The challenge of ensuring future food security as populations grow and diets change has its roots in soil, but the increasing degradation of the earth's thin skin is threatening to push up food prices and increase deforestation.
While the worries about peaking oil production have been eased by fresh sources released by hydraulic fracturing, concern about the depletion of the vital resource of soil is moving center stage.
John Crawford, Director of the Sustainable Systems Program in Rothamsted Research in England said:
We know far more about the amount of oil there is globally and how long those stocks will last than we know about how much soil there is.
Under business as usual, the current soils that are in agricultural production will yield about 30 percent less than they would do otherwise by around 2050.
Surging food consumption has led to more intensive production, overgrazing and deforestation, all of which can strip soil of vital nutrients and beneficial micro-organisms, reduce its ability to hold water and make it more vulnerable to erosion.
Such factors, exacerbated by climate change, can ultimately lead to desertification, which in parts of China is partly blamed for the yellow dust storms that can cause hazardous pollution in Asia, sometimes even severe enough to cross the Pacific Ocean and reduce visibility in the western United States.
Arable land in areas varying from the United States and Sub-Saharan Africa, to the Middle East and Northern China has already been lost due to soil degradation.
The United Nations' Food and Agriculture Organization (FAO) has estimated that 25 percent of agricultural land is highly degraded, while a further 8 percent is moderately degraded.
'Peak Soil' Threatens Future Global Food Security
Recent research findings have brought some rays of hope to China’s beleaguered soil. The Foshan Jinkuizi Plant Nutrition Company claims to have developed a soil remediation technology specifically designed for China’s heavy-metal polluted soil: a microorganism that can change the ionic state of heavy metals in the soil, deactivating the pollutants so they do not harm crops. The company claims that the method is cheap, convenient, easy to use, does not produce any secondary pollution, and is already in commercial production and use.
In another possible breakthrough, in April the Guangdong Geoanalysis Research Center announced a new product, Mont-SH6, which it says is a powerful absorber of toxic heavy metals such as cadmium, lead, mercury, copper, and zinc. Liu Wenhua, chief engineer at the center, claims that the product can reduce soil cadmium levels by over 90 percent, and that materials and manufacturing costs are low: remediation of 1.48 acres of cadmium-contaminated rice fields with this technique costs about $4,800. Mass production, according to Liu Wenhua, could bring this down to between $320 and $480.
The Soil Pollution Crisis in China: Cleanup Presents Daunting Challenge
The most succinct, systematic treatment of intergenerational principles left to us by the founders is that which was provided by Thomas Jefferson in his famous September 6, 1789 letter to James Madison. The letter was Jefferson’s final installment in a two year correspondence with Madison on the proposed Bill of Rights. Given the importance of this letter as background material for the bill of rights, and its independent value as a brilliant statement of intergenerational equity principles, it serves as the natural starting point for a discussion of the founders’ views on specific intergenerational issues.
Jefferson begins his letter by asserting that:
The question [w]hether one generation of men has a right to bind another … is a question of such consequences as not only to merit decision, but place also among the fundamental principles of every government…. I set out on this ground, which I suppose to be self-evident, ‘that the earth belongs in usufruct to the living’ ….
Generational Sovereignty and the Land – The Earth as Tenancy-in-Common - Thomas Jefferson's Usufruct, part 1 (part 2 below)
The contemporary issue to which Jefferson’s arguments most literally apply is the problem of topsoil depletion. As a planter in predominantly agrarian Virginia, who tended to view wealth as the direct or indirect product of the earth, it was natural for Jefferson to phrase his discussions of intergenerational relations — even intergenerational economic relations — in terms of soil:
Are [later generations] bound to acknowledge [a national debt created to satisfy short-term interests], to consider the preceding generation as having had a right to eat up the whole soil of their country, in the course of a life….? Every one will say no; that the soil is the gift of God to the living, as much as it had been to the deceased generation; and that the laws of nature impose no obligation on them to pay this debt.
Jefferson asserts that each generation has the right to inherit, undiminished, the same topsoil capital that its predecessors enjoyed. Our society’s failure to recognize and defend this most basic principle of intergenerational fairness during the past century has resulted in topsoil depletion that has reached crisis proportions. Soon we may have literally and irreparably “eaten up the whole soil of our country.”
