Still hand watering your vegies?
These alternatives will save you time and water
IT IS great to be finally home after a couple of weeks of travel, as my last few articles detailed, to the Melbourne International Flower and Garden Show, followed by a week on wonderful Norfolk Island.
Due to being absent from home for this time, I postponed planting my winter vegetable seeds until my return, about two weeks ago.
The only exception were four varieties of garlic, which were planted, watered and mulched heavily to retain moisture during my absence.
As it turns out, ex-tropical cyclone Debbie decided to deliver over 130mm of rainfall at home during my visit to Melbourne, which helped to provide some much-needed moisture to the soil prior to planting.
Nevertheless, I was surprised to discover how little of this moisture remained as I lightly cultivated the beds in preparation for sowing seeds.
I deduced that the hot, dry month or three leading up to ex-TC Debbie’s visit created a very deep, dry soil profile that not even 130mm of rain could fill.
At the moment I don’t have a permanent irrigation system for my vegetable garden (currently hand watered from my tank), and the dryish soil got me to thinking about what type of irrigation setups would be suitable for vegetable gardens and other "working bed" areas such as spaces for annual flowers, bulbs and herbaceous plants.
Garden beds that are regularly cultivated do pose some challenges when considering a permanent irrigation system that provides good, consistent coverage.
Now I’m sure that many gardeners would think that "a good sprinkler system will do the job perfectly", but sprinklers have many drawbacks.
If we were to consider the average size backyard vegie patch, the obvious choice would be some type of mini-sprinkler (micro-spray) system, as they are supposedly designed to work in smaller areas. They can also be positioned so that they take up minimal space
What drawbacks? Well, they don’t work well in windy weather (spray patterns distorted, missing the target), their consistency is affected as plants grow taller and block the sprays, they lose up to 50% to evaporation (in hot weather), and, for some plants, wetting the leaves increases the likelihood of diseases such as powdery mildew and rust.
There’s also an increased potential for weeds as sprinklers will also irrigate bare, unplanted areas.
The obvious alternative to sprinkler irrigation is some type of set-up that applies water directly to the soil, such as a drip system.
A suggestion for setting up a dripline system in a clay loam soil would be to use drippers spaced at 40cm intervals along the pipe, with each pipe laid about 50-80cm from the next.
For sandy loams, the spacings must be closer (dripper spacings 30cm, pipes about 30-50cm apart), for heavier clay soils, wider dimensions (dripper spacings 50cm, pipes about 60-100cm apart)
For a vegie garden, a series of dripline pipes laid on the soil surface presents quite a logistical problem for gardeners, as they’ll interfere with the regular cultivation of the beds.
A suggestion to overcome this challenge is to set up the driplines into small square or rectangular sections, each fitted with a "click" connector to the main delivery pipe, so that each section can be removed whilst cultivating or improving the soil, then reattached once the bed is readied for planting.
Of course, if the system is manually operated (either by turning on a tap or programming an "automatic" system), how often water is applied is totally reliant on the gardening skills, and plant and soil knowledge the operator has acquired through their practical experiences (in many cases this can be described as trial and error determined by guesswork!).
Over the last decade or so, technological advances in irrigation equipment have meant that, for most gardeners, much of this guesswork has been eliminated.
Small, sophisticated and inexpensive automatic irrigation controllers are becoming commonplace, and these, combined with soil moisture sensors, help to remove any operator error by only allowing irrigation when the soil moisture drops to a predetermined level, and preventing irrigation if the soil is adequately wet, say, after a rain event.
If technology is not your cup of tea, then you should definitely check out another self-watering style system, particularly useful in small plot vegie gardens, thought to come from Africa or China over 4000 years ago.
This system uses unglazed clay pots, filled with water, called ollas (pronounced "oh-yahs"), which are buried to their necks in the ground.
The porous property of the clay allows water to seep outwards into the surrounding soil, more as the soil dries, and less if the soil is moist.
This self-regulation means that water is only released as it is needed. Bill Mollison, the father of modern permaculture, reportedly said that ollas were probably "the most efficient irrigation system in the world".
Early, basic ollas were individual pots, filled manually every so often, and capped with a stone. There are now modern olla systems available, here in Australia, which are a series of capped ceramic "bulbs" interconnected with a small pipe supplying water to each olla via gravity from a large container.
If you garden in small raised beds, or in pots, then this is an ideal method of irrigating your vegies or flowers.
If a large enough supply container is used, refilling might not be needed for a week or two, allowing a worry-free visit to somewhere magical like , um, Norfolk Island!