Movement of Field-Applied Atrazine, Metolachlor, and Bromide in a Sandy Loam Soil

Heatwole, Conrad D.; Zacharias, Steffen; Mostaghimi, S.; Dillaha, Theo A.

doi:10.13031/2013.21384

Cited by 32 publications

(24 citation statements)

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“…Drift while spraying, volatilisation, etc inhibit an even application. A CV of 35% for pesticide application ( n = 41) is acceptable and comparable with other studies 23, 25, 42–45…”

Section: Resultssupporting

confidence: 87%

Spatial variability of atrazine dissipation in an allophanic soil

Müller

Smith

James

et al. 2003

Pest Management Science

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The small-scale variability (0.5 m) of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) concentrations and soil water contents in a volcanic silt loam soil (Haplic Andosol, FAO system) was studied in an area of 0.1 ha. Descriptive and spatial statistics were used to analyse the data. On average we recovered 102% of the applied atrazine 2 h after the herbicide application (CV = 35%). An increase in the CV of the concentrations with depth could be ascribed to a combination of extrinsic and intrinsic factors. Both variables, atrazine concentrations and soil water content, showed a high horizontal variability. The semivariograms of the atrazine concentrations exhibited the pure nugget effect, no pattern could be determined along the 15.5-m long transects on any of the seven sampling days over a 55-day period. Soil water content had a weak spatial autocorrelation with a range of 6-10 m. The dissipation of atrazine analysed using a high vertical sampling resolution of 0.02 m to 0.2 m showed that 70% of the applied atrazine persisted in the upper 0.02-m layer of the soil for 12 days. After 55 days and 410 mm of rainfall the centre of the pesticide mass was still at a soil depth of 0.021 m. The special characteristics of the soil (high organic carbon content, allophanic clay) had a strong influence on atrazine sorption and mobility. The mass recovery after 55 days was low. The laboratory degradation rate for atrazine, determined in a complementary incubation study and corrected for the actual field temperature using the Arrhenius equation, only accounted for about 35% of the losses that occurred in the field. Results suggest field degradation rates to be more changeable in time and much faster than under controlled conditions. Preferential flow is discussed as a component of the field transport process.

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“…Drift while spraying, volatilisation, etc inhibit an even application. A CV of 35% for pesticide application ( n = 41) is acceptable and comparable with other studies 23, 25, 42–45…”

Section: Resultssupporting

confidence: 87%

Spatial variability of atrazine dissipation in an allophanic soil

Müller

Smith

James

et al. 2003

Pest Management Science

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“…However, in some studies, pesticide concentrations in runoff from conservation tillage plots, especially no-tillage plots, were higher than in runoff from conventional tillage plots. As a consequence, conservation tillage plots may generate greater pesticide losses despite a lower water runoff volume (Heatwole et al, 1997;Kenimer et al, 1987;Shipitalo and Owens, 2006;Webster and Shaw, 1996). In other studies, water runoff volume was higher under conservation tillage (Gaynor et al, 1995;Myers et al, 1995).…”

Section: Runoffmentioning

confidence: 84%

“…Intensity and timing of rainfall after treatment are major factors affecting pesticide leaching (Granovsky et al, 1993;Heatwole et al, 1997;Isensee and Sadeghi, 1994;Masse et al, 1996). Their effects may be greater than those generated by tillage (Gaynor et al, 1995;Granovsky et al, 1993;Otto et al, 1997).…”

Section: Leachingmentioning

confidence: 99%

Tillage management effects on pesticide fate in soils. A review

Alletto

Coquet

Benoît

et al. 2010

Agron. Sustain. Dev.

