Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/23/2015
Publication Date: 7/26/2015
Citation: Sudduth, K.A., Baffaut, C., Drummond, S.T., Sadler, E.J. Instrumentation for full-year plot-scale runoff monitoring. Paper No. 152189840. In: ASABE Annual International Meeting Technical Papers. ASABE, St. Joseph, MI [available online]. 2015.
Interpretive Summary: A key component of the evaluation of alternative cropping systems is monitoring their impact on offsite movement of agrichemicals. This generally requires collection and analysis of runoff water from fields or test plots. Here we describe a system developed to measure runoff from a set of 18 cropping system plots and to sample the runoff water for analysis of pesticide and fertilizer concentrations. Achieving the desired accuracy and operational characteristics required combining commercial components with in-house circuitry and software in a unique configuration. The system has generally worked well during initial testing. This research will benefit scientists who wish to develop similar runoff monitoring systems by providing them guidance on system configuration and operation.
Technical Abstract: Replicated 0.34 ha cropping systems plots have been in place since 1991 at the USDA-ARS Goodwater Creek Experimental Watershed in central Missouri. Recently, instrumentation has been installed at 18 of those plots for continuous runoff water quality and quantity monitoring. That installation required several novel approaches to address infrastructure and instrumentation challenges. Plot berms, flumes, and flume approaches were designed to facilitate efficient farming operations with field-scale equipment. Commercial runoff samplers were employed in flow-proportional mode, but stage transducers available with the samplers did not have the required accuracy of 2 mm stage over the expected range in ambient temperatures. To meet this requirement, we designed a system based on a temperature-compensated differential pressure transducer mounted in a stilling well. A datalogger recorded stage data and controlled the sampler through a custom electronic interface. An electric heating system was installed to protect the stilling well and transducer from freezing down to approximately -10 C. A laptop-based program was developed to manage calibration and data downloads for the 18 systems, and a wireless telemetry link was established. This paper documents the design of the plot infrastructure and instrumentation and describes the initial performance of the system as deployed in the field.