Apropos of nothing in particular, a true story – told to me by my son – came to mind today while I was connecting the two water butts that will be the irrigation supply for the polytunnel. It’s been a bit of a saga, which I’ll come back to in a moment; but I wanted to fill out some of the science behind my piece yesterday on manure and greenhouse gases and, in particular, the relative virtues of so-called hot and cool composting. I’ve already written about being careful to locate manure from a trustworthy source. We once bought a couple of tons of so-called horse manure from a local farmer with an awful reputation for his management of the land. One year, for instance, he ploughed one of his fields straight down a steep slope towards a brook at the bottom. Needless to say, the next severe rainstorm took most of his topsoil away. He eked out a living by renting his fields for horses – far too many of them – and we discovered later that their principal diet must have been creeping buttercups which pass undaunted through their digestive system and infest any land they’re spread on.
Enthusiastic hot composters will tell you that you can put weeds of any type into their heaps and they will be killed by the heat. They will also tell you that you can compost trees, stones, and a whole bicycle in a fortnight. While it may be true that hot composting is a fast and efficient of turning green waste into something, it’s not altogether clear what that something is; and how much of something else – like methane, sulphur dioxide or ammonia is dispersed into the atmosphere at the same time. Here’s the science if you’re interested. The other thing worth mentioning is that worms and other insects and microorganisms can’t survive the high temperatures generated in hot composting and so the eventual product may not be as biologically rich as cool composted waste which seems to comprise a great proportion of worm casts. It may well be that the slow road is better for the allotment and garden and better for the atmosphere as well.
However, hot composting has its passionate followers and I’ve enjoyed watching some hilarious willy waving moments as its acolytes compare temperatures; competing for the killer degree centigrade that puts them at the top of the hot composting hall of fame. It’s no surprise that the same gardeners also compete to breed the hottest chillies – I think it’s a man thing.
Sadly, greenhouse gas generation increases with the temperature of the heap or windrow which suggests that although hot composting is probably a lot better than sending waste to landfill – because that’s where the waste is composted anaerobically, generating huge amounts of methane – it’s better to be patient and accept that you have to exclude your noxious weeds from the compost heap and watch it heat up quickly to 30C or 40C as you turn it in the early stages and then cool down to let’s say 20C when the worms, insects, bacteria and moulds will love you for providing perfect conditions for them to feast on your garden waste and turn it into compost in a month or so rather than a week or so. This, unfortunately, will exclude you from the A team – which brings me back to the story my son told me.
He was at a party in Birmingham when he chanced to hear a conversation between a young man and a rather attractive woman who was quizzing him on his occupation. “I’m a physicist”, he said; “I work on the hadron collider in Cern. “On the large one – she asked him with gathering interest. “No” – he said “- the smaller one”. “Oh” she replied, losing interest and turning away. “How sweet!” I was mulling over the pulling power of a hot heap, thrumming away at the Potwell Inn allotment, surrounded by muscular men drinking Jack Daniels neat and exchanging stories of vegetable derring do, when the thought of her magnificent put-down turned my thoughts back towards our quieter regime and I whispered a quiet “thank -you” to our heaps as I inspected the new tanks for leaks.
Joining two or three water butts together has taken me right out of my comfort zone. What I know about plumbing could be written on a postage stamp, but all I wanted to do was to join the tanks so I could pump water from the whole array rather than moving the pump from tank to tank. This involves joining them at the bottom rather than conventionally at the top – which means that there is a good deal of pressure on the connections when the tanks are full. The bits of push fitted plastic pipe that allow tanks to overflow into one another, just leak when they’re subjected to pressure. This simple objective has led me into a world of different dimensions, materials and fittings and four visits at least to purchase the wrong spares and return them for the right ones. I feel privileged to have acquired a dim understanding of the relationship between 3/4 BSP fittings and 22mm MDPE pipe – enough to hold my head up high in Screwfix anyway. Today I finally plugged them all together and pumped water in to test them. There was a moment of doubt when a couple of beads of water gathered on the joint and dripped down, and then – nothing. Job done. A wholly disproportionate flow moment followed – the psychological sort, not the watery one! Now all I have to do is build the sloping roof on the compost bins and install the guttering.
While all this was going on a female blackbird that seems almost hand tame was digging around the edges between the paths and the beds. She seems to have decided that we’re not a threat and feasts on the slugs, insects and eggs that she finds there. The polytunnel is warming the soil beautifully and so while the outside soil temperature is still 8C, the polytunnel soil is near 15C and the woodchip hotbed is 20C, as is the newest compost heap which is just waiting until I put the oldest heap through a riddle so it can go on to the beds and then I’ll turn the newer heap into the old space for a period of rest. The whole site was alive with activity in the sunshine today. It’s looking more loved and cared for than we’ve ever known – marvellous stuff.