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2015: The International Year of Soils


2015 happens to be the International Year of Soils,[1] and yet the year has been passing without much attention paid to this most important mixture of weathered rock, decayed organic matter, mineral fragments, water, and air. As George Monbiot wrote last spring, “Even if everything else were miraculously fixed, we’re knackered if we don’t address an issue considered so marginal and irrelevant that you can go for months without seeing it in a newspaper.”[2] CES Musings would be remiss if we ended 2015 without celebrating Earth’s soils and lamenting their abuse.

We might more accurately say, “lament their passing.” At the World Soils Day forum held in Rome in December 2014, a senior Food and Agriculture Organization (FAO) official said all of the world’s topsoil could be gone within 60 years if current rates of degradation continue. At the same forum, Volkert Engelsman of the International Federation of Organic Agriculture Movements stated, “We are losing 30 soccer fields of soil every minute, mostly due to intensive farming.”[3] Monbiot’s column summarizes our plight: “What appear to be great crises are slight and evanescent when held up against the steady but unremarked trickling away of our subsistence.”

Every year, an estimated twelve million hectares of land are lost each year to desertification, adding to the billions of hectares that are already degraded. (A hectare is a metric unit equal to 100 ares, which is equal to 10,000 square meters. The non-metric equivalent would be 2.471 acres.) This estimate, quoted in the April 2015 issue of Food Security, is likely to be an underestimate, because the evidence base is limited to identifying direct impacts of soil degradation on food production. The reference notes that additions of chemical fertilizers may mask the true condition and urges that “comprehensive soil conservation practices are required to respond to the multiple problems of soil degradation.”[4]

Plowing is responsible for much of the damage witnessed on cropland because it loosens soil and removes plant cover, which exposes land to wash away with rain or blow off with wind. Soil does not have to be washed or blown away, however, for its productivity to be lowered. Through improper soil and water management, a soil’s properties may be altered so that its fertility is seriously reduced or lost for good.

The FAO lists the following causes of nutrient loss:[5]

  • Excessive cultivation wrecks the structure of soils so that they are no longer capable of holding enough moisture.
  • Salinization by means of irrigation affects nearly seven percent of the land area of the world.
  • Waterlogging from high water tables and runoff affects areas such as Egypt, where about one-third of the Nile Delta has a water table only 80 centimeters (31.5 inches) below the surface.
  • Nutrients are also depleted by growing the same crops on the same land year after year.
  • Soil compaction can result from repeated passes over the same field with heavy machinery, particularly when the field is wet, or from the hooves of grazing animals as around the only waterhole in an area.
  • In industrialized countries, some of the best farmland is being paved over by urbanization.
  • Today a serious problem in several highly industrialized countries is the indiscriminate dumping of highly toxic chemical wastes and the growing application of sewage sludge to farmland, some of which contains dangerous heavy metals.
  • Pesticide use has been criticized, and in recent years particularly the more persistent insecticides, including DDT and chlordane. Radioactive fallout including Strontium 90 has also caused public concern.

As oceans rise, agricultural land along coasts is also being degraded by saltwater intrusion—the landward movement of saltwater into the surface water and soil.[6]

The map (see pdf) shows the various ways soils have been damaged: the darker the color in each category, the more severe the condition. Blue-green colors show water erosion. Erosion by wind is tan to brown. Chemical deterioration is shown in shades of pink, and physical deterioration (compaction, waterlogging and overuse) in shades of purple. Stable terrain is gray; non-used wasteland, dark gray; and ocean and other bodies of water, pale blue.

The Global Assessment of Human-Induced Soil Degradation (GLASOD) produced the map (see pdf) for the United Nations Environment Programme (UNEP) in 1990.[7] More recent reports show increasingly severe degradation. Some soil loss has been experienced since the first days of agriculture, but farming methods traditionally made efforts to put replacement nutrients back into the land in the form of manures and plant residues. They also paid attention to a site’s aptitude: crops were grown where the land was favorable, and marginal areas were left for animal grazing. Further crops were rotated and land was periodically left fallow to restore the soil. With the invention of nitrogen fertilizer it has been possible to produce crops on almost any site—for a while. Injection of fertilizers has been practiced much like mining: soil has been treated as a medium to hold chemicals and support plant roots.

