Too much compost in the soil? Steve Solomon Intelligent gardener

While I really like the  book "the inteligent gardener" I doubt his view on compost, that too much compost can throw the soil out of balance.
Second there are a lot of people gardening were there was no soil before, what other method is there than to either build it up or sheet mulch?
Can too much compost or arganic matter really be bad for the soil?

Too much organic material can be an indicator of waterlogged soil, for example I have areas that are over 50% organic matter, it is always wet so it goes anoxic  and does not break down that area is trying to revert to peat bog. To much compost can lead to leaching of excess nutrients just the same as too much of any fertiliser can. I assume that if you were to put say 2ft of compost down each year and not dig it in then you would not be getting down to the soil so plants wouldn't have access to the minerals present there, only those in the compost. Practically it would probably be very difficult to do that however as the amounts would be huge.

Skandi Rogers wrote:Practically it would probably be very difficult to do that however as the amounts would be huge.

That's how I look at it.  I can't see any way I am going to have too much compost to add, so for all practical purposes, I would say no, it isn't possible to add too much.

A lot of people do not realize it, but yes there is such a thing as too much compost. My soil has crept past "Above Optimal" on organic matter and it is at 7%. For us, we switched tto using liquid manure for awhile that gets the NPK in the ground, but without getting the organic matter too high. Seaweed also helps in the tilled soil as it helps lighten the soil.

When too much compost is present, it does not allow water to move through the soil properly.

In general I'd say "yes", soil can have too much compost. BUT, I'd have to add that it depends upon the situation.

On my main farm I add a couple of inches of compost between crops and flip it in. But I have to be careful. During wet years this can make my soil retain too much moisture. But on drought years I find myself wishing I had added more, and indeed I do add extra between crops when it's a dry year. That excess compost is the only thing that saves me when there's little rain.

5 miles away I have my seed farm. It's very warm, dry, and windy there. Lots of sun. As a result the soil.....what exists......dries out quickly. The compost degrades quickly. Rains tend to be infrequent but heavy, resulting in leaching. Thus I'm more aggressive on adding compost. In fact, I use pallet grow boxes there that contain 100% young compost and I grow 2 crops of seed (bean, pea, etc) before emptying the box and starting over. The old compost goes to help improve the ground soil on that little farm. I really don't think there is such a thing as using too much compost at that location.

10 miles away is a community built on fractured lava. No soil except the degraded organic dust between the lava chunks. I know of successful gardeners who haul in county compost by the truckload, often adding 1-4 pickup truckloads a month. I recently was visiting one place where the compost layer is now 20" deep after about 10 years of hauling. I'd guess they have about 1/4 acre covered in mulch. They grow in that compost all sorts of veggies and fruit trees. The area is in a dry zone with sporadic rain. I noticed that the compost layer was retaining moisture while the rest of their land was bone dry. In this situation, the excessive compost works for them.

I call it the peat moss effect. Peat comes out of the bag dry, and takes FOREVER to get it damp. You almost have to soak it in a bucket.

The same thing can happen with too much compost,  or a mulch made from compost. If you water, and think you watered well, you may be surprised to find that it is bone dry 1 or 2 inches below the surface. The peat (or compost) absorbed it all.

I lost a crop of corn, thinking i was watering adequately. Texas summers......

One more tidbit. I think its funny, if not oxymoronic. I think i watched (pbs- growing a greener world?) that 5% is the goal and that number is ruffly twice what occurs in nature.

But i bet everyone here has had a tomato, watermelon or potato sprout up from the compost pile.

wayne fajkus wrote:
But i bet everyone here has had a tomato, watermelon or potato sprout up from the compost pile.

That is one of the reasons I don't personally think you can have too much.  I have grown lots of plants in pure compost and haven't seen the negative effects people are talking about.  My clay soil retains far more moisture than my compost does, so the soil you are starting with must play a large part.

As several have noted, there are other things that come into play when talking about compost quantity such as structure of the medium (dirt, the mineral proponent of soil) if you have a coarse medium then it will hold far more compost with no adverse effect, than a fine medium would be able to handle.
Dirt can be divided into several different levels of structure; coarse (gravels all the way from large stones down to below pea size) these structures have huge voids and thus can hold far more organic material than the next level down in size which is sand, then we go down in size to silt, and from silt we go down to clay.
At each level of coarseness (or lack of coarseness) the amount of organic material that is able to be contained goes down in mass until we end up at clay. The caveat of these structures is the level of coarseness of the organic material, which also plays the role of coarse to fine to super fine and the effects are very similar.
A super fine clay can hold a lot of very coarse organic material and as we move up to coarse gravel medium we go down in size of organic particles the medium is able to hold without becoming water logged.

