A thousand words on poo!
As we turned into the allotment yesterday a light tipper lorry pulled away at great speed and off down the hill. “He was in a hurry” I said to Madame as we pulled over next to a newly dumped pile of manure whose new owner stood regarding it whilst trying to keep her two children out of it. Obviously I couldn’t just ignore the chance to see whether it was as good as, or better than, our usual supplier. It certainly looked alright, but when I took a handful and smelt it, there was a powerful whiff of ammonia. Without getting too nerdy about it, ammonia (NH3) is one of the principal greenhouse gas emissions from cattle farming. It’s generated when ammonium – which is a normal component of fresh manure – breaks down in a double chemical whammy that deprives the resulting manure of nitrogen, reducing its fertilizer value; and at the same time releasing ammonia into the atmosphere as a greenhouse gas. Farmers know about this (I hope) and manage their manure carefully to minimise losses.
We allotmenteers are mostly neither chemists nor farmers but our belief in manure is almost parallel to membership of the local church – we think it’s a terrific thing but we’d rather not get too involved in the theology. On the other hand, cattle produce mountains of the stuff and it can be quite a disposal problem and so combining the excess of poo on the farm with the excess of zeal among the faithful means that there’s a considerable temptation for entrepreneurial tipper lorry owners to solve the farmer’s problem and make a considerable amount of money in the process.
“How old is this?” I asked the allotmenteer who was still getting over the shock of my sticking my bare hands and nose into the pile. “He said it had been stacked for two years”. “Hm” I thought. “How much did he charge you?” “£100 – cash”, she said. There was not much over a cubic yard, around half a ton, which meant it cost roughly the same as my present source which was looking better by the minute.
Years ago I was given the honour of digging out about a four foot layer of horse dung from a stable. I imagine it must have been necessary to sell the thoroughbreds and buy some Shetland ponies, the filthy floor was so close to the rafters. If you want to know what a four foot layer of anaerobic, methane emitting manure smells like please put down your knife and fork now. This is not for the faint hearted; but straw being expensive and occasionally in short supply, there’s a temptation to put as little as possible down and my goodness it shows, or rather smells – acridly, stomach churningly, eye wateringly vile .
On the other hand a friend who runs a stable and lets me have a load of fresh horse manure for the hotbed every year (although not this one because of travel restrictions), is generous to a fault with her straw, and it shows in the horses gleaming state of health as well as in the healthy “countryside” aroma of their poo. In a nutshell, not all manure is equal and it pays to choose your source personally rather than rely on the A4 advert flapping on the entrance gate of the allotments. Try before you buy if it’s all possible and remember that among species there’s a hierarchy of value. My grandfather valued sheeps truckles above all else, but they’re better left on the land. I can’t imagine that he would feel the same about sheep muck from intensive farms where the sheep are fed on concentrates and never see a field.
Next comes the horse, but even then as I’ve already described, there’s a vast gulf between good and bad. If you’ve got loads of space it might be best to get it fresh, keep it covered and turn it yourself until it’s ready. Oh and check that they’re not worming the horses with some persistent vermifuge that will kill all your hard won worms. Cow’s manure comes last in the list and don’t ever use pig’s manure which is full of pathogens, and – if I haven’t already put you off – remember that e coli often comes as a freebie with manure, especially the fresh stuff, so keep it well away from salad crops and wash your hand carefully, perhaps with gel – like I did.
Good manure needs to be turned frequently to complete its decomposition and this obviously involves the farmer or stable in a lot of work which will be reflected in the price. Cheap is not always a bargain. So this pile of rather young manure which smelt strongly of ammonia was not all it was cracked up to be. But on the other hand we’ve had a tremendously wet winter and heaven knows how much nitrogen has been leached out of our soil during the past few months – so we’ll all be looking at organic ways of feeding it back.
What to do …?
Our allotmenteer has several choices to make. She could stack it and turn it regularly until it’s properly finished – which is extremely hard work. Leaving it as an uncovered pile will just mean more ammonia (nitrogen) escaping into the atmosphere as the weather warms up, while more will be washed away by the rain and could land up polluting the river. She can’t spread it among salad crops, tender plants or dig it into beds where she intends to grow root veg because they’re all adversely affected by fresh manure.
The one place I can think of where it would probably be OK is a good deep bean trench covered with soil. Another possible use is to use it in layers as a compost activator. She could mix it in layers with the free wood chip we have on the site which would reduce to compost reasonably quickly – the same would happen with dead autumn leaves because what this concentrated source of nitrogen needs is lots of carbon – even cardboard – to assist its decomposition and breakdown into “black gold“; odourless friable compost. Ideally she’d nurse it and turn it regularly and then spread it in the autumn and let the worms take it down.
There isn’t a 100% ram stamped ecologically pure way of composting – whether it’s manure or garden waste. The challenge isn’t to reduce wastage and greenhouse gases to zero – which I don’t believe is achievable – but to minimise it as far as possible. As Wendell Berry memorably said of intensive farming where manure is kept as slurry and cattle are kept in squalour, – they’ve taken a solution and turned it into two problems. Remember that in a small mixed farm where livestock are kept on grass, there isn’t – or shouldn’t be – any manure for sale at all because it’s just too valuable. Home compost made from vegetable material and activated with comfrey is as good as any animal manure you could get, unless it’s from your own livestock. The problem for small allotment holders is that we just don’t have space to grow comfrey and we don’t generate enough vegetable waste to compost our couple of hundred square yards sufficiently to compensate for what we take out. We too are intensive farmers! So beware of manure if it looks and smells like waste, because it probably is; and find a good source of safe horse manure and be prepared to put the work in. .