The hazards of babysitting allotments, and more thoughts on water.

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Every silver lining – it’s said – has an accompanying cloud, and one of the best things about allotmenteering is that there are always neighbours who will keep an eye on your plot while you’re away.  But there are risks – your neighbour might treat the job as more of an aspiration than a commitment, although it’s usually our children who go down that route. On the other hand the risk to the Good Samaritan is that something horrible like blight might happen to the neighbour’s tomatoes and it’s them that will have to break the news. We have a friend whose daughter’s hamster died one Christmas Eve many years ago.  He had to visit every pet shop in Bristol, with the deceased pet in his pocket, asking if they had another one “exactly like this.”  Mission accomplished,  and with the daughter in the dark about the ruse, they all celebrated Christmas without an accompanying cloud.

The reason for this visit to memory lane is that we arrived at the allotment this morning to find a Good Samaritan in a bit of a state – she’s always taken her responsibilities very seriously. Our neighbour’s tomatoes had suddenly developed some sort of disease while she was looking after them.  We knelt and prodded and poked and examined the source of the problem which was not centred on the leaves but in the stems which had developed long brown lesions.  When I cut one open and peeled it I could see decomposition beginning at the centre and it felt suspiciously soft. Later, at home, I checked with several books – the RHS book by Pippa Greenwood “Pests and Diseases” is especially approachable – and I decided it is probably Tomato Pith Necrosis, nasty but not completely fatal as long as you cut the infected stems off and burn/dispose of them. By the time we came on the scene she was already planning to dig them all up and burn them but we were certain it wasn’t blight (too early for a start) and she agreed to wait until the holder of the plot got back off holiday. She’d already texted him with the bad news and so I texted him later with the better news. The disease is soil borne and can be spread by splashing – for instance by watering with a rose from above – and also by handling.  Tomatoes hate having their leaves handled.  Needless to say we all solemnly washed our hands with gel and then we sped off to the Potwell Inn plot to make sure ours were alright.

IMG_5731.jpgHappily all was well in the tomato department but while Madame was picking some peas she found that the Pea Moth was cranking into gear – that’s why getting them sown and picked as early as possible is always a good idea.

Elsewhere the young leeks are doing fairly well, but along with the autumn and winter crops already growing, they’re a reminder that nothing stands still for long on an allotment, and the seasons are always queuing one behind the other.

Meanwhile I’ve been revisiting some of the calculations I did before I posted on the subject of watering with stored rainwater.  When I went back over the figures the combined water gathering area of the shed plus greenhouse is not 7 but only 5.5 square metres. So I had a look around, and if I roofed the compost bins that would give me an additional 4.5 square metres, and if, as well, I built a rain gathering roof between the shed and the greenhouse it would add yet another 2.5 square metres.  That would give a water harvesting area of just under 12.5 square metres. Because there is always inefficiency in harvesting, let’s say that the effective harvesting area is 10 square metres.  That means that for every mm of rain that falls we could harvest between 10 and 12.5 litres of rainwater.  The average annual rainfall in Bath is 761 mm so that would potentially yield nine and a half thousand litres in a year.  That’s about 5% – peanuts compared with the almost 200,000 litres that would fall each year on the whole plot in any case, but the thing is that it doesn’t rain every day and so the stored water is buffer against temporary shortages. Three thousand litres of stored water would provide 75 full watering cans a week for a month, or 25 a week if the drought went on for three months. The harvesting area could refill the tanks three times in an average year and, most importantly they could harvest during those short heavy thunderstorms and intense showers that would otherwise be wasted in run-off to the rivers.  Another thing I ddn’t factor in yesterday was that 20% of the overall area of the plots comprises pathways that don’t need watering anyway – that’ll teach me to check my calculations more carefully before I post!

So all this, combined with the other measures I wrote about yesterday, (soil improvements, mulching etc.) could easily be part of the way forward.  What really struck me was the sheer volume of rain that falls in a year, and how much of it is wasted in run-off.  I haven’t even mentioned grey-water because on an allotment it’s not a factor – but you can see the huge impact of more widespread adoption of water storage.

