http://nora.nerc.ac.uk/2442/
Abstract/Summary
The fate of global soil carbon stores in response to predicted climate change is a ‘hotly’ debated topic. Considerable uncertainties remain as to the temperature sensitivity of non-labile soil organic matter (SOM) to decomposition. Currently, models assume that organic matter decomposition is solely controlled by the interaction between climatic conditions and soil mineral characteristics. Consequently, little attention has been paid to adaptive responses of soil decomposer organisms to climate change and their impacts on the turnover of long-standing terrestrial carbon reservoirs. Using a radiocarbon approach we found that warming increased soil invertebrate populations (Enchytraeid worms) leading to a greater turnover of older soil carbon pools. The implication of this finding is that until soil physiology and biology are meaningfully represented in ecosystem carbon models, predictions will underestimate soil carbon turnover.
Saturday, July 5, 2008
Global Warming - Two Book Reviews
This is one of the best pieces I've read on global warming, because it contains a very elegant solution that does not involve the impoverishment of countries such as China now in order to acheive a reduction of carbon in the future. For anyone who happens to see this blog entry and doesn't want to read the entire article, the most interesting item to me was the observation that every carbon atom in the world ends up as part of a plant within 12 years.
From the article:
=============================================
There is a famous graph showing the fraction of carbon dioxide inthe atmosphere as it varies month by month and year by year [the graph is reproduced in the review]. It gives us our firmest and most accurate evidence ofeffects of human activities on our global environment. The graph isgenerally known as the Keeling graph because it summarizes thelifework of Charles David Keeling, a professor at the ScrippsInstitution of Oceanography in La Jolla, California. Keeling measured the carbon dioxide abundance in the atmosphere forforty-seven years, from 1958 until his death in 2005.
[...]
At this point I return to the Keeling graph, which demonstrates thestrong coupling between atmosphere and plants. The wiggles in thegraph show us that every carbon dioxide molecule in the atmosphereis incorporated in a plant within a time of the order of twelve years. Therefore, if we can control what the plants do with thecarbon, the fate of the carbon in the atmosphere is in our hands.That is what Nordhaus meant when he mentioned "genetically engineered carbon-eating trees" as a low-cost backstop to globalwarming. The science and technology of genetic engineering are not yet ripe for large-scale use. We do not understand the language of the genome well enough to read and write it fluently. But the science is advancing rapidly, and the technology of reading and writing genomes is advancing even more rapidly. I consider it likely that we shall have "genetically engineered carbon-eating trees"within twenty years, and almost certainly within fifty years. Carbon-eating trees could convert most of the carbon that they absorb from the atmosphere into some chemically stable form and bury it underground. Or they could convert the carbon into liquid fuel sand other useful chemicals. Biotechnology is enormously powerful,capable of burying or transforming any molecule of carbon dioxidethat comes into its grasp. Keeling's wiggles prove that a big fraction of the carbon dioxide in the atmosphere comes within thegrasp of biotechnology every decade. If one quarter of the world's forests were replanted with carbon-eating varieties of the same species, the forests would be preserved as ecological resources and as habitats for wildlife, and the carbon dioxide in the atmosphere would be reduced by half in about fifty years.
==================================
http://www.nybooks.com/articles/21494
From the article:
=============================================
There is a famous graph showing the fraction of carbon dioxide inthe atmosphere as it varies month by month and year by year [the graph is reproduced in the review]. It gives us our firmest and most accurate evidence ofeffects of human activities on our global environment. The graph isgenerally known as the Keeling graph because it summarizes thelifework of Charles David Keeling, a professor at the ScrippsInstitution of Oceanography in La Jolla, California. Keeling measured the carbon dioxide abundance in the atmosphere forforty-seven years, from 1958 until his death in 2005.
[...]
At this point I return to the Keeling graph, which demonstrates thestrong coupling between atmosphere and plants. The wiggles in thegraph show us that every carbon dioxide molecule in the atmosphereis incorporated in a plant within a time of the order of twelve years. Therefore, if we can control what the plants do with thecarbon, the fate of the carbon in the atmosphere is in our hands.That is what Nordhaus meant when he mentioned "genetically engineered carbon-eating trees" as a low-cost backstop to globalwarming. The science and technology of genetic engineering are not yet ripe for large-scale use. We do not understand the language of the genome well enough to read and write it fluently. But the science is advancing rapidly, and the technology of reading and writing genomes is advancing even more rapidly. I consider it likely that we shall have "genetically engineered carbon-eating trees"within twenty years, and almost certainly within fifty years. Carbon-eating trees could convert most of the carbon that they absorb from the atmosphere into some chemically stable form and bury it underground. Or they could convert the carbon into liquid fuel sand other useful chemicals. Biotechnology is enormously powerful,capable of burying or transforming any molecule of carbon dioxidethat comes into its grasp. Keeling's wiggles prove that a big fraction of the carbon dioxide in the atmosphere comes within thegrasp of biotechnology every decade. If one quarter of the world's forests were replanted with carbon-eating varieties of the same species, the forests would be preserved as ecological resources and as habitats for wildlife, and the carbon dioxide in the atmosphere would be reduced by half in about fifty years.
