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Assessment of acetochlor use areas in the Sahel region of Western Africa using geospatial methods

Citation

Hoogeweg, Cornelis et al. (2020), Assessment of acetochlor use areas in the Sahel region of Western Africa using geospatial methods, Dryad, Dataset, https://doi.org/10.5061/dryad.44j0zpc9x

Abstract

The goal of this study was to determine the co-occurrence between acetochlor use on crops and potentially vulnerable soils in the Permanent Interstate Committee for Drought Control in the Sahel region of Western Africa. Acetochlor, a pre-emergence herbicide, is used primarily on row crops and has the potential to reach groundwater or surface water following a rain event shortly after application. Off-field transport is often determined by soil properties; therefore, soils within potential use areas were assessed and mapped to establish areas with soils vulnerable to leaching and/or runoff. Corn and cotton production areas were used as surrogate crops for high potential use areas of acetochlor within areas identified using GlobCover land use data and the Spatial Production Allocation Model agricultural statistics data. The geospatial analysis identified approximately 462 million ha of potentially vulnerable soils in the Sahel region of which 65.7 million ha are within agricultural areas. An adjustment for corn and cotton production areas showed that 2.2 million ha or 3.3 % of agricultural fields could have potential restrictions for acetochlor use. Approximately 0.159 million ha of soils or 0.24% of agricultural fields are in the presence of shallow groundwater, defined by depth < 9 m.  In addition, 0.0128 million ha or 0.02 % were determined to be adjacent to surface water bodies. To understand the uncertainty associated with the use of specific land cover datasets, an overlay assessment was conducted using alternative data sources. Overlap between selected land cover datasets in the Sahel region varies and ranges from 24.7% to 75.5% based on a merged 2009 GlobCover and CCI LC datasets. In comparison with the merged 2005 and 2009 GlobCover dataset, the cropland overlaps range from 38.9% to 85.0%. This demonstrates that the choice of land cover dataset can have a significant impact on a spatial assessment. Results from this assessment demonstrate that only a small fraction of vulnerable agricultural soils across the region may be a risk for contamination by acetochlor of groundwater or surface resources, based on product label recommendations. Given the availability of spatial data in a region, the methods contained herein may additionally be used in other localities to provide similar information that can be helpful for water quality management.

Methods

See journal article Figure 8 for the detailed processing steps

Usage Notes

Included in this database are the following layers:

CILSS_BND - Vector based dataset representing the countries in the CILSS considered in this assessment

LU_PUA - Raster layer represeinting the Potential Use Area (PUA) of acetochlor in the CILSS

PUA_ARP - Raster layer representing soils adhering to the ARP (www.arpinfo) 3-2-1 soil criteria

PUA_ARP_SGW - Vector layer representing the ARP 3-2-1 soils within the potential use areas overlapping shallow (<9.0m) groundwater

PUA_ARP_SW - Vector layer representing the ARP 3-2-1 soils that are adjacent to surface waterbodies such as rivers in the CILSS

Attribute filed for the data set are not provided. Just the outlines of the areas resulting from GIS assessments

Funding

Monsanto Company (part of the Bayer Group), Award: #4512672972

Monsanto Company (part of the Bayer Group), Award: #4512672972