Nt. Basta et al., ATRAZINE RUNOFF FROM CONSERVATION TILLAGE SYSTEMS - A SIMULATED RAINFALL STUDY, Journal of soil and water conservation, 52(1), 1997, pp. 44-48
Citations number
30
Categorie Soggetti
Water Resources",Ecology,"Agriculture Soil Science
Atrazine losses in surface runoff from a silty clay loam under no-till
(NT) chisel (CH) and disk (DY) tillage were measured using simulated
rainfall. Atrazine (0.56 kg ha(-1); 0.50 lb acre(-1)) and rainfall (64
nm h(-1), 2.5 in h(-1), for 1.25 hr) were applied to small plots and
atrazine in sediment and dissolved in water was determined for all run
off samples. Total atrazine losses were CH (58.6 g ha(-1)) > NT (44.1
g ha(-1)) = DK (41.9 g ha(-1)). However, sediment losses were CH (2.84
MT ha(-1)) > DK (2.09 MT ha(-1)) congruent to NT (0.37 MT ha(-1)). Di
ssolved atrazine in runoff water accounted for more than 99.8% of tota
l atrazine loss, and atrazine lost through sediment transport was insi
gnificant Although atrazine partitioning between solution and solid ph
ases in soil ir often directly related to soil organic matter content
atrazine adsorption by soil organic matter did not control the amount
of atrazine last in runoff. Poor relationships between apparent Kd val
ues and soil organic matter content across simulated rainfall studies
suggest experimental conditions affect runoff losses of atrazine more
than atrazine adsorption by soil organic matter No-till systems reduce
water and herbicide runoff under natural rainfall conditions, but res
ults under simulated rainfall conditions are mixed. Presaturation of p
lots with water, high-intensity simulated rainfalls shortly after atra
zine application and other experimental renditions may outweigh tillag
e effects and mask differences in atrazine losses from land under diff
erent tillage systems. Future best management practices (BMPs) used to
reduce herbicide runoff from agricultural land will be developed from
simulated rainfall studies Identification of successful BMPs that min
imize herbicide runoff under environmental conditions requires careful
selection of experimental conditions used in simulated rainfall studi
es.