The Dangers of Neglecting Soil Erosion

Let's take responsibility for our own actions and manage our fields such that soil erosion does not degrade the future productivity of our soils or cause harmful effects for our neighbors and the surrounding environment.

Soil erosion is still eating away at the productivity of our soils and affecting our surroundings, and we are ignoring it to our own detriment. The May 1, 2023 dust storm in central Illinois caused a vehicle pile-up, resulting in the deaths of 6 people and at least 37 people were wounded. The reason is farmland denudation and soil tillage over large expanses, such that wind can pick up large quantities of dust and cause devastating effects. Unfortunately, once the dust has settled, we are quick to forget and move on to other things in our rushed society.

It would seem we had learned our lesson in America during the Dust Bowl of the 1930s, but of course, hardly anyone is alive from those days, and the memories are fading. Records show that the Dust Bowl was caused by fencerow-to-fencerow tillage and one-crop (wheat) agriculture in a fragile environment that was previously protected by highly diverse prairie vegetation. After several years of drought, wind started to pick up the fine dust of the formerly protected prairie soil, particularly in the area of northern Texas, western Kansas, and Oklahoma, and eastern Colorado and New Mexico. In 1935, it was estimated that 4.35 million acres had lost 849 million tons of soil, a rate of 195 tons per acre. The Soil Conservation Service in 1938 estimated an even higher loss at 490 tons per acre. Later, it was estimated that 10 million acres in the Great Plains area had lost 5 inches of topsoil, and 13.6 million acres lost 2.5 inches. The ravages of soil erosion led to decreased land productivity, reduced land values, and hundreds of thousands of environmental refugees. Even today, millions of acres are in grassland reserves due to Dust Bowl erosion, being unfit for crop production.

We in Pennsylvania are far from the west and typically don’t deal with wind erosion, although the events in Illinois, which has a very similar climate to ours, suggest that it could also happen here. Nonetheless, we typically deal with other forms of erosion, predominantly due to water and tillage. In fact, we distinguish 5 types of erosion in our farm fields:

• Sheet (or interrill) erosion – due to the impact of raindrops hitting the bare soil surface, dislodging soil particles from the soil matrix.
• Rill erosion – small rivulets no deeper than 4 inches deep, typically parallel on the slope until they converge, and easily erased by tillage.
• Ephemeral gully erosion – between 4 inches and 1.5 feet deep still farmable and can be erased with tillage, but they do not disappear in no-till fields, form in the same positions year after year, where runoff concentrates on the landscape, and if left unmanaged, become classic gullies
• Classic gully erosion – more than 1.5 feet deep, not easily farmed across nor erased by tillage, leads to land disfigurement and eventually leads to loss of land to production.
• Tillage erosion – downslope movement of soil due to tillage.

The first four are forms of water erosion, while the last is due to the physical act of tillage. The Natural Resources Conservation Service calculates average annual soil loss per acre due to sheet and rill erosion. According to the 2017 National Agricultural Census, the average annual soil loss rate in Pennsylvania was 4.4 T/A, which seems low compared to the Dust Bowl estimates, but is still above the tolerable soil loss level for many of our soil types. This estimate also ignores ephemeral and classic gully erosion and tillage erosion. Further, we have to remember that the estimate is just an average rate, while in reality, most soil erosion by wind or water occurs in erratic, unique events. One highly erosive event, therefore, can easily represent most soil erosion during a whole year or even a whole decade.

When we have significant rainfall at a time when the summer crops are not yet planted or emerged, the fields tend to be unprotected, which is a highly vulnerable situation. Indeed, reports have been coming in of rills and ephemeral gullies and soil being deposited on roads. These situations really need to be addressed for the farmer's own benefit, but also because it poses a threat to other people and the wider environment.

The best way to limit soil erosion by water is to keep soil undisturbed and covered because that dramatically reduces sheet erosion and improves infiltration, thus also reducing the other forms of water erosion. Reducing tillage is also essential to limit tillage erosion. That is why cover crops and no-tillage that leave residue on top are so beneficial in fighting soil erosion. It is also beneficial to grow different crops in rotation and break up fields so that growing crops occupy different parts of the landscape.

There are many more practices that can be combined with these practices or used in conjunction with tillage. These practices are especially important for organic producers who cannot control weeds with herbicides. Examples are contour farming, contour strip cropping, terraces and diversions, grassed waterways, etc. 

In the United States, we are blessed with many resources to help us understand erosion and know-how and technologies to deal with it. There are people working at your local Soil and Water Conservation Districts and the USDA-NRCS who are available to help you design and implement a soil conservation plan for your farm. Extension Services from land grant universities offer expertise to help you be successful with techniques such as no-tillage and cover crops. We also have farmer groups such as the Pennsylvania No-Till Alliance, which offer know-how, expertise, and experience in implementing these practices. There are also many employees of agribusinesses who can help you with technologies and advice to conserve soil. But it takes a decision and determination to address soil erosion, and a realization by the farmer that he/she is a steward of the land with a personal responsibility to take care of the resources under his/her control. Unfortunately, if we don't take action ourselves, government may come in to force us to deal with soil erosion, and this is not a desirable situation.

Quoted Sources:

Livia Albeck-Ripka, 2023. Six dead after dust storm causes crashes on Interstate 55 in Illinois. New York Times, May 2, 2023.

Bolles, K., S. L. Forman, and M. Sweeney (2017). "Eolian processes and heterogeneous dust emissivity during the 1930s Dust Bowl Drought and implications for projected 21st-century megadroughts." The Holocene 27(10): 1578-1588.