I think what you're looking at is called duff. My understanding is that loam is a mixture of silt, sand and clay (or maybe those three plus organic matter).

Loam is a soil type that consists of 45 percent sand, 25 percent silt, 25 percent clay, and 5 percent organic matter. What you are seeing on the forest floor is digested organic matter, aka duff in some circles. No question asked is a "dumb" question. "Dumb" questions are the ones never asked.

What is the difference between this "duff" and leaf mold? I mulch all my planting beds in fall with shredded leaves, and I have a wonderful, thin, black material under all that by spring. It's soft and crumbly, sometimes with skeletal remains of leaf veins. I thought this was leaf mold. Yes or no?

Karen

Duff and leaf mold are basically the same thing, though if one were to be nit-picky about definitions, the duff is more thoroughly decomposed. Duff and leaf mold are strictly organic (meaning of something that was once alive), without the mineral components of sand, silt, or clay.

Okay - this is good... I have a lot of "duff" (funny word), and I think that is the finely composted leaf mold, right? Anyway, I love the stuff and use it for topdressing my beds - how's that?

Carrie

Uh oh - I read somewhere on this forum that there could be "weed seeds" i.e. Poison ivy, etc. ... now maybe I'd better think twice about using it in the beds. I have never had a hot compost, so that is not the solution and I have buckets of this "duff" ready to go - now I don't know what to do with it.

(Too bad I can't bake a tray in the oven to kill the weed seeds......
Carrie

You can pasteurize it in a microwave in a smaller volume. I use a plastic shoe box.

John

Carrie: if you think about it, coming from your property and ultimately staying there, it probably has no different seeds blown in than what's normally in your garden beds.

Do you have a lot of poison ivy?

Karen

well, karen at one time yes, we had loads of it - and now not as much but of course, I have no idea if where I "scraped" is where it was... (if that makes sense)...

Also, did he say "microwave" the soil - I can do that - I really like that idea but have to do that when my husband is not home - he'd think I for sure have lost my mind!

Carrie

Carrie,

That's what he said. You can also bake the soil in the over to kill whatever you want dead.

350 for how many minutes!? (This is insane, LOL)

Carrie

If you use a microwave, it depends on the moisture content. Leave it in on high for about 15 mns. Take it out and use a candy thermometer if it is at least 165 deg your done. If not put it back in for a few mns. and check again. I picked up a microwave at a yard sale for this purpose for about 5$ I keep it on the bench where I mix my potting soil.

John

Seriously, I'd never heard of doing this - I honestly thought one minute zap on high would do the trick - now I must say - using the bake at 350 degrees may be the easier way to go - what do you people think? Thanks so much for this valuable information

Carrie

Carrie,

Bake it like you're baking a potato. Basically, you're trying to get the dirt to 160F+.

If you bake, make sure you have some ventilation because it might put off an oder you might not like.

Carrie, after reading your post again I realized that the area where the duff is is conducive to puff balls. They look like light brown golf balls. If you tramp on them you will see a dark brown powder fly out that is Mycorrhizal Fungi spores. Take a small baggie and put it over the puff ball and try to pick it with out breaking the shell. Burry it a couple ins in a container of damp potting soil or compost. Stick your hand in untill you find the puff ball and break it open. You can mix it then without breathing any spores. You can see the benefits on the link below.

John

I didn't notice any light brown golf balls, it is actually very black and just really fine... with no powder flying around - but I will double check tomorrow.

Thanks - will keep in touch and maybe even take a picture

Carrie

Photo of puff ball

john

{{gwi:262370}}

Carrie

Don't bake the duff / leaf mold. Yes, you will kill bad bacteria, fungii and weed seeds but you will kill the good guys too. Save the energy, time and effort and just use the material if you wish. If weeds come up, remove them. You may not even have any weeds. Don't fix what ain't broken. People seem too obsessed with possible pathogens and weeds.

These instructions are common in many university reports on making pottins soil.

Pasteurize compost by heating it to a temperature of about 160 degrees Fahrenheit for 30 minutes. If you can generate this temperature for that length of time throughout the compost, you will kill most disease organisms, while allowing many beneficial fungi and bacteria to remain.
John

Shows how much I don't know; I thought Duff was a beer! Go figure.

:)

Lloyd

There is no reason to pasturize compost, ever. As diseased plant material is digested by bacteria antibodies to those disease pathogens are developed and heating that finished compost will then be rendered sterile, not just killing off any potential disease pathogens but the beneficial bacteria in the compost as well.
While the presence of puff balls, as will any other type of mushroom, will indicate that your soil has fungi they may not indicate the presence of Mycorrhizal fungi.

Don't laugh, lloyd - I did a search on "duff" in one of the other forums (I think Carolina Gardening) and a few people referred to their "backsides" as "duffs"... that was a new one to me! LOL

Carrie E.g. Need to get off my duff and do some work....

Do a Google search on Pasteurizeing+potting+soil also do a search on Mycorrhizal fungi. And draw your own conclusion.