What we need to be striving for is a balance of particle sizes that allow the best water holding ability and thus air holding ability put against where that blend looses the ability to vacate and pull air back into the soil as the water sinks deeper.

So, for every soil type, there is an upper limit to the amount of organic material it can hold and still be in balance.

Redhawk

If you don't have dirt to begin with, how else would you build your soil than without compost? I use used potting soil which is sand cow manure and bark as well and some subsoil which I get from a crazy guy who digs out a cellar.

Angelika Maier wrote:If you don't have dirt to begin with, how else would you build your soil than without compost? I use used potting soil which is sand cow manure and bark as well and some subsoil which I get from a crazy guy who digs out a cellar.

In the thread called "Article on Starting a Nursery Business", the article talks about that very thing.  Basically, pile on as much organic material as you can find, in any form.  That is what I do on my place as well and I find it works very well.

I think I've created a "too much compost" scenario in parts of my yard. Soil is terrible, and wanting to plant an avocado tree which requires well drained soil in a lower spot in the yard, I've piled up a lot of compost and mixed it with soil. Probably 70% compost mounded about a foot above the overall yard level, the hope was that through the winter with the rains it would break down some, but the soil life is so minimal that I doubt much will happen.

So I'm thinking I will add more dirt and mix it in and level out some this "winter", and plant the tree in a couple months. Not sure if I'll kill another tree or not.

I think Steve's idea is not so much that the extra organic matter will throw things off, but that the extra potassium brought in by the organic matter will throw things off.

I would say that soil should only be 10% organic matter. If your compost is completely finished it will have around 10% organic matter, but most compost is not completely finished/aged and so it has alot more organic matter and quite possible alot of nitrogen which can produce nitrates in some vegetables (bad for your health) and that can also promote vegetative growth at the expense of fruit production and excessive nitrogen can make some shrubs/trees/vines not harden off properly esp if you are zone pushing. The soil life in compost is predominately bacterial vs fungal so in some technical sense it may not be what someone is trying to promote.  


Like everything else it depends and moderation but overall compost is very very rarely a bad thing so go ahead and add it.

Hmmm but still it is difficult to create soil if you haven't got soil in the first place without adding/collecting organic matter. I just organised a truckload full of woodchips. I mean soil is not laying around to be taken.

I believe in everything in moderation. Could one have too much compost? Maybe.  Each year I have volunteer seeds that didn't die from the heat in my compost pile, germinate and sprout in my 100% compost pile, and they grow like crazy, all perfectly green and healthy looking, but I just turn them back into the pile with my fork to be composted.

Redhawk was too modest to post this, but he's written an excellent soil primer that covers a huge amount of material. Anyone interested in soil-building and rejuvenation would do well to study it.

https://permies.com/t/67969/quest-super-soil

One of the things mentioned is how using a compost extract can boost soil life to the point where the microbial activity will address issues such as nutrient excesses, and the heightened bacterial content gives soil fungal life food to eat.

Also, soil composition with regards to bacterial and fungal life can vary greatly depending on what type of system the soil is from. One based largely on the decomposition of woody matter, for instance, or one that stressed not tilling, inverting, or otherwise unnecessarily disturbing the soil would probably have a much higher fungal population than a system that didn't.

-CK

Hmmm but still it is difficult to create soil if you haven't got soil in the first place without adding/collecting organic matter. I just organised a truckload full of woodchips. I mean soil is not laying around to be taken.

You can add organic matter by growing plants; they will pull carbon out of the air. That way, they will not bring in extra potassium (if that is a problem for you; once you get a soil test, you will know if you have to worry about that. Maybe you need extra potassium! )

It sound like Angelika has two primary problems:  A lack of actual aggregate/dirt (beyond the low quality fill she has in place) and the want to create soil with compost.  As Bryant and other's pointed out, there is an essential role that the aggregate substrate of soil plays, and without it you will have issues, and with it, you will have to consider the nature of the aggregate for the best amendment policy going forward.  That said, there must be some mineral soil around for you to work with, Angelika, but you might have to pay to import it.  The cheapest is probably fill, which is often a bit sketchy or dodgy as you don't know for sure what it's quality is as it usually comes from somebody who wants to get rid of it... and that might be for a reason that you might not like; BUT that can also likely be said of most imported aggregates, and so it may be possible to check out where it's coming from; and it is in your interest to do so.  You may also be able to inquire where your initial fill came from and get more information about it.  

