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How Much Compost is Too Much???

Posted by gawdinfever z5b/St. Louis, MO (My Page) on
Thu, Nov 22, 12 at 0:15

Okay, so I started composting a five years ago. Bought my current home 4 years ago. I'm thinking I can get pretty carried away. Up until this year, I drove around collecting leaves and posted on my local forums requesting anything compostable....

So far, I've spread about 15 wheelbarrows of compost and have left maybe 20 more....

What to do???

I want more beds, but how much compost is too much? Do most of you 'turn the compost into the soil' or do you just top off the beds?


Follow-Up Postings:

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RE: How Much Compost is Too Much???

When your soil holds too much moisture, because of the amount of organic matter, you have too much. I have found, over many years, that about 6 to 8 percent humus in soils is best, much more and the soil hold too much water for too long and a plants roots start to rot.
So why does that not happen in a container with a peat based soilless mix? Commercial mixes add perlite or vermiculite to enhance drainage and all of the home recipes for a potting mix I have ever seen include them also, to promote drainage.
Compost, and other forms of organic matter, can be layed onto your soils surface and it will be incorporated into the soil by the Soil Food Web. Tilling that same material into the soil uses excess amounts of a non renewable resources that may not be necessary.


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RE: How Much Compost is Too Much???

You can save some of the compost and reapply it when you noticed the soil is beginning to get hard again.


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RE: How Much Compost is Too Much???

Too many variables here - how large is your garden? what type of plants do you grow? what type of soil did you start with?

If the native soil was devoid of nutrients, you have a large yard or acreage, and you grow plants that are heavy feeders you can use a lot of compost.

Many people do incorporate compost into the soil and at times I do that by mixing some in a planting hole or when starting a new bed by tilling it in. However most of the time my compost is probably not 100% finished so I use it as mulch or under mulch but on top of the soil.


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RE: How Much Compost is Too Much???

I just finished incorporating (not surface spreading) 8 years of compost, about 100 cubic feet or more of OM into an area 250 square feet to form a new veggie garden area, with compost 4-5" deep before tilling recently undisturbed (but previously contractor excavated and regraded soil). By next fall much of the OM will be degraded. Year after next another 3-4" will be incorporated. You can never have "too much" compost unless you way overdo it.

OM is NOT humus, the final, completely biodegraded product of decompositon. Compost is not humus. Compost finally becomes humus.

Because I am trying to moderate very heavy clay I have laid a heavy layer on at first, but have no fear of doing it again in a couple of years, maybe next year depending on how the soil looks and works.

Others will tell you that repeated tilling will destroy the soil food web and that too much organic material will hold too much moisture causing roots to rot. Firstly, this area will be elevated above the surrounding by several inches and the soil will finally be better oxygenated by tilling and better drained by the addition of OM and raised elevation by doing so. My belief is that each additon of OM increases the activity of the soil food web by providing more fodder, my previous experience showing incredible production increases of veggies by this method.

To each their own. I'll do what has worked for me.

hortster


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RE: How Much Compost is Too Much???

Although there will always be some that disagree this, from ScienceDaily, is a good definition of humus, "Humus is a complex organic substance resulting from the breakdown of plant material in a process called humification." So humus is the residual of the total amount of organic matter put in soil that, for the time being, the Soil Food Web has not digested.

Here is a link that might be useful: About humus


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RE: How Much Compost is Too Much???

Couple issues with repeated tilling and with large amounts of OM.

Tilling may not 'destroy the soil food web' in the sense of sterilizing the soil, but it does change the species composition. Fungi get ripped up by the tilling and need time to regrow. Bacteria and similars aren't as affected by it, so repeated tilling will shift the SFW species composition from fungi to more bacteria. Bad or good? depends. Permacrops tend to do better with more fungi, annuals with more bacteria. Fungi are better at decomposing larger particles of OM that are too big for bacteria. Also earthworm species differ in their tolerance for repeated tilling. Some species repopulate quickly, others can't tolerate their tunnels being destroyed over and over. The soil food web depends on earthworms to break up the biggest particles, then fungi break up what the worms leave, then bacteria etc. work on what the fungi leave. Greatly simplified of course, but you get the idea.