But yesterday I also alluded to compost as part of the solution to global climate change, and again I checked the calculations I made when I built the 4 compost bins in February. I calculated that the absolute maximum compost we could make would be about 3 cubic metres – and that would be pushing it. All the organic gardening books suggest mulching with up to 15cm of compost.  Calculated for our standard allotment that would mean making around 30 – yes thirty – cubic metres of finished compost a year, and I’d say that would be an absolutely impossible target. Some form of rationing will have to be done unless we/you are as rich as Croesus.  There are other soil conditioners like leafmould that we can make, but they come (free) in the autumn and the heap spends a year shrinking to less than half its original size. So that makes about half a cubic metre. Apart from buying in manure, which I’ve no objection to except that it takes up so much space (27 cubic metres? – don’t be silly) – that’s a quarry lorry full. So that leaves us green manuring, and, because we’re not digging, the green manure would have to be composted – no problem there.

Sorry, that’s a lot of detail but it makes me wonder how realistic some of the gardening gurus actually are. TV gardening programmes are entertainment, and just as not everyone who watches Jamie Oliver actually cooks his recipes (which, incidentally are very good), so too with gardening shows.  Whole new gardens without a blemish are planted up in five minutes and never a pest appears to darken the horizon, and ….. I begin to wonder if coffee table gardening isn’t the first cousin of  the romcom – not much reality.

Finally, just to leaven the lump a bit, not all vegetables need a great deal of water.  While I was researching this I discovered that watering does nothing for parsnips, and carrots do worse if they’re watered any more than occasionally.  Our own experience with potatoes shows they need very little, so there’s some silver lining there.  For me the take-home point from all this work with a tape measure and a calculator is a better understanding of the inputs that make for a sustainable and drought resistant allotment. Far from being minor issues they need to be brought into the long term planning of facilities and crops.

 

Worrying about water

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Yesterday morning early I was trudging back and forth to the water trough, worrying about just how dry the soil has become over the past couple of weeks.  We had a decent spell of rain before that, but my impression is that we’re distinctly down over the average. Here in Bath the average annual rainfall figure is given as 761mm.  I did a bit of investigating and soon realized that I had no idea what that figure really meant, and so it came as a surprise to me that the figures given in mm aren’t ‘per square metre’ – in fact they’re not related to area at all. If you want to find out how many litres of water fall on your patch of ground in an average year, it seems that 10mm of rain is equivalent to 10 litres of rain per square metre – that’s to say, in average year our 250 square metres of allotment receives very roughly 20,000 litres of rainwater.

So far so boring, you may think, but many allotments are completely dependent on a water supply that can be turned off if there should be a drought.  Most of us are familiar with the need to have a waterbutt attached to the shed and/or the greenhouse but when you look at the data, a single waterbutt is hardly going to save the day – and that’s where I came in. Yesterday, let’s say I used 20 cans of water (it’s peak watering season), and so that’s 200 litres of water – or pretty much one whole water butt full – that’s to say if the Council or the water companies decided to pull the plug, on our allotment we’d have four good waterings left. So, at a pinch, we could probably survive for a month, but what about a three month drought? It’s a fairly simple calculation – we’d need 12 water butts – 3000 litres of stored water.  However, gathering that amount of water in order to store it would be a huge challenge – we have about 7 square metres of roof altogether, so we would need somewhere in the region of 500mm of rain allowing for some inefficiency.  Not only that, water butts take up a lot of space – we’d need to go for 1000L caged containers.  Any way you look at it, making provision for a drought is both complex and expensive.

IMG_5682The only way to mitigate our water use is to increase the water capacity of the soil by increasing the amount of organic matter and making use of mulches to reduce surface evaporation. It’s clear from our experiments with mixed plantings, that covering the ground completely (courgettes, for instance under sweetcorn) lashings of leafmould and so-on really increase the moisture holding capacity.  The Potwell Inn allotment needs most watering on the areas where the soil is exposed – it’s obvious really. Another approach – one which I’m sure the seed merchants will soon be all over – is to develop drought resistant varieties, but we could also start to develop extremely locally adapted plants through seed saving.

