COMPARATIVE GROWTH OF MULTIPURPOSE TREES AND THEIR INFLUENCE ON SOIL MOISTURE AND MAIZE PERFORMANCE IN SEMI-ARID CONDITIONS, CENTRAL KENYA
Maintaining trees in cropland can help reduce the levels of carbon dioxide in the atmosphere, increase agricultural productivity and achieve climate resilience. However, it is unclear how trees impact on soil moisture and crop performance in semi-arid conditions. A study was undertaken to evaluate the growth of an exotic tree (Grevillea robusta) and indigenous tree species (Cordia africana, Vachellia xanthophlea, Vachellia seyal and Faidherbia albida), and their influence on soil moisture content and growth performance of maize at a long-term experiment in Juja. Trees established in 2011 were monitored for growth by measuring diameter at breast height (DBH) and height over a period of one year. Basal diameter and biomass of maize crops established in the trial plots was monitored for one season. There was no significant difference in height and DBH of the trees. Nevertheless, G. robusta had the greatest height, followed by V. seyal and V. xanthophlea while C. africana had the lowest. Mean DBH was highest in V. xanthophlea followed by G. robusta while F. albida had the lowest. Soil moisture content was higher in plots with trees than those without trees. Maize plants grown in plots with trees were significantly taller and had more biomass (P<0.05) than those in plots without trees; no significant differences were observed in maize basal diameter. Given the ecological limitations of semi-arid areas in Juja, the growth and biomass accumulation observed in the tree species is promising, being able to positively influence soil moisture without negatively affecting biomass of maize.