==================================
http://www.nybooks.com/articles/21494
Friday, July 4, 2008
Good article on cover crops
http://attra.ncat.org/attra-pub/covercrop.html#web
Introduction:
Cover crops could be considered the backbone of any annual cropping system that seeks to be sustainable. In this publication we summarize the principal uses and benefits of cover crops and green manures. Brief descriptions and examples are provided for winter cover crops, summer green manures, living mulches, catch crops, and some forage crops. To impart a sense of the importance of these practices in sustainable farming, we summarize the effect of cover crops and green manures on: organic matter and soil structure, nitrogen production, soil microbial activity, nutrient enhancement, rooting action, weed suppression, and soil and water conservation. Management issues addressed include vegetation management, limitations of cover crops, use in crop rotations, use in pest management, and economics of cover crops. A selection of print and Web resources are provided for further reading.
[...]
Benefits of Cover Crops and Green Manures
Organic Matter and Soil Structure
A major benefit obtained from green manures is the addition of organic matter to the soil. During the breakdown of organic matter by microorganisms, compounds are formed that are resistant to decomposition—such as gums, waxes, and resins. These compounds—and the mycelia, mucus, and slime produced by the microorganisms—help bind together soil particles as granules, or aggregates. A well-aggregated soil tills easily, is well aerated, and has a high water infiltration rate. Increased levels of organic matter also influence soil humus. Humus—the substance that results as the end product of the decay of plant and animal materials in the soil—provides a wide range of benefits to crop production.
Sod-forming grass or grass-legume mixtures are important in crop rotations because they help replenish organic matter lost during annual cultivation. However, several years of sod production are sometimes required before measurable changes in humus levels occur. In comparison, annual green manures have a negligible effect on humus levels, because tillage and cultivation are conducted each year. They do replenish the supply of active, rapidly decomposing organic matter. (1)
The contribution of organic matter to the soil from a green manure crop is comparable to the addition of 9 to 13 tons per acre of farmyard manure or 1.8 to 2.2 tons dry matter per acre.
Introduction:
Cover crops could be considered the backbone of any annual cropping system that seeks to be sustainable. In this publication we summarize the principal uses and benefits of cover crops and green manures. Brief descriptions and examples are provided for winter cover crops, summer green manures, living mulches, catch crops, and some forage crops. To impart a sense of the importance of these practices in sustainable farming, we summarize the effect of cover crops and green manures on: organic matter and soil structure, nitrogen production, soil microbial activity, nutrient enhancement, rooting action, weed suppression, and soil and water conservation. Management issues addressed include vegetation management, limitations of cover crops, use in crop rotations, use in pest management, and economics of cover crops. A selection of print and Web resources are provided for further reading.
[...]
Benefits of Cover Crops and Green Manures
Organic Matter and Soil Structure
A major benefit obtained from green manures is the addition of organic matter to the soil. During the breakdown of organic matter by microorganisms, compounds are formed that are resistant to decomposition—such as gums, waxes, and resins. These compounds—and the mycelia, mucus, and slime produced by the microorganisms—help bind together soil particles as granules, or aggregates. A well-aggregated soil tills easily, is well aerated, and has a high water infiltration rate. Increased levels of organic matter also influence soil humus. Humus—the substance that results as the end product of the decay of plant and animal materials in the soil—provides a wide range of benefits to crop production.
Sod-forming grass or grass-legume mixtures are important in crop rotations because they help replenish organic matter lost during annual cultivation. However, several years of sod production are sometimes required before measurable changes in humus levels occur. In comparison, annual green manures have a negligible effect on humus levels, because tillage and cultivation are conducted each year. They do replenish the supply of active, rapidly decomposing organic matter. (1)
The contribution of organic matter to the soil from a green manure crop is comparable to the addition of 9 to 13 tons per acre of farmyard manure or 1.8 to 2.2 tons dry matter per acre.
Trumpet Vine
This is a volunteer plant growing on a fence behind the peach orchard. It loves the hot weather and blooms all summer, even during a drought.
