links of the above images: https://www.fao.org/3/cb4894en/online/src/html/chapter-04-2.html
The value of soil is something that is taken for granted. Soil is the foundation for all living things; without it, life on earth is not sustainable. Soil is a complex mixture of rock, organic matter, water, air, and living organisms that produces our food cleans our water and sequesters carbon.
Despite this importance to the human population, the soil is eroding faster than it is being replaced. In the last 30 years, roughly 30% of the earth’s arable land has deteriorated, according to David Pimentel, professor at Cornell University. “Soil erosion is second only to population growth as the world’s biggest environmental problem,” said Pimentel.
Specifically, soil and vegetation are being lost at an alarming rate around the globe, which has devastating effects on food production and accelerates climate change. The primary cause of rapid soil erosion is modern farming techniques. Tilling and removing crop residues after harvest is the key culprits of erosion. The tracks left by tractors in the soil are the erosion route for half of the soil that washes or blows away. Row crops, such as corn and soybeans, resulting in roughly 50 times more soil erosion than sod crops, such as red top and clover. The economic impact of soil erosion in the US costs the nation approximately $37.6 bn yearly in productivity losses and damage from soil erosion. According to Cornell University, it is estimated to be $400 bn per year. One way to reduce soil erosion is to use no-till farming methods, which leave crop residue (corn stalks) in the ground. The crop residues provide soil nutrition, water retention, and soil carbon. Currently, only 20% of corn in the US is grown using no-till.
Iceland is a prime example of the dangers of soil erosion. Since the country was settled in the 9th 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 deserts cover 45,000 km2 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 climate change. I would say that Iceland should serve as a warning to other countries. After all, it is far better to preserve than restore.
Soil stores carbon as it is one of the critical ingredients for plant growth. The amount of carbon stored in soil is rough twice the amount found in the atmosphere and three times the amount in vegetation. Across the US, agricultural methods have removed approximately 20% – 50% of the earth’s original soil carbon and up to 70% in some regions, according to the USDA. According to Ohio State University, land degradation may account for up to 30% of the world’s greenhouse gas releases.
While tillage of crop residue still locks carbon into the ground for a short period before it is released into the atmosphere, no-till methods lock carbon into the crop residue for a more extended time, delaying its release into the atmosphere.