Agriculture Reference
In-Depth Information
TABLE 12.12
Annual Runoff Coefficient and Soil and Nutrient Loss in Different Seasons in
West Usambara Mountains, Tanzania
Long Rainy
Season
Short Rainy
Season
Treatment
Off-Season
Annual runoff coefficient
(mm/mm/year)
Bare
0.03
0.12
0.004
Control
0.02
0.8
0.003
Miraba
0.01
0.03
0.003
Miraba
+ FYM+
mulching
0.01
0.02
0.002
Soil loss (Mg/ha/year)
Bare
103
49
17
Control
80
34
17
Miraba
0.1
0.6
0.02
Miraba
+ FYM+
mulching
0.1
0.5
0.01
Total N loss (kg/ha/year)
Bare
308
155
0.9
Control
248
94
0.4
Miraba
0.4
8
0.2
Miraba
+ FYM +
mulching
<0.4
<8
<0.2
P loss (kg/ha/year)
Bare
0.3
0.3
0.0009
Control
0.2
0.2
0.0004
Miraba
0.0004
0.1
0.0001
Miraba
+ FYM +
mulching
<0.0004
<0.1
<0.0001
K loss (kg/ha/year)
Bare
8.3
2.5
0.02
Control
4.5
2.4
0.01
Miraba
0.02
<2.4
0.01
Miraba
+ FYM +
mulching
<0.02
<2.4
<0.01
Source:
Msita, H.B. 2013. Insights into indigenous soil and water conservation technologies in Western
Usambara Mountains, Tanzania. PhD thesis. KU Leuven, Belgium. p. 194. With permission.
carbon stock. Such practices constitute what is embedded in the principles of CA.
The range of sequestration potential for the different CA practices considered is
far from negative for continuous cultivation practices to around 40 Mg/ha with the
retention of crop residues and substantial addition of FYM (The Ecological Society
of America 2000).
In South America where millions of hectares of farmland have been under CA,
several studies reported gains in yields and income (Hobbs and Gupta 2004; IIRR
and ACT 2005; Derpsch 2005; Bolliger et al. 2006). The gains were attributed to
the improvements in soil-related qualities associated with CA, such as soil moisture
availability, soil nutrient availability, and reduction of erosion hazards (Roldan et al.
