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SIMAZINE PERSISTENCE IN SOIL AND EF}'ECTS OF ITS RESIDUE
ON CROPS
M. T. H. RAGAB
Researclt Station,
Agrictilture Canada, Kentville, Nova Scotia BlN Il5. Corttribtttion tto. 1508,
received 7 Marclt 1974, accepted j lttly 1974.
Can. J. Plant Sci. Downloaded from www.nrcresearchpress.com by 80.82.77.83 on 10/26/17
For personal use only.
Rlcls, M. T. H. 1974. Simazine
on crops. Can. J. Plant Sci. 54:
persistence
713-716.
in soil and effects of its
lesidue
When 4.48 kg,zha of simazine (2-chloro-4,6-bis(ethylamino)-s-triazine) was rncorporated with soil to a depth of 15 cm, 53, 40 and lSVo was detected at 18, 63,
and 161 days, respectively, following which there was a gradual decrease to 1.5%
at 69O days. When crops were grown the year after application and the soil contained 0.18 ppm simazine, no residue was detected in coln (Zea mays L.), oats
(Avena sativa L.) or beans (Pltaseoltts vtrlgaris L.), but the latter two crops were
injured and Swiss chard (Beta vtilgaris var. cicla L.) did not grow. There was
slight toxicity to oats planted 2 yr after application when the soil contained
0.03 ppm simazine.
L'incorporation de 4.48 kg,zha de simazine (chloro-2 bis-6thylamino-4, 6 triazine-s)
ir une profondeur de 15 cm dans le sol, a laiss6 53, 40 ef 18% de r6sidus b 18, 63
et 161 jours respectivement, aprds quoi il s'est produit une baisse graduelle
jusqu'i 1.5Vo d 690 jours. Sur cultures 6tablies un an aprds I'application, en sol
contenant 0.18 ppm de simazine, on n'a d6cel6 aucun r6sidu de cet herbicide dans
le mais (Zea mays L.), I'avoine (Avenu sativaL.) ou les haricots (Plnseolus vu[garis L.), mais ces deux dernidres cultures ont 6t6 endommag6e,s et la bette i
carde (Beta vulgaris var. cicla L.) n'a pas pouss6. Le produit s'est r6v6l6 faiblement toxique )r I'avoine sem6e deux ans aprds I'application, en sol contenant 0.03
ppm de simazine.
(Harlow and Whiteside 1943). The land
Simazine (2-cbloro-4,6-bis(ethylamino)-s-tri-
to simazine application. Chemical analysis orr
extracts from this untreated soil showed that
no simazine residue or any other pesticide residue was present prior to treatment. The plots
were 5 y 7 m with l-m sod strips separating
them, and were arranged at random in four
times injures crops that follow in the crop-
ping system. Reduction in yield of
oats
(Avena sativa L.), wheat (Triticum aestivum
L.), soybeans (Glycina nmx Merr.), several
small seeded grasses, and legume forage
species have been reported for simazine
carryover (Roadhouse and Birk 1961; Fink
and Fletchall 1963, 1969; Holly and Roberts
blocks.
On 10 June 1968 commercially formulated
simazine 50W was applied by a power sprayer
over the surface of the soil at a rate of 4.48 kg
1963; Talbert and Fletchall 1964).
The present study was, therefore, initiated
to obtain information on the long-term persistence of simazine when incorporated in
the soil under the environmental field conditions of Nova Scotia. The simazine carryov€r elTects on some agricultural crops were
also investigated.
MATERIALS AND METHODS
The experimental site was at Canard, Nova
Scotia on soil classified as Somerset sandy loam
Can. J. Plant Sci, 54: 713-716 (Oct, 1974)
had
been fallowed and was cultivated just previous
azine) has been extensively used for control
of weeds, but its carryover in the soil some-
(a.i.) /ha in I,075 liters of water and immediately incorporated into the soil to a depth
of approximately 15 cm by a rotary cultivator.
Apart from the simazine treatment there was
no other control of weeds except that the untreated check plots were always kept mechanically weeded. No pesticide treatment of any
type was applied to plots throughout the ex-
perimental years.
Soi[ samples were randomly taken during the
1968, 1969 and 1970 growing seasons on the
dates given in Table 1 from each plot at 0- to
15-cm depth with a soil sample 2.5 cm diam.
Each soil sample was thoroughly mixed and
stored frozen in a carton until analvsis for
713
7t4
CANADIAN JOURNAL OF PLANT SCIENCE
Table I
Date sampled
.
