Table
1. Selected physical properties and chemical characteristics
of surface soils.
Location
pHa
HMa
OMb
CECa
sa
si
c
--------%--------
meq/100g
--------%--------
Mississippi
7.8
0.18
1.8
17.3
40
34
26
Tennessee
6.3
0.39
1.5
6.4
38
40
22
aDetermined
by North Carolina State Dep. Agric., Agronomic Div. Raleigh, NC
27607. PH 1:1 soil:water; particle size analysis: hydrometer method;
HM, humic matter: NaOH/DTPA (diethlenetriaminepentaacetic
acid)/alcohol extraction method. (1984. Commun. Soil. Sci. Plant
Anal. 15:1417-1422); CEC, cation exchange capacity: summation of
exchangeable cations. (1984. Commun. Soil Sci. Plant Anal.
15:1409-1416). bDetermined by A & L Agric. Lab. Inc. Omaha, NE 68114.
OM, organic matter; Modified Walkley-Black method. (Reference soil
test methods for the southern region of the United States. South.
Coop. Ser. Bull 289.)
Table
2. Rainfall amounts for Mississippi and Tennessee
locations.
Time
Mississippi
Tennessee
1988
1989
1990
1988
1989
DAT
------------mm------------
0-15
0
133
94
16
69
16-30
0
80
35
12
51
31-45
50
108
10
82
43
46-60
86
74
86
47
35
61-75
39
42
24
34
149
76-90
63
4
6
15
106
91-105
41
25
0
58
40
106-120
69
71
23
36
31
120-135
101
122
28
19
73
Total
449
659
306
319
597
Table
3. Imazaquin degradation regression equations for all
locations and cropping systems in 1988, 1989, and
1990.
Year
Tillage
systema
Mississippi
Tennessee
R2
Equation
R2
Equation
1988
CT
0.78
Yb=1.73
+ 0.010Xc
0.53
Y=1.38-0.0009X
NT
0.43
Y=1.33-0.007X
0.54
Y=1.17-0.006X
1989
CT
0.41
Y=1.50-0.006X
0.39
Y=1.10-0.011X
NT
0.29
Y=1.54-0.05X
0.57
Y=1.06-0.013X
1990
CT
0.32
Y=1.46-0.009X
NT
0.58
Y=1.46-0.04X
aCropping systems: CT = conventional tillage monocrop
soybean; NT = no-till soybean planted directly into wheat
residue. bLog of the herbicide concentration + 1 in ppb. cDays after initial herbicide application.
Table
4. Imazaquin initial predicted concentrations and first
half-life values for all locations and cropping systems in
1988, 1989, and 1990.
Year
Tillage
systema
Mississippi
Tennessee
Day
0
concentration
Initial
half-life
Day
0
concentration
Initial
half-life
ppb
days
ppb
days
1988
CT
52.7
30
23.0
34
NT
20.4
43
13.8
50
1989
CT
30.6
50
11.6
28
NT
33.7
61
10.5
24
1990
CT
27.8
34
NT
27.2
75
aCropping systems: CT = conventional tillage monocrop
soybean; NT = no-till soybean planted directly into wheat
residue.