Abstract

Field and laboratory studies show increased leaching of pesticides through macropores in frozen soil. Fast macropore flow has been shown to reduce the influence of pesticide properties on leaching, but data on these processes are scarce. The objective of this study was to investigate the effect of soil freezing and thawing on transport of pesticides with a range of soil sorption coefficients (K-f ). To do this we conducted a soil column study to quantify the transport of bromide and five pesticides (2-methyl-4-chlorophenoxyacetic acid, clomazone, boscalid, propiconazole, and diflufenican). Intact topsoil and subsoil columns from two agricultural soils (silt and loam) in southeastern Norway were used in this experiment, and pesticides were applied to the soil surface in all columns. Half the columns were then frozen (-3 degrees C), and the other half were left unfrozen (4 degrees C). Columns were subjected to repeated irrigation events where 25 mm of rainwater was applied during 5 h at each event. Irrigations were followed by 14-d periods of freezing or refrigeration. Percolate was collected and analyzed for pesticides and bromide. Pesticide leaching was up to five orders of magnitude larger from frozen than unfrozen columns. Early breakthrough (<<1 pore volume) of high concentrations was observed for pesticides in frozen columns, indicating that leaching was dominated by preferential flow. The rank order in pesticide leaching observed in this study corresponded to the rank order of mean K-f values for the pesticides, and the results suggest that sorption plays a role in determining leaching losses even in frozen soil.

Published in

Vadose Zone Journal
2019, Volume: 18, number: 1, article number: 180201
Publisher: SOIL SCI SOC AMER

SLU Authors

• Larsbo, Mats

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Jarvis, Nicholas

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network


UKÄ Subject classification

Soil Science
Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.2136/vzj2018.11.0201

Permanent link to this page (URI)

https://res.slu.se/id/publ/99565