Planting in hot compost ?

[snohare]

Hi guys, I have a burning question in my mind...
I just took delivery of two tonnes of well rotted bark chipping compost from a tree surgeon. The stuff is roasting hot in bits, mildly warm in others. Okay, it will cool as I wheelbarrow it from the heap (on the pavement outside the lotties !) to my plot, but what I am wondering is, how safe am I to plant into it ? I was told that the stuff I was getting would be old enough not to be sucking up nitrogen (from the bottom of a 300 tonne pile, been there years) but I was not expecting it to actually be hot. Some of it looks just like soil, but a lot of it just looks like very decomposed bits of chippings, with the occasional stick. Great for my hotbed coldframes that are going above my compost bin, but can I stick my tatties, artichokes and rhubarb into the stuff, with a bit of topsoil mixed in ? Would I be safest to add some pelleted chicken manure just to get around any problems with lack of nitrogen ?
I will cry if this stuff turns out to be no use...I paid £50 for it, half my annual lottie budget !
Of course, being an archetypal grippy Aberdonian, I am hoping I will be able to pick pre-roasted artichokes and baked tatties...

[GardenFan]

Hi,

I don't think it will rob nitrogen but I doubt it will add a great deal, what it will be great for is when mixed with top-soil is a fixer to lock in good stuff and to help hold water. I would mix it with chicken muck, fish-bone-blood or used coffee grinds if you can source them as these will help add good stuff into the mix. By the time you use it I think it will have lost a lot of its heat. In a deep pile you do get a lot of microbe activity that creates a lot of heat (you get the same thing in hotpile compost bins and long standing deep manure piles).

[maggieaggie]

I have encountered a similar issue with some compost i got from our local gren waste recycler. they give it away though... so no financial loss, but i thought i could plant straight into it. my garden guru told me that it was too rich and would burn out the seedlings from being to strong. treu to form, all my seedlings have died over the last week since i potted them up into it. i had seeds in it as well, and no sign of them in my greenhouse.
he reckons its great for enriching your soil, but that you will burn young plants out with the stuff. It sounds similar to what I got, including the heat.
good luck with it, whatever you do.
m

[SimonCole]

What a surprise! I am researching green waste composting through Bangor University at the moment I have just spent today collecting samples from a windrow (heap) in Shoton and I blistered my fingers with the heat!

Funnily enough, the question I am trying to answer is: 'What is the effect of composting green waste on the rates of nitrogen mineralisation?'... or in layman’s terms: how much nitrogen is left in green waste compost!
So far there has only been one scientific paper on this issue, which was inconclusive. If you could imagine that raw green waste contains vast amounts of nitrogen, we think that only small amounts are lost as ammonia and nitrogen dioxide. Thus it is very strong!

I would recommend that you mix it well and use it in moderation, but it is fantastic stuff. You also need to be sure to wash your hands well because, according to one of my colleagues (a chat we had today), green waste compost contains significant amounts of E.coli. I would not let this put you off using it because you need to ingest quite a large crumb of dirt for it to make you ill.

[snohare]

Thanks very much for your help guys, if nothing else there is a clear concensus that I should not be planting tatties straight into it which is what I was going to do ! Good job you posted Maggie, I think I will treat it as if it will have the same effect as your stuff.
Mmm, next question is how much coffee grounds etc do I need to mix it with, happily just in case I did dig out one spit's depth of soil from where I was putting the pile first of all...so I start off with a big pile of turves and loose, really good quality soil to mix in.
GardenFan, it sounds like you have a mix you have used or seen/heard of used - can you tell me what that is ? (BTW, you do realise that at the height of summer you are going to be in great demand amongst all these hot sweaty gardeners...! )
Simon, can you tell me - if I put in some fresh chicken manure mixed with sawdust, is that likely to absorb any appreciable amount of excess nitrogen ? Sounds very iffy to me, but it's an option I suppose. (I have the sneaky feeling that there will be so many free radicals going around that it's almost irrelevant ) Plus, any idea what else is likely to be in there in large quantities, or where I could find out more on the subject ? (I am what you might call scientifically literate, but chemically fairly illiterate.)
Glad you mentioned the E.Coli, up here is a real hotspot for 0157:H7 so I am not inclined to take chances, supposedly it only takes a dozen of the l'il critters to cause a raging infection instead of the usual 10 000 ! I suddenly thought of the lack of first aid facilities yesterday and was patting myself on the back for remembering that (new site so no-one has), but I never quite got around to thinking about pathogens...

[TPeers]

Quick way to clean hands enough to enjoy a cuppa at the lottie - baby wipes! I kid you not, they stink to high heaven but your hands should be clean enough not to pass on sufficient pathogens to make you ill.

I suggest you stack your pile of chippings until they cool, at which point they should be safe to use without burning growth - a good sign is when the first batch of weed seeds germinate!