As far as depth is concerned, yes there can be too much compost, laid too thick.  A compost pile, for instance, will collapse into itself and become anaerobic if it is left without turning or using.  It will likewise not do well if it is over watered; again going anaerobic.  The weight of a compost built too tall will cause these conditions, unless, as Jean Pain did with his massive heaps, there is enough fluffy woody debris that there is air space enough to keep it somewhat aerobic.  The same can be done with large volumes of worms, or turning it regularly, but the latter might not be in your interest in your garden.    

What sort of volume of soil are you working with?  I know that you have a nursery business, so you will be exporting your soil with every plant as well, so you may have to consider the importation of soil as part of your business.  You should be able to calculate how much you are likely to export in a given year and then be sure to import more than this per year.  
 
It might be good to consider sand, which is easy to work with, and might be easy to acquire affordably by the truckload, and you can check out the pit from which it is being hauled.  If you have the funds, then, in addition to this I would recommend getting some good quality powdered clay to dust in when you are adding the sand, which will boost your cation exchange capacity (ability to hold nutrients) as well as water retention abilities.  You will need some mineral base, and if you can find any that is not polluted, that can be brought by dump truck affordably, then you should do it.  Once you have a mineral base, the microbes do the work for you, extracting the minerals off the aggregate and making them available to the plants in exchange for sugars.  

Once you have a good mineral base and your compost working together to build a good microbial population that supports a good cover crop of plants, and some macro life like worms have very healthy populations, then you can add a lot more compost.  The biggest issue with compost is having it go aerobic.  Having good pore spaces and microbial life should help this out.  Also, if you cover your compost with a layer of mulch the compost is much better able to deal with excess water as the undisturbed compost layer will have an intact biological system that filters and absorbs water after the iniital impact is taken by the mulch.  Without the mulch layer, the rain will impact the surface, destroying it's pore structure which was likely already bad because of sun and wind exposure.  Compost that is dry by wind or exposed to too much heat or UV is dead (or in the very least dormant) compost.  Keep it damp, but not wet, and not exposed to dramatic weather, and the best (most biologically integrated) way to do this is to protect it will mulch.    

I think Roberto you said that well it is about the mineral base! That probably was the core of my question. I got a bit of clean subsoil which is sandy clay from someone who dug it out. And I once bought a meter of basalt because someone recommended it to me. FOr the nursery I buy potting mix and if plants die i chuck it in the garden, this is sand, cow manure and ONCE AGAIN some finer woodchips probably bark.But the sand probably is not enough to do the trick. I am waiting for the test it will take time to send it over...
Isn't the lacking mineral content a problem of sheet mulching/lasagna gardening? It is organic matter only gardening.

Perhaps this belongs in a separate topic (if so, please tell me; I'm new to the forums), but the topic under discussion here makes me wonder: What would be a good way to build vegetable beds on a hard surface like, say, a parking lot?  I have seen some videos of urban community gardens being built in inner cities on surfaces like that, and I wonder what kind of "recipe" they use for their beds.  Of course, I could imagine bringing in truckloads of a premium organic growing medium hand crafted by a knowledgeable farmer (and I'm sure some of you fall in that category), but that would probably cost big bucks, probably out of economic reach of many of these communities.  So I guess I'm asking what would be a good low cost method for such a community to build their beds from scratch?

Isn't the lacking mineral content a problem of sheet mulching/lasagna gardening? It is organic matter only gardening.

 I think that you have a real good train of thought on this, Angelika, and it is worth considering.  My guess for the success of the lasagna raised bed garden is because it is not tilled, and is built in layers that will naturally want to compost down.  When this is the case and your humus is built in successive layers of biomass, the layers become integrated right down to the subsoils beneath them, where fungi will send runners down to interface with the strata to bring the minerals up for the rest of the soil community, which becomes unified throughout the layers due to the fungi.  The diversity of the materials will give enough minerals from their bodies for the beginning of the system, so there is no mineral deficiency as it is being established.  I personally would add some mineral soils, even in trace amounts, in these layers, which would eliminate the concern.  Mineral soils could easily be added during transplanting time as well.   It takes very little actual mineral soil to give all the actual nutritional minerals that are needed by the plants.  Most of the mineral soil that is 'necessary' in a soil system is as aggregate/strata, and not for the soil system's  or plants' need for minerals.  Bryant's pages on soil are a good resource on this.  The book Teaming With Microbes (might be available through your library) is a very good source of primer info on the role of microbiologically rich soil in gardens.  In Dr. Elaine Ingham's words "There is an infinity of minerals in the soil."  meaning that they can not be exhausted no matter what technique you use.  The problem, in her opinion (and I am convinced she is right), is that most agricultural techniques have such little in the way of active microbiological communities that the minerals are not being taken up, and the natural fertility of the soil is lost due to the same lack of complete microbial community.  

