(Walking on Earth column published in the Tucson Green Times, November 2010)
By Melanie Lenart
Using the shovel end as a ruler, Laura Mielcarek checked the depth of the hole we had just dug next to the driveway. “Maybe a little deeper,” said Mielcarek, a landscape architect, eyeballing the mini-channel designed to divert water from the street into this pit. Soon it would host a plum tree.
Once again, the Casa Crew is knee-deep in home improvements for one of its six member families. In the past couple years, we’ve joined forces to install four rainwater harvesting cisterns, one skylight and some graywater pipes.
Now the Tucson group is spending a Sunday morning helping my partner and I plant some streetside fruit trees.
Planting trees takes effort if you do it right. These 7-foot-tall trees needed holes about three times wider than their 15-gallon buckets, plus soil loosened below. That’s a lot of digging.
It went fast between the eight of us, though.
Now two trees, a tangerine and a plum, shade the public walkway in front of our central Tucson home. Encouraged by group member Torey Ligon, a local food enthusiast, we decided to choose species whose fruit we would really eat.
We selected our trees from the lush greenery at Civano Nurseries, an offshoot of the neighboring Civano community aiming to make city living more sustainable. The helpful staff reminded us that the trees would need a lot of water, especially in the beginning and in summer.
Fortunately, we plan to tap into monsoon streetflow for some of our summertime watering needs. The tangerine rests in a curbside depression, probably a former driveway, ready for overflow. The plum tree sits near the freshly dug mini-channel at the intersection of our paved driveway and the street.
Utility lines also helped define the planting spots. A natural gas line bisects the area, as we discovered by calling Bluestake (800-782-5348). Avoiding the underground pipes, we shaped contours so water would pool in the basins around the trees.
As for plant food, we mixed in soil with remnants of food scraps that we’ve been composting for years in a shallow pit. With a bit of water and the occasional overturning, banana peels, watermelon rinds and leftovers come to resemble soil in a matter of weeks.
Soon we’ll be able to taste the products – or, in this case, produce – of our discarded leftovers, water, and sunshine. Another ingredient behind plant growth, of course, is carbon dioxide, a greenhouse gas blamed for three-fifths of the ongoing global warming.
Based on a recent University of Arizona analysis, the average streetside tree on campus pulled down 42 pounds of carbon dioxide a year, given local growing conditions and reasonable watering. Some trees saved more carbon by shading buildings and reducing cooling needs.
With fruit trees, carbon savings also will come from the reduced need to truck in produce from Florida and other distant lands.
Keeping the trees alive and collecting carbon dioxide will take water, something in short supply in these parts. But it would take water to grow them anywhere. It seems fair to devote some local water to local food.
At least some of that water will get recycled – into the juice dripping off a homegrown, organic plum or tangerine.
Author: Melanie Lenart is an environmental scientist and writer based in Tucson, Arizona.
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