A well drained soil probably won't have much drainage issue with a lot of OM added to the soil, but your soil volume will shrink as the OM decomposes. Not much of an issue with annual crops where you start over every year and can add more OM to replace soil volume, but it's an issue with permacrops because the plants settle and you can't get into the soil to redo it every year.

Too much compost? got any friends who could use some?


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RE: How Much Compost is Too Much???

  • Posted by jolj 7b/8a-S.C.,USA (My Page) on
    Fri, Nov 23, 12 at 17:09

Most people say 5-10% compost, but I have seen plants grow in 6-12 inches of well rotten animal manure that was never turned or mixed with anything. One place the horse stable had pile the manure & wood shaving mix 10 feet high & let it rot.
The ground was covered by 12 inches of well rotted mix & plant where growing in it with out any help from anyone.
But I think 50% sand or clay with well rotted compost, with 4-6 inches of mulch is not to much.
I have collards in a bed & some of them are in 4 inches of coffee compost from an old compost pile that is now part of the bed. I have put out 3 truck loads of grass clippings & 2 truck loads of leaves. I had to stop gathering because My DW has a broken foot or that number would be double.
As long as you have some soil & good drainage, I do not think you can have to much compost or mulch.
I know someone is going to link a site that disagrees with me. But I can only know what I have seen or done & there is a link to say any thing you want to hear. So you have to do what you thing is best & learn as you go.


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RE: How Much Compost is Too Much???

It also depends on what your starting soil is.

For heavy clay soil in a warm climate, the clay holds more water than compost, so adding compost helps aerate and "dry out" the soil quicker after a heavy rain or watering.

My hope is that after digging in 50% wood chips to my clay soil it will become a good no-till for many years.


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RE: How Much Compost is Too Much???

Many people, because they never take a good, in depth, look at their soil often think they have more organic matter then they actually do. A few people that do finally take that good, in depth, look at their soil are often surprised to learn that after adding "tons" of organic matter to that soil how little is really there.
Balance is the key here.


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RE: How Much Compost is Too Much???

kimmsr Brings up a good point. When organic matter content is discussed, at what depth are we speaking? With the current practice of shallow cultivation, such as the lasagna bed system, or roto tillers, very little is being incorporated beyond 6-8 inches. Under proper conditions tomatoes for instance will send roots as deep as 5 feet. Its quite possible, and I suspect probable that under these management styles one is encouraging very shallow root systems, and then in drought years, without a irrigation system, one has problems. Studies have been done, and experience has shown that vegetables grown in deeply worked soils, Such as double or triple digging to three feet, do much better under drought conditions.


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RE: How Much Compost is Too Much???

  • Posted by jolj 7b/8a-S.C.,USA (My Page) on
    Sat, Nov 24, 12 at 17:03

emgardener, 50% wood chips is not to much.
I was talking about 50% finished compost, which is not to much for my raised beds.
I start my bed with the same ideal as your no till.
Build it right from the ground up & never have to build another foundation for the bed again.
1) Start with good soil if you have it, I do.
2) cut, till or turn the soil to a depth of 20-24 inches.
3) add finished compost to this trench/bed & turn it into the soil.
4)Repeat until the trench is 12 -24 inches above the paths between beds. This takes time & labor the first time & the new fad is less work,so to appeal to more city dwellers.
But I am old school organic gardener who has not reason not to Double dig.I think deep digging is more important to no till in clay then raised bed, I had it work great in flower bed of white clay, with not containering of the 20 X 30 inch beds, for 10 years now.
But I will be building cement block beds next, like Jon H.
It is hard to argue with his hundreds of pounds of food for the hungry. I also want a bed that will last till my grandchildren are able to grow their on food.
I have Collards in a well composted bed, not double dig or raised. I have 6-8 inches of mulch around them & if I can keep the perennial grass out of them, it will be a no till bed for the 4-6 year or as long as the collard last.
I will let you know how it works, the real test other than the P-grass, will be the Summer/Fall heat in 2013.


