Agriculture Reference
In-Depth Information
TABLE 16.20
Relationships between Different Forms of C (C Inputs, Soil C Sequestration
Rate, and SYI) of Pearl Millet-Based Systems in Semiarid Tropical Conditions
Coefficient of
Determination (
R
2
)
Independent Variable
Regression Equation
C sequestration rate
SYI
Y
(pearl millet) = 0.02
X
+ 0.34
0.67*
Y
(cluster bean) = 0.05
X
+ 0.84
0.77**
Y
(castor) = 0.01
X
+ 0.5
0.56*
Total C inputs
Y
(pearl millet) = 0.003
X
+ 0.17
0.45
Y
(cluster bean) = 0.008
X
- 0.29
0.56*
Y
(castor) = 0.002
X
+ 0.36
0.45
Profile mean SOC content
Y
(pearl millet) = 2.01
X
- 0.07
0.61*
Y
(cluster bean) = 5.99
X
- 0.44
0.77**
Y
(castor) = 1.64
X
+ 0.16
0.64*
Source:
Srinivasarao, Ch. et al.,
Can J Soil Sci
, 92, doi: 10.4141/cjss2011-098, 2012.
Note:
* and ** denote significance at P < 0.05 and 0.01, respectively.
TABLE 16.21
Relationships of SYI to CR C Input, Total Cumulative C Input, %
Change in SOC Stock, and the Magnitude of SOC Sequestered
after 15 Years of Cropping
Parameters
Regression Equation
R
2
Annual CR C input (
X
)
SYI
Soybean
= 0.001
X
+ 0.37
0.21
NS
SYI
Saflower
= 0.002
X
+ 0.17
0.26
NS
Total cumulative C input (
X
)
SYI
Soybean
= -0.005
X
+ 0.48
0.10
NS
SYI
Saflower
= 0.002
X
+ 0.20
0.53*
C buildup % (
X
)
SYI
Soybean
= -0.001
X
+ 0.46
0.03
NS
SYI
Saflower
= 0.004
X
+ 0.24
0.63*
Profile SOC (
X
)
SYI
Soybean
= -0.001
X
+ 0.51
0.03
NS
SYI
Saflower
= 0.01
X
- 0.19
0.63*
C sequestrated (
X
)
SYI
Soybean
= -0.001
X
+ 0.45
0.03
NS
SYI
Saflower
= 0.008
X
+ 0.29
0.63*
Source:
Srinivasarao, Ch. et al.,
Can J Soil Sci
, 92, doi: 10.4141/cjss2011-098, 2012.
Note:
NS, nonsignificant; *, significant at
P
= 0.05 level.
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