Agriculture Reference
In-Depth Information
TABLE 11.4
Development of Soil Organic Carbon with Agroforestry Practices
Depth
(cm)
SOC
(Mg ha
−1
)
Period
(Years)
Woody Species
Country
Reference
Intercrop
G. sepium
200
123
a
10
Malawi
Makumba et al. 2007
G. sepium
200
149
10
Malawi
Makumba et al. 2007
G. sepium
200
225
10
Zambia
Kaonga and Bayliss-Smith 2009
L. leucocephala
200
245
10
Zambia
Kaonga and Bayliss-Smith 2009
S. siamea
200
245
10
Zambia
Kaonga and Bayliss-Smith 2009
Various
20
30.5-37.4
10
Zambia
Kaonga and Coleman 2008
Improved Fallow
C. cajan
200
149
4
Zambia
Kaonga and Bayliss-Smith 2009
S. sesban
200
150
4
Zambia
Kaonga and Bayliss-Smith 2009
T. vogelii
200
155
4
Zambia
Kaonga and Bayliss-Smith 2009
Various
20
27.3-31.2
4
Zambia
Kaonga and Coleman 2008
A. angustissima
120
26.3
2
Zimbabwe
Nyamadzawo et al. 2008b
S. sesban
120
25.4
2
Zimbabwe
Nyamadzawo et al. 2008b
Rotational Woodlot
A. polyacantha
15
21.6
5
Tanzania
Kimaro et al. 2011
G. sepium
15
18.8
5
Tanzania
Kimaro et al. 2011
A. crassicarpa
15
15.8
5
Tanzania
Kimaro et al. 2011
A. mangium
15
25.6
5
Tanzania
Kimaro et al. 2011
A. nilotica
15
22.7
5
Tanzania
Kimaro et al. 2011
Note:
SOC, soil organic carbon.
a
Comparative values from these studies are found in the text.
Between the first and second years of the cropping phase in Kaonga and Coleman
(2008), soils were sampled to 20 cm and analyzed for total SOC (Table 11.4). The
total soil C after 1 year of cropping was 1.0 and 1.2 times that of the initial soil C.
SOC to 200 cm depth (Kaonga and Bayliss-Smith 2009) was comparable to the
150 Mg ha
−1
C found in nearby natural miombo vegetation and more than nine-tenth
of the 165 Mg ha
−1
C found in an adjacent natural fallow. Nyamadzawo et al. (2008b)
reported that fallows of
A. angustissima
and
S. sesban
accumulated 26.3 and 25.4
Mg ha
−1
in SOC (Table 11.4) after 2 years of fallowing, and fallowing resulted in
3.7-9.1 Mg ha
−1
more SOC compared with continuous maize cropping. After an
improved fallow of 1-1.5 years with various species in Kenya, Albrecht and Kandji
(2003) found an increase in SOC in the top 30 cm of 1.69-2.15 Mg ha
−1
C in coarse
soils, and from 2.58 to 8.34 Mg ha
−1
C in fine-textured soils.
Rotational woodlots differ from improved fallows in that the tree species may be
selected for wood production rather than N fixation. However, rotational woodlots
also usually increase SOC and promote increased yields in subsequent cereal crops.
Tree and crop components are established at the same time, and the intercropping
continues for 2-3 years with crop yield declining because of competition from the
