Nodulation, leaf harvesting intensity and interval of the black-eyed bean (BEB) (Vigna unguiculata L. Walpers) cowpea type at the University of Zimbabwe, Harare, Zimbabwe

A glasshouse pot experiment was carried out at the University of Zimbabwe, Crop Science Department in 2006 to 2007 rainy season to determine the effect of leaf harvesting intensity and interval on cowpea biological nitrogen fixation through nodulation. The experiment was designed as a three factor factorial. The first factor was leaf harvesting frequency with two levels: leaves harvested weekly or fortnightly. The second factor was leaf harvesting intensity with three levels: harvesting one leaf, two leaves and three leaves per branch. The third factor was soil with two levels: Mutoko sand and UZ red clay soil. The experiment was arranged in a Randomized Complete Block Design (RCBD) with three replications. There was no significant difference (p>0.05) on the number of nodules formed at different intensities and frequency at 6, 9 and 12 weeks after crop emergence. Significant difference (p<0.05) in nodule weight was observed as it decreased with increase in leaf harvesting intensity. Harvesting weekly produced lower nodule weight (0.31 g) than harvesting fortnightly (1.08 g). Mutoko sand soil produced higher nodule weight (0.69 g) than UZ clay soil (0.43 g). Leaf yield increased with increasing leaf harvest intensity, harvesting weekly produced higher yield (10.43 g) than harvesting fortnightly (3.22 g) and Mutoko soil had lower leaf yield than UZ clay soil. There was a significant (p<0.05) difference in seed yield, highest yield was obtained when no leaves were harvested and lowest yield when three leaves were harvested. Soil type effect also significantly (p<0.05) reduced harvestable seed weight from 1.00 g on sand soil to 4.12 g on clay soil. Similar trends were observed for aboveground and total biomass yield. In this study, leaf harvesting intensity and interval has been observed to affect nodulation, grain and biomass yield of glasshouse grown Black-eyed bean (BEB) cowpea. The extent to which these effects were felt also depends on the characteristics of the soil

The effect of undersowing euca!yptus (Euca/ypfus Camaldulensis L.) with maize (Zea mays L) and cowpeas (Vigna unguiculata L.) on tree growth and crop performance

A journal article on the effect of undersowing Euca!yptus with maize and cow-peas on tree growth and crop performance in Zimbabwe's agricultural sector..Maize (Zea mays L.) hybrid R201 and cowpea (Vigna unguiculata L.) variety IT82D- 875 were separately inter-row interplanted with gum-tree (Eucalyptus camaldulensis L.) during the 1995-96 cropping season at Domboshava Training Centre. Planting E. camaldulensis with cowpeas and maize had no marked effect on the yields of the two annual crops. Sole clean-weeded E. camaldulensis had significantly thicker circumference than the Eucalyptus in the other treatments, but was comparable to Eucalyptus interplanted with the annual crops in terms of branching habit. However, E. camaldulensis interplanted with maize showed a slightly higher performance (branching and circumference) than that interplanted with cowpeas. This was probably related to the fertilizer added to the maize/£. camaldulensis intercrop since no fertilizer was added to the cowpea/£. camaldulensis intercrop. Management factors such as clean weeding in sole Eucalyptus markedly increased tree performance as observed through parameters of stem circumference and branching compared to those of the unweeded sole Eucalyptus situation. Neither tree branching pattern, height growth nor soil moisture were significantly affected by intercropping with annual crops. Undersowing annual crops to E. camaldulensis will facilitate maximum utilization of land and light in the early years of E. camaldulensis woodlot establishment. This approach will also allow better tree growth when compared to the unweeded situation which is common in small-holder farming

Introduction of improved fallows of Sesbania and pigeon pea under a maize stand.

The productivity of soils in smallholder agriculture can be improved by the introduction of short-duration (2-5 years) improved fallows. The availability of land is a constraint, so these improved fallows should be designed so that farmers can derive other benefits over the duration of the fallow phase. The introduction of improved fallow species of Sesbania sesban, Cajanus cajan and a 50:50 mixture of the two species under a maize stand in the first year of fallow establishment had no effect on maize grain yield, neither was the growth of the tree species curtailed. The grain yields of pigeon peas grown alone or under maize were similar but the tree species affected the weight of maize stover. Establishing these tree fallows under annual crops during the first year of fallow establishment may induce farmers to use this approach since they can harvest some grain in one of the years during the fallow phase. Transactions of the Zimbabwe Scientific Association Volume 72 (Supplement) 1998, pp. 84-8