I read an incredible peer reviewed white paper the other day. It was on the impacts of no-till farming under arid conditions and the benefits to watershed hydrology. The title of the article is "Conservation Tillage in Dryland Agriculture Impacts Watershed Hydrology" by Van Wie et. al. 2013 (Full reference below).
What was particularly interesting to me about the article was the emphasis not just on no-till, but on the importance of this in arid conditions and locations. Although the study was primarily in the Palouse region of Washington, the study related to myself as a farmer in the high-desert of Colorado; Colorado being one of the driest states in the country with abnormally high rates of evapotranspiration (evaporation from soil and transpiration from plants). The article discusses that the utilization of no-till methods is a BMP (Best Management Practice) for soil management (Van Wie, et. al. 2013). The benefits to the watershed, as found by the authors of the article were many.
In addition to enhancing soil structure and biological activity in the soil, the authors found that less fertilization was required, there was less water runoff and therefore less pollution to watersheds and there was less need for irrigation, since the soil was now able to maintain a greater amount of water in the root zone - thus less pumping of water from the watershed was needed (Van Wie, et. al. 2013).
By utilizing no-till there is less run-off of water, specifically in the winter months when rain falls on frozen soil and snow (Van Wie, et. al. 2013). When this occurs, the water runs off and contributes to streamflow instead of infiltrating the soil. This is due to lower soil temperatures in tilled soil vs. no-tilled soil (Van Wie, et. al. 2013). By using the Water Erosion Prediction Project (WEPP) model, the team was able to determine an absolutely astonishing difference between the tilled and no-tilled fields when it came to soil infiltration vs. run-off. The tilled soil generated a 66.0 mm of run-off during a 5 month period while the no-till soil generated a run-off of only .3 mm! In other words, the soil that was not tilled held 220 times more water than tilled soil! In addition to this staggering result, during run-off events such as high amounts of precipitation or snowmelt, while there were numerous events with tilled fields, there were zero observed events with the no-till fields (Van Wie, et. al. 2013)!
Not only is there reduced to virtually zero amounts of run-off from the fields utilizing this BMP of not tilling their fields, but the moisture that is held in the soil is also dramatically increased and the amount of evaporation decreased to a an almost astonishing extent. The results from the study were that the fields that were conventionally tilled had an average evaporation loss of 3 mm/day while the no-till fields had an average evaporation loss of .001 mm/day! The tilled fields lost water at a rate of 3,000 times those that were not tilled (Van Wie, et. al. 2013)!
Finally, in addition to the obvious benefits to the watershed and the environmental benefits to not tilling our soil, the increase in yields were also discussed by the authors: a 21-26% increase in crop yields with no-tilled BMPs vs conventional tilling methods were found (Van Wie, et. al. 2013)!
So here are the benefits to not tilling your soil in a nutshell:
- Increased moisture held in the soil - reduced evaporation.
- Decreased run-off and pollution,
- Increased infiltration of moisture particularly in the winter months.
- Decreased need for fertilization.
- Decreased need to pump water and use precious resources.
- Keeps the soil structure intact which reduces erosion.
- Increased microbial activity in soil.
- Greater amount of carbon sequestration.
- Increased crop yields of 21-26%! Photo Credit: pnl.gov
The results of this study were astonishing to say the least. At our farm we don't till our ground. We have been aware of many of the benefits to not tilling our soil, but we had no idea of the extent to which these benefits were. To learn that tilled soil evaporates water at a rate of 3,000 times that of soil that has not been tilled and to learn that no-till soil held 220 times more water than tilled soil are results that blew me away!
Clearly, the science is obvious and the results are clear. Tilling our soil is ruining our environment, creating smaller yields, and is contributing to over pumping of our precious water resources!
Van Wie, J. B., Adam, J. C., & Ullman, J. L. (2013). Conservation tillage in dryland agriculture impacts watershed hydrology. Journal of Hydrology, 483, 26. doi:10.1016/j.jhydrol.2012.12.030