What happens? Microbial actions slow down but does not stop.

The "best" thing is to fertilize in the fall when cool season grasses can use it most. I give mine three feedings in the fall. The last one is a quick acting nitrogen source just after the grass first stops top growth that gives it what you need to give it to have its best head start on spring. It gives it the carbohydrate stores needed to stay strong through the winter and have energy for best growth next spring.

Putting on something after that point really is just waiting for the microbial action to pick up next spring.

A little organic matter is fine, if not any great help. But, too much might actually be a detriment over winter just like too much can be a detriment, by smoothering, in the warm months. Since it sure isn't getting broken down much over the winter, it would be easier to add too much.

Personally, I'd sit back in the easy chair and read up on the best ways to help next spring, summer and fall for being at this place next year. ;)

Bacterial activity slows way down. One way to determine how much bacterial activity you might have is to dig in and find out how deep the earthworms have gone and what they are doing. Earthworm activity is a pretty good indication of soil bacterial activity.

From TN. My lawn is surrounded by woods with large trees of all kinds. You can imagine in the fall I get so many leaves its hard to see the grass. This fall I thoroughly mulched the leaves 4-5 times over a 6-8 week period. Question: Is is possible to mulch too many leaves in one season? Will the leaf particles decompose in Dec-Feb and benefit the lawn in March when growth picks up? My mulched leaves are not smothering the grass. After mulching the grass is green, but there's a whole lot of pulverized leaves.

If the leaves aren't smothering the grass, you don't have too many.

I have put down 6 to 8 inches of leaves and then mulch mowed them and then I see lots and lots of worm castings in that area telling me that the Soil Food Web is at work moving those leaves into the soil. The following spring the grass in that are grows greener, thicker, faster than the grass in the surrounding area and by late summer there is no evidence of the shredded leaves.
Often when I finish mulch mowing the soil will be brown from the leaves but the grass will most often start to grow even then.

What is the difference between a layer of mulched leaves and a layer of compost? Don't they both feed the microbes and improve the soil? If I mulch the leaves on my lawn very well this fall/winter, should I plan on applying a layer compost in early spring or delay a few months?

Mulched leaves are free. Compost can cost $70 per 1,000 square feet.

Mulched leaves have nearly zero fertilizer value and provide no microbes. But they're free and provide a valuable micro-mulching effect.

Compost has nearly zero fertilizer value but it has plenty of microbes. I don't use compost any more. Too expensive for what you get.

Ground up grains (like corn, soy, coffee, alfalfa, wheat, etc.) have lots of fertilizer value. This is all I use. Cost is about $2 per 1,000 square feet.

Dave, tree leaves have lots of nutrients as does compost but those nutrients are not readily available so no soil test will extract them and so comes the concept they have none. If tree leaves and compost had no nutrients then those of us that use them in our gardens would not have gardens, nothing would grow because there would be nothing to feed those plants. Many of us that use leaves and compost (made up of those leaves) have found from our periodic soil tests that the nutrient load of our soil has increased and is in balance with no other inputs.
That this waste vegetative material has all the nutrients necessary to grow strong, healthy plants is a basic premise of organic gardening and we would fail if they did not have those nutrients.

I disagree that tree leaves and compost have lots of nutrients. If they did we would eat them. Instead we eat the seeds, nuts, beans, and fruits that hold both the protein as well as carbohydrates we need. Or we eat the animals that eat the seeds, nuts, beans, etc. Only a few mammals (koalas, pandas, llamas, camels, and giraffes among them) seem to be able to eat tree leaves and survive. All the nutrients in compost have been eaten, so to speak, by the microbes and insects that ate the original feedstuffs (tree leaves, kitchen waste, animal dung, etc.). Then other critters came in to eat the microbes and insects. Then other critters came in to eat those critters. In the end, there is absolutely no food value left in compost. If there was then another set of critters would come in to eat it. What is left is essentially peat with the exhausted carcasses of the microbes and the inedible humic and fulvic type acids that concentrate compounds that other microbes can use later on. Essentially the acids are ready to be converted into plant food. This is the "near zero" fertilizer value left in compost.

My message would be that the mulching effect of compost and tree leaves is much more important than the micronutrients in tree leaves and the microbes in compost. The stabilized humic acids in compost are a plus, granted, those are hard to get a good grip on. The power of mulch is the great value to organic lawns.

Mulch helps in two important ways. First and foremost, soil is home for the microbes. They thrive best when the soil temp is relatively constant and the moisture level is relatively constant. Mulch (mulch, tree leaves, or compost as examples) helps keep the soil from getting too hot and evaporating away the moisture. The constant temp and moisture allows more aggressive fungal growth which softens the soil and opens it up for moisture next time it rains or gets irrigation. Those fungi and the bacteria find the food in the soil and turn it into plant food.