John

1) I don't have those little "puff balls"... although i may somewhere else in the woods - keeping my eyes opened..

2) cowgirl - I tend to agree with you - so if I use this beautiful black "whatever" soil... as a topdress and a few weeds come up - they will be yanked. I have the time and the energy to weed, that's no problem. This soil/duff - whatever - is too good to pass up and it's FREE!!

Thaks everyone - this thread is very interesting and I hope more give their input on baking; microwaving; doing nothing, etc. etc. I've learned a lot

Carrie

No science here, but fact: I don't even cook food that much, I'm not going to cook my dirt!

Karen

Man, I sure would hate to think about cooking or baking my garden soil!! A dirty job that would take forever. I think that there is an irrational fear of weed seed and other things normally found everyday in nature (and there will always be a few that wash in, blow in or that birds bring in). It is pretty easy to deal with the few that make it to the garden and manage to come up. I have a sharp hoe, can pull them and shredded leaf mulch does a wonderful job of eliminating unwanted weeds. Go boldly forward without unreasoning fear.

It takes many years in most areas to accumulate the small amount of topsoil found on a forest floor, unless it is a place where water washes it up to accumulate faster or wind does something similar. It is good stuff, finely composted leaves and debris. I always thought that leaf mold was basically compressed, molded leaves that were pretty far along toward decomposting, but mostly still recognizable although very crumbly. The ones that I have from time to time are like that.
Just my .02
Bill P.

I made the assumption that the duff would be used in place of sphagnum in a potting mix. I guess if I had it available that is what I would do. That is why I recommended pasteurizing. I would check the PH though no matter where it is used. I also think you would be better off using good quality compost.

John

Hi John

Went to the link you provided Re: MycFungi; it goes to a commercial site that right at the top has a link to investor relations. Now I'm kinda a suspicious/cynical guy when it comes to somebody trying to sell something and the thing that jumped out at me with the before and after pictures presented, is the plant tops and above ground background. They are exactly the same! I'm no gardener but I have to ask myself what are the odds of that happening before and after? I suspect some foto manipulation going on there.

Not to say MycFungi isn't good stuff, I wouldn't know it if it bit me in the leg.

Lloyd

Upon looking further, I clicked on the Mycorrhizal link on the left of the pictures and lo and behold they state, "Same Root System with Mycorrhizal component graphically removed". So it isn't really a before and after photograph per say. Too bad they didn't make that distinction in all the links.

Lloyd

pt03,

My daughter use to do graphic work for Plant Health care. And I did a little test project for them. I planted seeds for 24 tomato, eggplant and peppers. 12 each in a commercial high end potting soil and 12 each in the same potting soil with a product called Mini Plug added. After two weeks the untreated plants were a little ahead of the mini plug treated plants. They told me that would be expected. After eight weeks the mini plug treated plants were approx. 20% bigger than the untreated plants. I photographed the plants and then washed the potting soil from the roots and photographed again. There was a dramatic difference, about 50% more roots on the mini plus treated plants. I then turned the photographs over to them in exchange for product. I never seen the photographs published anywhere. I dont know why I think those photos would be more dramatic than the graphics they use.

John

I had a cold compost in a raised bed that I decided to grow something in, it looked good but wasn't ready yet. I just turned it and put some simple starter Jerry Bakers recipe and covered for 2 weeks with plastic. Put my tomatoes in and they just loved it.

Use the leaf mold as is in the garden. Don't waste time and energy trying to sterilize it. Gardens are not sterile places. And, you'll stink up your kitchen trying to sterilize soil or leaf mold in the oven or microwave, plus burn up tons of electricity and spew out greenhouse gasses, for nothing.

If you were using it in pots, then you might want to sterilize it, but I never bother. Gardens are not sterile places! they need an active microbial community to work. Now if you knew the leaf mold came from a spot that has problems with some particular disease that is not already present in your garden, maybe sterilizing it would be a good idea, but it's not likely to be the case unless you're transporting the stuff long distances, like across the state. Best to use local stuff, which is what you're doing. Really local stuff!

I like what cowgirl said - Don't fix what ain't broke.

thanks - actually, I never really intended to bake any soil in my kitchen... but everyone has so many different ideas and I am open to hear all of them

Like I said, I really don't mind weeding so I am going to spread this "duff" or whatever it is called into my garden and weed away in the spring if it has anything undesireable... This stuff is so beautiful, I can't wait to spread it.

Carrie

There are many people that seem to think that soils should be "treated" to reduce to potential of "weed" seeds and disease pathogens being in that soil, forgetting that in the process of "treating" that soil they are really just killing off beneficial soil microbes that will help control disease pathogens but are less hardy than the disease pathogens. Many "weed" seeds have evolved of eons to be much more resistant to adverse soil conditions, too, and then many float around on the wind or are carried around by birds and when they find a "clean" soil with very little to no competition they will germinate and grow and since many "weeds" grow better in poorer soils (soil that have had the Soil Food Web killed by pasturization are not good soils) they flourish.
The best thing anyone can do for their soil is add material, organic, that will encourage the Soil Food Web to flourish and help grow strong, healthy plants that are better able to withstand diseases and insect pests and will crowd out any unwanted ("weed") growth.