HI Kurt,

What would be a good way to build vegetable beds on a hard surface like, say, a parking lot?  I have seen some videos of urban community gardens being built in inner cities on surfaces like that, and I wonder what kind of "recipe" they use for their beds.

 I was involved in a community garden in Vancouver Canada that was built on an area that was paved.  We removed the pavement completely with picks.  

Some gardens are built on top of pavement or concrete.  I would definitely choose one with concrete over one with pavement.  As the beds become established some of the nasty stuff in the pavement is bound to get involved with the living soil and it will get in your food.

Most urban areas now have some kind of green waste processing that is centralized and the community gardens often have the access to some of this composted material at a discount or free from the city.  That said, the quality can be... not exactly premium, heavy on the woody debris still, and in my opinion would make a nice hugulkultural type organic woody base for a deep raised garden, but is generally not that great.  

Gilbert, why don't cover crops NOT add potassium and dead plants (compost etc) do? I grow fanstasic dandelions and we regularily phone around tree services and bed for mulch. That means there are at least 20+ truckloads full of tree mulch spread over half an acre (I will get the test results early january), my guess is high in potassium.
As for Kurt and what was mentioned in some urban areas you don't want to use the subsoil. In my case fill over swamp with concrete bits asphalt bits underdeath yes I don't want to use it. I have drainage problems in plaecs too. It is an important question because many people garden in urban areas.
A friend of mine recommended to incoorporate road base into the soil it is that black stuff I think basalt. I don't know weather or not it did anything since the particles are pretty big.
I mentioned that in another thread, that sheet mulching is mostly geared towards planting seedlings and not to direct seed which I find more labour saving.

Angelika, I would guess that it's because all the ingredients for making the green manure (grown in place) are using what's already there to grow from seed, plus sun and water. The potassium is going into the growing plants from the soil. If you add dead plants from elsewhere, they contain the potassium taken from the soil they grew in.

So growing green manure takes potassium out of the soil, when it dies, only what came out of the soil is returning to it.

-CK

I'm struggling with the nitrogen issue. I have way too much organic matter - 24.9%, yet my nitrogen is very low. I assume this is a gift of living in the PNW of the US where everything leaches out. My confusion is with the worksheet: he want you to subtract the N contribution of the organic matter at a rate of 15-25lbs per 1% OM. Which would direct me to add basically no nitrogen. Not only the soil test but the performance of my garden says I do need to add nitrogen. Now I'm unsure how to calculate that addition. Thanks for any advice.

Side note - I'm only dealing with about 250 SF, so the whole "per acre" measurement is a lot of math!

Melody KirkWagner wrote:I'm struggling with the nitrogen issue. I have way too much organic matter - 24.9%, yet my nitrogen is very low.

What you are dealing with is something called nitrogen fixation, not organic matter as a whole since I assume you have a lot of woody debris; possibly having cleared some forest to plant in? (Granted that is a lot of assumptions).

What happens is, as that woody debris breaks down, it literally robs nitrogen from the soil. This process is continuous in a living forest where debris gets put on the forest floor and breaks down into eventual topsoil. But when the process is stopped from clearing, say taking a forest and clearing it into field, the process lasts about 7 years. The good news is, after 7 years, the process reverses, and nitrogen is given back into the soil.

So for me, a person that clears a lot of forest back into field on my own farm, as well as for others; I know the first 7 years I have to put down a huge amount of nitrogen if I expect a decent crop. This is a two edged sword because I want to put that land into corn since it takes a lot less rock picking, but I can take the edge off some if I plant it into grass with such varieties as clover and alfalfa. These glean nitrogen from the air and put it down into the soil. But adding an overabundance of nitrogen will be rewarded after 7 years are up, and I can get 7 relatively low nitrogen years from this phenomenon too.

This is the entire principal of a hugel. Hugels often fail because people think any wood can work, when it has to be dead wood, and the longer it has been lying on the forest floor, the better, so that the wood does not rob nitrogen from the soil, but rather puts it back into the hugel and makes their crops above it grow. In short, adding really dead wood is like having pure nitrogen in your soil for 7 years.