A Few Drops of Rain
The San Antonio garden has been getting a half inch or more of rain every day since Wednesday. The Lockhart garden had gotten less than half an inch total when I got here Thursday evening. No rain at all yesterday, and only a few spatters late this afternoon.
But the little bit we've gotten, together with the 75% cloud cover has made a significant difference. I actually enjoyed being in the garden today and spent some time just sitting and relaxing this afternoon, breathing in the fragrance of 4 0'clocks, listening to the neighborhood sounds -- grackles, bluejays, cicadas, a neighbor's rock music (faintly), dogs barking. Every evening this summer until this one, a flock of wood geese has flown over toward the end of the day. I wonder where they are today ...
The Irish potatoes still survive, but I fear the heat stress has been too much for them. I don't expect a good crop. I dug up a marginal one last week. There were 8 tiny spuds attached to the roots. If the weather stays relatively cool like this, I may yet get a potato crop, but I'm not counting on it. I didn't plant the potatoes until February. It's always a crap shoot for me -- plant them too early, and they're likely to be killed by frost. Plant them too late, and they're likely to burn up before they have a chance to produce a crop. Don't know if it's something I'm doing wrong, or if this just isn't a good place to grow Irish potatoes.
There are baby melons on the cantaloupe vines.
Sunday, June 15, 2008
Making Shade
I made the mistake of ordering an althea hibiscus shrub from Wayside Gardens without ascertaining the delivery date. I'd actually forgotten about placing the order when the plant finally arrived, way past the proper planting date for the climate here.
I made a second mistake. I should have kept the poor tiny thing in a container until fall, when the odds of its survival would have been greater. But no, I decided to plant it out, at my weekend home.
Since the baby plant has to go several days between watering, I mulched it heavily, but even that wasn't enough. Every weekend when I get here, I find it a little more stressed and crispy.
Clearly, its days were numbered unless I could think of some way to give it some shade. So I made a wire frame on which I draped branches newly cut from a pecan tree. Time will tell for sure, but the little althea looks a bit better already.
I made a second mistake. I should have kept the poor tiny thing in a container until fall, when the odds of its survival would have been greater. But no, I decided to plant it out, at my weekend home.
Since the baby plant has to go several days between watering, I mulched it heavily, but even that wasn't enough. Every weekend when I get here, I find it a little more stressed and crispy.
Clearly, its days were numbered unless I could think of some way to give it some shade. So I made a wire frame on which I draped branches newly cut from a pecan tree. Time will tell for sure, but the little althea looks a bit better already.
Hardscrabble Days in the Central Texas Garden
For a couple of years I've used this blog for purely selfish purposes, but this afternoon I was browsing through gardening blogs and came across a request for What's Blooming in My Garden Now blog entries. What a great idea!It's hard times for gardening here in Central Texas. August weather came early this year, in the latter half of May, and the heat has continued with relentless ferocity into June. A few plants can be considered to be "blooming" only in the broadest sense of the term. I have a Reve d'Or rose, for example, that's producing flowers that are beautiful for about ten minutes, before they shrivel up and turn brown.
OK, here's the list of blooms I found in the garden this afternoon:
Ruellia (a couple of cultivars plus numerous wild volunteers)
Marigold
Zinnia
Sunflower
Plumbago
Bougainvilia
Perennial Phlox (variety developed by Fanick's in San Antonio)
Echinacea
Vinca minor
Daylily
Reve d'Or rose (sort of)
Older varieties of Hybrid Tea rose (sort of)
Knockout rose and miniatures
Star Jasmine (Rhynchospermum jasminoides)
Althea Hibiscus (sort of -- flowers shrivel up and dry out soon after opening)
Petunias (old fashioned purple ones)
Coral Vine (Antiginon leptopus)
Impatiens
4 o'clocks
Crape Myrtle
canna lily
lantana
penta athena
Mealy Blue sage (Salvia farinacea) and various cultivars
Here's what I'm harvesting for the table:
Tomatoes (tons of tomatoes)
Squash
New potatoes
Green beans
Black eyed peas and Mandy beans will be ready to begin harvesting in a few days
Speckled butterbeans
Chiles (lots of different kinds)
Last of the sweet corn (plants all dried up from the hot weather)
Edible amaranth (red Chinese variety)
Herbs (oregano, basil, last of the dill and cilantro (marginal), chives, garlic greens, parsley,chicory, stevia, sage)
Last of the beets
Last of the strawberries
Last of the mulberries
The peach crop has failed, due to not enough chilling hours for some varieties and late frost for others. Same with the pears. The blackberries have dried up on the vines. (I'm glad my garden is not my sole source of food -- I'd be in big trouble).
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