Tag: fallow

Fertile Soil Gone From Midwestern Farms

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Evan Thaler/NPR

Farming has destroyed a lot of the rich soil of America’s Midwestern prairie. A team of scientists just came up with a staggering new estimate for just how much has disappeared…

The new study emerged from a simple observation, one that people flying over Midwestern farms can confirm for themselves. The color of bare soil varies, and that variation is related to soil quality.

The soil that’s darkest in color is widely known as topsoil. Soil scientists call this layer the “A-horizon.” It’s the “black, organic, rich soil that’s really good for growing crops,” says Evan Thaler, a Ph.D. student at the University of Massachusetts, Amherst.

It’s full of living microorganisms and decaying plant roots, also called organic carbon. When settlers first arrived in the Midwest, it was everywhere, created from centuries of accumulated prairie grass. Plowing, though, released much of the trapped carbon, and topsoil was also lost to wind and water erosion. The soil that remains is often much lighter in color.

RTFA. The history isn’t unknown. The effects are still (sometimes) debated. It takes many tons of additives annually to keep productivity and profitability close to each other. Healthy? That’s another question.

Abandoned farmlands are another key to sustainable bioenergy

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Pongamia plantation photo from Tree Oils India Limited

Biofuels can be a sustainable part of the world’s energy future, especially if bioenergy agriculture is developed on currently abandoned or degraded agricultural lands. Using these lands for energy crops, instead of converting existing croplands or clearing new land, avoids competition with food production and preserves carbon-storing forests needed to mitigate climate change. Sustainable bioenergy is likely to satisfy no more than 10% of the demand in the energy-intensive economies of North America, Europe, and Asia. But for some developing countries, notably in Sub-Saharan Africa, the potential exists to supply many times their current energy needs without compromising food supply or destroying forests.

Researchers…estimated the global extent of abandoned crop and pastureland and calculated their potential for sustainable bioenergy production from historical land-use data, satellite imaging, and ecosystem models. Agricultural areas that have been converted to urban areas or have reverted to forests were not included in the assessment…

“At the national scale, the bioenergy potential is largest in the United States, Brazil, and Australia,” says lead author Campbell. “These countries have the most extensive areas of abandoned crop and pasture lands. Eastern North America has the largest area of abandoned croplands, and the Midwest has the biggest expanse of abandoned pastureland. Even so, if 100% of these lands were used for bioenergy, they would still only yield enough for about 6% of our national energy needs.”

The study revealed larger opportunities in other parts of the world. In some African countries, where grassland ecosystems are very productive and current fossil fuel demand is low, biomass could provide up to 37 times the energy currently used.

No reasonable researcher is looking for a single answer to our energy questions. But, here’s another piece of the puzzle identified and offered to a world seeking economic sense.