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RE: How Much Compost is Too Much???

jolj. 50 percent of what?
Are you speaking of a depth in the soil of 2 inches or 12 inches? There is a large diffference between those extremes. While a ton or two of compost might be 50 percent of soil at 2 inch depth (depending on the area covered) you would need many tons of compost to get even 6 percent at a 12 inch depth for the same area, you might need more then is available in your corner of the world.


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RE: How Much Compost is Too Much???

I have been gardening in 100% compost since 2008. I see no problem with it.

Here is a link that might be useful: John's Journal


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RE: How Much Compost is Too Much???

This photo is of two tomatoes on the right and two zuks to the left growing in 100% compost. John

Here is a link that might be useful: John's Journal


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RE: How Much Compost is Too Much???

I typically see 1-3" recommended as the maximum. A good video with some explanation, from GGWTV, can be found below and starts around the 7 minute mark.

If you really have more compost than you can use, how about sharing the wealth with a school or religious institution's garden? They're often looking for free compost.

Here is a link that might be useful: Growing a Greener World episode on compost.


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RE: How Much Compost is Too Much???

Here's one reason why adding 50% compost to soil is not an outrageous amount and will not raise your soil OM fraction to much. Back of the envelope calculation, just to illustrate:

1 cu ft of soil + 1 cu ft. of compost (i.e. 50/50 by volume). You could use any volume unit.

Let's say compost weighs maybe half as much as soil. So we have half as much compost as soil by weight. Our unit is now .5 units.

Compost has a LOT of water in it, even when dry enough to sift. Another factor of 50%, so our compost is now .25 units.

Of the dry matter, a lot of it is minerals and not organic matter. Another factor of 50%, and we now have .125 units of organic matter to our 1 unit of soil.

This is in the range of a good topsoil - 10% OM - but that OM will continue to degrade over time.

This is a very rough calculation, but it is based on data I've looked at for a number of compost products, so as an order of magnitude estimate, it's pretty accurate.

This is why you can you a LOT of compost. :-D


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RE: How Much Compost is Too Much???

  • Posted by pt03 2b Southern Manitob (My Page) on
    Mon, Nov 26, 12 at 14:06

Zog use too many numbers, make head hurt.

;-)

Your last line...you meant "This is why you can youse a LOT of compost"?

Lloyd


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RE: How Much Compost is Too Much???

Youse gotta problem wit Zog's spelling? :-p


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RE: How Much Compost is Too Much???

Hello I have a 60 x 60 vegetable garden that started out as vigin concrete (clay) In two short years (this will be the third)on this spot it is as nice as my last garden of fifteen years. I however garden against the grain of popular thought, first a lot of these concepts of top dressing and lasagna this and mulch that takes years to see any real result and to be perfectly honest the gardens look like hell with cardboard rotting leaves and such (to each there own). I go against the popular thought and roto-till at least six times a year I have for eighteen year. I have five of my neighbors drop off thier lawn clippings every week and I sprinkle them bettween my rows (3 ft apart) let it dry for a week and then roto-till them under, I do this non stop once a week for a quick thirty minutes theres no weeds and the garden does the composting. Also three times in the summer I go by my neighbors horse pasture and pick up three large drums of horse manure spread it on the clippings and till it under a week later and let the garden compost it. All this talk about nitrogen depletion is bunk and if you want to be on the safe side go to home depot and get a fify lb bag of slow release lawn fertilizer 20-20-20($24) Ive used it for years on my garden in the spring and tilled it in 8-12 inches, I use a half of bag in the spring and so it will cost $12 a year and youve got the nitrogen covered. In the fall I put on at least a foot of leaves straw and all the thrown out peat moss and vermiculite that the local green house bags up and some more manure and till them in so they dont end up all over the yard when the next wind comes along and I let the garden soil compost them them this is done by the 15 of Sept and I add two inches of water to the freshly tilled garden and low and behold everything has broken down come the following April. My soil has great drainage is loose and very fertile. When I created the garden I did however till in fifteen decomposing hay bails and I tilled in four inches of shredded trees which havnt broken down completely and helps keep the soil loose. One final thought Im assuming most of the people who post on here are not big commercial gardeners and have small family gardens why then do people talk about drought? If you cant water a 20 x20 back yard garden why plant it? This is the way I do it like I state to each thier own but reading some of these threads I think that some people are getting way to technical when in reality its dirt feed it and harvest your vegetables.


