World Running Out of Farmland

Published on: 08:22AM Jun 08, 2011

"The Nation that destroys its soil destroys itself." – President Franklin D. Roosevelt

Grain prices have more than doubled over the last year as the world is starting to realize that the food supply is running out. In 9 of the 10 last years, the global consumption of grain has outpaced production according to the USDA. To meet future demand, experts are predicting that global agriculture will need to produce more food in the next 50 years than what was produced during the previous 10,000 years, putting more and more pressure on future farmers and the land they use to produce our food.

Not only is the world running out of grain, it is also running out of farmland at an alarming rate. Hundreds of thousands of acres across the globe have disappeared due to erosion, urban development, and overuse over the last century. The American Farmland Trust estimates that farmland is disappearing at a rate of 2 acres per minute.

The National Soil Tilth Laboratory highlighted, "Each human on earth lives off the farming equivalent of about a third of a football field today. Population growth and urbanization will shrink that available land base in half by 2050."


Despite soil’s importance to the survival of the human population, soil is eroding faster than it is being replaced. In the last 30 years, roughly 30% of the Earth's arable land has eroded according to David Pimentel, professor at Cornell University. "Soil erosion is second only to population growth as the biggest environmental problem the world faces," said Pimentel.

Over half of the U.S.’s best cropland is experiencing an erosion rate 27 times the natural rate or 11,000 pounds per acre (approximately 1/26 of an inch of soil/year) according to the USDA. The natural, geological erosion rate is about 400 pounds of soil per acre per year. Based on these levels of erosion it would take approximately 26 and over 700 years respectively, for one inch of top soil to erode.

Parts of Iowa, which has some of the best soil is the world, have seen topsoil levels erode from a depth of 18 inches down to 10 inches according to the USDA. Productivity drops off sharply when topsoil reaches 6 inches or less, the average crop root zone depth.

Andres Arnalds of the Icelandic Soil Conservation Service estimates that roughly 38,000 square miles of land (100,000 square kilometers) each year becomes severely degraded or turns into desert due to erosion. "We are overlooking soil as the foundation of all life on Earth," said Arnalds. "Soil and vegetation is being lost at an alarming rate around the globe, which in turn has devastating effects on food production and accelerates climate change."

The economic impact of soil erosion in the U.S. costs the nation approximately $37.6 billion each year in productivity losses and damage from soil erosion according to Cornell University. Worldwide it is estimated to be $400 billion per year.

The primary causes of rapid soil erosion are conventional tillage programs coupled with highly sloped and large amounts of precipitation. In areas prone to erosion, fall tillage and the removal of crop residues after harvest are key drivers of erosion. On sloped land in the spring, there is a window of opportunity for erosion between the start of tillage and when the crop establishes a root system strong enough to hold the surrounding soil. This window typically lasts for four to six weeks and is most susceptible to erosion during hard rain falls.

Sloped land also has waterways, which are natural occurring drainage pathways that rainwater follows. Farmers maintain these waterways by planting the area with grass to provide an outlet for water to flow through without removing topsoil.

Row crops, such as corn and soybeans, result in roughly 50 times more soil erosion than faster growing, densely populated crops such as wheat, alfalfa, and grasses. Farmers in areas prone to erosion will plant a cover crop (rye, clover, and vetch) in the fall when they intend to plant row crops the following spring. The farmer can then choose to plant directly into the cover crop or plow them under. The latter provides the farmer with many valuable nutrients that they would otherwise have to apply to the land in the form of commercial fertilizer.

In addition to the solutions listed above, in areas prone to erosion farmers can reduce soil erosion by using strip or no-till farming methods. The main difference in the two methods is strip-tilling bands fertilizer in a 4 inch trench approximately 6-8 inches below the surface of the soil and seed is then planted directly above the band of fertilizer making the fertilizer available to the plant that year. While no-till operations spread the majority of fertilizer over the top of the ground making it less accessible to the crop in the first two years following application and plant directly into the un-tilled soil. With both options crop residue is left on the surface of the soil and breakdown over time, providing nutrition, water retention, and soil carbon. Currently, only 20% of corn in the U.S. is grown using no-till.

Iceland is a prime example of the dangers of soil erosion. Since the country was settled in the ninth century, over half of the vegetative cover has been destroyed and 40% of its soil has eroded according to a national survey completed in 1997. Now desert covers 45,000 square kilometers, or 40% of the country.

Despite spending the last 100 years trying to improve its soil, Iceland needs to import a large portion of its food supply and is continually battling the degraded soil. Arnalds noted that Iceland should serve as a warning to other countries. "It is far better to preserve than restore," he said.

Soil stores carbon as it is one of the key ingredients for plant growth. The amount of carbon stored in soil is roughly twice the amount of carbon found in the atmosphere and three times the amount in vegetation. Across the U.S., agricultural methods have removed approximately 20% to 50% of the Earth's original soil carbon, and up to 70% in some regions according to the USDA.

Land degradation may account for up to 30% of the world's green house gas releases according to Ohio State University. While tillage of crop residue still locks carbon into the ground for a short period of time before it is released into the atmosphere, no-till methods lock carbon into the crop residue for a longer period of time, delaying the release into the atmosphere.

Soil erosion also limits one of the best natural water filters. Topsoil filters out many of the impurities and the next sandy gravel layer will further filter the substance before it enters an aquifer. Surface water sifts through soil and by the time it reaches an aquifer, it is some of the purest, cleanest water on Earth.


Farmland has also been disappearing in the U.S. due to urban development. Farmland has been used to create new highways, industrial parks, and housing developments. The American Farmland Trust estimates that between 1992 and 1997, more than six million acres of agricultural land, an area the size of Maryland, was used for urban development.

There has been a 5% decrease in farmland in the tri-state area of Alabama, Tennessee, and Georgia from 1987 to 2007. Wisconsin's farmland has decreased by 19% from 1978 to 2008. Virginia lost 521,000 acres of farmland from 2002 to 2007.

The decline in farmland has lead to the U.S.'s food supply being grown in smaller areas with a higher concentration. The high concentration of crops is dangerous because of the risk of: drought, floods, insects, disease among crops, and depleting quality of soils. The U.S. food supply could be at risk as any unexpected interruption in the food chain could wipe out a significant portion of food production.

The loss of farmland to soil erosion and development is a growing concern across the globe. The increasing demand for farmland and food production is already outpacing supply. Development and erosion will need to be kept at a minimal to limit the loss of potential food production.

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