A joint contribution from the Department of Soil Science, Egerton University,
PO Box 536, Njoro, Kenya, and the Agricultural Research Organization, the
Volcani Center, Israel, No. 603/01, 2001 series.
Smallholder farmers in arid and semi-arid regions use indigenous soil and
water conservation (ISWC) techniques, such as trash lines and stone lines
spaced about 15 m apart across the slope. This work evaluated the effects of
size of trash lines and decreasing the space between trash or stone lines to 2
m on runoff, erosion, and corn and cowpea yields. Big trash line (BTL), small
trash line (STL), and stone line (SL) techniques, and a control (no ISWC
technique) were evaluated in 12 runoff plots (2 by 6 m each) with 10%
slope in a semi-arid area in Kenya, during 5 consecutive rainy seasons. The
ISWC techniques significantly (P ≤ 0.05) decreased runoff and soil loss,
and increased corn and cowpea yields, compared with the control treatment in
most of the rainy seasons. The BTL was, in general, the most effective
technique; no consistent differences were found between the STL and SL
techniques. In BTL, STL, SL, and control, the seasonal average runoff for each
treatment was 25, 31, 29, and 51 mm, respectively; the seasonal average soil
loss was 0.23, 0.33, 0.3, and 0.67 Mg/ha, respectively; and the seasonal
average biomass (grain and stover of corn and cowpea) was 4.8, 4.0, 4.0, and
2.5 Mg/ha, respectively. The seasonal biomass increased linearly and
significantly (P ≤ 0.01) with increasing water infiltration. As more water
infiltrated, more water was available for crop production, and the yield was
higher.
trash lines, stone lines, steep land, seal formation.
Effects of land use, slope gradient, and soil and water conservation structures on runoff and soil loss in semi-arid Northern Ethiopia