Microstructural changes in soils induced by wetting and drying: Effects on atrazine mobility

Wetting and drying affects soil structure and pesticide migration, which both may lead to land degradation. The effect on soil structure has been mainly addressed by classical methods at the macroaggregate scale, and the effect on herbicide leaching has not been thoroughly addressed. We aimed to cha...

Full description

Saved in:
Bibliographic Details
Published in:Land degradation & development 2019-04, Vol.30 (7), p.746-755
Main Authors: Dor, Maoz, Emmanuel, Simon, Brumfeld, Vlad, Levy, Guy J., Mishael, Yael G.
Format: Article
Language:English
Subjects:
aggregate stability
Aggregates
Agricultural development
Agricultural land
Agricultural practices
Agrochemicals
Atrazine
Calcium carbonate
Cementation
Clay
Clay loam
Clay soils
Disaggregation
Drying
Durability
Herbicides
Land degradation
Land use
Leaching
Loam
Loam soils
Microstructure
micro‐CT
Migration
Mobility
Particle size distribution
pesticide fate
Pesticides
Pollutants
Sand
Sandy loam
Sandy soils
Size distribution
Soil aggregates
Soil contamination
Soil pollution
Soil stability
Soil structure
soil wetting and drying
Wetting
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Wetting and drying affects soil structure and pesticide migration, which both may lead to land degradation. The effect on soil structure has been mainly addressed by classical methods at the macroaggregate scale, and the effect on herbicide leaching has not been thoroughly addressed. We aimed to characterize the effects of wetting and drying on soil microstructure, aggregate packing and stability, and subsequent effect on pesticide mobility in three agricultural soils. We developed advanced methods to quantitatively describe soil microstructure changes, induced by wetting and drying. Changes in soil packing, observed by micro‐CT, indicate that large aggregates in a Clay soil disintegrate, whereas particles from a Sandy Loam form larger aggregates. To reflect these changes in terms of soil stability, we developed an aggregate durability index, based on changes in soil particle‐size distribution measured by laser granulometry. For a Clay soil, the index decreased from 17.0% to 1.7%, indicating soil disaggregation upon wetting and drying. Whereas for a Sandy Clay Loam soil, the index increased from 0.4% to 2.6%, indicating formation of more durable aggregates, explained in terms of cementation by CaCO3. As expected, wetting and drying did not alter a Loamy Sand soil structure. The adverse effects of wetting and drying on soil structure correspond with the trends of atrazine mobility. As atrazine is trapped within the Clay soil aggregates, disaggregation leads to a 35% enhancement in pesticide mobility, whereas stabilization of a Sandy Clay Loam aggregates reduced atrazine leaching by 23%. Finally, wetting and drying directly affects the soil microstructure, which has an immense indirect effect on pollutant mobility, with both potentially leading to land degradation.
ISSN:1085-3278
1099-145X
DOI:10.1002/ldr.3256