Factors affecting the placement of agricultural best management practices in the agricultural conservation planning framework (ACPF) toolbox in the mid‐Atlantic region

There has been a recent push to conduct spatially explicit landscape planning at finer hydrologic unit scales to mitigate diffuse pollution. The Agricultural Conservation and Planning Framework (ACPF) helps identify potential locations for agricultural conservation practices by using high‐resolution soils and elevation data. This spatially explicit approach attempts to identify runoff and nutrient pathways, but output may be influenced by user‐specified parameters and the properties of the digital elevation model (DEM) being used. Here we assess differences in the density and location of conservation practices sited by the ACPF toolbox across three DEM resolutions in three agricultural catchments, each in distinct physiographies (Ridge and Valley, Piedmont, Coastal Plain) of the United States mid‐Atlantic region. Output frequency did not vary much for contour buffer strips or water and sediment control basins (WASCOBs) across DEM resolution, particularly compared with landscape type. The DEM resolution was crucial for the density of grassed waterways but of little consequence for contour buffer strips. Placement density of WASCOBs and contour buffer strips varied by region. Grassed waterways are sited based on either discrete values or statistical distributions of stream power index (SPI). A higher density of grassed waterways was placed in lower relief landscapes when a single standard deviation threshold was applied. Using discrete SPI values for the grassed waterway tool generated more consistent output across watersheds than output based on statistical distributions. These and other reported findings can help guide user decisions in future applications of the ACPF toolbox, particularly across different areas of study. Core Ideas ACPF inputs and terrain resolution were varied to assess effects on BMP placement. Practices are sited with discrete values or statistical distributions of terrain products. Distributions of terrain products change as a function of spatial resolution. Grass waterway results can be erroneous with standard deviation method. End users must understand these factors, but published guidance is sparse.