Topic: Collecting water

[Heartysoup]

Steady on now !!
We're a passionate bunch us growers !!!

I'm in Manchester, so I'm not generally short of rain, it's just catching it that's the problem.

Ceres, I can see where Bjerreby's coming from re:space, but if it can double as a shelter for plants then it's sorted. I'll stew on it a bit more and then look for some bits and bobs to rig something up, I'll do something as a trial and take it from there. And of course there's always the chance that there may be complaints.

zigzag, that's a good idea and if I could lay my hands on one of those bottles that's from a water cooler type thing, it'd be speedier. The dentist round the corner uses them, I'll have a word.

Given that I'm in Manchester, at the bottom of the site and on the dampest plot, it makes absolute sense to dig down. I'll be needing some more top tips from you lot on getting that right...... NOW PLAY NICELY !!


TERMS OF MESSAGE
The author in no way wishes to offend any other member of Allotments 4 All, guests to the site and anybody else who happens upon this topic in some other way.   ;)

[Bjerreby]

but quite honestly, you cannot save a significant amount of water from a shed roof or a lean-to.

I have 3 (full) butts on my small 6' x 4' shed, 2 normal size and one very large one.  The amount of water I collect IS significant.  Why are you trying to discourage someone from harvesting water?

Discouraging? I simply point out that it is impossible to save significant amounts of rain from a shed roof. You might think a 250 litre water butt significant. I don't.

Tell us this Ceres. How big is your collection area and how big is your allotment? If your allotment dries out, how long will you be able to water it using what you have saved? Can you get by, year after year, without mains water, and still provide all the water your plants ideally need? I doubt it. And my explanation is that you cannot save a significant amount of water from a shed roof.

Catchment area is one thing. Storage capacity is another. As spring is the driest time of year, I'd need to store nearly 5 tonnes of water (5000 litres) if I was to be free of the tap. I am not prepared to have 20 * 250 litre water butts standing around taking up space where I can grow stuff.

If I have overlooked something, then please do me a great favour and let me know what, rather than make out I am negative. :(

And for guidance, I repeat, I store 1500 litres in a total of 6 butts. I go in for catchment, but it has its limitations.

[Digeroo]

How much water do you need?  5000 litres seems a huge amount.  How big is your allotment Bjerreby?  Can you use all that seaweed to do a bit of mulching and keep the water in?   If I had 6 butts I think that most years I would have more than enough water.  It must be a lot drier over there. 
Also depends on the type of soil, my garden is very much drier than my allotment.  Am I right but I remember something about most of the soils in Denmark being very sandy so presume that means it does not hold water very well.  Suggest you line your growing areas with that seaweed of yours to keep the water from draining away too quickly.

[Bjerreby]

How much water do you need?  5000 litres seems a huge amount. 

Well let's take this one step at a time. Take my spuds. I have about 16 m2 of potatoes planted in April. By the time they are lifted at the end of July, they require about 300 mm of rain to stop them splitting and to grow optimally. That means for the spuds alone, I need 16 * 0.3 = 4.8 m3. (Edit: okay 300 mm is a bit much maybe, but 200 mm IS necessary, requiring 3.2 m3)

But then, I have a total of 96 m2 veggie beds, and it all needs water. Not as much as the spuds, but it needs water all the same. Then let me say, I estimate we have had about 0.1 m rain in total between 1st April and now.

I have a SIGNIFICANT shortfall of precipitation, and all I can do is 2 things:

1   Let it dry out
2   Open the tap.

Regarding soil type, I have extremely heavy clay, which I have improved by digging in tonnes of seaweed. The clay retains moisture very well, and the seaweed helps too. Furthermore, I pile on about 0.1 m seaweed as a mulch to prevent drying out. And guess what? I still have cracked spuds.

I am sure you can see why I think a 250 litre butt connected to a shed roof is insignificant, when 5000 litres isn't even enough for ideal watering here.

Here is HALF of my water collection / storage system....



and here is how I mulch to minimize evaporation...