Field-Scale Bromide Leaching as Affected by Land Use and Rain Characteristics
- Yang Yang *a,
- Ole Wendrotha and
- Riley Jason Waltona
Natural heterogeneity in soil properties limits the understanding on water and solute transport at a field scale. The objective of the current study was to adopt a new experimental design with scale-dependent treatment distribution and to assess the impact of land use and rain characteristics on Br– leaching under field conditions. On a transect with two land use systems, that is, cropland and grassland, rainfall intensity and the time delay between solute application and subsequent rain were arranged in a repetitive pattern at different scales. Soil samples in 10-cm increments down to 1-m depth were collected along the transect for Br– analysis after rainfall simulation. Owing to continuous macropores, supporting the development of preferential flow, soil Br– was more evenly distributed with soil depth and reached greater depth in grassland. Increasing rainfall intensity enforced the deep leaching of Br–. Frequency-domain analysis revealed that the dominant factor controlling Br– leaching varied with depth. At 0 to 10 cm, rainfall intensity was strongly correlated with Br– concentration; while in the soil layer below, application time delay was the main driver for the spatial distribution of Br–. With increasing soil depth, the spatial behavior of Br– was mainly caused by soil properties such as soil texture and topography, rather than rainfall characteristics. Nevertheless, rainfall intensity was found to be positively correlated with Br– concentration in deep soil, indicating a great risk of deep leaching and groundwater contamination under heavy rainfall. These results have direct implications for the surface application of chemicals.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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