Bags of NPK (nitrogen, phosphorus and potassium) have been applied according to a formula originating at a factory or government office rather than in response to widely varying field conditions. A glance at the Global Soil regions map showing the US Department of Agriculture (USDA) soil taxonomy system[8] reveals that soils do have distinct character, and effective nourishment of the soil must take these differences into account.

Mollisols, shown here in dark green, are exceptionally high in fertility and they coincide to a large extent with the world’s major grain producing areas. They include the North American prairie states; the Pampas in Argentina, Uruguay and southern Brazil; Gran Chaco in eastern Bolivia, Paraguay, northern Argentina and a portion of Brazil; and the Ukraine-to-Central Asia Black Earth belt.[9] Nevertheless, societies have thrived for thousands of years on the yields of soils quite unlike mollisols. Until recently the people, the animals and the plants of any region would have been evolving together, creating the unique character of that place.

The famed soils of US prairies were formed from material deposited during the most recent ice age, which reached its peak about 18,000 years ago. As glaciers retreated, streams of melted ice dropped sediment on the land, building layers of productive soil.[10] Rainfall too sparse to leach away nutrients, fires frequent enough to prevent the growth of trees, and animals to deposit their urine and feces while disturbing the earth with their activities—these contributors combined to create soils that are still productive after the last two centuries of concentrated human abuse.[11]

Prairie soils such as these may hold a key to saving what remains of the world’s agricultural land. The majority of the plants that cover the world’s rich grasslands are perennials; they live many years and develop deep, abundant roots that hold soil in place despite flood and drought. The grain crops that provide about half the human world’s food calories[12] are annuals; they must be replanted each year, and the planting requires soil disruption. Scientists have long known that perennials are the backbone of nature’s preferred soil management system, and in recent decades developments in plant breeding have raised the hope that some of these annual grain crops might become perennialized.

The famed Kansas prairie provided inspiration for one of the most far-sighted efforts this direction. Founded by Wes Jackson in Salina, Kansas, the Land Institute has worked for over 30 years to develop an agricultural system with the ecological stability of the prairie and a grain yield comparable to that from annual crops. Since 70 percent of global cropland is devoted to grain raised either for humans or to feed agricultural animals, the development of perennial grains has the potential to make agriculture a soil-nourishing rather than a soil-destroying enterprise. [13]

Practitioners of industrial agriculture are aware of soil loss, but a certain amount is accepted as a consequence of food production. In order to hold the damage to what the Natural Resources Conservation Service (NRCS) calls the Soil Loss Tolerance Rate of five tons per acre per year,[14] low-tillage and no-till methods have been increasingly applied in conventional farming..[15]  The data shows that approximately 35.5 percent of US cropland, or 88 million acres, was planted under no tillage culture in 2009.[16]

A means of plowing introduced in the 1950s in Australia by P.A. Yeomans, however, aims to prevent erosion while at the same time contributing to soil replenishment. The Keyline chisel plow [17] loosens sub-soil without soil inversion, and thereby creates small ridges on the soil surface that encourage rain water to sink deeper into the ground as it falls. The keyline contour system captures water at the highest possible elevation and combs it outward toward the ridges. Naturally occurring organic material already in the soil and/or cover crops subsequently planted and turned under will decompose rapidly with the increase of moisture and air levels within the soil. The method also directs water into catchment ponds along a slope, where it is stored for future use in the fields below.[18]

The general public comes closest to recognizing the importance of soils when considering the future of the food supply. Headlines ask, “Which agricultural practices must we employ to feed nine billion people?” or “Can organic practices yield as much as conventional methods?” Organic? GMOs? Antibiotics? Free range? Insecticides? These topics are increasingly concerns of knowledge-seeking consumers. But while the topics are not irrelevant to the more fundamental problem being addressed by The Year of Soils, they are less crucial in the bigger picture.

The big picture is Planet Earth, and the fragile covering of earth the planet has learned to create. It is good to hold this double meaning of the word in mind when reading again what Thomas Berry wrote in 1998: “Earth is primary. Earth must be the primary concern of every human institution, profession, program, and activity.”[19]

Soils are the foundation material of life for Earth creatures. Dirt is said to be the substance of which we are made. Humans have exploited earth—soils, dirt—since at least the beginnings of agriculture, and soil scientists are telling us earth loss may prove as dangerous for human survival as human-induced climate change. Not only human life but all of Earth life is at stake in how we treat our soils. Soil conservation is essential for the long-term security of whatever number of whichever species a habitable planet requires.


