Agriculture Reference
In-Depth Information
TABLE 12.1
Soil Loss Rates due to Interrill and Rill Erosion on Different Geopedologic
Units in Uluguru Mountains, Tanzania
Soil Loss (Mg/ha/year)
Interrill
Rill
Geopedologic
Units
Slope
(%)
Mean
s.d
Min
Max
Mean
s.d
Min
Max
N
Mountain Ridges
Hyperferrallic
Cambisols
>60
115***
35
70
143
258***
15
240
275
5
Leptic Cambisols
50-60
61**
15
45
79
161***
15
141
175
4
Mountain Foothills
Hyperferrallic
Cambisols
>60
98***
12
81
110
235***
11
222
254
6
Endoleptic
Cambisols
50-60
44**
6
37
49
111***
9
96
121
5
Chromic Lixisols
40-50
41**
15
21
60
91***
14
68
107
9
Profondic Acrisols
30-40
13
NS
4
7
24
28*
5
24
35
7
Source:
Kimaro, D.N., J. Poesen, B.M. Msanya, and J.A. Deckers,
Catena
, 75, 38, 2008. With
permission.
Note:
Max, maximum; Min, minimum;
N
, number of observations; NS, not significant; s.d, standard
deviation; s.e, standard error.
s.e = 11; *
P
< .05; **
P
< .01; ***
P
< .001.
Mg/ha/year was observed in the arable lands on the slopes of Mount Kilimanjaro,
Tanzania (Temple 1972). In the Uluguru Mountains, Tanzania, interrill and rill ero-
sion processes are dominant and result in mean soil loss ranging from 91 to 258
Mg/ha/year (Table 12.1). The soil erosion processes demonstrated in this area vary
spatially along the landscape both in terms of the type of process and the degree of
severity. Such spatial information could form an important guide for understanding
the behavior and occurrence of soil erosion in a complex mountainous environment.
The information could be taken as a guide for setting up soil and water conservation
priorities in East African Highlands.
12.2.1.1 Tillage Erosion
Tillage erosion, also referred to as “arable erosion” (Zachar 1982) or mechanical
soil erosion (Kiburys 1995), is the process of soil movement caused by the force
applied by agricultural tools and by gravity (Lindstrom et al. 1992; Govers et al.
1994; Dercon 2001). At the scale of farm plot, tillage erosion can be recognized by
a less fertile tillage step at the top of the field (due to soil profile truncation) and the
development of a soil bank with a high soil fertility status at the bottom of the field if
the physical barrier is present (Turkelboom et al. 1999; Nyssen et al. 2000; Poesen et
