Minnesota Water Resources Conference - Water Resources Center ...

Concurrent Sessions II 1:15–2:45
Track B: Agricultural Drainage Impacts
BOOK OF ABSTRACTS
Tuesday, Monday, October 27 23
Effect of Tillage and Nutrient Sources on Dissolved Organic Carbon Fluxes from Soil
Holly Dolliver, University of Wisconsin-River Falls, holly.dolliver@uwrf.edu; Satish Gupta, University of Minnesota
Soils are a crucial component of global carbon cycling. The soil organic carbon pool is highly dynamic and
strongly influenced by tillage and other management practices. Fluxes of dissolved organic carbon from the
terrestrial environment can substantially impact aquatic chemistry and biology. The objective of this field study
was to quantify the effects of tillage and nutrient sources on both fluxes and storage of soil organic carbon.
Tillage treatments included chisel plow and no-tillage. These tillage treatments have been in operation since
1993; however, the study was conducted from 2003 to 2007. The nutrient sources were two types of manure (hog
and beef manure) and a synthetic fertilizer (urea). Both runoff and leachate were collected from 2003-2007. In
addition, three soil cores to a depth of 120 cm were also taken from each plot to quantify soil carbon storage.
Measuring and Modeling the Impacts of Shallow Subsurface Drainage in a Cold Climate
Gary Sands, University of Minnesota, grsands@umn.edu; Wan Luo, University of Minnesota; Jeffery Strock, University of
Minnesota
The hydrologic and water quality impacts of shallow subsurface drainage have been investigated for the
previous seven years through field research at the University of Minnesota Southern Research and Outreach
Center (south-central Minnesota). Seven-year pooled results from this study indicate that subsurface drains
placed at 90cm discharge about 20 percent less water and nitrate compared to the more traditional drain depth
of 120cm. A modeling study has been undertaken using the DRAINMOD NII model to investigate the influence
of shallow drainage on drainage hydrology and water quality over a longer climatic record, additional soils
types, and additional drain depths, than were previously studied in the field research. This paper will report on
the progress of the modeling effort and will present the results of calibration and validation of the DRAINMOD
NII model with data from the shallow drainage field experiment.
Evaluating Field-Scale Agriculture Drainage and Best Management Practices on Water Quality
Lucas Bistodeau, Minnesota State—Mankato, lucas.bistodeau@mnsu.edu; Shannon Fisher, Minnesota State—Mankato
Past research with plot-scale studies has addressed agricultural nutrient losses; however, applying this
knowledge to field-scale applications has proven to be difficult. By understanding nutrient and pesticide
transfer mechanisms in a field-scale setting, we can formulate land management practices to reduce non-point
source pollution to surface waters. Our objectives were to 1) evaluate agricultural nutrient practices (NO 3
-N, TP
and OP) to reduce non-point source pollution and 2) evaluate the effect that subsurface tile drainage spacing
has on nutrient and acetochlor losses. Nutrient results from 2007 and 2008, in a paired watershed, showed 15.2
and 24.3 meter spaced subsurface tiled systems using late fall, higher rate-applied anhydrous ammonia had
higher nitrate-nitrogen flow-weighted mean concentrations (11.3 mg/L) than the BMP spring-applied urea
fields (9.2 mg/L). Total phosphorus flow-weighted mean concentrations of variable rate applied P & K fields had
a significant difference between BMP fields with concentrations of 0.14 mg/L and 0.05 mg/L. Quicker response
time and higher peak flow values were observed in narrower tile spacing for both years.
Minnesota Water Resources Conference, October 27–28, 20078 26