Regional Gardening Reports :: National Gardening Association

In the Garden:
Southwestern Deserts
March, 2007
Regional Report

Share |

A Master Gardener composts right in her vegetable bed using drip emitters to moisten the organic matter.

Compost and Global Warming

It seems everywhere one turns these days, there's discussion of global warming and what to do about it. Even the Oscars telecast showcased the concept, and former Vice President Al Gore's documentary, An Inconvenient Truth, received the coveted gold statue.

Gardeners, in our own small way, have been contributing to the fight against global warming for years, whether or not we think about it in those terms. Planting a tree to shade the house for energy efficiency, eliminating the use of chemical fertilizers and pesticides and growing food organically, reusing materials such as concrete chunks to build raised beds, planting for wildlife, and composting -- all are earth-friendly gardening practices that reduce negative impacts.

As Gore remarks, global warming shouldn't be a partisan issue, it's a social and moral issue. The question should be: What kind of world are we leaving behind for future generations? Developing worldwide consensus for environmental problems seems overwhelming for most of us, but we can all do something. Composting is an easy place to start, and there's nothing better for your garden's productivity than lots of organic matter.

Compost and Landfills
The percentage varies somewhat depending on region, but in the low desert's year-round growing climate, 30 percent of refuse sent to landfills is material that could be composted: grass clippings, trimmings from trees and shrubs, spent plants, and kitchen waste. Each Arizonan generates an average of 5.9 pounds of solid waste per day, 2000 pounds headed to the landfills annually. If we composted our green waste, that amount could be reduced by 600 pounds per person!

Some people think that as long as it's organic, it will decompose in the landfill, so why bother. There are a couple of problems with that. In the arid desert, a researcher at the University of Arizona found that the materials in landfills didn't degrade. Taking core samples, his team of "garbologists" found newspapers that could be read and hot dogs that could be eaten. No, nobody sampled, but the point is, food was identifiable! Landfill waste is so compacted by heavy equipment that air and water (essential for decomposition) can't penetrate the layers. And with the desert's dry soil, low humidity, and limited rain, the issue is magnified. So, more and more acreage must be consumed by landfills for all of the garbage we generate.

Another factor related to garbage disposal is methane. According to Gore's book, organic materials that can't decompose naturally with oxygen ferment in landfills and release methane. Methane is 23 times more potent than carbon dioxide in terms of exacerbating global warming, and 60 percent of methane in the atmosphere is produced by human activity.

If turning compost isn't your cup of tea, it's perfectly okay to let the organic matter sit in a pile to decompose slowly. If you can locate it where it might get moistened by rainfall -- perhaps below house eaves or under a rain gutter -- the process will be faster. I used to be an avid compost turner, but as the joints started to creak over the years, I've segued to this lazy method that works just fine: When I trim plants, I just snap the stems and branches into smaller chunks and toss it on the ground as mulch. It breaks down further over time as I walk on it, and it makes a really satisfying crunching sound, like walking through woods in autumn.

I also saw this great idea in the landscape of Maricopa County Master Gardener Judy Curtis: She made small compost piles surrounded by chicken wire throughout her vegetable garden, with a drip emitter brought up through the bottom of each pile. When her drip irrigation runs, the compost material is moistened at the same time. By the end of the growing season, she has nice little piles of dark, rich compost already in place for the next round of planting.

Care to share your gardening thoughts, insights, triumphs, or disappointments with your fellow gardening enthusiasts? Join the lively discussions on our FaceBook page and receive free daily tips!


Today's site banner is by mcash70 and is called "Daylily 'Macbeth'"