Wednesday, November 4, 2009

Water in the Dry Lands: Creating Oases of Food in Dry Climates

“There are no more bananas!” My daughter storms out of the kitchen, raging about the vast injustices of the world. Although we eat locally much of the time, last week’s treat of a bunch of bananas disappeared soon after it was purchased, directly into a hole in my daughter’s stomach, it seems. As the temperate zone in which I live descends into winter, we begin to rely more on the fruit that we’ve frozen during the warm season, and we also rely on the influx of fresh mandarin oranges, bananas, and other treats from warmer climes.

Hot climates can be wonderful for growing food. Consistent heat and sunlight ripen crops to perfection long before they would ripen in other, more temperate regions of the world. However, these natural hot houses have their downside. The constant heat of more desert-like climates dries out the land, and crops need to be well-irrigated so that they can grow. In warm climates like Florida, the source of winter fruit for many a North American, this irrigation can have devastating impacts on the groundwater, depleting the aquifer.

What is a farmer or a gardener in the dry lands to do? Novel irrigation techniques are a start. When water runs through open ditches and trenches in the gravity flow system, up to half of it can be lost to evaporation – a waste of this most precious resource. In Israel, where water is supremely scarce, drip irrigation and micro-sprinklers are a very efficient way to use water. These systems use sensors to determine when the crops need to be watered. Combine these efficient irrigation techniques with crops that need less water, and irrigation becomes up to ninety percent efficient.

Australia is another country with a desperate need to conserve water. It is no wonder that Bill Mollison, one of the founders of the permaculture movement, hails from Australia. Permaculture is a system of design that creates agricultural and garden systems that mimic natural ecological systems. To conserve water through permaculture, farmers and gardeners might contour the land using swales, diverting soil moisture to the places that need it the most. A farmer could use grazing animals to eat grasses and return moisture and nutrients to the soil through their manure. To increase the efficiency of water use, grey water from the home or the farm might be used to irrigate crops.

Using novel irrigation and permaculture techniques, it is possible to create oases of food in dry climates. However, in many cases our current methods of food production tend towards the unsustainable, since they rely on rivers that are running dry and aquifers that are gradually depleting. As we run out of reservoirs of abundant water, we will be challenged to create areas of abundance in dry lands, and we may need to reframe what abundance means and how we design our landscapes to create it.

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