Sustainablog

The World Agroforestry Centre has recently released a paper titled ” Trees on Farm: Analysis of Global Extent and Geographical Patterns of Agroforestry.” The researchers used five global geodata sets to estimate the percent tree cover on 22 million square kilometers of agricultural land around the world.  They were surprised to find that nearly half of that land had 10% or more tree cover (which is considered “significant” from an agroforestry point of view).  The area involved is vast - as large as the Amazon basin.

Even for North America, the percentages were surprisingly high (39% over 10% cover, 17% over 30%).  Values in Europe were similar. The highest levels are in central America (98% above 10% cover), South America (81%), and Southeast Asia (82%).  Overall, the lowest tree cover is in the most arid areas, but even there >20% of the farmland has 10% tree cover.

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The chart above shows the historical average yields for wheat and corn in the US.  Note that until the 1930s the relative yields of the crops were similar and were not changing.  After that time yields of both crops began to rise steadily, but corn yields have grown at a much faster pace.  What explains this difference?

There are several interacting factors behind this, and they work together to create the “orphan” status of wheat as a crop.  Corn is a hybrid crop which enhances its yield and the ease of increasing its yield through breeding.  Wheat is harder to hybridize so it isn’t practical except for extremely high yielding wheat areas like Northern Europe.  Instead, US wheat is largely a “saved seed crop” meaning that the grower can simply save back some of the grain and replant it rather than needing to buy new hybrid seed each year.  That system is workable, particularly if the grower periodically buys some “certified seed” to have a purer stand and to take advantage of breeding improvements.  The down-side of a “saved seed crop” is that there is not a very big private seed industry to invest in the crop.  Most of the breeding is done by University and USDA breeder supported by tax dollars and there is a small private industry as well.  As I said in the previous post, these breeders have done a remarkable job with the resources they have, but in an increasingly ag-unaware society, that support is never generous.

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I read an article today about a major shortfall in the Kenyan wheat harvest that will drive the need for major imports to meet food needs.  There were three major factors behind this disappointing harvest.  Tight credit and high energy prices kept some growers from even planting.  The rains were not well timed to achieve good yields.  Also a new strain of a very serious wheat disease, UG99 Stem Rust, further reduced yields.

This news has nudged me to write a series of posts about wheat because as a crop, it has a lot more problems than one bad harvest in Kenya.  The Kenya example just stands as an example of the vulnerability of this extremely important world food crop-a crop that is really an “orphan” in today’s agricultural scene.

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A polar bear is the perfect example of “Charismatic Megafauna” - the kind of animal whose image can easily be used to generate sympathy.  I care about polar bears as much as anyone, but I’m a little concerned about how images of animals like this are being used to promote Climate Change awareness and to fund-raise for environmental organizations. If we are going to make the personal life-style changes, the new business strategies, and the public policy decisions to counter this threat, we need to do it with a clear-eyed understanding of what is at stake.  The “faces” we should be thinking about are those of starving people in poor nations.

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Every once in a while I come across something in the scientific literature that really surprises me.  Because there isn’t much oxygen in a worm gut, it creates the ideal conditions for these particular microbes (”de-nitrifiers”) to turn nitrate (NO3) into nitrogen gas and also generate some nitrous oxide in the process.

Nitrous Oxide

Ok, some background. Nitrous oxide (N2O) is a very potent greenhouse gas with 310 times the global warming potential of carbon dioxide. Its really an Achilles heel for agricultural sustainability because around 80% of the human-generated emissions of this gas come from farms. If even a small amount of the farmer’s nitrogen fertilizer gets converted to N2O it becomes a major part of the total carbon footprint of that field
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When thinking about “carbon footprints” it helps to have real numbers to put things in perspective. The EPA estimates that for the US, agriculture represents about 8% of total human-related greenhouse gas emissions. The following is a list with a little of the detail of what makes up the footprint of an acre of a rain-fed Midwestern corn crop with a few other things thrown in for comparison. Since we grow 80-90 million acres of corn its something that matters. The values are all expressed as pounds of CO2 equivalents. If you want Carbon equivalents multiply by 12/44

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My earlier blog about greenhouse gas emissions from composting generated a lot of good discussion so I am writing to respond.

