Water, Carbon, and Methane Flux Analyses of Crop and Soil Water Gradients: A Synthesis of Picarro Crds Studies.

Picarro Cavity Ring-Down Spectroscopy (CRDS) systems are continuous high-frequency analyzers with exemplary performance characteristics.  Here we present two studies demonstrating the capacity of the Picarro G2311f high-frequency eddy-covariance flux system to characterize carbon, water, and methane fluxes across contrasting crop stage and soil moisture conditions, and we further explore the use of Picarro analyzers to scale agrosystem dynamics regionally. 

In a comparative study led by the AmeriFlux QA/QC Tech Team from Lawrence Berkeley National Lab, U.S.A., five high-frequency eddy-covariance systems, including the Picarro G2311f flux system, were assessed within an alfalfa crop ecosystem near Davis, California, U.S.A.  Results of experiments demonstrate the response of the flux system under variable irrigation condition and crop stage, and highlight the sensitivity in response of the Picarro G2311f under high and low carbon and water fluxes. 

In a second study, the Picarro G2311f analyzer was applied to an assessment of methane fluxes of crop systems within the densely agriculture-allocated Willamette Valley in OR, U.S.A.  Eddy-covariance derived methane fluxes were related to crop growth/harvest stage, LAI, soil moisture, as well as historic land use, since much of the crop lands in the Willamette Valley were established on historically wetland regions.  At the relatively dry “Silverton” site, methane fluxes were predominantly negative; whereas, periodic positive methane fluxes reduce the sink strength of the crop soil ecosystems.  Comparisons to methane fluxes of crop ecosystems established in wetlands are assessed, and tall tower assimilations are used to consider the total crop ecosystem influence on whole valley methane budget.

The Picarro G2311f flux system is an important tool for eddy-covariance analysis of whole crop-ecosystem carbon, methane, and water fluxes.  Deciphering management controls on agriculture fluxes is key to optimizing production resources and minimizing GHG emissions.