Soil erosion is a natural process where soil is detached and moved by wind or water, but human activities dramatically accelerate this rate. Conventional plowing, or tillage, significantly increases a field’s vulnerability to soil loss. The repeated mechanical action of plows alters the soil’s physical structure, leaving it exposed and easily transported by natural forces. The increased rate of erosion stems from two primary effects of plowing: the internal destruction of soil structure and the external removal of protective surface cover.
The Breakdown of Soil Aggregation
Soil aggregates are clusters of individual soil particles—sand, silt, and clay—held together by organic matter, root networks, and microbial “glues.” These aggregates are the foundation of healthy soil structure, creating macro-pores that allow for essential water infiltration, drainage, and air movement. Soil with stable aggregates is highly resistant to wind and water erosion.
Plowing physically fractures these stable macro-aggregates, a process known as pulverization. The mechanical agitation shears the organic matter and root fibers that bind the particles, breaking them down into much smaller, individual, and detached soil particles. This destruction eliminates large pore spaces, reducing the soil’s capacity to absorb rainfall and making it prone to surface sealing. Once the aggregates are broken, the soil loses its structural integrity and becomes a loose, fine mass that is highly susceptible to transport.
Removal of Protective Surface Cover
A second factor contributing to accelerated erosion is the plow’s function of inverting and mixing the topsoil layer. Conventional plowing is designed to bury crop residue, such as stalks and stubble, and surface weeds deep beneath the soil. This action leaves the soil surface bare and exposed to the elements.
In a natural system, crop residue acts as a physical shield against the kinetic energy of raindrops and the force of wind. This protective cover intercepts rainfall, slowing its velocity before it reaches the soil surface. The presence of residue also slows surface water runoff and acts as a windbreak, preventing soil particles from being lifted. By eliminating this barrier, plowing ensures the pulverized soil is directly exposed to the full erosive power of rain and wind.
Plowing and the Acceleration of Water Erosion
The conditions created by plowing—pulverized soil and a bare surface—dramatically increase the rate of water erosion. When raindrops strike bare soil, they detach soil particles, a process called splash erosion. The impact also breaks down weak aggregates and clogs surface pores with fine particles, which seals the soil surface and reduces its infiltration rate.
Since water cannot soak into the sealed surface quickly, it accumulates and moves across the field as surface runoff. As the runoff flows, it carries detached soil particles, a process known as sheet erosion. On sloped ground, the water concentrates into small channels called rills, which subsequent tillage can erase. If these channels deepen into gullies, they remove vast amounts of topsoil and cannot be crossed by farm machinery.
Plowing and the Acceleration of Wind Erosion
Plowing creates a soil surface vulnerable to wind erosion by removing residue and generating loose, fine particles. Tilling leaves a smooth, dry surface that offers little resistance to the wind, allowing air speeds near the ground to increase. The fine particles created by the breakdown of aggregates are precisely the size most susceptible to being lifted and transported.
Wind moves soil through three primary mechanisms. Larger particles (0.5 mm to 2 mm) are rolled along the surface in a process called surface creep. Medium-sized particles (0.05 mm to 0.5 mm) are lifted a short distance, traveling in a bouncing motion known as saltation, which accounts for the majority of soil movement. The finest particles, including organic matter and clay, can be carried high into the atmosphere for long distances through suspension, often resulting in dust storms.