How far is too far? As a grandpa, this is a subject of great concern. The distance an ornery grandson can travel in just a few seconds is amazing. Sometimes this distance really matters and sometimes it doesn’t. In a busy parking lot, yes, it really matters. In an empty field, it probably doesn’t much matter. But as a responsible Grandpa, I better know how far is too far for the different situations or I will have to deal with the consequences.
Likewise, how far is too far for soil to move in the erosion process? Well I guess that depends on your situation and your perspective. If the erosion process moves soil down a hillslope only 15 feet, do you care? If the erosion process transports sediment off of your field, do you care? Well the answer to those questions probably depends on your perspective.
If your perspective is protecting your soil health, then any soil transport is a negative. If your perspective is protecting water quality, then as long as the soil doesn’t enter a water body, you probably have more pressing priorities. Your perspective matters.
I remember, many years ago, being in a debate with a colleague about the usefulness of the RUSLE2 (Revised Universal Soil Loss Equation). My colleague said the RUSLE2 model (which is recommended by 9 out of 10 resource professionals) had no real validity. His reasoning was that although RUSLE2 could model erosion, it could not model whether the soil moved a foot or a mile. And if the model couldn’t predict where the eroded sediment was being deposited, then how could RUSLE2 be relevant? His real question was, “Is this soil moving within the field and just impacting the farmer’s productivity, or is it getting to a water body and contributing to offsite damages?” We could only predict that soil movement was occurring. No one knew how far the soil moved.
With all the pressure on farmers to reduce their environmental impact, the ability to model the movement of soil erosion is critical. Just telling a farmer how much soil erosion he has isn’t enough.
Through the exceptional work of Dr. Seth Dabney and Dr. Dalmo Vieira, (USDA’s Agricultural Research Service), RUSLE2 now has the ability to easily model the detachment, transport, and deposition of sediment. Yes, this means we can now predict how far that sediment is moving. This is COOL! Now we can model soil erosion and soil transport from the top of the hill to the concentrated water entering a stream. And this leads to precision conservation. Depending on a farmer’s objectives or our objectives, we can apply soil conservation practices to achieve soil health or water quality…or both.
Good work Seth and Dalmo. Now, can you construct a model that predicts how far I can let my grandsons travel in different situations, and how long it will take them to travel that distance? I seem to have a hard time keeping up with them even under safe conditions.