Agriculture Reference
In-Depth Information
TABLE 16.16
Relationships of C Inputs, Profile C Content, Stocks, Sequestration
Rate, and Different Forms of C with SYI in a 20-Year Long-Term
Experiment
Correlation
(
r
)
Parameters
Regression Equation
(
R
2
)
Internal C inputs (
X
)
SYI (
Y
)
Y
= 0.0002
X
+ 0.17
0.95
0.91***
Total C inputs (
X
)
Y
= -0.00007
X
+ 0.222
0.97
0.95***
Profile mean C content (
X
)
Y
= 0.18
X
- 0.17
0.99
0.98***
Profile C stocks (
X
)
Y
= 0.008
X
+ 0.051
0.70
0.48*
CSR (
X
)
Y
= 0.015
X
+ 0.30
0.99
0.98***
Source:
Srinivasarao, Ch. et al.,
Eur J Agron
, doi: 10.1016/j.eja.2012.05.001, 2012.
Note:
* and *** denote significance at
P
< 0.05 and 0.001, respectively.
TABLE 16.17
Relationships of SYI with C Input, C Buildup, Profile SOC, and C
Sequestration in a 13-Year Long-Term Experiment
Correlation
Parameters
Regression Equation
(
r
)
(
R
2
)
Annual CR C input (
X
)
SYI (
Y
)
Y
G
= 0.2
X
+ 0.03
Y
F
= 0.72
X
+ 0.05
0.99
0.98
0.97
0.97
Total cumulative C input (
X
)
Y
G
= 0.003
X
+ 0.1
Y
F
= 0.01
X
+ 0.35
0.94
0.85
0.88
0.73
C buildup % (
X
)
Y
G
= 0.003
X
+ 0.1
Y
F
= 0.01
X
+ 0.27
0.96
0.98
0.93
0.97
Profile SOC (
X
)
Y
G
= 0.01
X
- 0.25
Y
F
= 0.02
X
- 1.02
0.96
0.98
0.93
0.97
C sequestrated (
X
)
Y
G
= 0.01
X
+ 0.17
Y
F
= 0.02
X
+ 0.57
0.96
0.98
0.93
0.97
Source:
Srinivasarao, Ch. et al.,
Int J Agric Sustain
, 10(3), 1-15, 2012.
profile SOC stock (
R
2
= 0.63*,
P
< 0.05), and SOC sequestered (
R
2
= 0.63*,
P
< 0.05)
(
Table 16.21
). However, the correlation of SYI with the annual input of CR is weak
(
R
2
= 0.26). But these relationships may not be always significant in the case of soy-
bean. Thus, the maintenance of SOC stock through application of FYM and chemical
fertilizers is essential to the sustainability of rainfed production systems, particularly
in cropping systems like soybean-safflower, which need high external inputs. Any
improvement in SOC enhances available water capacity of the soil profile (Du et al.
2009), which reduces frequency and intensity of the drought stress. Although the appli-
cation of organics may not drastically increase the SYI of soybean, it can sustain the
Search WWH ::
Custom Search