Environmental Engineering Reference
In-Depth Information
Generally, yield and height of crops appeared to increase with increasing distance
from the trees irrespective of the crop type (Table 14.3; Figures 14.1-14.3), except
for cocoyam growing under Cola millenii (Figure 14.4) where plants growing two
metres from the bole were taller than those growing 10 m from the bole or tree trunk.
For cassava and maize, yield increased as distance from tree trunk is increased,
with Ceiba pentandra having a greater stimulating influence (on the yield) than
Cola millenii . However, at the time of preparing this chapter, the yield of cocoyam
growing under Cola millenii had not been determined.
From the results, it appears that shading contributes to reduced growth vigour
of crops. The only exception is cocoyam, which tended to do better closest to the
bole of Cola millenii , which, according to farmers, generally combines poorly
with other crops.
Table 14.3 Crop yields (kg) in relation to distance from the trunk/bole of tree
Crop under
Distance from bole/trunk of tree
different tree
combinations
2 m
4 m
6 m
8 m
10 m
Cassava under
1.80
7.80
13.80
14.00
17.50
Ceiba pentandra
(0.30)
(1.30)
(2.30)
(2.33)
(2.92)
Cassava under
1.80
3.90
9.60
11.40
14.0
Cola millenii
(0.30)
(0.65)
(1.60)
(1.90)
(2.33)
Maize under
0.60
0.65
0.65
0.70
0.75
Cordia millenii
(0.12)
(0.13)
(0.13)
(0.14)
(0.15)
Notes:
1. Crop planted in concentric rings two metres apart from base of tree bole/trunk.
2. Upper values represent total yield per concentric ring.
3. Lower values in parenthesis represent mean weight per crop.
250
200
150
100
50
0
12 3 45 67 8 9 0
No. of weeks
2m
10 m
Figure 14.1 Effect of distance from tree trunk (2 m or 10 m) on height growth of maize
under Cordia millenii
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