Simazine in the top l5 cm of soilt
Days
after
application
Can. J. Plant Sci. Downloaded from www.nrcresearchpress.com by 80.82.77.83 on 10/26/17
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28 June 1968
l2 Aug. 1968
18 Nov. 1968
l3 May 1969
27 Nov. 1969
I May 1970
30 Sept. 1970
Precipitation//
Simazinel
between sampling
content
(ppml
(cml
I .06+0.11
0.80 + 0.08
12.1
18
o-l
oo.l
l6l
36.7
13.6
337
535
690
843
33.
0.3
7:t0.03
0.18+0.02
0.05 +0.01
0.0310.01
<0.02$
1
41.0
46.8
'fSimazine treatment;4.48 kg (a.i.)/ha, 10 Junc 1968.
+Means of four replications with standild errors. Correctcd for thc 957r recovery of the forlified checks
$Sensitivity of the method.
//From qeather records at location ofexperilnent
residual simazine. On 23 November 1968 all
plots were rotovated to a depth of approximate-
ly
15 cm.
Two weeks after sampling on 13 May
1969,
plots were again rotovated as described above.
The seedbed was prepared and on 5 June half
of each plot was seeded to oats, and on 16 June
the other half was seeded to corn (Zen mays
L. ), beans (Pltaseoltts vrtlgaris L. ) and Swiss
chard (Beta vrilgaris var. cicla L.). Recommended rates of fertilizer were applied. Random samples of corn kernels, oat grains and
bean pods were obtained from each plot at
harvest and frozen in plastic bags for later
residue analyses. The plots were left without
rotovation until spring 1970.
Aftel soil sampling on I May 1970, plots
were again rotovated as described earlier and
the seedbed was prepared. In June, all the plots
were sown with oats and observed throughout
the season for simazine phytotoxicity.
After thawing, the soil samples were airdried at room temperature, sieved through a
20-mesh screen, mixed thoroughly and subsampled for mechanicai analysis and simazine
residue determinations. The textural analysis
of Bouyoucos ( 195 1 )
The pH and percent organic matter content
were determined by the glass electrode and
was made by the method
appropriate soil collection and crop sample by
thin-layer chromatography (Abbot et al. 1965).
RESULTS AND DISCUSSION
The soil of the experimental plots was 707c
sand, llak stlt and 19% clay. The percent
organic matter was 2.9 and the pH value
was 4,8.
Chemical analysis of soil samples showed
that there was a rapid reduction in simazine
dr-rring the first 18 days after its incorporation into the soil at which time 537o of that
initially applied was recovered (Table 1, Fig.
1). The rate of simazine dissipation between
18 and 63 days was still rapid in spite of
the receipt of a very low amount (0.7 cm)
of
precipitation (rainfall). The amount of
simazine had dropped to 0.80 ppm. This
rapid rate of dissipation continued up to the
third sampling at 161 days following which
there was a more gradual loss of simazine
until at 843 days no detectable residue was
present. This pattern of simazine dissipation
,::- ."tt
agrees
with that found by Road-
.
dichromate oxidation, respectively (Atkinson et
al. 1958),
Simazine residue determinations in the soil
and crop samples were performed colorimetrically using essentially the pyridine-alkali-ethyl
cyanoacetate procedure as previousiy described
(Ragab and Leefe 1972). Duplicate samples
were analyzed from each plot and the analytical results *ere corrected for the recovery of
the fortified untreated check samples.
The analytical results were qualitatively confirmed on pooled cleane<l-uF extracts from each
;"1
tl;'"i
;l;.,1 \ \
d,"i
I
.,-
\ --.-.--
___-__
Fig. 1. Simazine residues in the top 15 cm of
soil.
7t5
RAGAB-EFFECTS OF SIMAZINE RESIDUE ON CROPS
Birk (1961) in Ontario irnd Clay
and Stott (1973) in England.
In the spring of 1969 when the various
Can. J. Plant Sci. Downloaded from www.nrcresearchpress.com by 80.82.77.83 on 10/26/17
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house and
crops were planted the year following application, the soil contained 0.18 ppm simazine (Table 1). This residue was not harmful
to the growth of corn. Swiss charcl did not
grow, whereas beans and oats exhibited
simazine toxicity with significantly lower
yields than plants grown in untreated soil.
The maturity of oats was delayed and the
grains were still green at harvest. In no case
was any appreciable residue of simazine detected in the crops (Table 2). Thus a residue
of 0.18 ppm simazine in soil does not result
in any detectable simazine in these crops.
This study demonstrates that during the
1969 grou'ing season in Nova Sco,l.ia, simazine carryover from treatment in 1968 was
detrimental to the growth of oats, beans and
Swiss chard. Accordingly, it is strongly advised that such sensitive crops should not
be planted 1 yr after simazine treatment.
