Dn Mungai

Wind protection in a hedged agroforestry system in semiarid Kenya

In semiarid Laikipia (Kenya) severe crop damage and loss of mulch material may be caused by south to south-easterly winds from June to September. Demonstration agroforestry systems which surround farms with live fences had some success in protecting crops, mulch and soil, but great care must be taken, because air may be channelled through or over them. For demonstration purposes, a deliberate gap was made in a two meter high Coleus barbatus live fence to study its effect on wind speed and damage to crops. The effectiveness of protection given by this hedge together with intercropped Grevillea robusta trees was quantified using electrical cup anemometers. The combination of hedges and trees gave protection to a maize/bean intercrop but the biomass distribution was not the most suitable one. This picture was complicated by variable wind direction and interactions between wind and the biomass of hedges and trees. The lowest efficiency of wind reduction occurred closest to the deliberate gap, where also the lowest protection by the Grevillea trees was found. South to south-easterly winds increased the gap effect and caused gradients in tree protection perpendicular to the southern hedge. This gave at times wind speeds even higher than outside the system. Only visually wind effects could be detected. Trees and hedges strongly competed with the crops if not root pruned.

New Approach in Research Education to Solve Problems of Dryland Farming in Africa

For quite some time now, Africa has faced food shortages that are largely due to deterioration of agricultural environments and high population growth rates, leading to a combination of production pressures. The agricultural problems are particularly pronounced in dryland farming, and the means to mitigate them have to be mainly of a low external input nature. A case study from Kenya of an integrated research education approach holds much promise for contributions to solve such food production problems in the drylands of Africa and other low external input sustainable agriculture (LEISA). The approach emphasizes interdisciplinary research education of local scientists by problem‐oriented research in tackling environmental hazards facing the farmers. Six primary sequential steps, from problem identification via field quantification to the contributions to solutions, are distinguished as essential. In the Kenyan example, it was possible to give a “weather advisory,”; that is, an extension message with stron...

Measuring solar radiation transmission in tropical agriculture using tube solarimeters; a warning

In Kenya, the ratio of the output of north-south (N-S) mounted tube solarimeters (TSLs) to that of dome solarimeters and an east-west (E-W) mounted TSL confirmed large divergences of the N-S mounted instrument around solar noon and early and late in the day, owing to direction-related geometrical factors of radiation interaction with the glass envelope, which are not fully understood. A difference in solarimeter output of NE-SW mounting compared with E-W mounting remained within the accuracy limits. High ambient temperatures (near 40°C) with low wind speeds (less than 0.3 m s−1) appeared to increase tube output relative to that of the Kipp solarimeter by 10–20%. Condensation inside the tube increased the output by less than 5%. Ancillary indoor data in the Netherlands confirm these ambient effects. These errors may add to the geometrical ones and together they lead to instrument-based distortions in the interpretation of derived parameters such as radiant energy conversion to dry matter and radiation extinction in mulches and crops. An example of the latter, for grass mulches, is given that confirms earlier results obtained in Dar es Salaam. Calibrations of the tubes as a function of time and ambient conditions against a standard instrument and, where possible, near E-W mounting are therefore necessary under tropical conditions. Under these conditions, filtered TSLs appear to be unreliable for determination of photosynthetically active radiation, as a comparison with a Line Quantum Sensor confirmed.

What rights and benefits? The implementation of participatory forest management in Kenya: The case of Eastern Mau Forest Reserve

ABSTRACT The study espoused the access analytical framework to investigate how introduction of Participatory Forest Management (PFM) in Kenya has changed the various actors’ ability to benefit from the forest resources of Eastern Mau Forest Reserve. Data collected through key informant interviews, and a household survey showed that implementation of PFM has triggered new income opportunities for forest adjacent communities in seedling production and beekeeping. However, PFM bestowed no real decision-making powers to the established Community Forest Associations (CFAs) over important forest resources such as timber and firewood. Members of the local communities and other actors have continued to access these resources through various structural and relational means, in the same way as before the introduction of PFM. Further, it is documented that PFM has introduced additional burdens on the local communities, especially the poorest households, as a result of increased enforcement of rules. Based on these findings, it is suggested that the PFM policy in Kenya, in its current form, is unlikely to realize its dual objectives of forest conservation and livelihood enhancement. To attain them would require a further devolution of rights to the CFAs.