Vol. 16—1962 - NorthEastern Weed Science Society

304
FACTORSCONTRIBUTING TOTHELOSSOF
AMIBENPHYTCTOXICITY IN SOILS
W.E. Rauser 1 . and cJ.:. S\.iitzer 2
Abstract .3
This study was tindetiaken to det~:rrnine the general
persistence of Amiben (J-amiM-.:2,5-dichlorc:benzoic acid) in sc:l,.;l.,
and the effeot of leaching, rnic·ro-crganisms.,,: and otherfaotors, on
its aotivity. .,
Amiben was used as the triethylamine salt formulation
oontaining two pounds acid equivalent per gallon. Application of
herbicide was made to four 50il types - muc~,sand, clay and.jl.oam ,
Herbioidal aotivity in soil samples was qetermined by using'a
biologioal test based on the dry weight of oat seedlings.
Leaohing stiudd e a wer-e carried out; in glass tubes, 9 in .
by 1 13/16 in. After leaching, the soil vras pushed from the tubes
and sliced into one inch segments which were then tested for
~liben activity.
Amiben applied tqmuck (at 3, 6 o:r;~ Ib/A) and leached
with 2, 5 or $ in ()f water was found to rem~,;in mainly in the.~pper
-,ne inoh layer. The greatest movement dawnt-iard was found with the
highest rate of chemical. Leaching was Independent. of the inj,tial
moLst.une vcont.errt.rof the so i+'. or the volume 0,'water applied.
As little as 2 inc~es of vlat'er wa~I,folJIld to remove
amiben almost completelyfro~ the sand soil whereas almost all of
the applied chemical was found 'an the surface UJ,ch of clay,
regardless of the applied ylat,er-.
"
The direct dependence of the downward movement of
herbicide on the application rate, but not on the applied water,
sugf;ests a mass aotion effeot in \1hich the herbicide was swept
along allowing adsorption on colloid s(')il constituents. Soils
high in colloids (muck) woul.d be expe ct e d to, retain much of the
chemical near the surface wher-eas those containing fe",., colloids
(sand) ',"auld be unable to hold much. Such expectations were'
supported by the data obtained.
Research Officer; Canada Department of AgricultuNe:,
Exper-Lraerrt al, Farm, Scot·t; Saskat chevran ,
Associate Professor, Depar-trnent. of Dota;r.y, Ontario J,gricU:lture
College, Guelph, Ontario.
Paper accepted for publication in 1Jleeds~ The Journal of the
~;1eed 80.ciety of America.