Composting, in theory and practice

There is an old adage that says ‘in theory the theory and the practice are the same but in practice we don’t find this to be so’. The same seems to be happening with composting. We gardeners have long been composting and with a few years experience most of us have worked out how to make it work for us. There are a lot of slightly different ways of composting and of getting a better or worse product in more or less time. We gardeners have, by trial and error, found what works, and in most cases it is remarkably similar; a large bin of mixed materials kept warm and moist. Now the ‘general public’ are also being persuaded to compost their biodegradable wastes and I fear composting may be likely to get a bad name from this. Firstly because it will inevitably be done under duress by some who do not want to get it right, then there will be some who do not know how to get it right, and the vast majority who will still come unstuck following the recommended methods and supplied bins.

Invariably the usual bin as supplied by councils and so on is far too small, or rather too badly insulated, and then what are you to do when it is full? Of course you don’t need just one bin you need a second or third to be filling while the first is ‘rotting’ and then maturing. But even with three such bins the process will not be very effective as such small masses usually fail to heat up. Emptying the bins out once filled, mixing and repacking them can get them to heat sufficiently but only if extra insulation is added around the bin.

The bins are small because most households without much garden do not produce much kitchen waste even if other compostable wastes are included. (Paper, cardboard, cotton and wool clothing all compost well if well wetted and mixed in). So when these relatively small amounts are added they rot but rarely properly compost because there is no heat build up. This may allow some pathogens to survive which would be destroyed if the bin is emptied, mixed, insulated and cooked properly. But few are likely to undertake this!

And then there is the problem of what do all these new composters do with all their uncertain productions. They certainly won’t be shoveling out suspiciously peaty looking stuff from hatches in the bin bottom as shown in some ads. If they follow the only possible solution with but one bin they will have to remove it or it’s contents, put back the raw bits and find a use for the oldest and most rotted stuff from the base-which is unlikely to be desirable as a top dressing. Indeed unless they are sensible composters the likely result is probably best dug into a potato patch or runner bean trench- but I doubt they have one! It is unlikely to be worthy for filling their window boxes, planters and hanging baskets. A soil improver in the long run but not nice, and good compost should be nice, but most importantly; for many where is their soil to be improved for those with barely a garden?

But trying to make those by nature uninterested in composting use inadequate methods and inadequately insulated bins may result in some nasty infestations of all sorts of vermin. An answer at the moment is not to get everybody composting but to get many to deliver their (already well sorted) wastes to local composting sites - in practice the ‘sorting’ bit leaves a lot to be desired spoiling the results. Thus big composting sites produce a well composted product but this is likely to have a lot of bits of ‘this and that’ which you and I would not want to have in our own compost heaps. An alternative solution that might provide a better grade of safer compost is giving out wormeries instead of compost bins as these are much more suited to those with small amounts of garden or just kitchen wastes and far more vermin proof. But then these are even trickier to deal with, especially once they get full than compost bins. To say nothing of build your own methane digesters etcetera. Indeed maybe there should be an obligation on councils to collect full compost bins once people have produced them, or to empty their wormeries once these filled up. Of course it would be nice if any gardener then disposing of such contents on behalf of the council could be rewarded, not only for using up their own wastes; but for as many of their neighbour’s as possible. Being paid for getting organic material seems a good deal to me, admittedly I’d want to check the stuff and recompost it all before I put it near my crops but it would be worth the effort. And you only need one or two keen gardeners in a street to get through a lot of compost.

Well made compost is delightful stuff and not at all different in appearance to good topsoil. It can be so friable that it seems to have peat in it and it is fertile in a way potting compost rarely manages. Although prone to seedling weeds your plants simply burgeon when grown with well made garden compost mixed in with their soil or potting compost. In fact trials have shown plants given compost do resist pests and diseases more effectively. (Well so do we if we are well fed nutritionally)

Indeed the problem for keen gardeners is getting enough compost so perhaps recycling more of our neighbour’s may help. But what is the ideal composting method once you have got your hands on enough stuff? The simple rule is bigger is better. The more stuff you can get the more efficient the heating process- the mass goes up by the cube but the area goes up by the square thus mice have trouble keeping warm and cows keeping cool. The bigger the volume the more it heats up and the better it cooks. But there is an optimum handling size for most gardeners and that is just about the size of four pallets tied at the corners. Any smaller than this and you need extra insulation and more mixing, any bigger and it takes too much stuff to get it full unless you have acres to scavenge.

