102
3.5 Nitrogen Uptake by Maize Plants as Influenced by
the Previous Cropping Systems at Lilongwe and Dowa
Sites
Figure 3 shows N uptake by the maize plants. There were significant differences
(P < 0.05) as influenced by both cropping system and N fertilizer application. Plots
that were previously legume-based showed significantly higher (P < 0.05) N uptake
than the Sole MZ and Sole MZ + 92 N. Increasing N application rate led to significant increases in N uptake by the maize plants. However, from plots that were previously legume-based, N uptake rates at 45, 90 and 120 kg N ha
−1
were not significantly
different; but all these were significantly higher (P < 0.05) than the treatment with
0 kg N ha
−1
.
The legume-based systems led to higher N uptake by a range of 38% in the
PP + MZ intercrop to 68% in the Sole CP at 0 kg N ha
−1
as compared to that in the
Sole MZ. On the other hand, at the highest rate of 120 kg N ha
−1
, the legume-based
systems led to increases in N uptake by a range of 28% in PP + MZ intercrop to 48%
in the Sole CP over the Sole MZ. Plots that previously contained Sole CP and Sole
PP showed slightly higher N uptakes than the rest of the treatment plots.
Similar to the Lilongwe site, in the Dowa site, plant N uptake by subsequent
maize was significantly influenced by both the previous cropping systems and N
fertilizer application. Increasing fertilizer N application led to significant
increases in N uptake (Fig. 3). Nitrogen uptake rates at 45, 90 and 120 kg N ha
−1
were all significantly higher (P < 0.05) than that at 0 kg N ha
−1
but were not
significantly higher amongst themselves. The legume-based systems led to
higher N uptake by a range of 23% in the CP + MZ intercrop to 41% in the
PP + MZ at 0 kg N ha
−1
than that in the Sole MZ. On the other hand, at the highest rate of N (120 kg N ha
−1
) the legume-based systems led to increases in N
uptake by a range of 23% in PP + MZ intercrop to 36% in the PP + CP intercrop
over the Sole MZ.
3.6 Maize Grain and Total Dry Matter Yields and Harvest
Indices as Influenced by the Previous Cropping Systems
at Lilongwe and Dowa Sites
Maize grain and total dry matter or aboveground biomass were significantly
(P < 0.05) influenced by both cropping system and N application (Fig. 4).
Increasing the rate of N application led to increase in yields. Treatments that
were previously legume-based showed significantly higher (P < 0.05) maize
grain yields at all the four rates of N fertilizers than that by the treatments under
the previous Sole MZ. Amongst the previous legume-based treatments, the
0 kg N ha
−1
showed significantly lower yields than those by the rest of the higher
K. O. W. Njira et al.
3.5 Nitrogen Uptake by Maize Plants as Influenced by
the Previous Cropping Systems at Lilongwe and Dowa
Sites
Figure 3 shows N uptake by the maize plants. There were significant differences
(P < 0.05) as influenced by both cropping system and N fertilizer application. Plots
that were previously legume-based showed significantly higher (P < 0.05) N uptake
than the Sole MZ and Sole MZ + 92 N. Increasing N application rate led to significant increases in N uptake by the maize plants. However, from plots that were previously legume-based, N uptake rates at 45, 90 and 120 kg N ha
−1
were not significantly
different; but all these were significantly higher (P < 0.05) than the treatment with
0 kg N ha
−1
.
The legume-based systems led to higher N uptake by a range of 38% in the
PP + MZ intercrop to 68% in the Sole CP at 0 kg N ha
−1
as compared to that in the
Sole MZ. On the other hand, at the highest rate of 120 kg N ha
−1
, the legume-based
systems led to increases in N uptake by a range of 28% in PP + MZ intercrop to 48%
in the Sole CP over the Sole MZ. Plots that previously contained Sole CP and Sole
PP showed slightly higher N uptakes than the rest of the treatment plots.
Similar to the Lilongwe site, in the Dowa site, plant N uptake by subsequent
maize was significantly influenced by both the previous cropping systems and N
fertilizer application. Increasing fertilizer N application led to significant
increases in N uptake (Fig. 3). Nitrogen uptake rates at 45, 90 and 120 kg N ha
−1
were all significantly higher (P < 0.05) than that at 0 kg N ha
−1
but were not
significantly higher amongst themselves. The legume-based systems led to
higher N uptake by a range of 23% in the CP + MZ intercrop to 41% in the
PP + MZ at 0 kg N ha
−1
than that in the Sole MZ. On the other hand, at the highest rate of N (120 kg N ha
−1
) the legume-based systems led to increases in N
uptake by a range of 23% in PP + MZ intercrop to 36% in the PP + CP intercrop
over the Sole MZ.
3.6 Maize Grain and Total Dry Matter Yields and Harvest
Indices as Influenced by the Previous Cropping Systems
at Lilongwe and Dowa Sites
Maize grain and total dry matter or aboveground biomass were significantly
(P < 0.05) influenced by both cropping system and N application (Fig. 4).
Increasing the rate of N application led to increase in yields. Treatments that
were previously legume-based showed significantly higher (P < 0.05) maize
grain yields at all the four rates of N fertilizers than that by the treatments under
the previous Sole MZ. Amongst the previous legume-based treatments, the
0 kg N ha
−1
showed significantly lower yields than those by the rest of the higher
K. O. W. Njira et al.