163

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-Reducing tillage intensity through the implementation of conservation practices is a way to reach a more sustainable agriculture. Reducing tillage is indeed an efficient way to control soil erosion and to decrease production costs. Nonetheless, the environmental impact of reduced tillage is not well known because conservation techniques may induce strong changes in soil physicochemical properties and biological activity. Knowledge on the fate of applied pesticides under conservation practices is particularly important from this point of view. We review here the advances in the understanding, quantification and prediction of the effects of tillage on pesticide fate in soils. We found the following major points: (1) for most dissipation processes such as retention, degradation and transfer, results of pesticide behaviour studies in soils are highly variable and sometimes contradictory. This variability is partially explained by the multiplicity of processes and contributive factors, by the variety of their interactions, and by their complex temporal and spatial dynamics. In addition, the lack of a thorough description of tillage systems and sampling strategy in most reports hampers any comprehensive interpretation of this variability. (2) Implementation of conservation tillage induces an increase in organic matter content at the soil surface and its gradual decrease with depth. This, in turn, leads to an increase in pesticide retention in the topsoil layer. (3) Increasing retention of pesticides in the topsoil layer under conservation tillage decreases the availability of the pesticides for biological degradation. This competition between retention and degradation leads to a higher persistence of pesticides in soils, though this persistence can be partially compensated for by a more intensive microbial activity under conservation tillage. (4) Despite strong changes in soil physical properties under conservation tillage, pesticide transfer is more influenced by initial soil conditions and climatic conditions than by tillage. Conservation tillage systems such as no-tillage improve macropore connectivity, which in turn increases pesticide leaching. We conclude that more knowledge is needed to fully understand the temporal and spatial dynamics of pesticide in soil, especially preferential flows, in order to improve the assessment of pesticide risks, and their relation to tillage management.

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“…Gish et al, 1995) have demonstrated an increased leaching of relatively mobile pesticides under no-till (e.g. Isensee et al, 1990;Gish et al, 1991a;Granovsky et al, 1993;Heatwole et al, 1997;Kumar et al, 1998;Elliott et al, 2000). However, caution should be exercised when generalizing the effects of tillage on leaching by macropore flow.…”

Section: Soil Tillage and Trafficmentioning

confidence: 99%

A review of non‐equilibrium water flow and solute transport in soil macropores: principles, controlling factors and consequences for water quality

Jarvis

2007

European J Soil Science

1,032

589

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This review discusses the causes and consequences of 'non-equilibrium' water flow and solute transport in large structural pores or macropores (root and earthworm channels, fissures and interaggregate voids). The experimental evidence suggests that pores larger than c. 0.3 mm in equivalent cylindrical diameter allow rapid non-equilibrium flow. Apart from their large size and continuity, this is also due to the presence of impermeable linings and coatings that restrict lateral mass exchange. Macropores also represent microsites in soil that are more biologically active, and often more chemically reactive than the bulk soil. However, sorption retardation during transport through such pores is weaker than in the bulk soil, due to their small surface areas and significant kinetic effects, especially in larger macropores. The potential for non-equilibrium water flow and solute transport at any site depends on the nature of the macropore network, which is determined by the factors of structure formation and degradation, including the abundance and activity of soil biota such as earthworms, soil properties (e.g. clay content), site factors (e.g. slope position, drying intensity, vegetation) and management (e.g. cropping, tillage, traffic). A conceptual model is proposed that summarizes these effects of site factors on the inherent potential for non-equilibrium water flow and solute transport in macropores. Initial and boundary conditions determine the extent to which this potential is realized. High rain intensities clearly increase the strength of non-equilibrium flow in macropores, but the effects of initial water content seem complex, due to the confounding effects of soil shrinkage and water repellency. The impacts of macropore flow on water quality are most significant for relatively immobile solutes that are foreign to the soil and whose effects on ecosystem and human health are pronounced even at small leached fractions (e.g. pesticides). The review concludes with a discussion of topics where process understanding is still lacking, and also suggests some potential applications of the considerable knowledge that has accumulated in recent decades.

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Movement of Field-Applied Atrazine, Metolachlor, and Bromide in a Sandy Loam Soil

Cited by 32 publications

References 0 publications

Spatial variability of atrazine dissipation in an allophanic soil

Spatial variability of atrazine dissipation in an allophanic soil

Tillage management effects on pesticide fate in soils. A review

A review of non‐equilibrium water flow and solute transport in soil macropores: principles, controlling factors and consequences for water quality

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