The following paragraphs present a summary of the monitoring results, focusing
on annual run-off (mm a
À1 ), soil loss rates (Mg ha
À1 ) and maize grain yields
(Mg ha
À1 ) per monitoring year. Further results, such as event-based soil losses
and run-off rates, or nitrogen leaching in the case of Ban Bo Muang Noi in
Thailand, can be found in Pansak et al. (2007, 2008), and in the case of Chieng
Khoi in Vietnam, in ENBW (2011) and Vu Dinh et al. (2012b).
7.3.2 Run-Off and Soil Loss as Affected by Soil Conservation
and Time
A common feature of all the treatments at Ban Bo Muang Noi was the reduction in
annual run-off and soil loss rates through the use of soil conservation treatments
(Table 7.3, Fig. 7.5a). Plots with hedgerow systems showed a progressive reduction
in run-off and soil loss over time, while the control without hedgerow was
characterized by a lower decrease in run-off and soil loss from the first to the
second year. However, total soil loss (1.6–2.5 Mg ha
À1 ) from the control plots
without hedgerows strongly reduced in the third year, confirmed by the significant
interaction between SCT and the relevant year (e.g., there was reduced rainfall in
year 3). In the third year, the lowest run-off was observed in the fertilized leucaena
hedge treatment, while the ruzi grass barrier treatment revealed the lowest soil loss.
In the third year, fertilizer application also significantly reduced run-off and soil
loss in most treatments, when compared to the unfertilized ones (data not
presented), probably due to the increased and better established plant soil cover.
Table 7.3 Run-off (mm a
À1
) during the period 2003–2005 in Ban Bo Muang Noi, Thailand, and
during 2009–2010 in Chieng Khoi, Vietnam, as affected by soil conservation technology
Year
Run-off (mm a
À1
)
Rainfall
(mm a
À1
)
Min.
tillage
Vetiver grass
strips
Ruzi grass
barriers
Leucaena
hedges
Ban Bo Muang Noi
a
Min. tillage
Vetiver grass
strips
Ruzi grass
barriers
Leucaena
hedges
2003
80 (2.2)
66 (2.9)
72 (0.5)
70 (1.7)
1,352
2004
65 (3.8)
34 (0.8)
53 (1.5)
34 (6.0)
1,288
2005
43 (5.5)
19 (1.0)
22 (2.6)
19 (7.4)
1,051
Chieng Khoi
Farmers’
practice
Panicum grass
barriers
Arachis cover
crops
Relay
cropping
2009
64 (46.5)
28 (6.9)
48 (28.3)
51 (13.9)
1,035
2010
162 (78.3)
69 (30.7)
14 (5.7)
130 (79.8)
1,329
a
Adapted from Pansak et al. (2007, 2008)
Note: Only fertilized treatments are presented. Numbers in brackets denote standard error of the
means
7 Soil Conservation on Sloping Land: Technical Options and Adoption Constraints
243
on annual run-off (mm a
À1 ), soil loss rates (Mg ha
À1 ) and maize grain yields
(Mg ha
À1 ) per monitoring year. Further results, such as event-based soil losses
and run-off rates, or nitrogen leaching in the case of Ban Bo Muang Noi in
Thailand, can be found in Pansak et al. (2007, 2008), and in the case of Chieng
Khoi in Vietnam, in ENBW (2011) and Vu Dinh et al. (2012b).
7.3.2 Run-Off and Soil Loss as Affected by Soil Conservation
and Time
A common feature of all the treatments at Ban Bo Muang Noi was the reduction in
annual run-off and soil loss rates through the use of soil conservation treatments
(Table 7.3, Fig. 7.5a). Plots with hedgerow systems showed a progressive reduction
in run-off and soil loss over time, while the control without hedgerow was
characterized by a lower decrease in run-off and soil loss from the first to the
second year. However, total soil loss (1.6–2.5 Mg ha
À1 ) from the control plots
without hedgerows strongly reduced in the third year, confirmed by the significant
interaction between SCT and the relevant year (e.g., there was reduced rainfall in
year 3). In the third year, the lowest run-off was observed in the fertilized leucaena
hedge treatment, while the ruzi grass barrier treatment revealed the lowest soil loss.
In the third year, fertilizer application also significantly reduced run-off and soil
loss in most treatments, when compared to the unfertilized ones (data not
presented), probably due to the increased and better established plant soil cover.
Table 7.3 Run-off (mm a
À1
) during the period 2003–2005 in Ban Bo Muang Noi, Thailand, and
during 2009–2010 in Chieng Khoi, Vietnam, as affected by soil conservation technology
Year
Run-off (mm a
À1
)
Rainfall
(mm a
À1
)
Min.
tillage
Vetiver grass
strips
Ruzi grass
barriers
Leucaena
hedges
Ban Bo Muang Noi
a
Min. tillage
Vetiver grass
strips
Ruzi grass
barriers
Leucaena
hedges
2003
80 (2.2)
66 (2.9)
72 (0.5)
70 (1.7)
1,352
2004
65 (3.8)
34 (0.8)
53 (1.5)
34 (6.0)
1,288
2005
43 (5.5)
19 (1.0)
22 (2.6)
19 (7.4)
1,051
Chieng Khoi
Farmers’
practice
Panicum grass
barriers
Arachis cover
crops
Relay
cropping
2009
64 (46.5)
28 (6.9)
48 (28.3)
51 (13.9)
1,035
2010
162 (78.3)
69 (30.7)
14 (5.7)
130 (79.8)
1,329
a
Adapted from Pansak et al. (2007, 2008)
Note: Only fertilized treatments are presented. Numbers in brackets denote standard error of the
means
7 Soil Conservation on Sloping Land: Technical Options and Adoption Constraints
243