Soil Moisture in the Veggie Patch
[Circa October 2004: from the book Tales of a Backyard Farmer]
Thank God for the Royal Adelaide Show! Without it, I reckon we’d get no rain at all in September (has it ever NOT rained during the grand parade or for the precision driving team?) By mid-August I was starting to panic – what is normally our wettest month left the garden looking parched. It reminded me of all those droughts in the outback, and the tales the old folk used to tell. My uncle received a letter from his cousin up in the bush, who claimed it was so hot that when he’d seen a dingo chasing a kangaroo, they were both walking! It must have been pretty dry too, because he’d pinned the stamp on the envelope…
Standing in a small garden plot is no way to avoid the troubles of the world – they are evident everywhere – just on a much smaller scale. Here too, one watches the sky as avidly as a grazier or pastoralist.
There’s something about real rain on a garden that’s altogether different from water out of the tap. One can keep things alive and moving along using tap water, but only rain brings out the crickets, the weeds, and that wonderful green flourishing growth that is the hallmark of a happy plant. It brings me out too – I love that smell of summer rain on dry earth. But unlike a European summer, we here in Adelaide have dry spells that last for weeks going on months. The lifeline to the garden is the garden hose.
When running a vegetable garden as big as this one is, one would be stuck completely were it not for a town water supply. I trudge up and down between the rainwater tank at the house and the seedlings in the veggie patch, carrying my watering can and regretting not at all these small “fat-burning expeditions” that give me the chance to observe the garden and its inhabitants from different angles. But this is just no way to keep water up to the mature plants. For that I need rain in NSW, Victoria and Queensland, from whence it wends its way down through the Murray-Darling catchment and ultimately out of my tap in suburban Adelaide.
In August I called one of my farmer mates out on the flats on the other side of the Mt Lofty ranges, and asked him if he knew of anyone in the district selling pea-straw (the quantities I need are a bit expensive if bought locally).
This stuff makes wonderful garden mulch, as the stalks are curled and twisted, and once tucked around the veggies, doesn’t blow away in the howling gully winds that come up on summer nights from the south-east and strike along the foothills of the Mt Lofty ranges bordering the Adelaide plains. A deep pea-straw mulch over the whole garden stretches out my watering times to between seven and ten day intervals. The soil surface under the mulch remains cool and moist, allowing earth worms to work right up into the root zones of the veggies, opening up macropores that allow the soil and its micro-flora and -fauna to breath, and the root systems to remain active in taking up nutrients and moisture. This is real water conservation, and one gains some organic matter into the bargain.
A bale of pea-straw covers just a few square meters of the veggie garden, so I needed about 50 bales. I had work to do along the eastern flanks of the ranges, so hired an 8 x 5 trailer to get double value out of the trip by bringing back a load of pea-straw. My route took me up the Torrens Gorge to Palmer (population 80) out on the opposite foothills on the road to Mannum from Birdwood. I’d rung ahead, and the farmer’s wife had agreed on a good price per bale of pea-straw. Not only that, I left the empty trailer there and came back to find she’d loaded up and tied down 38 bales ready for my return journey.
At Palmer one can see the big Mannum-Adelaide pipeline coming up from the Murray alongside the road, and the redbrick pumping station in the background. Once this pipeline reaches the top of the ranges, it empties its contents into the Torrens River gorge – one can see this grey-green Murray water running down the riverbed on its way to storage in the Kangaroo Creek Dam behind Adelaide. So here’s our water supply coming in from the eastern states; our own pitiful end-of-winter supply of rain-fed storage is evident in the low levels in the Chain-of-Ponds storage reservoirs between Gumeracha and Inglewood.
As early as August this year there was talk of drought in the eastern states of Australia, and this must inevitably impact on my small world in a garden thousands of kilometers away from the head of the catchment up near Toowoomba in Queensland. On a larger scale again, the rainfall in eastern Australia can be seriously depleted by the El Niño effect. Cold nutrient-rich currents that well up into the eastern Pacific near Peru, combined with easterly trade winds in the equatorial regions of the Pacific Ocean, normally mean that oceanic waters above Papua-New Guinea are higher and warmer than in the eastern Pacific near the Americas. During El Niño years, this warm water shifts eastward away from our side of the Pacific basin, creating marked changes in our east coast climate, and lower-than-average rainfalls. The Murray River slows to a trickle – barely enough to keep the mouth free of sand-bars as it meets the ocean at Goolwa in South Australia. The giant ocean currents that regulate the Earth’s climate transport heat from the equator to the poles, and effect the weather conditions on all the land-masses. Man’s pollution of the earth’s atmosphere through the burning of fossil fuels and forests has warmed up conditions in our little “glass-house” planet. The reaction of the ocean currents to the distribution of this extra heat finally impacts on me in my small garden down at the end of a once-great river.
So I capture what rainfall I can, in the household tank and in the garden beds. Mulching keeps it there against needless losses due to evaporation. I grow native plants in the front garden and don’t water the lawn all through summer. How then to best get this precious water onto the veggie patch without undue wastage? One of my childhood memories is that of seeing my parents outside at dusk in summer time, hose in hand, watering the garden beds.
Even nostalgia is not what it used to be – I need something less labour-intensive than that, but can’t bring myself to the level of “set-and-forget” irrigation systems that mean the rich men of my district rarely dig their toes into their own lawns, or need turn on a tap themselves.
My compromise is a long garden hose (lots of hoses really, all joined together!) I connect this to the tap at the back door, and it reaches anywhere on the property. On the end of the hose is a Pope sprinkler – one of those ones with no moving parts that send up a sparkling shower of big drops that deliver water over a radius of several meters. At strategic points in the veggie garden I’ve got old boxes, barrels, tree stumps or up-turned pots, and the sprinkler sits on these for an hour or two each week, giving the garden a good soak below the mulch. The big drops from this sprinkler mean that even under windy conditions, not too much of my precious water supply blows over my neighbour’s fence. And despite all I’ve read in books, over-head watering doesn’t seem to bother the veggies – not even the lettuces or tomatoes. Perhaps that’s the great advantage of organic growing – healthy plants can thrive, even in less-than-ideal conditions. As I move the sprinkler from bed-to-bed, I am struck again by how inter-dependent we all are on the health of our planet as a whole.