Supplemental information for "Effectiveness of Cover Crops on Water Pollutant Reduction from Agricultural Areas"
The Supplemental Material provides additional information that may not have explicitly been referenced in the associated article. These additional data add substance to the discussion and are intended to add transparency. The dataset is in spreadsheet form and includes U.S.-specific studies reporting total nitrogen, nitrate, total phosphorus, phosphate, and sediment or erosion concentrations or losses from control and cover crop field plot studies. Where pertinent data were not reported in tabular format, DataThief software was used. Some aggregation was done on these data to appropriately bin them into grass, legume, brassica, and mixed categories, based on the type of cover crop evaluated. Further loss reduction calculations were done based on reported concentrations or losses from the literature reviewed in a site-year approach, where possible. Because of this, the resulting percent loss reductions reported here may be slightly different from those reported in the original source.
Further, each study was aggregated to a study component average (e.g., legume treatment, which may have included more than one type of legume) in an attempt to represent the study findings while reducing the variability associated with the site-year approach. These data were used to develop a series of correlations to evaluate trends associated with cover crop use in the U.S. to support Conservation Practice Standard 340. Data not reported by a given study were left blank, and calculations based on missing data were represented with #N/A.