Grain Legumes and Green Manures for Soil Fertility in ... - cimmyt

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Table 2. The effect of time of planting green manure
legume and type of maize/legume intercrop on maize
leaf area (cm 2 ) 6 WAP.
Maize leaf area
Intercrop Planted at same Planted 2 weeks
time
after maize
Maize/dolichos 2077a 2529
Maize/velvet 1311 b 2790
Maize/sunnhemp 2269a 2094
Maize/fishbean 1891a 2925
LSD (P < 0.05) 753
SED 365
Time of planting 1887 2584
LSD (P < 0.05) 377
SED 183
CV% 23
Means followed by the same letter in acolumn are not significantly
different IP < 0.05).
1.6
1.4
U
eo 0.8
0
..J
0.6
c , 0.4
e 0.2
~
. ~
Vi
20 40 60 80 100 120
Time (Days)
Figure 2. Effect of time of planting green manure legumes on Striga
of December. This was followed by poor rainfall
distribution in February where 60 mm of rainfall fell
on one day during the month. The subsequent
months also had a very low rainfall frequency. The
experiment was severely affected.
Striga asiatica counts. Although not significantly
different, legumes planted two weeks after maize
(PLTW) allowed slightly higher Striga asiatica counts
of 0.25 compared to 0.06 for simultaneous planting
in the field at Mlezu (80 days after plantirlg). Legume
intercropsshowed that they do not differ in the
way they suppress S. asiatica emergence. Time of
establishment of the legume is more important.
Discussion
Table 3. The effect of intercrop type and time of planting
of green manure legumes on Strig;: asiatica dry weight (gl
pot)
I)ntercrop
S. asiatica dry weight (g/pot)
Planted Legumes planted
simultaneously 2 weeks later
I Maize/dolichos 0.24 0.26
Maize/velvet bean 0.05 0.13
Maize/sunnhemp 0.26 0.49
Maize/fish bean 0.17 0.50
Significance (P < 0.05).
(lntercrop·Time)
NS
SED 0.20
Table 4. The effect of intercropping and time of
planting of green manure legumes on maize yield (g/pot)
Intercrop
Maize grain yield (g/pot)
PLST
PLTW
Maize/dolichos 2.1 2.7
Maize/velvet bean 1.4 11.9
Maize/sunnhemp 12.4 7.9
Maize/fish bean 5.2 4.9
Significance (P < 0.05).
IIntercrop·Time)
NS
SED 7.0
Grain yield. There were no interaction effects of
type of intercrops and their time of planting on
maize yield. Maize/dolichos and maize/velvet
bean resulted in higher yields when legumes were
planted two weeks later, although this was not significant.
The opposite was true for maize/
sunnhemp and maize/fish bean (Table 4).
Field Experiment at Mlezu
The rainfall distribution at Mlezu is in Figure 3. The
experiment was established during the second week
250
208.6
The study demonstrated that differences in planting
date for the component crops influenced competition
between component crops in the green manure
legume/maize intercrops (measured as leaf area
and plant height). Planting legumes and maize at
the same time increased inter species competition
for growth limiting factors, resulting in reduced
maize leaf area and maize plant heights. Where the
planting of maize and legumes was staggered, interspecies
competition was reduced and maize attained
higher leaf areas and height than with simultaneous
planting. Velvet bean reduced maize leaf
area. This could be attributed to velvpt bean's ro-
200
"§
/ill Frequency
~ '" ~Rainfall
§ fi 150
108.5
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