| Sumario: | We studied the effects of four different methods of land clearing in western Nigeria
on soil physical properties of an Alfisol and on the root growth of the following crop.
The methods used were manual clearing and clearing with a shearblade, a treepusher,
and a treepusher/root rake. Soil physical properties measured were bulk density,
saturated hydraulic conductivity, infiltration rate and cumulative infiltration, total
porosity, pore size distribution, and soil water retention. Mechanical clearing increased
bulk density and proportion of medium-sized pores (2 to 14.3-µm radius) and decreased
infiltration rate, cumulative infiltration, saturated hydraulic conductivity, total porosity, and proportion of macropores (>14.3-um radius). Soil water content at a potential
of 0 kPa was significantly reduced, whereas that at potentials of -10 and -33 kPa was
increased. In comparison with the forested control, the magnitude of changes in soil
physical properties was in the order of manual clearing < treepusher < shearblade <
treepusher/root rake. Although the differential effects of land clearing methods on the
soil were reflected only in the initial pattern of maize root growth during the seedling
stage, it was sufficient to affect grain yield. Root growth of mucuna and cowpea were
not affected by the changes in soil physical properties.
|
|---|