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Irrigation! Makes me irritable so I went for a barrel of fun

Now that my present garden is working its way  into  its adolescence I have the option to fiddle with its makeup and constituent parts.
After designing the thing -- albeit by trial and error -- and layering all the matter and stuff to make the plants grow I've been fretting over the conundrum of  how to irrigate it.
What a headache irrigation is! How essential, how basic, how very Australian it is to wonder how to keep the water up to plants...
And there is no clear consensus.
Since we've had a very wet Summer, I've relied on hand watering . But when you live on sand -- I mean real sand of the  golden seaside variety -- it's no good watering deep because there aint nothing down there but more sand.
While I've built up the mulch layer aggressively and perched my garden atop the sand, I face the complication that mulch can be often impermeable and also steal the water from anything below.
Despite all the drip feed irrigation systems, I've installed Leeaky Hose 
Leeaky Hose takes advantage of the fact that water acts as its own conductor. It is designed so that water ‘sweats’ through its walls at a controlled rate over long distances at low water flow. At pressures of 4psi or below the hose will deliver moisture to the surrounding soil through capillary action. As a rough guide, Leeaky Hose releases water below ground at around 2 litres per metre per hour.
 Cheap. Easy.  I can lay one hose per length of bed --even on sand-- by running it below the mulch layer.
It's like putting a water snake to bed and tucking it in. 
And since Leeaky hose functions best at low pressures I run water into the hose from an upright, raised 100 litre water barrel (pictured above left). Over the space of several hours (over 6 hours I find is appropriate) I can control how much water I use to irrigate any one 5 metre long bed.  In my setup I can irrigate one or two beds at the same time by relying on gravity to sweat the water into the soil after I've filled up the barrel from the house rain  water tank.
I move the barrel around the garden rather than rely on long feeder lines.
Using such a precise -- and seemingly small  ( a standard domestic 3 minute bathroom shower sprays about 60 litres of water) -- allotment such as 100 litres enables me to precisely focus on my water budget. While I have a 3,000 litre rain water tank, that volume should not be enough for the garden for the whole year despite my considered savings. (But then it may...?)
So while I'm wondering when I will run out of harvested rain water -- with a eye on my location's median rainfall per month -- I suspect that I'm making the best use of the water the heavens give me.  
Irrigating under cut grass
Since my primary garden resource is grass clippings  (and manure and seaweed...) I've learnt that you have to now and then 'fluff up' the grass clippings mulch so  that the clippings don't mesh together and prevent air and water getting to what lies beneath. Meshing can be an advantage sometimes -- like a wooly blanket -- but grabbing handfuls of dried cut grass and sifting them is a great way to sense the happenings at the soil level -- and for now, I don't as yet have that much humus type soil.  
So far, using Leeaky,  I can monitor how effectively the dampness is spreading across the top layer of what is slowly becoming excellent sandy loam. Previously by relying on hand watering the irrigation was uneven and often simply wasteful as the rush of water simply drained away into the sand and all that I soaked  was the mulch.
Of course I can do other things too. I can locate and bring home some clay to spread about. I can harvest more rain water  off my 158 square metre roof. 
So that now, after months of mulching I have a garden which is  two thirds grass clippings mulch and one third gravel mulch..and a wee lawn.  Where vegetables grow (one third of the total area) there's also manures, seaweed, compost and whatever I can find to build up soil quality and depth.
After reviewing the cost of further rain harvesting ventures, it seems that the cheapest and most efficient way I can harvest more rain water is to put in a pond -- on sand!(by using a liner)
That, of course, leads me into my passion for pondlife and the fact that I've always created several ponds anywhere I've lived and grown stuff.
I have one small pond already; another small one is scheduled to follow soon...then the big one -- the lake! -- perhaps.

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Comment by Dave Riley on October 20, 2011 at 7:21

Well I am doing wicking beds but without the boxing in I guess. I hadn't seen that site but it is very useful. I've thought of the option of laying plastic sheeting along the pathways but if I trap water I am also trapping salt and lots of other stuff so that they'll concentrate. So instead of one continuos sheet of impermeable plastic I've been wondering about using occasional pieces -- like a buried gar bag or something like that here and there. To my mind that option -- like wicking beds -- would foster a sort of riparian -- riverbank -- ecology. 

I'm also wondering about a sort of tourist presentation: rather than one environment, offer the biota several: (a)very wet, (b)moist, (c) dry watered by osmosis. It seems to me that on sand encouraging critters like worms into the root layer is hampered by the fact that the water table is so far down and there isn't much organic matter between that and the surface. I see the pathways between the beds as worm homes -- moist and out of the heat.(In the same way you find  snails and slugs under a cooling rock). 

To extend that logic it makes sense to create wicking billabongs/ponds where the water is suspended in place. But I doubt that I'd be bold enough to wick the whole shebang. So maybe what I should consider is burying a gutter of plastic along the centre of the pathways  and back filling with all the mulch on top of that. That way the wicking stream would  stay wetter than the mulch pathway it flows through (without fear of contamination)  and the pathway would stay wetter than the beds it separates. This may encourage a whole orchestra of osmotic and critter possibilities. 

I'll experiment and report back.

What I'm doing anyway is extending the amount of organic matter so that the trenches are less permeable. What I'm not doing is making that layer impermeable.

That Bribie was interested in wicking is totally understandable  I live on a sand spit 'island' too.

Sometimes of course -- and this is the downside perhaps of wicking --  is you don't want to waterlog  the garden over Summer. Here nothing stays on the surface after rain. Nothing. But constant rain can drown the soil sometimes. Already I get a profusion of different fungi throughout the year. If I knew my way I'd be harvesting any fungal edibles there.

I used yo live in Northgate on clay and that trained me to be careful re waterlogging.

Comment by Elaine de Saxe on October 18, 2011 at 12:00
There is a garden club on Bribie which ran a wicking bed workshop a couple of years ago. I did not go to it since it was a Sunday afternoon and getting home would have been difficult so there must be people on Bribie who have these beds if you find the idea useful to follow up.
Comment by Elaine de Saxe on October 18, 2011 at 11:58

Or make your new beds into wicking beds. See Colin Austin's site. There's upside and downsides to everything but wicking beds with the addition of soil micro-organisms and an in-bed wormery come close to an ideal for sandy soil.

 

Your leaky hoses are doing better than mine were. One short length emptied a 20 L drum in a few minutes and the drum was just up on a brick, no great 'head' or so I thought.

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