The challenge for you will be getting a high concentration of nitrogen, without adding too much phosphorous. You really do not have to worry about potash because the plants just store excess amounts of it, but phosphorous can really reek havoc with local bodies of water. That is because of what it does; generates growth...as in blooms within the water body. This is difficult with manures because you get, what you get, what you gt. If you add enough manure to get the 25% nitrogen you need, you probably will be high on your phosphorous and potash. In the interest of pollution control, when you do your calculations always target phosphorous, get it to where it needs to be, but no more. That is your limiting factor. Your nitrogen might be low, but you'll have to live with that. The same if your potash is low or high, it won't pollute if it is high, and you'll have to live with it if it is low (to be morally conscious at least).

Melody KirkWagner wrote:I'm struggling with the nitrogen issue... yet my nitrogen is very low.... the performance of my garden says I do need to add nitrogen. Now I'm unsure how to calculate that addition. Thanks for any advice.

One alternative solution to adding nitrogen is to add the microbes which convert atmospheric nitrogen into a usable nitrogen. There are many different kinds of nitrogen fixing bacteria on our planet, but I'm going to refer to a select few here, as a lot of them need a host plant to live on, such as legumes like clover. Azospirillum and Azotobacter are two nitrogen fixing bacteria that are free living, meaning they don't need the roots of a host plant to live on. I have a small bag of Azospirillum and mixed some in a watering can to pour on one of my compost piles I was trying to get to finish. Did it help? I think so. I did not approach it scientifically with an untreated control pile and send samples to a lab for analysis. All I have are my visual observations. If it didn't help my composting process, I at least have compost populated with Azospirillum for my plants.

My sister has an urban compost pile into which she puts every kind of kitchen waste and paper waste and autumn leaves, and turns it a couple of times. She uses the well finished compost as potting soil in large pots because the ground soil is contaminated with lead. She's been growing tomatoes, kale, lettuce, herbs, etc in nothing but compost in big pots for about 10 years straight. At the end of the season she dumps the pots back into the compost pile, and in spring she fills them again. It seems to work great for her.

Another way could be a hicken tractor. I find it a bit small, but for a part of your flock it adds nitrogen and even a bit of phosphorous. I would love to have too much of it my garden was half or less the target level!

Travis Johnson wrote:
The challenge for you will be getting a high concentration of nitrogen, without adding too much phosphorous. You really do not have to worry about potash because the plants just store excess amounts of it, but phosphorous can really reek havoc with local bodies of water. That is because of what it does; generates growth...as in blooms within the water body. This is difficult with manures because you get, what you get, what you gt. If you add enough manure to get the 25% nitrogen you need, you probably will be high on your phosphorous and potash. In the interest of pollution control, when you do your calculations always target phosphorous, get it to where it needs to be, but no more. That is your limiting factor. Your nitrogen might be low, but you'll have to live with that. The same if your potash is low or high, it won't pollute if it is high, and you'll have to live with it if it is low (to be morally conscious at least).

I have this exact issue going on... In the past, I made a LOT of compost, using a fairly high concentration of brewer's grain, and I spread it liberally. Our soil tests showed high phosphorous where I did this, 2-3x optimal levels.
After some research, I found the brewer's grain is high in phosphorous (it seems to accumulate in seeds, which might explain manure from livestock fed grain as well). I have since cut back on the amount of BG I use in the compost.
I have also heard that the phosphorous accumulated in plants and returned to the soil via compost is more stable than phosphorous applied in a mineral form.

So, too much compost? Yep, it's possible. However, it boils down to "too much of WHAT" is in your compost and WHAT your soil actually needs. Without a plan (soil test, compost test) you are just hoping for the best...

Angelika Maier wrote:Hmmm but still it is difficult to create soil if you haven't got soil in the first place without adding/collecting organic matter. I just organised a truckload full of woodchips. I mean soil is not laying around to be taken.

Of course it is, top soil is everywhere.

Like anything,it is just a bmatter of moving it where it is not needed, to where it can be better be put to use. Since this involves earth moving, there can be a cost, but not always.
For instance, I have a gravel pit and the topsoil (overburden in gravel pit speak) is covering the high value gravel I want to extract. So I scrape it off and pile it up, to be sold for those in need of good top soil. But I have also taken literally truckload after truckload of top soil from the Dept of Transportation when they scrape the sides of the road in what they call "ditching". Here in maine you see the signs up everywhere..."Fill wanted!"