I might add that the power of fungi is not well known. Next time you see a mold spot through the wrapper on your bread, leave it alone for a couple days. What starts out as one spot soon becomes many spots. Then all of a sudden it explodes into fur balls an inch in diameter. Before you know it the fur balls take over the entire inside of the bag. This same thing can happen in your soil if you provide the right moisture environment in your soil. Mulch helps that process along. The result is extremely soft soil.

I like tree leaves mulch-mowed into my lawn because they are free with no delivery charges, perform the mulching function, and they do have trace amounts of nutrients not found at the soil surface. As far as being a great source of protein for the soil microbes, they aren't. We have a compost pile behind the garage but that's reserved for my wife's gardening.

We do not eat tree leaves because of the taste, not because of a lack of nutrients. Tree leaves are also quite difficult to digest, our system is not ready to do that with this material. To say that tree leaves, and other types of organic matter, have no nutrients is to then deny that they feed the forests.

But we do eat bitter rhubarb stalks and chocolate, vinegar, and other plant materials that are distasteful. In the Caribbean they eat grass soup. We eat these distasteful things after considerable processing including cooking and mixing with sugar, animal fat, and sometimes lye. We don't eat bark or wood (and likely leaves) because there is no nutrition other than carbohydrate in the form of cellulose...which we don't have the microbes in our guts to digest. When plant parts are edible, we find a way to eat them. Those parts with no commercial value (like orange peels, animal skins, bark, etc.), go into compost.

Forest floors have leaves and the microbes that decompose leaves (eventually) into the humic acids I mentioned. Forests also have dead animals (blood, hair, meat, and skin are all excellent sources of protein, plus bones) animal urine and dung (relatively quick release nitrogen), dead birds (blood, feathers, meat, skin, and bones), bird guano (uric acid is a good source of nitrogen), and bazillions of dead insects and their wastes. There are also seeds, nuts, beans, and fruits that might not have been eaten by the birds, animals, and insects. I don't have any problem accounting for the nutrients in a forest. The leaves make a great mulch to protect the soil biology underneath from the drying sun and wind as well as erosive, pounding rain drops.

Let me rephrase my question because I see this discussion getting off track. Over and over I hear that compost is good for lawns. It builds soil structure and adds soil life. If we can agree on this fact, my question is: does the mulching of leaves on a lawn serve the same effect as compost? If so, can a good autumn mulching of a thick downfall of leaves substitute for an economical and beneficial application of compost? If not, what's the difference between the two, and what DOES mulched leaves do for lawns? This is the question I need advice with.
At the risk of returning to the previous discussion of the nutritional value of compost, this is what Paul Tukey says in his Organic Lawn Care Manual about the nutritional content of leaves and compost (pg 145).
Leaves: N.8/ P.4/ K.2/ Ca 0/ Mg 0/ S 0
Compost: N 1/ P.5/ K1/ Ca.3/ Mg.2/ S.3

I hear that compost is good for lawns. It builds soil structure and adds soil life. If we can agree on this fact, my question is: does the mulching of leaves on a lawn serve the same effect as compost? If so, can a good autumn mulching of a thick downfall of leaves substitute for an economical and beneficial application of compost? Not everyone will agree, but in my experience, Yes leaf mulching, although not quite as good nutritionally, does substitute for a thin application of compost. Earthworms, fungus and other life forms will thrive on the leaf litter improving the soil significantly. I found it interesting that Scotts/Miracle grow company is now advocating leaf mulching on their site linked below
Bill Hill

Here is a link that might be useful: Scotts take on leaf mulching

What that article refers to, BillHill,is a study done by Joe Vargas turfgrass strudents at MSU in the 1980's. After having added shredded leaves and compost made mostly from shredded leaves to my soil that when I started was deficient in the major nutrients and had a low soil pH (like 5.7) I now have optimal levels of those major nutrients in my soil with a soil pH of 7.2. Nothing other than the compost (made of shredded leaves, kitchen waste, 1 pot of coffee grounds per day) and shredded leaves has been added to this soil, no grain seeds or meal, no rock dusts, no commercially available plant food.
Leaves, mulch mowed into your soil, provides a a nutrient base for the Soil Food Web to live on and they are what feeds your turf grass, or any other plant you grow. Over time, as the residual level of organic matter, humus, grows depending on your soil type that organic matter makes for a much better soil that holds sufficient moisture but allows the excess to drain away. That organic matter holds the right nutrients so the soil bacteria, the Soil food Web, can supply to your plants what they need, when they need it and with the moisture that is held there, since plants cannot uptake any nutrients without moisture, the plants grow strong and healthy because they have what they need, when they need it.

