Author
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Feyereisen, Gary |
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FOLMAR, GORDON |
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Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/20/2009 Publication Date: 11/3/2009 Citation: Feyereisen, G.W., Folmar, G.J. 2009. Development of a lysimeter system to simultaneously study runoff and leaching dynamics. Transactions of the ASABE. 52(5):1585-1591. Interpretive Summary: Degradation of fresh waters (e.g. streams, lakes, reservoirs, and groundwater) in the U.S. has been attributed in part to losses of nutrients from agricultural activities via surface runoff, and subsurface drainage and flow. Methods used to study the processes by which nutrients are lost to natural waters include field and plot monitoring, as well as laboratory investigation. Several methods have been proposed to collect soil blocks from the field and move them into the laboratory, where conditions can be controlled for experimental evaluation. These soil blocks or columns, known as lysimeters, are collected, moved to the lab, and prepared for test such that water applied to the soil surface can be leached out the bottom of the lysimeter. The leachate is collected, measured and chemically analyzed. Also, to test nutrient losses by surface runoff, soil is layered and packed into boxes and subjected to artificial rainfall simulation. Rarely are leaching and runoff evaluations made with the same experimental setup. This paper describes a lysimeter system that can be used to test for both leaching and runoff nutrient losses from a cube of undisturbed soil collected from agricultural fields. An initial rainfall simulation test of the system was successful in that runoff and leaching volumes equaled rainfall volumes within expected variability of the rainfall simulator. The system is being used to compare nutrient losses of various methods of poultry litter application. Technical Abstract: Better control of agricultural non-point source nutrient losses from soil requires understanding of associated environmental processes. This study was conducted to develop a laboratory system for analysis of hydrologic and nutrient dynamics within a soil ped associated with agricultural activities. The research objective was to identify a soil lysimeter size, materials of construction, and method of soil collection to simultaneously study surface and subsurface processes. A steel lysimeter 60 cm wide and long by 60 cm deep was driven into the ground with a 1.1 – Mg drop hammer, excavated, and undergirded with a 12.7 mm thick PVC plate to capture an undisturbed soil monolith. PVC spacer plates, temporarily situated between the steel lysimeter walls and the sample soil block, were removed after the lysimeter was excavated and bottomed. The remaining gap was filled with liquefied petrolatum (petroleum jelly) in order to suppress by-pass flow and potential chemical interaction of the soil solution with the steel lysimeter walls. An initial test of the design was conducted by excavating and preparing ten lysimeters for rainfall simulation. The ratio of the sum of leachate and runoff volume to precipitation volume was 0.97and 1.02 for the two treatments, within expected variability due to the rainfall simulator from a perfect balance of 1.0. Hydraulic conductivities calculated from leachate volume vs. time measurements taken during the rainfall simulation were well within the range expected for the Matapeake series soils, suggesting that the design effectively sealed by-pass flow along the lysimeter edges. The experimental method provided researchers opportunity to study both surface and subsurface processes in one assemblage. |
