Repeated equipment traffic increases the bulk density and changes the pore size distribution (PSD) of soil. Spatial variability of chemical movement in soil may be partially explained by differences in PSD. The purpose of this study was to determine the relationships between soil pore size distribution and surface soil compaction on the transport of water, bromide, and atrazine (6-chloro-N-ethyl-N‘-(1-methylethyl)-1, 3,5-triazine-2,4-diamine) during multiple desaturation cycles. Undisturbed cores (8.2 cm diameter; 6.6 cm high) from a Crete silt loam (Pachic Argiustoll) were collected from wheel track (WT), nonwheel track (NWT), and row (ROW) locations in a conventionally tilled, continuous corn field. Atrazine (4.9 Kg ha−1) and KBr (66 Kg Br−1) were surface applied and equilibrated for 72 h. Effluent was collected at decreasing matric potentials between −1 and −100 kPa. The PSD indexes and bulk densities were significantly different among three locations (PSD indexes were 0.045 in WT, 0.061 in ROW, and 0.069 in NWT; bulk densities were 1.39 Mg m−3in WT, 1.30 Mg m−3in ROW, and 1.21 Mg m−3in NWT). Effluent analysis revealed more water and bromide were eluted from cores with higher PSD indexes and lower bulk densities. However, the reverse was true for atrazine. These data indicate that water and atrazine transport can be influenced differently by PSD and bulk density.
ASJC Scopus subject areas
- Soil Science