SOIL-MOISTURE CHANGES AND MAIZE PRODUCTIVITY UNDER ALLEY CROPPING WITH LEUCAENA AND FLEMINGIA HEDGEROWS AT CHALIMBANA NEAR LUSAKA, ZAMBIA

Soil moisture changes and maize yield were studied in 2-year-old alley s of Leucaena leucocephala and Flemingia macrophylla at Chalimbana, Za mbia. Field tensiometers were installed at 15, 30 and 45 cm depth, in fertilized and unfertilized alleys within the double hedgerows, and th e first, second and third rows of maize, and were monitored throughout one maize growing season in 1989/1990. In general, maize growth (indi cated by height and dry matter measured at roughly fortnightly interna l) was higher (P < 0.01) in fertilized alleys than in unfertilized all eys, and there were no differences between Leucaena and Flemingia alle ys. In both fertilized and unfertilized alleys, the maize plants were 20% shorter (P < 0.01) in the first row (nearer the hedgerows) than in the second and third maize rows. Maize dry matter yield was 30% more (P < 0.01) in unfertilized Flemingia alleys than in corresponding Leuc aena alleys. The grain yield was similar in the fertilized alleys of L eucaena and Flemingia. However, in unfertilized alleys, the grain yiel d in Flemingia alleys was 50% more than that of the corresponding Leuc aena alleys. The fertilized alleys produced twice as much grain as unf ertilized alleys when hedgerow prunings were added to the plots. The p runings as a source of nutrient did not appear to have any noticeable effect on crop productivity. The soil moisture content under both Leuc aena and Flemingia hedgerows was higher than under the maize rows in t he alleys throughout the growing season. The study shows that, under c onditions of low fertility and no addition of fertilizers, Leucaena is twice as competitive, as Flemingia for soil resources, and reduces yi eld of alley-cropped maize from 2.2 t ha-1 to 0.7 t ha-1. If, however, fertilizer is added, there are no short-term differences between the two hedgerow species.