Generational Sovereignty and the Land – The Earth as Tenancy-in-Common - Thomas Jefferson's Usufruct, part 2
In a paper published in the scientific journal New Phytologist, plant ecologist Nishanth Tharayil and graduate student Mioko Tamura show that invasive plants can accelerate the greenhouse effect by releasing carbon stored in soil into the atmosphere.
Since soil stores more carbon than both the atmosphere and terrestrial vegetation combined, the repercussions for how we manage agricultural land and ecosystems to facilitate the storage of carbon could be dramatic.
In their study, Tamura and Tharayil examined the impact of encroachment of Japanese knotweed and kudzu, two of North America's most widespread invasive plants, on the soil carbon storage in native ecosystems.
"Our findings highlight the capacity of invasive plants to effect climate change by destabilizing the carbon pool in soil and shows that invasive plants can have profound influence on our understanding to manage land in a way that mitigates carbon emissions," Tharayil said.
Tharayil estimates that kudzu invasion results in the release of 4.8 metric tons of carbon annually, equal to the amount of carbon stored in 11.8 million acres of U.S. forest.
Invasive Plants Can Release Soil Carbon, Accelerate Global Warming
Fields that are not tilled after crop harvesting reflect a greater amount of solar radiation than tilled fields. This phenomenon can reduce temperatures in heat waves by as much as 2 °C, as researchers have demonstrated in a recent study.
Straw Albedo Mitigates Extreme Heat
Plants are often thought of as the masters of photosynthesis, the process by which sunlight, carbon dioxide and water are converted into usable energy, but when it comes to efficiency, they are beaten out by a rather surprising rival: bacteria.
Plants use resources, such as minerals and water, to promote their growth, but they also are restrained by the enzymes they need to complete photosynthesis, particularly an enzyme commonly known as RuBisCo.
Both plants and bacteria rely on RuBisCo to fix, or transform, carbon dioxide in the initial stages of photosynthesis. Unfortunately, RuBisCo can also react with oxygen, creating an unusable molecule that the plant must spend further energy to recycle. The result wastes far more nutrients than the plants need, costing both resources and money, and places a theoretical limit on crop yields.
Recently, research teams from Cornell University and Rothamsted Research in the United Kingdom began looking for ways around this barrier. They selected genes from bacteria that have evolved a way to bypass this dilemma and inserted them into plant cells, hoping that the bacterial addition would bestow the same advantages onto plants and provide food crops a way to boost yields under the pressures imposed by climate change.
"If proved effective, this technology would decrease the amount of key nutrients like nitrogen and, most notably, water needed by the plant, while increasing the yield," said Lin Myat, a postdoctoral fellow of molecular biology and genetics at Cornell and lead on the study. Both nutrients are valuable additions to any crop plant, especially under the pressure of increasing droughts.
In some key food crops, such as wheat or rice, the unwanted RuBisCo reaction happens roughly one-quarter of the time. While some crop plants like corn have devised ways to reduce the likeliness of this wasteful reaction, they require additional energy to do so. With a growing population to feed and limited resources, finding new ways to avoid the RuBisCo problem without expending extra energy in crop plants has become an increasingly studied topic.
Scientists Look to Bacteria to Protect Crop Yields in the Face of Climate Change
In 2011 more than half of the terrestrial world’s carbon uptake was in the southern hemisphere – which is unexpected because most of the planet’s land surface is in the northern hemisphere – and 60% of this was in Australia.
That is, after a procession of unusually rainy years, and catastrophic flooding, the vegetation burst forth and the normally empty arid center of Australia bloomed. Vegetation cover expanded by 6%.
Human activity now puts 10 billion tonnes of carbon into the atmosphere annually, and vegetation in 2011 mopped up 4.1 billion tonnes of that, mostly in Australia.
There remains a great deal of uncertainty about the carbon cycle and how the soils and the trees manage the extra carbon. Nobody knows what will happen to this extra carbon now in the hot dry landscapes of Australia: will it be tucked away in the soil? Will it be returned to the atmosphere by subsequent bushfires?
As scientists are fond of saying, more research is necessary.
How Nature Affects the Carbon Cycle
