16 May 2016

Improving Cropping System Management Helps Improve Water Quality

A new article in the Journal of Environmental Quality by scientists at the University of Illinois,
          Illinois River Nitrate-Nitrogen Concentrations and Loads: Long-term Variation and Association with Watershed Nitrogen Inputs.
              Authors: Gregory F. McIsaac, Mark B. David, and George Z. Gertner. 2016. Journal of Environmental Quality doi:10.2134/jeq2015.10.0531

reports that improved cropping system management has helped to provide improved water quality. The authors observed a
          "significant downward trend in flow-weighted nitrate-N concentration after 1990 despite high concentrations in 2013 after the 2012 drought."

Other notable text in the McIsaac et al. (2016) article includes:
          " Other than better alignment of N fertilizer application rates with corn N needs, it is difficult to document specific conservation practices. To our knowledge, there is no evidence of widespread adoption of other conservation practices that target and reduce nitrate loss in this basin, such as the use of winter cover crops, treatment wetlands, or drainage water management. We believe that relatively constant N fertilization rates combined with steadily increasing corn yields have improved N use efficiency and likely contributed to the nitrate-N concentration declining in the Illinois River.”

          “Jones et al. (2016) also reported a significant decline in April–July nitrate-N concentrations from 1999 to 2014 in 9 of 41 stream locations in Iowa and no significant trend in loads. This occurred despite an increase in N fertilizer application, increased area planted to corn, and a decline in fertilizer use efficiency. Nitrate-N loads were correlated with precipitation, which was highly variable (Jones et al., 2016).”

Link here to the abstract and to freely download the McIsaac et al. (2016) paper, which is OPEN ACCESS:

Link here to the abstract of the Jones et al. (2016) paper, which was referenced by McIsaac et al. (2016): http://www.jswconline.org/content/71/3/206.abstract
          Crop rotation and Raccoon River nitrate
              Authors: C.S. Jones, A. Seeman, P.M. Kyveryga, K.E. Schilling, A. Kiel, K.-S. Chan, and C.F. Wolter. 2016. Journal of Soil and Water Conservation 71(3): 206-219

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