PATTERN OF SOIL-MOISTURE DEPLETION IN ALLEY CROPPING UNDER SEMIARID CONDITIONS IN ZAMBIA

The pattern of soil moisture changes was studied during a cropping season in an alley cropping experiment of maize with Leucaena leucocephala and Flemingia macrophylla at the SADC/ICRAF Agroforestry Research Station in a semiarid region near Lusaka, Zambia (28-degrees-29'56'' East and 15-degrees-21'32'' South). Soil moisture potential was monitored at regular intervals using tensiometers installed at 15, 30 and 45 cm depths in fertilized and unfertilized alleys within the double hedgerow, and the first, second and third rows of maize in the alleys. Soil moisture moved mostly towards the top horizon during very dry conditions. Alleys that had received a combination of fertilizer and hedgerow prunings depleted more moisture than those that had only hedgerow prunings. There were no differences in moisture utilization pattern between leucaena and flemingia hedgerows. The hedgerows depleted the same amount of moisture as the maize plants. However, during dry conditions, there was a higher soil moisture content under the hedgerows than in maize rows, indicating that there was no apparent competition for moisture between the hedgerows and the maize plants.