[SimonCole]

Simon, can you tell me - if I put in some fresh chicken manure mixed with sawdust, is that likely to absorb any appreciable amount of excess nitrogen ? Sounds very iffy to me, but it's an option I suppose. (I have the sneaky feeling that there will be so many free radicals going around that it's almost irrelevant )

I would have thought that both the manure and sawdust would add nitrogen. Other than that, I would just mix it well and use it in moderation. Letting your heap sit on soil and uncovered should also help to remove some nitrogen through leaching. The great thing about green waste compost is not the nitrogen that it adds, but a molecule called lignin, which takes over 10,000 years to break down. It and other ‘humus’ molecules hold vast amounts of water and nutrients in the soil, that would otherwise drain through.

Plus, any idea what else is likely to be in there in large quantities, or where I could find out more on the subject ? (I am what you might call scientifically literate, but chemically fairly illiterate.)

Salinity is also sometimes a problem or on occasions we see excesses of P, K and other micronutrients such as boron, copper etc.
There is some stuff on google or in the scientific journals (you can do a search if you have access).

Hope all goes well

[dexterdoglancashire]

On the cleaning hands front, I've got some face wipes in "Dexter's Den" and also some antibacterial hand washing stuff you just squirt on your hands, rub your hands around until they are dry (it feels icy cold) you dont need to wash it off. You can get it from Asda and Superdrug (and probably other shops as well). Bernie aka Dexterdog

[snohare]

Cheers guys, that tip about the handwash stuffie will come in handy with my Conservation Volunteers too as we are required to wash our hands before tea breaks and are at great risk from E.Coli.
Not getting on as well as you though DDL, still struggling to get my beds and compost bins made ! It's this nonsense of having to sleep all the time..
Simon, I was under the impression that ligniferous bacteria evolved way back in the days of giant-cycad-eating dinosaurs, and that was why cellulose evolved leading to modern woody plants ? So how does lignin last so long in the soil ?
I shouldn't be pestering you actually, my neighbour works at the Macaulie Land Use Research Institute which I'd guess you know of, and so do several of my pals...but none on soil research sadly, just beetles and stuff.(And of course alcohol-based preservation techniques research in the evenings !)

[SimonCole]

Plants have always had a very great need for lignin because it is both hydrophobic (repelling water) and very strong. No other biological molecules that the plants can easily produce have both of these characteristics. Cellulose has a high tensile strength, but it lacks rigidity and it cannot prevent water from leaving the plant like Lignin can. Lignin forms part of the walls around vascular tissue in plants, helping to hold in water. The long breakdown is probably due to Lignin's inert nature... it is very tightly bound with strong bonds that require specialised enzymes that can find nicks in it's structure.
Dare I say, I don't think that I've heard of the Macaulie Land Use Research Institute... Probably because they centre their work on alcohol-based preservation techniques and they're not in the same pub.s

[snohare]

Aha, different pubs - that explains it ! That and the fact that they hide under the acronym MLURI - just so no-one knows they are actually skiving in there !
Interesting stuff on the lignin Simon - as you can imagine I am really keen to develop good soil structure, I have seen what commercial growing does to fields long term...trashed just was not the word, I remember one field that went from yields of 7 million trees to 250 000 in about ten years; nothing to do with lack of nutrients or diseases, they were well fed and sprayed, simply wrecked drainage and soil structure. Given that I have no academic access to journals, what keywords should I google to find out more ? I ask only because being an Aberdonian on 56K pay-as-you-go dialup, it breaks my heart to have to do anything the slow way online...!

[SimonCole]

Pub.s as in publications

Have a look around the TWIRLS website... http://www.bangor.ac.uk/ies/TWIRLS/C...omposition.htm
There should also be some links under 'information services'. This has some good stuff on compost but not a lot on soil structure.
I would google 'soil structure'. This seems to be a fairly OK site, but it does recommend some fairly drastic action: http://www.dgsgardening.btinternet.co.uk/soil.htm#size

What you should do to your soil tends to depend upon what you've got. For example, you could add lime to a clay soil, but this will release more toxic heavy metals that may not benefit the plants. There are some soils where people have added so much organic matter to enrich the soil that it has caused the accumulation of boron and heavy metals, which are toxic to plants. In such cases, you don't notice much of a difference to plant growth overall, but odd things like poor germination and disease susceptibility add up. I think that a good amount of organic matter is a great thing to have in the soil. It is similar to clay, in that they both hold water and bind up nutrients to prevent them from being leached from the soil. The site above also says how it breaks up clays.

If there is any general rule that I would apply, that is to always keep something growing on the soil and never let in go bare. I don't like the idea of great gaps and rows so plant quite close to prevent nutrients leaching from bare soil. This is the biggest problem with agriculture, and as you say, the structure breaks up and water cannot drain, then the whole lot slumps downhill... the end.

As to lignin, I would look again, through the TWIRLS links. But I do rate the molecule highly. You should have plenty in green waste compost because it is very woody.

We just had several tons dumped at our lottie site, last week. I don't know what we'll do with all of it. It has buried our carpark!
My Nan says that I should bake my potatoes in some of the heaps