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Table 1. Rainfall amounts and type for 1994 and 1995.
Precipitation
1994 1995
DAT Amount DAT Amount

mm
mm
1 51* 2 48*
2 15 16 23
13 51 30 41*
22 23 45 33
23 20 47 25
26 70 105 66
28 13 107 50
40 6

42 33

49 32*

55 39

56 24

58 11

83 29

93 64

110 32

123 27

Total 542
287
*Denotes a simulated precipitation event.





Table 2. Effect of filter strip width on total runoff, sediment, and herbicide loss1.
Filter strip
Sediment Herbicide loss
width Runoff2 loss Fluometuron Norflurazon
m kL/ha kg/ha -----% of applied-----
none 1,170a 1,660a 9.8a 8.6a
0.5 780a 960b 4.5b 4.2b
1.0 1,100a 990b 5.6b 4.4b
1Means are average over years.
2Means within a column followed by the same letter are not different as determined by Fisher's protected LSD at P<0.05.





Table 3. Filter strip effectiveness in reducing fluometuron and norflurazon concentrations in runoff following simulated precipitation in 1994 and 1995.1


Filter strip

Year DAT width Fluometuron2 Norfluazon2


m --------------- µg/L ---------------
1994 1 0 730a 590a


0.5 420b 520a


1.0 320b 280b

1994 49 0 43a 86a


0.5 34ab 92a


1.0 32b 50b

1995 2 0 550a 380a


0.5 510a 320a


1.0 320b 180b

1995 30 0 37a 57a


0.5 31ab 58a


1.0 20b 34b

1Concentrations are averaged over sampling intervals within runoff events.
2Means within columns and followed by the same letter are not different according to Fisher's protected LSD at P<0.05.




 Table 4. Regression parameters describing the effect of filter strip width on fluometuron and norflurazon concentrations in runoff following initial and early-season simulated events in 1994 and 1995.
Year DAT Intercept Slope R2 Prob.>F
Fluometuron
1994 1 774 -477 .46 **
1994 49 42 -3 --- ns
1995 2 591 -266 .40 **
1995 30 38 -18 .22 *

Norflurazon
1994 1 610 -315 .64 **
1994 49 90 -35 .31 **
1995 2 399 -210 .52 **
1995 30 60 -24 .37 **
وو  *Significant at the 0.001 level.
**Significant at the 0.0001 level.
ns=no significant effect.

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