Abstract:
Traditional shifting cultivation is a common agricultural practice in Northwestern
lowlands of Ethiopia particularly in Metema district. However, due to population
increment and shortage of lands, the fallow has decreased from time to time, whereby
declining soil productivity becomes a problem. The main objective of this study was to
determine the effect of fallowing period on soil physico-chemical properties. For this
study, first a reconnaissance survey was conducted to identify current fallowing periods
the farmers are practicing. The farmlands having different fallowing periods including no
fallow, 5 years, 10 years, 15 years and forestlands were purposively selected and soil
sample were collected using an auger. From each site, one forest soil taken that helps to
compare changes due to farming and fallowing, and a 20 m by 20 m sampling plot
delineated and 5 sub-samples were taken at three depths (0-10 cm, 10-20 and 20-30 cm)
and the samples at each depth were bulked and a composite sample drawn. Soil organic
carbon, bulk density, pH, porosity, CEC, N, AP
and AK were analyzed in the laboratory.
As a result, statistically significant differences (p≤0.05) were obtained between the
fallowing periods for soil pH, OC, TN, AvaP, CEC, AvaK levels. Length of fallow periods
was also important for soil fertility restoration and improvement of soil properties. Tenyear
fallow
periods
recovered
higher
total porosity, CEC, TN, AP, and AK than with no
fallow, 5 years, 15 years fallow. The increase in soil fertility in all fallow lands have been
attributed to the decay of above-ground and root biomass of fallow vegetation and the
presence of native leguminous species among the vegetation. Generally, the soil pH, OC,
TN, AvaP, AvaK and porosity increases from no fallow to 10-years fallow and decrease
after 10-years fallow period. Soil bulk densities have the reverse trends that decrease with
an increase fallow periods. The optimum fallowing length is 10 years fallow. Thus, the
farmers should leave their farms for 10 years for sustainable crop production and their
better livelihood improvement.
