SLIP, SLIDING AWAY: SOIL EROSION CAUSES MAJOR PROBLEMS

The state of Texas, including the Brazos River basin, has experienced some record extremes in the past five years, whether extreme drought or heavy flooding, and those conditions in turn have created problems in some areas with soil erosion, resulting in the loss of land and often creating structural concerns for property owners.

During times of drought, the land becomes parched, and much of the erosion results from strong winds blowing soil away. Extreme examples of this include the Dust Bowl conditions of the 1930’s, in which soil was swept up by high winds and carried away.

During times of high precipitation, it is water which carries away the soil. Rainfall that is not absorbed by soil, intercepted by vegetation, or captured by ponds or reservoirs, becomes runoff, running downhill and gaining momentum.

People who live near rivers often experience soil erosion along the river’s banks, and during times of extreme flooding, the course of the river can even be changed due to heavy erosion.

The World Wide Fund for Nature and its partner organization, the World Wildlife Fund, are among those expressing concern about erosion.

“Soil is the earth’s fragile skin that anchors all life on Earth,” the WWF website states. “It is comprised of countless species that create a dynamic and complex ecosystem and is among the most precious resources to humans. … “Half of the topsoil on the planet has been lost in the last 150 years.”

The far-reaching impact of soil erosion is an issue of concern for the WWF.

“The effects of soil erosion go beyond the loss of fertile land,” the organization’s website said. “It has led to increased pollution and sedimentation in streams and rivers, clogging these waterways and causing declines in fish and other species. And degraded lands are also often less able to hold onto water, which can worsen flooding. Sustainable land use can help to reduce the impacts of agriculture and livestock, preventing soil degradation and erosion and the loss of valuable land to desertification.

Erosion remains a problem in Texas, and the fight against it has brought about some interesting partnerships.

One study conducted by Texas AgriLife research scientists took place at Fort Hood, a U.S. Army post in Killeen. Because of military training with large armored vehicles, the ground is compacted, plant cover is lost and soil erosion is accelerated, with excess sediment being deposited in streams and lakes.

AgriLife researchers, working with the United States Department of Agriculture’s Natural Resources Conservation Service and the U.S. Army’s Integrated Area Management, have teamed up to solve the erosion problem in this high impact area and learned lessons which can be applied to other areas.

To offset erosion at Fort Hood, scientists measured nutrient and sediment losses at the post’s watersheds, and placed more than 30 sediment retention ponds to trap sediment from stormwater runoff.

Other conservation efforts were also implemented, including gully plugs, which are rock dams that stop erosion from gullies, as well as contour ripping, which is deep plowing to reduce soil erosion. This allows water to soak into soil, reducing runoff and erosion.

“Our monitoring showed a remarkable reduction in runoff and erosion as a result of those conservation practices,” said Dennis Hoffman, a senior research scientist who worked on the project. “One area of the training lands … showed a 90 percent reduction in sediment running into the creek. Our research has shown that these practices work really well.”

For several decades, the Natural Resources Conservation Service (once known as the Soil Conservation Service) has recommended grass hedges as one barrier to soil erosion. These hedges help to slow and reduce runoff, and help to prevent the formation of gullies.

When it comes to reducing erosion caused by flooding, several options are available:

• Planting vegetation leads to root systems in the soil, which helps to stabilize it and prevent erosion.
• Placing geotextile fabrics in problem areas can also help stabilize soil, and can be done in conjunction with growing vegetation.
• Adding a layer of mulch to the soil can help soak up extra water, thereby reducing erosion.
• Retaining walls can also be built around areas of erosion or potential erosion to prevent water runoff. Runoff leads to increased erosion, and the retaining walls, especially when combined with other methods of erosion prevention, can have a significant positive impact.

It is also recommended that those who are experiencing serious erosion issues contact an engineering firm who may then assess their specific concerns and offer potential solutions.

While there is a financial cost involved in addressing soil erosion, there is an even greater cost to not trying to reduce soil erosion.

“The economic impact of mitigating soil erosion significantly burdens the agri-business sector and the Nation as a whole,” the U.S. Department of Agriculture’s Natural Resources Conservation Service states. “Dust contributions to the atmosphere and delivery of sediment, nutrients, and chemicals to water resources are primary environmental concerns addressed by public policy makers and the stewards of our working lands. Understanding and managing these processes has important long term implications for cropland sustainability, natural resource condition and health, and environmental quality.”