrid tea roses could probably benefit from transplanting every fall as they certainly suffer from fungi in the soil left from the previous year. Thoroughly removing everything on the soil surface and spraying lime-sulfur in winter helps kill off such problems. Insects are another story.

The point is, rotation is good, but there are ways to help nature over the winter in a location that you want to use over and over again for some crops every year that can win the battle against disease.

oops, digdirt, so sorry. Either we have too many states, or it is time to rename some with words starting with, say, Q or Y.

Of course, you'll notice that naturalized trees and shrubs, and perennials in general, exhibit fairly wide species diversity. And they "pull" far less from the soil seasonally than a garden crop. So they are able to live in one spot on just the solar budget pretty indefinitely, though their eventual "output" will vary hugely according to the circumstances.

A perennial tends by definition to be very well adapted to its climate and soil. That's why successful fruit trees need little or no fertilizing and yet produce more per square foot - and the same square feet - year after year than most annual vegetable crops. The same can be said for naturalized annuals, when we can find them, IME. Self-seeding (naturalized) vegetables essentially practice a sort of rotation with a little help from the gardener to remove them from spots where they have been for a couple of years. I've got parsnip, mustard, russian kale, and walking onions doing this in two garden plots. The parsnip is particularly impressive as it competes vigorously with weeds and produces big volumes on little or no annual input or labor.