Environmental Engineering Reference
In-Depth Information
Table 11.2 Soil physical properties under various land-use stages at Tano-Odumasi
Land-use
Soil depth
Bulk density
(g/cm
3
)
stage
Field type
(cm)
Porosity (%)
Agroforest
Plantain, cocoyam.
0-15
1.31
50.41
(
proka
cassava, trees,
15-30
1.47
44.49
managed) JC
oil-palm, fruit
Mean
1.39
44.45
trees (mango, pear)
Annual cropping
Maize/cassava
0-15
1.19
55.09
(
proka
intercrop
15-30
1.46
45.06
managed) Barnie
Mean
1.33
50.08
Annual cropping
Maize/cassava
0-15
1.29
51.00
(slash-and-burn)
intercrop
15-30
1.65
37.67
JC
Mean
1.47
44.34
Native forest
0-15
0.92
65.42
(sacred grove)
15-30
1.48
44.02
Mean
1.20
54.72
Source: Based on data from PLEC field survey
Soil chemical properties versus various land-use stages at
Tano-Odumasi
The results of the chemical analyses (Table 11.3) indicated all nutrients in the
topsoil (0-15 cm), except phosphorus and potassium in the
proka
annual
cropping, to be generally higher in the
proka
-managed land-use stages.
However, the
proka
annual cropping recorded the lowest levels of phosphorus
and potassium. The higher levels of phosphorus and potassium on the freshly
prepared field of the slash-and-burn annual cropping may be due to the ash from
the burnt biomass and an earlier application of NPK fertilizer to a tomato crop
on that field.
In the sacred grove there was a higher content of nutrients in the subsoil
(15-30 cm) than in the top 0-15 cm.
Residual effect of slash-and-burn and no-burn on soil chemical
properties
Slash-and-burn and slash-and-no-burn have significant residual effects on the
chemical properties of soils. This is demonstrated by a study of farmers' fields at
Nkawie in central Ghana (Tables 11.4 and 11.5; Quansah
et al
., 1998;
Amoakohene, 1999). The land-use stage and the field type are annual cropping
and maize/cassava intercrop respectively. The mulch was a mixture of
Panicum