Kimmsr, I agree with what you say about the soil food web and the benefits of adding organic material to the soil. I also mulch leaves and apply compost to beds and problem areas of the lawn. That being said, my lawn, shrubs and gardens do much better when fed with organic fertilizers such as soy and corn meal, alfalfa and others in addition to compost and leaf mulch. Stan, If you mulch your leaves this fall, Save your black gold (compost) for you flower shrub and vegetable gardens where it does the most good. Any compost left over can go on your lawn's weak (compacted soil, drought stressed) areas. The following year, those week areas could be your finest lawn. - Bill Hill

Let me rephrase my question because I see this discussion getting off track. Over and over I hear that compost is good for lawns. It builds soil structure and adds soil life. If we can agree on this fact,

I can't agree and that's where we get off track. Compost provides shade, minimal nutrition, and beneficial microbes. It does not build anything, microbes do. It does not add soil life, but the shade it provides facilitates the population growth of soil microbes. Beyond the addition of the microbes that wash off of it, compost does not add life. Or maybe that's the life you were talking about.

But regardless of whether I agree about the above "fact,"...if we can agree on this fact, my question is: does the mulching of leaves on a lawn serve the same effect as compost?

Yes.

If so, can a good autumn mulching of a thick downfall of leaves substitute for an economical and beneficial application of compost?

Yes.

If not, what's the difference between the two, and what DOES mulched leaves do for lawns?

I already went there and you said it was off track.

Paul Tukey is well meaning but not well informed. If you want to take your organic gardening seriously, you have to completely forget about NPK and start thinking in terms of protein, carbohydrate, vitamins, enzymes, and minerals. If Mr Tukey ever indicates something similar, I'll start to read his stuff. NPK was invented by chemists who believe the soil contains chemicals and minerals. While it does contain minerals, it is more important to know that it contains microbes that need to eat real food. They do not eat NPK they eat food. When they can't get food (and often when they can) they eat each other. The NPK mentality has been around for 200 years and it isn't going away soon. Once you embrace the idea of organic food and drop the visions of chemicals (NPK), you are bucking the entire world of agriculture but you are on your way to understanding how organic fertilizer works. You will also understand why compost is not a fertilizer (no food in it).

As you can read in kimmsr's messages, he has a more austere approach to organic gardening. If there was a 'vegan' category for organic gardening, he'd be one of the champions of that cause. I read every word he writes looking for some biological insight into his methods. I trust that he gets the results he claims, but I don't fully understand why. And I clearly disagree with him (and the rest of the world) on the value of compost. I think people get good results with compost if they do not already have a good supply of microbes in their soil. Compost provides a "micromulch" much like mulched leaves. It is my belief that the micromulch provides additional shade under the shade of the grass blades to prevent moisture loss and stabilize soil temp. That function allows the soil fungi to grow extraordinarily fast and that's where the big benefit comes from.

Chemists are locked into NPK and can't see the biology of the soil. I'm locked into food value. It could be there is something else, call it another force of life, that I'm not seeing. I'll admit I'm blinded by the strength of my current beliefs. And maybe that other force of life provides the nutrition from leaves and compost that kimmsr talks about.

I personally do not think that just mulching leaves is not enough. Sure it's a lot of carbon stuff for earthworms, bugs, etc to chew on and break them down but there's not enough protein to go around in artificial environment like your yard. Untouched forest is a huge nutrient cycling with a lot more protein material involved as Dchall mentioned. I've seen dramatic improvement in my mother's lawn with just twice application of soybean meal a year. We had been mulch mowing for maybe 15 years and it always looked decent and we had a lot more earthworm as a result but the grass isn't as thick or anything spectacular on mulching leaves alone.

This is organically cared for St augustine lawn in Houston during the winter yet it looks like it is during the spring. Mulch mowed for many years.

The next two pictures are neighbor's. Mulch mowed as well but one used weed and feed and another one probably never used anything.

No one has ever intimated that just mulch mowing leaves into the soil is enough, just that is a part of the total lawn care program, a part. Mulch mowing the leaves back into the soil, kind of almost like what happens in a forest eventually, is better for any lawn than raking the leaves off and throwing them away, just as mulch mowing the clippings when mowing is good for any lawn. Doing both will help reduce the amount of lawn food that must be applied to keep a lawn as many subdivisions require.
Keep in mind also that some research done back in the 1970's indicated that having a green lawn around your house could reduce your summer temperatures by about 10 degrees.

Hi kimmsr. Lawn food? I was thinking you were successful with mulch mowing and compost alone. Was I mistaken?

Now I'm confused.

You made an invalid assumption based on too little information.

No we didn't.

kimmsr said,
You made an invalid assumption based on too little information.

That's my normal mode of operation ;-)

We know you use compost but I thought from reading your messages that you relied solely on compost for nutrients. Was it you I read elsewhere that also used Milorganite? If so do you use it every year?

Probably not a whole lot happening right now on the ice cube I'm living on! LOL!!

It gives it the carbohydrate stores needed to stay strong through the winter and have energy for best growth next spring.

Lisa11