Forget about pipes or airbricks underneath- just you try and suck air through a compost heap. And avoid like the plague any clever devices to assist you, they are as impractical a solution as bins provided with stirring mechanisms. Forget about ‘special activators’ although they help they are far more expensive than the best activators which are urine and animal droppings. Another misconception is the ‘add a thick layer of soil’ over each layer of materials as you build the heap. This comes from the Indore (not indoor) method brought from India where the thick layer of soil is needed to stop the heap decaying away to nearly nothing in the background heat. In the UK and other cold climes a thin sprinkling of soil helps by adding micro-organisms, and by adding lime, if it has any, which absorbs ammonia thus retaining richness. A thick layer on the very top is thus a good idea but other thick layers of soil just get in the way.

Of course you add some soil as it helps to prevent flies and smells but only a thin layer, this also inoculates the materials. Lime is another useful dressing for keeping the bin sweet as long as the compost is not to be used on lime haters later~~! Wood ashes are also good as their value is mixed in and less prone to loss than if they’re spread directly on the garden. Soot, if it’s clean likewise. And I add my vacuum cleaner contents despite dire warnings that it may contain toxic residues ‘walked in from the street’ –well not in rural Norfolk it don’t.

Cardboard and newspaper compost really well but only if they are interleaved with other stuff and pre-soaked well, preferably in something really yucky. The same goes for woolen and cotton clothes, feather pillows and old fur coats. (Leather does not compost easily though and is best left out.) Indeed I am always amazed at the plethora of different materials that go into any bin, which then produces something remarkably similar every time.

Tough woody stuff and thorny stuff needs burning or turning into a wildlife pile but almost everything else that was once alive can go in. Now I have one big point of disagreement with convention here- I maintain that it is quite ok to put blighted potatoes, tomatoes and their blighted haulm into my bins. I do make good compost so don’t recommend this to novices. But in twenty five years I have never had blight from using compost made with blighted material- blight comes on the wind some years and not others, it comes in warm wet summers. I’m sure it does not come from my home made compost! Of course I do make my bins carefully as I go and then dig them out and mix them, usually with additions of fresh stinging nettles, grass clippings or whatever to bulk the contents up to half the bin’s height again if possible. It always sinks. Indeed this is when you know it’s done. An iron bar plunged in can also tell you or make a hole and place a thermometer, the temperature should rise for a couple of weeks, peak and then cool again. That is then time for the really keen to give a second mixing to the bin, inside to outside, edges to middle and correct for dryness or wetness with water or shredded paper. A second mixing makes the compost mature much much more quickly.

However just a single mixing after the initial filling is the essential bit, and then about six months maturing will finish the job off as the worms work over the cooling heap. A variation I use is during the last months of maturing I leave the sides exposed but a lid on to repel rain. This is so the contents really dry down, moist on the dryish side and definitely not claggy. This means that once the heap is mature I can sieve the compost easily; the fine stuff goes through to be used, the bits of junk picked off and the spoil of bits still undigested go back in again. Bones often go through three or four times, bigger ones and teeth more so (and I gather crowns and fillings may last forever so don’t dispose of your partner this way).

The sieved compost is then bagged to mature and ameliorate a bit more if I am to use it as potting compost but otherwise it is put out straight away as a top dressing around almost everything (in proportion to it’s need and my liking for it). This does cause a profusion of weed seedlings which are of no account, indeed their lack indicates insufficient compost has been applied recently. But of course the most important use is for mixing in with the top soil when planting each and every plant. In twenty five years other than seaweed sprays, lime, wood ashes and compost I’ve not used any other source of fertility and my compost has been the main one. I import no manures except for mushrooms or trials, just compost. You know mine is so good to smell and feel that once a pregnant lady asked if she could eat some; I had to decline as these are such litigious times, shame really, I wonder what compost raised babies would grow like?