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Water: Coastal Zone Act Reauthorization Amendments

Table 2-2. Effects of Conservation Practices on Water Resource Parameters (USDA-SCS, 1988)

Table 2-2. Effects of Conservation Practices on Water Resource Parameters (USDA-SCS, 1988)
NOTE: Values in the tables are taken from published research, model simulations, and results of simulated rainfall plots. Both the range (in parentheses) and additional values within the range (after parentheses, separated by comma) are presented. The values describe the percentage change in mass loads caused by the use of the practice on a nonirrigated, nonlegume, continuous row crop that has been grown under conventional tillage. Values inside the range are shown behind the range values and are separated by commas (-30, -90), -76. Values from model simulation are marked by an M, e.g., -30M, and values from a rainfall simulator are marked with an S, e.g., -29S. Few data are available for arid conditions and that zone is not included in the table. Not all soil-climate combinations have available reference data. A minus is a decreased value; a plus is an increased.

(a) (b) (c) (d) (e) (f) (g)


Water Budget
(% Change)


Phosphorus
(% Change)

Nitrogen
(% Change)

Pesticides
(% Change)

Practice and Number Climate and Soil Surface Runoff Deep Percolation Sediment Yield
(% Change)
Sediment Runoff Nitrogen Adsorbed Phases Nitrate in Surface Runoff Nitrate in Percolate Strongly Adsorbed SWb Weakly Adsorbed Leachate Weakly Adsorbed SWb

Contour Farming
330
H-Sa                      
Sandy
Silty
Clayey
(-65, -75)
(-60, -40)
(-19, -20)
#
+10
+5
(-20, -50)
(-65, -30)
(-29, -55)
-20
(-60, -65)
-55
-10
(-60, -65)
-20
-15
(-45, -54)
-55
-5
(-25, -72), -40
(-12, -25)
#
+10, +7
+10
#
#
#
#
#
#
#
#
#
SA-Sa                      
Silty
Clayey
(-27, -59)
-54
#
#
(-22, -59)
-26
#
#
#
#
#
#
#
#
+10
#
#
#
#
#
#
#
Ha                      
Sandy
Silty
Clayey
-30
-16
(-17, -29)
+10
#
#
-60
(-30, -48)
#
-60
#
#
-30
#
#
-60
#
#
-35
(-25, -41)
-12
+10
+6
+7
#
#
#
#
#
#
#
#
#
SAa                      
Clayley -15 # # # # # # # # # #
Strip-Cropping Contour
585
H-Sa                      
Silty
Clayey
Sandy
-5M
-28M
No change
+9M
+366Mc
No change
(-37,90M),-49
-89M
-99M
-80M
-52M
-99M
-86M
-89M
-99M
-81M
-51M
-98M
-43M
-26M
-39M
+158M
+220Mc
+12M
#
#
#
#
#
#
0, +6
#
#

Cons. Tillage- No Till
329
Ha                      
Clayey
Silty
 
Sandyd
(-33), +48)
(-91, +36)
 
(-26M, -88), -61
#
No change
 
#
(-73M, -82)
(-75, -99)
 
(-66M, -99S)
-53M
(-64, -95)
 
(-51, -87S)
-30M
(+900, -22)c
 
(0, +155)
-53M
(-60s,-94)
 
(-69s,-90s)
-11
(-42,+800)
-40,+100
(-67,-80)
(-49M,+8)
(8M,+16)
1,+8c
0
#
-78
 
#
#
(+5M,-50)
 
#
-51M
SA-Sa       u-72s.-82   -72,-70 -42s,-45 *    
Silty +36 # -96 (-80,-90) +138 (-50,-90),-60 (0,+45) +2 # # #
H-Sa                    
Silty (-21,-90) # (-88,-99) (-75,-90) (+450,+160 0) # # # (-75,-90) # +500
Cons. Tillage (Other types)
329
H-Sa                    
Silty

Clayey
(-15,-73)
-51,-20
-30
+5
 
+10
(-43,+95)
-85,-55
-70
-90,-84
 
#
+1850,+17
50c
#
-91,-82
 
#
+1800,+95
0c
#
#
 
#
#
 
#
#
 
#
#
 
#
SA-Sa                    
Silty
Clayey
-54
(-29,-89)
#
+10
#
(-70,-42)
#
#
#
#
#
#
#
#
#
#
#
#
#
#
#
#
Ha










Sandy
Silty
Clayey
(-40,-89)
(-20,-26)
(-10,-61),-20
+5
#
+10
(-40,-66)
(-49,-61)
(-29,-86)
-34,-41
-91
#
#
-3
#
#
-95
#
#
-88
#
#
#
#
#
#
(-69,-51)
(-33M,-2)
#
#
#
#
(+15,+27)
(+60M,-2)
SAa                      
Silty
Sandy
Clayey
(-16,-25),-20
20
-31
-88M
#
#
#
(-38,-92),-69
-45
-90M
#
#
#
#
#
#
#
#
#
#
#
Not sig.
#
#
#
(-38,-81)
#
#
#
#
#
+63,+27
#
#
Terraces with Underground outlets
600
H-Sa                      
Sandy
Silty
Clayey
-14
(-24,-60)
(-30,-36)
#
(+12,+500)c
(+5,+380)c
(-95,-98)
(-87,-95)
(-95,-95)
#
-95
#
#
-60
-30
#
-95
-95
#
(-70,+55)u
-30
#
+15
+10
#
#
#
#
#
#
#
#
#
SA-Sa                      
Silty
Sandy
Clayey
-14
(-73,+43M)
(-15,-36M)
+67
+162
(+5,+293M)c
(-95-98)
(-95,-92M)
(-95,-91M)
-99M
-97M
-96M
-42M
-72M
-65M
-99M
-97M
-96M
-42M
-78M
-91M
+20
+37M
(10 to high values)
#
#
#
#
(-73,-91M)
(-84,-91M)
(-69M,-78M)
WASCOBf
638
Ha                      
Sandy
Silty
Clayey
-40
(-88,-42)
#
+15
#
#
(-95,-99)
(-95,-92M)
(-90,-95)
#
#
#
-40
-71
#
-95
-95
#
-50
(-86,-44)
#
+15
+8
#
#
#
#
#
#
#
#
-4
#
SAa                      
Sandy
Silty
Clayey
#
-73
-30
#
#
+5
(-95,-98)
-95
(-90,-95)
#
-73
#
#
+58c
#
#
#
#
#
-50
#
#
#
#
#
#
#
#
#
#
#
#
#
a Climatic conditions: H-S = Humid - Snow; H = Humid; SAS = Semi-Arid - Snow; and SA = Semi-Arid.
b SW = Surface Water
c Measured values were small numbers; percentage change may have large values.
d Data have scattered values.
e Measured values were large numbers.
f Water and Sediment Control Basin
u = Unknown, site-dependent, or conflicting values.
# = No reported value.

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