Drainage and vertical transport of herbicides in two mollisols of the Argentinian rolling pampa | [Drenaje y transporte vertical de herbicidas en dos molisoles de la pampa ondulada Argentina]

CAPRILE, A.C; APARICIO, V.C; PORTELA, S.I.; SASAL, M.C; ANDRIULO, A.E.

Ciencia del Suelo

ASOCIACIÓN ARGENTINA DE LA CIENCIA DEL SUELO

Lugar: Buenos Aires; Año: 2017 vol. 35 p. 147 - 159

0326-3169

The objective of this study was to evaluate deep drainage dynamics and associated herbicide (glyphosate, atrazine, acetochlor) losses in two soils of different texture cultivated with a maize-soybean sequence under no tillage. We used field lysimeters containing a Typic Hapludoll (Junín series) and a Typic Argiudoll (Pergamino Series). The applied doses varied from 3 to 7 L ha -1 for glyphosate (48% ap), 2 L ha -1 for atrazine (50% ap) in 2009 and of 2.5 and 3 L ha -1 for acetochlor (84% ap) in 2003. Since 2006, drainage volume was measured after each rain event producing drainage and herbicide concentration was measured in pooled samples corresponding to 13 periods separated according to occupation (crop and fallow) and herbicide application moment. Despite the absence of differences in accumulated soil drainage during 2001-2012, there were differences when shorter time periods were analyzed, recording pulses of different drainage type (masal and preferential flow) associated with texture and initial moisture conditions. When glyphosate and AMPA were detected, Junín drainage was 20 times more concentrated in glyphosate and contained 75 times the amount of AMPA than Pergamino due to its smaller volume. Atrazine was detected in all drainages up to 3 years after its application while the acetochlor was detected up to 9 years after its last application. These results raise questions about the possible increase in groundwater contamination risk due to increasing glyphosate doses and the detection of atrazine and acetochlor, several years after its last application.