M. Sarr et al., Effects of soil faunal activity and woody shrubs on water infiltration rates in a semi-arid fallow of Senegal, APPL SOIL E, 16(3), 2001, pp. 283-290
The effects of soil faunal activity on the physical properties of the soils
of a 2-year-old fallow in the sahelian zone of Senegal were studied. Facto
rs studied included the presence or absence of woody shrubs and the effect
of protection of plots from grazing and removal of fuel wood. The experimen
tal design included a control in which termite activity was excluded by tre
ating the soil with the persistent insecticide dieldrin.
In both the protected and unprotected area of the experiment, termite burro
wing activity (as measured by the number of entrance holes per square-metre
) and water infiltration rates were significantly (ca. 80%) lower in termit
e exclusion plots than in plots not treated with insecticide 2 years after
initial treatment. In protected plots where termites were present, there wa
s a significant increase in infiltration rates in the part where woody shru
bs were removed. In unprotected plots, by contrast, the presence of shrubs
significantly increased infiltration rates, whether or not termites were pr
esent.
Burrowing activity of earthworms was greater in the protected than in the u
nprotected area, and in the unprotected area burrowing in dieldrin treated
plots was significantly increased by almost 65%. Activity of ants appeared
to be little affected by the different treatments. The results demonstrate
that the presence of healthy soil faunal populations was important in the i
nfiltration of water in fallow soils and that protection from grazing and h
uman activity improves faunal activity and water infiltration. (C) 2001 Els
evier Science B.V. All rights reserved.