Agriculture Reference
In-Depth Information
3.8.2 (year
system interaction). Soil organic matter content in the upper
soil layer (Fig. 3.8.1a) decreased sharply (by 24%) in CS during the first
2 years and then stabilized in the subsequent 2 years, whilst there was
no initial decrease in LIS and a subsequent significant increase (23%) in
1997. No significant differences in the 7-30 cm layer were observed under
CS over the 4-year period; in contrast, soil organic matter progressively
increased in LIS over the trial period (from 1.95 to 2.35%) (Fig. 3.8.1b).
Values of soil organic matter content in the combined soil layer (0-30 cm)
were mainly a result of those found in the upper layer. Soil organic matter
content was observed to be significantly higher in LIS than in CS in all
layers after 4 years when averaged over crop rotations (Table 3.8.3).
Probably due to high initial values, aggregate stability was not affected
by crop management systems to the same extent as soil organic matter, but
was more affected by crop rotation (Table 3.8.2). Rotation 3, which
includes clover, improved aggregate stability in 1995 and 1997 (Table
3.8.4). It is worth observing the interaction 'year
×
rotation' illustrated in
Fig. 3.8.2, showing an aggregate stability increase in the 0-7 cm layer over
time in the rotation which included clover.
×
Table 3.8.3.
Crop management system and rotation effects on soil organic matter.
Soil organic matter (%)
1993
1995
1997
Soil depth (cm)
0-7
7-30
0-30
0-7
7-30
0-30
0-7
7-30
0-30
Mean effects
CS
b
2.07
b
b
2.08
b
b
2.03
b
b
2.09
b
2.71
2.13
2.27
2.15
2.16
LIS
2.83
1.95
2.18
a
2.66
a
2.16
2.31
a
3.28
a
a
2.35
a
b
2.58
a
Rot. 1
2.70
a
2.25
a
2.38
2.37
2.22
2.31
2.58
2.13
b
2.27
b
Rot. 2
2.80
b
1.90
b
2.09
2.38
2.13
2.21
2.67
2.32
a
2.43
a
Rot. 3
2.82
b
1.97
b
2.20
2.34
2.12
2.18
2.79
2.12
2.29
Interactions
CS
×
Rot. 1
2.65
2.41
2.46
2.08
2.18
2.16
2.08
1.99
2.01
CS
×
Rot. 2
2.86
2.02
2.22
2.13
2.20
2.18
2.11
2.06
2.07
CS
×
Rot. 3
2.62
1.97
2.12
2.01
2.07
2.06
2.05
2.05
2.05
LIS
×
Rot. 1
2.75
2.10
2.25
2.67
2.26
2.35
3.08
2.28
2.47
LIS
×
Rot. 2
2.74
1.79
2.01
2.64
2.06
2.20
3.23
2.58
2.73
LIS
×
Rot. 3
3.03
1.97
2.21
2.67
2.17
2.28
3.53
2.19
2.50
Year
2.77
2.04
2.23
2.37
2.16
2.24
2.68
2.19
2.33
Values followed by the same letter in the same column are not statistically different at the 0.05
probability level.
Search WWH ::
Custom Search