Can conservation trump impacts of climate change on soil erosion? An assessment from winter wheat cropland in the Southern Great Plains of the United States

Authors: Garbrecht, Jurgen; Nearing, Mark; Steiner, Jean; Zhang, Xunchang; Nichols, Mary

Submitted to: Weather and Climate Extremes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2015
Publication Date: 6/20/2015
Citation: Garbrecht, J.D., Nearing, M.A., Steiner, J.L., Zhang, X.J., Nichols, M.H. 2015. Can conservation trump impacts of climate change on soil erosion? An assessment from winter wheat cropland in the Southern Great Plains of the United States. Weather and Climate Extremes. 10(A):32-39. doi:10.1016/j.wace.2015.06.002.

Interpretive Summary: Conservationists are concerned that conservation practices that were effective in the past may no longer be effective in the future under projected climate change. In winter wheat cropland in the Southern Great Plains of the U.S., increased precipitation intensity and increased aridity associated with warmer temperatures may pose increased risk of soil erosion from vulnerable soils and landscapes. An investigation was undertaken to determine which conservation practices would be necessary and sufficient to hold annual soil erosion under a changing climate at or below the present soil erosion levels. Computer models were used to project the climate half a century into the future (2041-2070), and the soil erosion from winter wheat crops was simulated under the projected climate and for various conservation practices. It was concluded that a broad range of proven conservation tools were available to agriculture to offset projected future increases in soil erosion even under assumed worst case climate change scenarios in Central Oklahoma. The problem of reducing future soil erosion increases is not one of a lack of effective conservation tools, but one of adoption and implementation. The time-scale of climate change by far exceeds the time-scale of a producer's planning horizon and the uncertainty of the pathway climate will take in the future lessens the urgency to change from the wide spread use of intensive tillage for winter-wheat crops in Central Oklahoma. Increasing the implementation of today’s conservation programs to address current soil erosion problems associated with the large year-to-year climate variability in the Southern Great Plains would greatly contribute towards mitigation of projected future increases in soil erosion due to climate change.

Technical Abstract: With the need to increase crop production to meet the needs of growing population, protecting the productivity of our soil resource is essential. However, conservationists are concerned that conservation practices that were effective in the past may no longer be effective in the future under projected climate change. In winter wheat cropland in the Southern Great Plains of the U.S., increased precipitation intensity and increased aridity associated with warmer temperatures may pose increased risk of soil erosion from vulnerable soils and landscapes. An investigation was undertaken to determine which conservation practices would be necessary and sufficient to hold annual soil erosion under a high greenhouse gas emission scenario at or below the present soil erosion levels. Advances in and benefits of agricultural soil and water conservation over the last century in the United States are briefly reviewed, and challenges and climate uncertainties confronting resource conservation in this century are addressed. The Water Erosion Prediction Project (WEPP) computer model was used to estimate future soil erosion from winter wheat cropland in Central Oklahoma and for 10 projected climates and 7 alternative conservation practices. A comparison with soil erosion values under current climate conditions and conventional tillage operations showed that, on average, a switch from conventional to conservation tillage would be sufficient to offset the average increase in soil erosion under most projected climates. More effective conservation practices, such as conservation tillage with a summer cover crop would be required to control soil erosion associated with the most severe climate projections. It was concluded that a broad range of conservation tools are available to agriculture to offset projected future increases in soil erosion even under assumed worst case climate change scenarios in Central Oklahoma. The problem is not one of a lack of effective conservation tools, but one of adoption and implementation. Increasing the implementation of today’s conservation programs to address current soil erosion problems associated with the large year-to-year climate variability in the Southern Great Plains would greatly contribute towards mitigation of projected future increases in soil erosion due to climate change.