Environmental Engineering Reference
In-Depth Information
Table 8.2
Total SOC and quantities estimated per
unit of soil surface (ha)
Land use category
Total SOC (Mg 1,000)
SOC
(Mg ha
−
1
)
Permanent irrigated and irrigated arable lands
19,852.5
31.6
834.8
33.8
Vineyard
1,568.5
32.2
Olive groves
Total
22,255.7
Table 8.3
SOC pools for the different croplands
Land use category
DPM
RPM
BIO
HUM
−
1
)
(Mg ha
Permanent irrigated and irrigated arable lands
0.22
4.79
0.69
25.90
0.20
9.30
0.63
23.68
Vineyard
0.01
8.00
0.62
23.52
Olive groves
DPM
decomposable plant material;
RPM
resistant plant material;
BIO
microbial biomass;
HUM
humified organic matter
The total SOC for the cropland included in the analysis is calculated at about
22,256 Mg under current climate (Table
8.2
). Even if differences in the total SOC
values of the three Land Use classes were observed, the SOC content per ha shows
similar values for the three categories.
Larger differences among Land Use categories for the SOC compartments were
observed (Table
8.3
). The HUM compartment, in general, is the largest SOC pool.
The DPM values per ha are lower in olive groves than the other two LU catego-
ries. The RPM contents are higher (about double) in tree cropland than irrigated
lands. Smaller differences in BIO and HUM compartments among LU categories
were observed.
The last part of the analysis is related to the evaluation of the impact of a cli-
mate change scenario (A1B) on the SOC pools in croplands. The comparison
between the SOC projection in the period 2091/2100 versus the SOC content in
the year 2000 showed a general reduction of the carbon pools (Fig.
8.5
). The mean
SOC loss under the A1B climate change scenario at the end of the 21st century
is equal to
−
19.1 %. The reduction values ranged from
−
86.5 % (DPM of olive
groves) to
−
14.2 % (HUM of Irrigated lands). On average, excluding the DPM of
olive groves value, the RPM is the SOC compartment that showed the highest car-
bon reduction (
−
31.2 %), while the HUM compartments revealed the lower aver-
age carbon reduction (
−
15.2 %).
This exercise provided information on the SOC pools in Mediterranean crop-
lands, and projections of SOC variation under climate change conditions. A reduc-
tion in the SOC pool under climate change conditions was estimated in Sardinian
croplands, as reported by other authors for other areas (e.g. Cox et al.
2000
; Jones
et al.
2003
). The inverse model run also allowed the estimate and comparison with
literature values related to the litterfall rates.