Hi, folks. Below are some temperature parameters and processing information that some might find useful for your soil pasteurization projects, either by conventional or microwave oven.
Table 1. Temperature necessary to kill soil pestsF
C
Target
115
46.1
Water molds (pythium and phytophthora)
120
49
Nematodes

135
58
Worms, slugs, centipedes
140
60
Most plant pathogenic bacteria
160
71.2
Soil insects
180
82.2
Most weed seeds
215
102
Few resistant weed seeds & plant viruses

Best practices
1. Always screen the soil for metal and other unwanted objects prior to processing in any oven.
2. Because some unpleasant smells can result from processing media with decomposing organic matter, it's best to perform this task outdoors or in a well-ventilated garage or shed. Bagged potting soils, of good quality, are usually not a problem, but outdoor processing is better for you and your home environment.

By Conventional Oven
To begin processing in a conventional oven, set the temperature at 250° to 275°F. Next, screen your soil to remove any unwanted items (note the warning above). After screening, add any amendments that you normally use, except for vermiculite or perlite, but include sands, small stones, leaf mulch, sphagnum peat, etc. to get it as friable as possible. A baked brick is not the goal. Third, make sure that the soil mixture has adequate moisture for seed germination, moist but not soggy. In any case, the mixture should not be more than three to four inches deep. Put the mixture in a pan or glass dish and cover with aluminum foil. Next, place an oven thermometer in the center of the mixture and heat until the soil temperature (as indicated by the thermometer) is at least 180°F or higher if your target requires it. Then, lower the oven temperature and maintain the soil temperature at 180°F or higher for 30-40 minutes.

The amount of moisture in the soil prior to processing will determine how rapidly the target temperature is reached. It is important to monitor the processing temperature as higher temperatures may cause the accumulation of some toxic materials in the soil and should be avoided in a conventional oven if possible. Remove the soil from the oven and allow it to cool in a well-ventilated area.

By Microwave Oven
The primary benefit of using a microwave oven for soil sterilization is that it is both a convenient as well as a faster method (2 to 5 minutes per kg of soil compared to 30 minutes in a conventional oven). Secondly, MW eliminates soil borne pathogens without excessive detrimental effects to some key soil life, such as prokaryotes, micro-organisms important for cell respiration. 4 KG (about 9 lbs) seems to be the maximum amount of material that can be treated effectively in standard microwaves at a time of about 7 minutes.

Some additional benefits of using a microwave is that these ovens not only kill fungi and pathogens, but wont dry out the soil, yet will still generate temperatures high enough to kill most weed seeds. Overheating also is not as problematic as when using steam or conventional ovens, so keep the power on high. Most important, research shows that there is less post-processing recolonization by Fusarium and other fungi from MW processing as from steam or conventional ovens. MW is also economical in that used MW units can be acquired inexpensively at flea markets, etc. making it a very cost-effective solution for many gardeners. However, make sure the integrity of the microwave door seal has not been compromised and, second, prior to using a microwave oven, it's even more important to screen for metals!!!

When processing, as in any microwave cooking, be sure to use a microwavable dish or 1.5 mil polypropylene bags. The nice thing about the poly bags is that the same bag can be used to store the processed soil. However, it's a good idea to let the media cool outside the bag to speed up the cooling phase. Expect the rate of cooling to be greater after treatment for drier than relatively moist media. It's important that moisture be present in the soil, but not as much as in a conventional oven. Having water in the media is important because when the media is heated by MW radiation the heat is transferred to other soil components by conduction through the water molecules, thereby increasing the efficiency of heat transfer throughout the media.

Finally, treat the media in the MW as you would any other in the MW. Halfway through the processing, stir it up to insure that all particles are treated. Continue the processing. When finished, check the temperature to insure that your target temp is reached. If not, heat again for another minute. Overheating in an MW is less critical than in a conventional oven.

In any event, you will need to test your own equipment and types of media you use to establish appropriate processing baselines for your situation.

Most of all, have fun!

Keep in mind that if you do "sterilize" soil in your oven or microwave you will stink up your kitchen.

I agree, sterilizing soil in the microwave stinks to the high heavens.. I made that mistake only once.. never again. I never tried the regular oven, and won't.

This was the highlight of the thread for me.

----

Carrie, after reading your post again I realized that the area where the duff is is conducive to puff balls. They look like light brown golf balls. If you tramp on them you will see a dark brown powder fly out that is Mycorrhizal Fungi spores. Take a small baggie and put it over the puff ball and try to pick it with out breaking the shell. Burry it a couple ins in a container of damp potting soil or compost. Stick your hand in untill you find the puff ball and break it open. You can mix it then without breathing any spores. You can see the benefits on the link below.

John