J. Troiano et al., INFLUENCE OF AMOUNT AND METHOD OF IRRIGATION WATER APPLICATION ON LEACHING OF ATRAZINE, Journal of environmental quality, 22(2), 1993, pp. 290-298
A study was conducted to relate leaching of a herbicide, atrazine l-N'
-(1-methylethyl)-1,3,5-triazine-2,4,-diamine], and inorganic water tra
cers, Br- and Cl-, to the amount of deep-percolating water produced fr
om irrigation. Soil at the site was classified as a Dehli Loamy Sand (
Mixed, Thermic, Tepic Xeropsamment) which was an unstructured sandy so
il that was low in organic C content, conditions conducive to solute l
eaching. The relationship between depth of solute movement and amount
of deep-percolating water was measured in sprinkler, basin, and furrow
irrigation methods. Soil distribution of inorganic tracers indicated
that graded levels of added water treatments, which were based on refe
rence evapotranspiration, produced corresponding increases in the dept
h of percolated water. Atrazine's soil distribution indicated greater
downward movement in response to increases in amount of deep-percolati
ng water. Magnitude of leaching differed between irrigation methods an
d increased in the order: sprinkler < basin < furrow. Simulations usin
g the LEACHM model provided a physically based explanation for the dif
ferences in water movement between sprinkler and basin methods. The to
tal amount of applied water was similar at each level of percolation b
ut sprinkler irrigations were more frequent, resulting in more evapora
tion and, consequently, less water available for deep percolation. Bot
h amount and method of water application are important factors that de
termine pesticide movement and that, in irrigated agriculture, must be
considered as integral components of pesticide management.