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Title: Spatial Variability and Scaling of Infiltration on Undulating Agricultural Terrain

Author
item Green, Timothy
item Ahuja, Lajpat
item Dunn, Gale
item Ascough Ii, James
item McMaster, Gregory
item Ma, Liwang
item Erskine, Robert - Rob
item SALAS, J - COLORADO STATE UNIVERSITY
item Palic, Daniel
item Murphy, Michael

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2007
Publication Date: 12/10/2007
Citation: Green, T.R., Ahuja, L.R., Dunn, G.H., Ascough Ii, J.C., Mcmaster, G.S., Ma, L., Erskine, R.H., Salas, J.D., Palic, D.B., Murphy, M.R. 2007. Spatial Variability and Scaling of Infiltration on Undulating Agricultural Terrain. American Society of Agronomy Meetings New Orleans, November 7,2007 (282-3).

Interpretive Summary: This presentation focuses on surface water infiltration and soil physical properties affecting spatial soil water, nutrient, and plant estimation along with uncertainty and scaling associated with spatial variability. The field site in northeastern Colorado, USA comprises undulating agricultural terrain cropped with winter wheat under conventional tillage. We illustrate potential complexities encountered in the field concerning spatial variability of infiltration rates and associated soil properties. Our field experiments include 150 measurements locations at ten landscape positions. Data were analyzed for spatial scaling behavior at each landscape position and at different scales across the field. Furthermore, process-based modeling of infiltration and its scaling behavior will be discussed. These results are intended to shed new light on research needed to address spatial variability of soils and interactions between land areas when modeling infiltration, runoff, and plant water use under different climates and land management strategies.

Technical Abstract: This presentation focuses on surface water infiltration and soil physical properties affecting spatial soil water, nutrient, and plant estimation along with uncertainty and scaling associated with spatial variability. The field site in northeastern Colorado, USA comprises undulating agricultural terrain cropped with winter wheat under conventional tillage. We illustrate potential complexities encountered in the field concerning spatial variability of infiltration rates and associated soil properties. Our field experiments include 150 sorptivity and steady infiltration measurements followed by gravimetric sampling of soil water contents at two depths (48 hours after drainage) taken at ten landscape positions. At each landscape position, dry sorptivity and steady infiltration were measured using fifteen 0.30-m diameter rings distributed randomly in nested patterns within an area of 30-m by 30-m. Soil hydraulic properties were also estimated from soil core data using similar media concepts and functional normalization. Data were analyzed for spatial scaling behavior by fitting power-law variograms and estimating a Hurst coefficient at each landscape position and at different scales across the field. In addition to quantifying the observed spatial variability in soils and infiltration rates, inferences will be made for scaling up measurements. Furthermore, process-based modeling of infiltration and its scaling behavior under different soil scaling in space will be discussed. These results are intended to shed new light on research needed to address spatial variability of soils and interactions between land areas when modeling infiltration, runoff, and plant water use under different climates and land management strategies.