Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 26, 2005
Publication Date: November 15, 2005
Citation: Neurath, S.K., Sadeghi, A.M., Shirmohammadi, A., Isensee, A.R., Torrents, A. 2005. Spatial variability in the upper soil layer of a no-till field using a small-scale dye experiment. Soil Science. 170(11)881-891.
Interpretive Summary: The purpose of this study was to investigate the spatial variability of water infiltration through the upper soil layer of a no-till corn field. Infiltration experiments along with dye tracer were established on an isolated section (33 cm by 33 cm) of a well-established no-till field. The variation of infiltration was estimated by measuring the dye concentrations in the soil samples obtained from the 0-3 cm, 3-6 cm, and 6-10 cm depths of the infiltration test area. Results indicated that the dye concentrations were highest in the top layer with less variability compared to the middle and lower soil layers and that the majority of the infiltration solution appeared to pass through 23% of the total infiltration area. Findings from this study will provide better insight into the role of preferential flow and leaching characteristics of agrochemicals in no-till agricultural management practices.
Small-scale (33 cm by 33 cm) dye experiments were performed to evaluate the spatial variation of infiltration by evaluating dye distribution within the upper 10-cm soil depth of a well-established no-till corn field. The variation of infiltration was estimated by measuring the dye concentrations in the soil samples obtained from the 0-3 cm, 3-6 cm, and 6-10 cm depths of the infiltration test volume (10,890 cm3). Contour maps of dye concentrations were prepared for each soil layer and used to estimate the percentage of the infiltration area that had higher than average dye concentrations. Results indicate that: i) statistically, the dye concentration in the upper soil layers (0-3 cm) have a higher average dye concentration with less variability than the middle and lower soil layers; ii) the majority of the infiltration solution appeared to pass through 23% of the infiltration area; and iii) the spatial distribution of the dye concentrations are highly heterogeneous. The statistically and spatially heterogeneous dye distribution may suggest that, under ponded infiltration conditions in no-till systems, preferential flow may be the primary mechanism affecting the distribution of infiltrating water throughout the 0-10 cm depth.