Land Erosion: Causes, Impacts, and Solutions

The primary causes of soil degradation during agricultural production are water, wind, and tillage. Additionally, landslides (a form of gravitational erosion) can occur on extremely steep slopes. Water erosion and landslides occur under extremely wet soil conditions, while wind erosion is a concern with very dry soil. Tillage erosion occurs on fields that are either steep or have undulating topography and is not affected by soil moisture conditions, because the soil movement downslope is caused by the action of farm implements.

Erosion is the result of the combination of an erosive force (water, wind, or gravity), a susceptible soil, and several other management- or landscape-related factors. A soil’s inherent susceptibility to erosion (its erodibility) is primarily a function of its texture (generally, silts more than sands and clays), its aggregation (the strength and size of aggregates, which are related to the amount of organic matter), and soil water conditions. Many management practices can reduce soil erosion, although different types of erosion require different solutions.

Water erosion occurs on bare, sloping land when intense rainfall rates exceed a soil’s infiltration capacity and runoff begins. The water concentrates into tiny streamlets, which detach the saturated soil and transport the particles downhill. Runoff water gains more energy as it moves down the slope, scouring away more soil and also carrying more agricultural chemicals and nutrients, which end up in streams, lakes, and estuaries.

Reduced soil health in many of our agricultural and urban watersheds has resulted in increased runoff during intense rainfall and increased problems with flooding. Also, the lower infiltration capacity of degraded soils reduces the amount of water that is available to plants, as well as the amount that percolates through the soil into underground aquifers. This reduction in underground water recharge results in streams drying up during drought periods. Watersheds with degraded soils thus experience lower stream flow during dry seasons and increased flooding during times of high rainfall.

is of greatest concern when the surface is unprotected and directly exposed to the destructive energy of raindrops and wind. While degraded soils tend to promote erosion, the process of erosion in turn leads to a decrease in soil quality. Thus, a vicious cycle is begun in which erosion degrades soils, which then leads to further susceptibility to erosion, and so on. Soil is degraded because the best soil material— the surface layer enriched in organic matter—is removed by erosion. Erosion also selectively removes the more easily transported finer soil particles. Severely eroded soils, therefore, become low in organic matter and have less favorable physical, chemical, and biological characteristics, leading to a reduced ability to sustain crops and increased potential for harmful environmental impacts.

The image of wind erosion from the Dust Bowl era provides a graphic illustration of land degradation. Wind erosion can occur when soil is dry and loose, the surface is bare and smooth, and the landscape has few physical barriers to wind. The wind tends to roll and sweep larger soil particles along the soil surface, which will dislodge other soil particles and increase overall soil detachment. The smaller soil particles (very fine sand and silt) are lighter and will go into suspension. They can be transported over great distances, sometimes across continents and oceans. Wind erosion affects soil quality through the loss of topsoil rich in organic matter and can cause crop damage from abrasion. In addition, wind erosion affects air quality, which is a serious concern for nearby communities.

The ability of wind to erode a soil depends on how that soil has been managed because strong aggregation makes it less susceptible to dispersion and transport