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Doctorat
Royaume-Uni
2002
TILLAGE EFFECTS ON SOIL EROSION ON AGRICULTURAL LANDS IN SEMI - ARID TURKEY
Titre : TILLAGE EFFECTS ON SOIL EROSION ON AGRICULTURAL LANDS IN SEMI - ARID TURKEY
Auteur : AKSIT SELAHATTIN
Université de soutenance : University of Leicester
Grade : Doctor of Philosophy (PhD) 2002
Résumé
The thesis evaluates the effects of tillage on soil erosion on agricultural lands in semiarid
Turkey. Data collection has been undertaken in two-winter seasons, 1997-8 and
1998-9. Data collection was carried out under natural rainfall conditions. Land left bare
and untilled during the winter season, on which the soil surface was compacted, has a
high runoff potential. Tilled surfaces contribute less runoff because of high
depressional storage induced by the surface roughness following tillage. After two years
of tests, runoff values show that across-slope tillage is able to decrease the surface
runoff to around 60% of that on down-slope tilled land and around 20% of that on
untilled land. The results of this study show that overall, runoff is largely controlled by
treatment. Soil loss results mirror those from runoff from the three treatments, but the
differences are not as great. Tillage is more effective in reducing runoff than it is in
reducing soil loss. Furthermore, across-slope tillage when compared to down-slope
tillage reduces runoff to a greater extent than it does soil loss. Measurements of splash
detachment (the principal souce of sediment detachment in interrill areas) shows that
rates of detachment do not vary among the three treatments to the same extent as does
soil loss.
During the 1998-9 field season rills formed on the most sand-rich soil of the six study
sites (site 2). Except for rill cross section size on the across-slope tilled plot, rill
properties do not conform well to predictions of previous models. Further work is
needed to improve the prediction of rill properties.
The final part of this thesis is concerned with the application of an erosion model to
predict the erosion from the experimental plots and to compare the predictions of this
model with the field data. Runoff and soil loss were tested using the EUROSEM model
and from the results of these tests an evaluation of important parameters in the model
was made. The results show that the EUROSEM model performs poorly in predicting
both runoff and soil loss from the plots.
Mots clés : Tillage, agricultural land, soil loss, runoff, rilling, EUROSEM model
Page publiée le 2 février 2015, mise à jour le 12 mars 2018