According to a new study published in the Proceedings of the National Academy of Sciences, more than a third of the farmland in the U.S. Corn Belt has completely lost its carbon-rich topsoil due to erosion. The affected area is nearly 100 million acres and the amount of carbon loss is nearly 2 million tons.
The study, led by scientists at the University of Massachusetts, Amherst, found that the greatest loss of carbon-rich topsoil was on hilltops and ridgelines. This indicates that tillage – the repeated plowing of fields – was the primary cause of the erosion because loosened soils move downslope.
The loss of topsoil has reduced corn and soybean yields in the Midwest by 6%, resulting in a loss of nearly $3 billion a year for farmers. In addition, the loosening of the topsoil increases runoff of sediment and nutrients into nearly waterways, worsening water quality.
Previous studies have shown that no-till farming practices can have a significant impact on reducing erosion. A study published last November found that if farmers shifted entirely to no-till practices, it would reduce soil erosion from U.S. agricultural fields by more than 70%, as well as significantly reducing nutrient and sediment runoff.
No-till farming is the practice of planting crops without tilling the soil. Instead, seeds are planted through the remains of previous crops by planters or drills that cut seed furrows, place the seeds, and close the furrow. Currently less than 15% of farmland in the upper Mississippi River watershed is farmed with no-till practices.
Even partial changes in tilling practices could produce positive results for topsoil retention and for waterways.
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One-Third of Farmland in the U.S. Corn Belt Has Lost Its Topsoil
Photo, posted September 15, 2010, courtesy of the United Soybean Board / Soybean Checkoff via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio.
Very few people can argue with the goal of reducing or reversing soil loss in agriculture. Therefore, for that reason alone, No till deserves serious consideration by growers. However, it should be noted that no-till can have adverse and limiting effects as well. One article that looks at the pros and cons of this system can be found at https://blog.agrivi.com/post/no-till-farming-one-step-closer-to-sustainability.
For those of us who are interested in biologically based food systems, the work that the Land Institute in Salina, KS is doing is of interest, because their goal is a No till system that has more flexibility and less negative impact than conventional No-till, which is often used to enable farmers to keep monocropping certain crops continuously in the government subsidized feed, fuel, and food systems. There are many ways to rejuvenate worn out, depleted soils, of which No till is just one tool.
Amazing blog post