ASSESSMENT OF TILLAGE EROSION RATES ON STEEP SLOPES IN NORTHERN THAILAND

Citation
F. Turkelboom et al., ASSESSMENT OF TILLAGE EROSION RATES ON STEEP SLOPES IN NORTHERN THAILAND, Catena, 29(1), 1997, pp. 29-44
Citations number
22
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geosciences, Interdisciplinary","Water Resources
Journal title
CatenaACNP
ISSN journal
0341-8162
Volume
29
Issue
1
Year of publication
1997
Pages
29 - 44
Database
ISI
SICI code
0341-8162(1997)29:1<29:AOTERO>2.0.ZU;2-C
Abstract
The switch from shifting cultivation to more permanent highland croppi ng systems in northern Thailand led to an increase in soil tillage int ensity. In order to quantify soil losses by tillage erosion, a tillage experiment was set up and an on-farm survey was conducted. Soil fluxe s due to manual tillage on five slopes (32-82%) were measured by monit oring tracers, by measuring tillage step characteristics and by collec ting soil material in a trench. The trench method yielded soil flux va lues that were significantly smaller than those obtained by the tracer or the step method. Soil fluxes resulting from one manual tillage pas s ranged between 39 and 87 kg/m on the tested slopes. On slopes up to 60%, there were no significant differences in soil fluxes. However, on slopes steeper than 70%, soil fluxes increased significantly because the angle of repose for soil clods was exceeded. The soil fluxes are u sed to construct a nomogram for estimating soil loss rates resulting f rom manual tillage erosion as a function of slope and plot length. Rat es on a typical upland field (slope 30%-50%, slope length 30-50 m) ran ge from 8 to 18 t/ha . tillage pass, so tilage erosion is a significan t contributor to the total soil loss. It dominates on short fields and fields with buffer-strips, whereas water erosion is the more importan t form of soil loss on middle size and long fields. Increasing land pr essure will result in increasing tillage erosion rates, and these need to be considered when assessing soil degradation rates or when studyi ng hillslope evolution. (C) 1997 Elsevier Science B.V.