The take home lesson from all this, so far as I can see, is that in the teeth of global heating, we allotmenteers are going to have to adapt very quickly. It’s easy to feel virtuous when we grow our own organic food, but we need to be modest about our potential.  Collective action across a whole allotment site could be worth investigating – we’ve got three underground streams running through the site – it would take a lot of work and investment but at the moment it’s just running into the river.

When I sat down to write this I felt a bit glum, but now I’ve done the maths and given it some thought, sustainability is a real possibility on the allotment. It seems almost a crime to be pouring purified drinking water on our plants when alternatives are possible. It’s easy to think that the only harvest that matters on an allotment is the stuff we can eat, but we need to harvest every scrap of green waste we can get our hands on, and every available fallen leaf so we can make quality moisture retaining composts and mulches; and then every possible harvestable drop of rain to reduce our tapwater consumption.

To repurpose an old saying – “We have seen the enemy – it is us!”

 

These were the flowering broad beans – yesterday

 

However there was a mild overnight frost and we shall have to hope that they survived. They’re pretty well protected from any cold wind but not fleeced. Yesterday was such a beautiful day that you could forget that this is still early spring and quite likely to throw a nasty surprise. As ever we scan the weather forecast and try to second guess what will happen on our patch but forecasts deal in the generalities of towns and cities not sites and plots. I noticed on a friend’s facebook page that someone had commented that there was no point in wasting time teaching children to grow things because they could learn gardening in half a day. I couldn’t possibly comment.

IMG_5117Our allotment site is served by cattle troughs which are turned off in October and on again in April. That, of course, means that there’s a period – especially in early spring – where everyone is sowing and nurturing young plants, but there’s no water supply unless you’ve got some storage. For several days we’ve seen allotmenteers wandering around the site, watering cans in hand, looking for an inch of water at the bottom of a trough. I’ve never been so glad that we installed some storage last winter, and so at the beginning of spring we had 1000 litres of rainwater in the butts.  We’ve moved into a period of high atmospheric pressure without any rain just at the time when the growing plants need it most. You wouldn’t believe the pleasure that turning a tap and filling a can can bring. This wasn’t so much for watering, the earth is hardly parched at this time of year and it’s only the plants under cover that need it.  Yesterday I wanted to spray the growing plants with dilute seaweed foliar feed. Applying it to the leaves does seem to work but it involves getting out the big sprayer which, being bright yellow, is liable to send out misleading signals to other organic gardeners. On the other hand, allowing people to imagine you’re using all manner of toxic chemicals might discourage them from grazing.

Back at the Potwell Inn Madame and me had one of our Big Talks which always involves a bit too much wine and no time or energy for cooking. I love our Big Talks – very therapeutic. So supper was one of those storecupboard pot luck meals, rendered even more interesting by the fact that I retrieved an unlabelled box from the freezer and had to defrost it to see what was inside. It was the simplest of tomato sauces made during the glut last summer and it was absolutely lovely. Linguini + tomato sauce + a bit of Parmesan and, for me a few anchovies scraped from the bottom of a jar in the fridge. It was an unbelievably good way to anticipate this coming season.

IMG_5120But there was no basil yet.  We’ve got a succession growing well in pots, and just as an experiment I took one of the two varieties and stuck a pot in the propagator with the young chillies.  Here’s a side-by-side of the difference between the two pots.  It can’t be temperature making all the difference because the kitchen stays at a steady 20C, and that’s the setting in the propagator.  So it must be mainly down to the overhead UV light.

Finally, a photo of the chillies which are almost ready for their big pots so we can get the tomatoes going. The stowaway basil plant is on the left at the back. These get a foliar seaweed spray once a week and I’m very happy with their progress.  The biggest disappointment was that not a single Bhut Jalokia  (the 1000000 Scoville unit chilli) germinated. Next season then!

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