• Yes, composting is certainly better than some outcomes like food scraps going into a garbage dump which does not do anything to capture the methane

• Yes, an anaerobic digester would be a very good thing to use for most waste streams.  A recent example is what was done at Gill’s Onions

• Many wastes can also be put through a fast-pyrolysis process to form syngas and biochar.  This is another way to get at the carbon-neutral energy that is in the manure or other waste

• Greenhouse gas emissions are not the only metric that matters as was pointed out, but manures in particular are undesirable fertilizers based on multiple other metrics as well: tendency to leach more nitrates because of extended release, more nitrous oxide emissions for the same reason, and excess levels of phosphorus relative to nitrogen leading to water pollution

• Compost is indeed a very good way to build soil carbon and that is a super important thing to do for true sustainable farming, but there are other ways to accomplish that that don’t have the greenhouse gas issues.  One is the use of biochar.  The other is to practice no-till farming and grow cover crops which I describe in another post.

• There may be ways of composting that don’t emit as much methane, but I’ve seen far more theoretical arguments that way with no actual measurements taken.  As a microbiologist I have a hard time imagining how you could avoid having some anaerobic conditions in a big pile of manure.  Starting from 14 times as much carbon equivalents as synthetic nitrogen, the process would have to be vastly improved to be acceptable

• Un-composted manure has similar drawbacks as a fertilizer.  When it is stored for later use on a farm, at least 1-2 percent of its total methane potential gets released even with very good manure management practices

• Chicken manure is more attractive to farmers as a nitrogen source because the levels are higher, but there is every reason to believe it would generate methane in storage and during composting if someone bothered to measure it

“No-till” Soybeans Following Wheat

There is a sub-set of farmers who have been practicing a much more sustainable form of agriculture for decades and we are coming up on the 50th anniversary of it’s beginnings.  I want to start writing about this event early because many environmentally-conscious folk are not aware of this hugely significant “revolution” that has occurred in agriculture over the past half century.  No, I’m not talking about “Organic Farming.” That movement is about a decade older in the US and has had a much smaller impact.  I’m talking about “No-till” agriculture and variants that are focused on reducing the amount of “tillage” or “plowing” that are needed to farm.

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by Lester R. Brown

In April 2005, the World Food Programme and the Chinese government jointly announced that food aid shipments to China would stop at the end of the year. For a country where a generation ago hundreds of millions of people were chronically hungry, this was a landmark achievement. Not only has China ended its dependence on food aid, but almost overnight it has become the world’s third largest food aid donor.

As noted in Plan B 3.0: Mobilizing to Save Civilization, the key to China’s success was the economic reforms in 1978 that dismantled its system of agricultural collectives, known as production teams, and replaced them with family farms. In each village, the land was allocated among families, giving them long-term leases on their piece of land. The move harnessed the energy and ingenuity of China’s rural population, raising the grain harvest by half from 1977 to 1986. With its fast-expanding economy raising incomes, with population growth slowing, and with the grain harvest climbing, China eradicated most of its hunger in less than a decade—in fact, it eradicated more hunger in a shorter period of time than any country in history.

While hunger has been disappearing in China, it has been spreading throughout much of the developing world, notably sub-Saharan Africa and parts of the Indian subcontinent. As a result, the number of people in developing countries who are hungry has increased from a recent historical low of 800 million in 1996 to over 1 billion today. Part of this recent rise can be attributed to higher food prices and the global economic crisis. In the absence of strong leadership, the number of hungry people in the world will rise even further, with children suffering the most.

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Today’s post is by Lisa Moore, a climate scientist at EDF.

NOAA recently released a terrific scientific report that explains, in plain English, the current and projected effects of climate change on the U.S. The nonpartisan report, prepared by the 13-agency U.S. Global Change Research Program, tells a grim but important story, clearly and with lots of powerful maps and charts. I encourage you to check it out to see how climate change will affect your area of the country.

Here are some of the “business-as-usual” projections that my colleagues and I find most striking and disturbing:

You think August is hot now?

By the end of this century, we could be in for much more severe summers all across the country (see maps that follow).

• If you live in New Hampshire, summer could feel like it does today in North Carolina (p.107).
• If you live in Michigan, brace yourself for summers that feel like today’s summers in Oklahoma (p 117).
• And if you live in Texas, you now experience 10 to 20 days a year over 100 °F. By the last two decades of this century, look for 100 such days - that’s more than three months (p. 90).

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