The results on crop toxicity are in agreement with those reported earlier by Roadhouse and Birk (1961), Fink and Fletchalt
(1953), and Talbert and Fletchall (\964).
Since plants are known to absorb, trans-
locate and metabolize triazine herbicides
(Montgomery and Freecl 1961; Ragab and
McCollum
l96l; Sikka and Davis
1966)
cropping would definitely contribute to the
loss of simazine activity in the r;oil. The
amount of simazine left in the soil in
November 1969 following these crops was
0.05 ppm (Table 1). This amount corresponds to 2.5Vo of the originally, applied
sirnazine (Fig. 1).
Almost 2
oat plants.
Precipitation, cool temperatures, soil tex-
ture, soil reactions and plant uptake by
ciops are believed to be the major factors
influencing the persistence of simazine in
soil in the investigation reported herein.
Since the simazine was incorporated into
the soil, it is doubtful that volatilization or
photochemical decomposition had contributed significantly to the disappearance of
simazine from the soil.
ABBOTT, D. C., BUNTING, J. A. (Mrs.) and
THOMSON, I. 1965. The thin layer chromatographic determination
2.
Apparent
Recovery
residue
Crop
(.qo)l
0Pm)t
Corn kernels
Oat grains
92.4
93.2
95.1
<0.02!i
tMean of fou determinations.
+Mean of eight determinations.
$Sensitivity of thc method.
of triazine herbicides in
soil and water. Analyst 90: 356-361.
ATKINSON, H. J., GILES, G. R., McLEAN,
A. J. and WRIGHT, J. R. 1958. Chemical
of soil analysis. Can. Dep. Agric., Ottawa, Onlario. 90 pp.
BOUYOUCOS, C. J. 'l95 1. A lecalibration of
the hydrometer method fol making mechanical
analysis of soils. Agron. J. 43: 434-438.
CLAY, D. V. and STOTT, K. G. 1973. The
persistence and penetration of large doses of
simazine in uncropped soil. Weed Res. l3:
42,50.
methods
FINK, R. J. and FLETCHAI-I-, O. H.
1963.
Forage crops established in soil containing
atrazine or simazine residues. Weeds 11: 81-83.
FINK, R. J. and FLETCHALL, O. H. 1969.
Soybean injury from triazine residues in soii.
Weed Sci. 17: 35 36.
L. C.
and WHITESIDE,
G.
B.
Soil survey of the Annapolis Valley fruit
growing area. Can. Dep. Agric. Tech. Bull.
47 pp.
HOI-LY, K. and ROBERTS, H. A. I963. Persistence of phytotoxic residues of triazine her1943.
Residue of simazine in com. oatrs and beans
grown in a sandy loam soil treated with 4.,18 kg (a.i.)
simazine/ha in the previous;ear
Bean pods
1970) after treat-
somewhat detrimental to oats planted in
June. Typical symptoms of simazine toxicity
were present on a small percentage of the
HARLOW,
Table
yr (l May
ment, the amount of detectable simazine in
the plots was 0.03 ppm (Table 1). This low
amount of the retained simazine in soil was
<0.02
<0.02
bicides in soil. Weed Res.
3:
1-10.
MONTGOMERY, M. and FREED, V. H.
1961. The uptake, translocation and metabolism of simazine and atrazine by corn plants.
Weeds
9:
231-237.
RAGAB, M.
T, H. and McCOLLUM, J. P.
1961. Degradation of C"-labelled simazine by
plants and soil microorganisms. Weeds 9: 7284.
716
CANADIAN JOURNAL OF PLANT SCIENCE
RAGAB, M. T. H. and LEEFE, J. S.
1972.
Residues in soils and strawberries resulting
from simazine applications. Can. J. Plant Sci.
52:
147-149.
ROADHOUSE,
F. E. B. and BIRK, L.
A.
1961. Penetration and persistence in soil of the
Can. J. Plant Sci. Downloaded from www.nrcresearchpress.com by 80.82.77.83 on 10/26/17
For personal use only.
herbicide 2-chloro-4,6-bis (ethylamino)-s-tria-
zine (Simazine). Can. J. Plant Scl
4l:
252-
260.
SIKKA, H. C. and DAVIS, D. E. 1966. Dissipation of atrazine from soii by corn, sor-
ghum, and Johnsongrass. Weeds 14: 289-293.
TALBERT, R. E. and FLETCHALL, O. H.
1964. Inactivation of simazine and atrazine in
the field. Weeds 12: 33-37.
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