[1] “2015 International Year of Soils,” Food and Agriculture Organization of the United Nations, accessed October 28, 2015, http://www.fao.org/soils-2015/about/en/.

[2] George Monbiot, “Ploughing on Regardless,” The Guardian, March 25, 2015, accessed October 28, 2015, http://www.monbiot.com/2015/03/25/3703.

[3] Chris Arsenault, “Only 60 Years of Farming Left If Soil Degradation Continues,” Scientific American, December 5, 2014, accessed October 28, 2015, http://www.scientificamerican.com/article/only-60-years-of-farming-left-if-soil-degradation-continues/.

[4] R.J. Rickson and L.K. Deeks, “Input Constraints to Food Production: The impact of Soil Degradation,” Food Security, Volume 7, issue 2, 351-364, accessed October 28, 2015, http://link.springer.com/article/10.1007%2Fs12571-015-0437-x#page-1.

 [5] Natural Resources Management and Environment Department, “Keeping the Land Alive. Soil Erosion: Its Causes and Cures,” Food and Agriculture Organization of the United Nations Corporate Document Repository, accessed October 28, 2015, http://www.fao.org/docrep/t0389e/t0389e02.htm.

[6] Tess Malijenovsky, “Saltwater Intrusion: The Parts You Can’t See,” Coastal Review Online, March 26, 2015, accessed October 28, 2015, http://www.coastalreview.org/2015/03/saltwater-intrusion-the-parts-you-cant-see.

[7] ISRIC World Soil Information, “Global Assessment of Human-induced Soil Degradation (GLASOD),” accessed October 28, 2015, http://www.isric.org/projects/global-assessment-human-induced-soil-degradation-glasod.

[8] Natural Resources Conservation Service, “Global Soil Regions Map,” accessed October 28, 2015, http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/use/worldsoils/?cid=nrcs142p2_054013.

[9] “Mollisols,” Wikipedia. Last modified on 24 June 2015, accessed October 28, 2015, https://en.wikipedia.org/wiki/Mollisol.

 [10] “Prairie,” National Geographic: Education, accessed October 28, 2015, http://education.nationalgeographic.com/encyclopedia/prairie.

[11] “North American Prairie,” Blue Planet Biomes, accessed October 28, 2015, www.blueplanetbiomes.org/prairie.htm.

 [12] “Grain Harvest Sets Record, But Supplies Still Tight” (Product Number: VST101), Worldwatch Institute, 2003, accessed October 28, 2015, http://www.worldwatch.org/node/5539.

 [13] “Our work,” The Land Institute, accessed October 29, 2015, https://landinstitute.org/

[14] Bob Wise, “Plowing Bedrock: How Bad is Soil Erosion in US Cropland?” Resilience, accessed October 28, 2015, http://www.resilience.org/stories/2014-09-29/plowing-bedrock-how-bad-is-soil-erosion-in-us-cropland.

 [15] Brad Plumer, “No-Till Farming is on the Rise. That’s Actually a Big Deal,” The Washington Post, accessed October 28, 2015, http://www.washingtonpost.com/news/wonkblog/wp/2013/11/09/no-till-farming-is-on-the-rise-thats-actually-a-big-deal/.

[16] John Horowitz, Robert Ebel, and Kohei Ueda, “No-Till Farming Is a Growing Practice,” US Department of Agriculture Economic Research Service, last updated May 26, 2012, accessed October 28, 2015, http://www.ers.usda.gov/publications/eib-economic-information-bulletin/eib70.aspx.

 [17] “Keyline Designs,” Keyline, accessed October 28, 2015, http://www.keyline.com.au/.

[18] Ken Yeomans, “Yeomans Keyline System and Concepts,” Yeomans Plow, accessed October 28, 2015, http://www.yeomansplow.com.au/yeomans-keyline-system.htm.

[19] Thomas Berry, “The Determining Features of the Ecozoic Era,” available from CES.