| dc.description.abstract | In addition to low soil moisture and its holding capacity, constraints to arable agricultural
production in Botswana include low levels of nutrients, especially phosphorus. The objectives
of the study were to determine the effect of phosphorus on the growth, yield, and uptake of
nutrients by intercropped maize and cowpea. The experiment was conducted at Botswana
University of Agriculture and Natural Resources grounds at Sebele, as a split plot in a
randomized complete block design with three replications. Four levels of phosphorous as the
main treatments were used and the source of phosphorus was single superphosphate. Tine
levels of phosphorus (P) were 0, 50, 100 and 150 kg/ha. There were three sub-treatments
being intercropped maize and cowpea, sole maize and sole cowpea. The maize variety was
Kalahari Early Pearl (KEP) while a local cowpea landrace Tswana (mogweokgotsheng) were
used. Data were tested for normality and subjected to analysis of variance (ANOVA).
Application of P did not reveal significant differences in dry matter accumulation. Also,
differences in the P application rate did not show significant differences. In the uptake of all
macro-and micro-nutrients tested in the whole plant dry matter. However, the different
cropping systems revealed differences in the uptake of both macro- and micro-nutrients.
Intercropped cowpea produced the highest whole plant dry matter in grams compared to sole
cowpea, with dry matter for intercropped plants being about 2.3 times more than for sole
plants. This could be due to low inter-row competition for intercropped cowpea. Thus, maize
and cowpea roots explored different parts of the soil due to differences in their root
architecture. There was some significant P application rate x cropping systems interactions
for Fe and Cu in whole plants as well as Ca, Mg, Na and Fc in cowpea seed. For whole
plants, the highest Fe uptake was shown by intercropped cowpea plants that did not receive
any P whereas for the seed, intercropped cowpea which received 50 kg P/ha exhibited the highest Fe content. Seed from sole cowpea plants extracted the highest amount of Ca and Mg
at all P application levels. Positive, highly significant relationships were established for
whole plant P and K (r = 0.7971, p = 0.0000), whole plant P and Mn (r = 0.8577, p = 0.0000),
and whole plant P and Fc (r = 0.6160, p = 0.0000) as well as for seed P and Mg (r = 0.7915, p
= 0.000004) and seed P and K (r = 0.7949, p = 0.000003). Taken together, this study has
shown that the application of P did not affect the production of dry matter on the Luvisols at Sebele.
It has also been shown that P application did not affect the accumulation of nutrients in whole
plants as well as in the seed. However, it was shown that intercropped cowpea accumulated
more nutrients in whole plants and in seeds. Therefore, cowpea crop should be used
in cereal legume cropping system by Batswana farmers because of it ability to accumulate
more nutrients. | en_US |
