upon ongoing field experiments (Vu Dinh et al. 2012a, b; ENBW 2011). The final
modeling study looks at the longer term developments of the use of SCT in the
sloping environments of Southeast Asia (Lippe et al. 2011).
7.3.1 Description of Study Sites and the Experimental Design
The case study area in north-east Thailand was Ban Bo Muang Noi in Loei
Province, whereas the field trials and the modeling study in Vietnam were
conducted in Chieng Khoi commune, Son La province in north-west Vietnam.
A summary of the environmental features of both sites is given in Table 7.2.
A relatively fertile humic Lixisol was found in Ban Bo Muang Noi, whereas soil
fertility levels in Chieng Khoi were comparatively low for SOM, total nitrogen and
available phosphorous, probably a result of the continuous cropping history and the
steep slopes, making the site prone to soil erosion. Annual rainfall regimes are
similar at both sites, with figures ranging from 1,000 to 1,300 mm
À1 a year during
the study period.
Table 7.2 Environmental features of the study sites – Ban Bo Muang Noi in north-east Thailand
and Chieng Khoi in north-west Vietnam
Site conditions
Ban Bo Muang Noi
Chieng Khoi
Monitoring years
2003; 2004; 2005
2009; 2010
Elevation (m.a.s.l.)
572
516
Slope (%)
21–28
35–53
Climate type
Tropical Savannah
Tropical Monsoonal
Rainfall (mm a
À1
)
1,352; 1,288; 1,051
1,035; 1,329
Soil type
a
Humic Lixisol
Haplic Luvisol
SOM (%)
3.5
0.76–1.26
Tot N. (%)
0.14
0.08–1.3
Avail. P (mg kg
À1
)
14
b
2.46–2.7
c
Land use history
2001–2003 grass fallow;
before 2001 swiddening
Since 1999 maize-based cropping,
upland rice (1997/1998);
before 1997 secondary forest
Maize-based field trials:
T 1 (control)
Minimum tillage
d
Farmers’ practice
e
T 2
Min. tillage + grass strip
(Vetiveria zizanioides)
Farmers’ practice + contour strips
(Panicum maximum)
T 3
Min. tillage + grass barrier
(Brachiaria ruziziensis)
Min. tillage + cover crop
(Arachis pintoi)
T 4
Min. tillage + hedgerow
(Leucaena leucocephala)
Min. tillage + relay cropping
(Phaesolus calcaratus)
a
WRB 2007
b
Bray (II)
c
Bray (I)
d
Weeding only when necessary
e
Plowing, hoeing, weeding
7 Soil Conservation on Sloping Land: Technical Options and Adoption Constraints
241
modeling study looks at the longer term developments of the use of SCT in the
sloping environments of Southeast Asia (Lippe et al. 2011).
7.3.1 Description of Study Sites and the Experimental Design
The case study area in north-east Thailand was Ban Bo Muang Noi in Loei
Province, whereas the field trials and the modeling study in Vietnam were
conducted in Chieng Khoi commune, Son La province in north-west Vietnam.
A summary of the environmental features of both sites is given in Table 7.2.
A relatively fertile humic Lixisol was found in Ban Bo Muang Noi, whereas soil
fertility levels in Chieng Khoi were comparatively low for SOM, total nitrogen and
available phosphorous, probably a result of the continuous cropping history and the
steep slopes, making the site prone to soil erosion. Annual rainfall regimes are
similar at both sites, with figures ranging from 1,000 to 1,300 mm
À1 a year during
the study period.
Table 7.2 Environmental features of the study sites – Ban Bo Muang Noi in north-east Thailand
and Chieng Khoi in north-west Vietnam
Site conditions
Ban Bo Muang Noi
Chieng Khoi
Monitoring years
2003; 2004; 2005
2009; 2010
Elevation (m.a.s.l.)
572
516
Slope (%)
21–28
35–53
Climate type
Tropical Savannah
Tropical Monsoonal
Rainfall (mm a
À1
)
1,352; 1,288; 1,051
1,035; 1,329
Soil type
a
Humic Lixisol
Haplic Luvisol
SOM (%)
3.5
0.76–1.26
Tot N. (%)
0.14
0.08–1.3
Avail. P (mg kg
À1
)
14
b
2.46–2.7
c
Land use history
2001–2003 grass fallow;
before 2001 swiddening
Since 1999 maize-based cropping,
upland rice (1997/1998);
before 1997 secondary forest
Maize-based field trials:
T 1 (control)
Minimum tillage
d
Farmers’ practice
e
T 2
Min. tillage + grass strip
(Vetiveria zizanioides)
Farmers’ practice + contour strips
(Panicum maximum)
T 3
Min. tillage + grass barrier
(Brachiaria ruziziensis)
Min. tillage + cover crop
(Arachis pintoi)
T 4
Min. tillage + hedgerow
(Leucaena leucocephala)
Min. tillage + relay cropping
(Phaesolus calcaratus)
a
WRB 2007
b
Bray (II)
c
Bray (I)
d
Weeding only when necessary
e
Plowing, hoeing, weeding
7 Soil Conservation on Sloping Land: Technical Options and Adoption Constraints
241