Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED ASSESSMENT AND ANALYSIS OF PHYSICAL LANDSCAPE PROCESSES THAT IMPACT THE QUALITY AND MANAGEMENT OF AGRICULTURAL WATERSHEDS

Location: Watershed Physical Processes Research Unit

Title: Ephemeral gully erosion: Impacts on physical soil quality and crop yield

Authors
item Wilson, Glenn
item Wells, Robert
item Dabney, Seth

Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 15, 2010
Publication Date: June 29, 2010
Citation: Wilson, G.V., Wells, R.R., Dabney, S.M. 2010. Ephemeral gully erosion: impacts on physical soil quality and crop yield. Federal Interagency Sedimentation Conference Proceedings. June 27-July 1, 2010. Las Vegas, Nevada. CD-ROM

Interpretive Summary: Soil erosion by water remains a major problem in many regions of the US. Sheet and rill erosion have been considered the main cause; however, in many cases the main source of sediment is from gully erosion. Ephemeral gullies are small gullies that are filled in by tillage only to form again in the same location. Estimates by the USDA suggest that ephemeral gully erosion ranges from 18 to 73% of the total erosion. Refilling of ephemeral gullies by tillage causes high erosion rates to continue which damages the soil next to the gully. The objective was to quantify the impact of filling of ephemeral gullies on crop yield and the health or quality of the soil adjacent to the gully. There has been a limited amount of work relating crop yield to the depth of topsoil adjacent to ephemeral gullies but no work has directly measured the relationship of soil quality to gully erosion. An ephemeral gully was sampled for physical, chemical, and microbial properties in a field currently in no-till corn in Topashaw Canal Watershed, Mississippi. Soil properties were measured and sampled every 7.6 m out to 37 m from each side of the gully center along five transects and a similar transect away from the gully that represented natural conditions. In addition to corn yield measurement, the following soil properties were determined at each location: shear strength, penetrometer resistance, particle size distribution, total organic carbon, water stable aggregates, microbial biomass, enzyme activity and chemical analysis (N, P, K, Ca, Mg, EC, pH). At selected locations, the saturated hydraulic conductivity, bulk density/porosity, water retention curve, soil erodibility and excess shear stress were measured. Filling of the gully by scraping soil from the adjacent areas reduced corn yield. The slope of the water retention curve was not found to be an indicator of soil physical quality for this site. The best indictors of soil physical quality were available water capacity, shear strength at the surface, and soil penetration resistance at the surface and 5 cm depth.

Technical Abstract: Soil erosion by water remains a major problem in many regions of the US. More streams in the US are listed as impaired by sediment than by any other contaminant. Sheet and rill erosion have been historically considered the main cause; however, in many cases the dominant source of sediment is from gully erosion. Estimates by the USDA suggest that ephemeral gully erosion ranges from 18 to 73% of the total erosion with a median of 35%. Refilling of ephemeral gullies by tillage serves to maintain high erosion rates and degrades the soil adjacent to the gully. The objective was to quantify the impact of filling of ephemeral gullies on crop yield and soil quality adjacent to the gully. There has been a limited amount of work associating reduced crop yield to the reduction in topsoil depth adjacent to ephemeral gullies but no work to date has directly measured the relationship of soil physical quality to gully erosion. An ephemeral gully was sampled for physical, chemical, and microbial properties in a field currently in NT corn in Topashaw Canal Watershed, Mississippi. Soil properties were measured and sampled every 7.6 m out to 37 m from each side of the gully center along five transects perpendicular to the gully and a similar transect removed from the gully to represent baseline conditions. In addition to topographic surveying and corn yield measurement, the following soil properties were determined at each location: shear strength, penetrometer resistance, particle size distribution, total organic carbon, water stable aggregates, microbial biomass, enzyme activity and chemical analysis (N, P, K, Ca, Mg, EC, pH). At selected locations, the saturated hydraulic conductivity, bulk density/porosity, water retention curve, soil erodibility and excess shear stress were measured. Filling of the gully by scraping soil from the adjacent areas significantly reduced corn yield. The slope of the retention curve at its inflection point was not found to be an indicator of soil physical quality for this spatially limited data base. The best indictors of soil physical quality were available water capacity, shear strength at the surface, and soil penetration resistance at the surface and 5 cm depth.

Last Modified: 4/16/2014
Footer Content Back to Top of Page