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Losing our most valuable natural resource water erosion part III
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Today’s column finishes up the discussion of water erosion with how to minimize soil loss based upon the USLE, the Universal Soil Loss Equation - A=RxKxLSx CxP. To mitigate the predicted annual soil loss, A, we will briefly deal with each factor of the equation.

• R – This is the rainfall erosivity factor. First, if it doesn’t rain, there is no water erosion. We cannot change when rainfall occurs or how intense it is. Simply, harder, longer lasting rainfall can result in more erosion. Harder because the greater the force the raindrops strike the soil surface with the more energy is available to break soil particles loose and longer because once the rainfall rate exceeds the ability of the soil to take in water, infiltration, water will flow and take soil particles along. We can’t change these factors but if we place a barrier, vegetation or crop residue on the surface, we can absorb the energy and soil can remain in place. A simple analogy if why a catcher in baseball wears a mask chest protector, they are going to be hit. The protective equipment absorbs much of the impact of the force of the ball. Not all of it but enough to normally prevent serious damage. Especially making sure the soil isn’t bare when the most likely erosive rains normally occur. And by promoting good soil structure, conservation tillage or no-tillage, we can increase the ability of the soil to take in water and store it.

• K – The soil erodibility factor describes how susceptible the soil is to water erosion. Producers can’t change the soil texture but can over time through crop rotations and reducing tillage increase organic matter to stabilize/improve soil structure and allow it to hold more water. They can accumulate residue at the soil surface to absorb rainfall impact and prevent surface crusting. If producers can eliminate tillage they can increase the number and connectivity of macropores which increases the infiltration rate and decreases runoff.   

• LS – LS is the length and steepness of slope. Planting along the contour or at least across the slope where possible helps break up slope length. Those terraces you see on hillsides, mounded up soil across the slope, decrease slope length and trap dislodged soil. In some cases, establishing permanent vegetation such as perennial grasses is the best solution.

• C – This factor takes into account vegetative cover and cropping systems. This is discussed above. The key is to make sure the soil is covered and protected.

• P – Finally we have P, the supporting practice factor. What is being done augment C? This can be grassed waterways, buffer strips and other practices which supplement cropping practices.

Wind and water erosion are natural phenomena and only present problems when they become accelerated, where erosion is greater than soil formation. There is no way to totally eliminate erosion but it can certainly be minimized.

Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.