Environmental Engineering Reference
In-Depth Information
Generally the potassium at virtually all depths was higher in the soil under the
burnt conditions than under the unburnt conditions at week 1. By week 5, however,
there was a higher potassium content at all the different depths of the soil under the
slash-no-burn conditions.
Except for soils from 0 to 5 cm during week 1, the calcium content at all depths
was relatively higher under the burnt conditions when compared to the slash-no-burn
conditions for both weeks 1 and 5 (Table 14.4).
In general, there was no significant difference between all the vegetative
growth parameters of the maize crop that were studied under both the slash-
and-burn and slash-without-burning (
proka
) conditions (Figures 14.5-14.9). This
is evident in the height growth (Fig. 14.5). Similar observations were made for the
leaf length (Figure 14.6) number of leaves (Figure 14.7), leaf width (Figure 14.8)
and mean stem diameter (Figure 14.9).
In terms of yield, each crop produced a maize cob irrespective of whether it was
from a slash-and-burn or slash-no-burn
proka
plot. The weights or biomass of the
entire crop (not dehusked) were 2.10 kg and 2.40 kg respectively for the plants
under both
proka
and slash-and-burn experimental conditions. Crop yield was
slightly higher on the slash-and-burn field than in the slash-no-burn or
proka
field.
This small difference may be reflective of the fertilizer effect of the ash when com-
pared to the situation under the
proka
farm, which has no ash associated with it
because of the avoidance of burning. Total yield of maize produced under the slash-
and-burn condition was slightly higher (2.40 kg) than that under the slash-but-
unburnt (
proka
) condition (2.10 kg). However, statistically, these values were not
found to be significant (Table 14.5; Figure 14.5).
The results obtained seem to indicate that the
proka
method may not confer
any advantage to the growth and development of crops in a slash-no-burn
100
80
60
40
20
0
1&2
3
4
5
6
7
Week no.
Slash-no-burn
Slash-and-burn
Figure 14.5 Effect of slash-and-burn and slash without burning on vegetative growth of
maize
