TILLAGE AND FERTILIZER EFFECT ON ROOT DISTRIBUTION, WATER UPTAKE AND YIELD OF MAIZE IN INLAND VALLEY SWAMPS IN SOUTHWESTERN NIGERIA

摘要

Information on the hydraulic properties of a soil is important in understanding soil drainage, solute transport and water supply to plants, for improved agricultural production. Such information is, however, scarce for the wetlands in southwestern Nigeria. This study evaluated the effect of mound-tillage (MT), ridge-tillage (RT), and no-tillage (NT), with fertilizer (F) and without fertilizer (Fo) on root growth, water extraction and yield of maize in three representative inland valley swamps, namely, very poorly drained (AY11L), poorly drained (AY13D), and imperfectly drained (AY22R) in the Ayepe area of Southwestern Nigeria. Root growth of maize was significantly (P<0.05) increased by the application of fertilizer. The increases were greater in the 30 cm depth of the MT than RT and NT systems. Soil water storage (theta), root water extraction (r_z) and total transpiration (R_z) varied greatly among the tillage and fertilizer combinations, but generally higher in the mound-till with fertilizer than the ridge-till and no-till with fertilizer treatments in the 1989/90 dry season trial and higher in RT with fertilizer than RT without fertilizer in 1990/91 diy season trial. Green maize yield increased greatly in MT (3.89t/ha) compared with RT (2.77 t/ha) and NT (3.13 t/ha) in AY13D (poorly drained). Yields in AY22R (imperfectly drained) averaged 3.88 t/ha in MT, 2.73 t/ha in RT and 2.72 t/ha in NT. The moun -tillage system may be a more suitable soil and water management practice than the ridge-tillage and no-tillage systems for increases in crop production in the wet inland valleys in southwestern Nigeria.