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RE: How Much Compost is Too Much???

Thanks Oil_robb for posting, it's good to hear the wide variety of methods people use :)


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RE: How Much Compost is Too Much???

Oil_Robb wrote:

"If you cant water a 20 x20 back yard garden why plant it?"

Because there are some places in the country that are in a perpetual drought and the city fines you if you go over a particular amount of water usage, but people still like to have fresh homegrown tomatoes???

Plus it's wise to save water(and ALL other resources) no matter how much water is at your disposal or what part of the country you live.

Kevin


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RE: How Much Compost is Too Much???

You must have pretty widely spaced rows if you can till between them every couple weeks without damaging the roots of your crops. Glad it works for you though.


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RE: How Much Compost is Too Much???

I don't know about that. My ex-husband used to run a rototiller down his rototiller-width rows as soon as a weed showed up. He grew spectacular corn and tomatoes. We used to have a killdeer in our garden every year and he would till around her.


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RE: How Much Compost is Too Much???

  • Posted by pt03 2b Southern Manitob (My Page) on
    Tue, Dec 11, 12 at 8:07

"he would till around her"

Me too! But they can be tough buggers to see.

Lloyd


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RE: How Much Compost is Too Much???

Hi Toxcrusadr
Most of my rows are 40" wide except corn 12" onions 8" and my cattle 6 panels (4'x16')cattle pen trellis which are 6' wide becase I plant on both sides of the trellis. I take off the two ouside tines off the tiller and so I have a tiller thats only tills a 1 foot path. When preparing my seed rows I stake them and then tiil and go in between the rows and with a 12" flat shovel I scoop up the loose soil creating a 6" deep trench in between the rows. I plant on these mounded up rows as it gives the plants a full 16" of loose soil to grow thier roots into and it allows drainage when we get heavy rain, it also allows me a place to scatter all kinds of grass clipping to incorporate all year long.


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RE: How Much Compost is Too Much???

..
I think we're taxing the tox.

I just referred to him elsewhere myself.
..


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RE: How Much Compost is Too Much???

Did the mother do her broken wing routine, Lloyd?


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RE: How Much Compost is Too Much???

  • Posted by pt03 2b Southern Manitob (My Page) on
    Wed, Dec 26, 12 at 19:22

Ya, they always do. It almost seems the kildares in this particular field do their act close to the nest and if I stop and sit for ten minutes or so she will go back to the nest and I can mark it. In the other field she tries to lead me off and I have a heck of a time trying to find the nest.

Lloyd


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RE: How Much Compost is Too Much???

"The soil food web depends on earthworms to break up the biggest particles, then fungi break up what the worms leave, then bacteria etc. work on what the fungi leave. Greatly simplified of course, but you get the idea."

I like this above. I wish you could "like" on this site.

"Zog use too many numbers, make head hurt."

Funny!

"This is the way I do it like I state to each thier own but reading some of these threads I think that some people are getting way to technical when in reality its dirt feed it and harvest your vegetables."

Funny!

"We used to have a killdeer in our garden every year and he would till around her."

"Me too! but they can be tough buggers to see"

"I think we're taxing the tox.
I just referred to him elsewhere myself."

You guys are funny! I am busting a gut on this thread!


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