Comparison of two methods for quantification of tillage erosion rates in olive orchards of north-west Syria

Abstract

The hilly area of north-western Syria is characterised by olive cultivation on hill slopes. Most of the sloping olive fields are frequently ploughed by a local, donkey-drawn tillage implement (fadhan), which potentially results in tillage erosion. The aim of this study was to compare different methods for the assessment of tillage erosion rates in sloping olive fields. Two basic approaches for the assessment of tillage erosion can be used; either marking the soil matrix, or using aggregate-sized tracers. These two approaches were applied and compared in olive fields to determine a relation between slope and average soil displacement. Aluminium cubes were used to represent the coarse fraction (CFT) and a sodium chloride solution was used to measure the movement of the fine fraction (FFM). The field experiments included 35 strip plots containing 40 aluminium tracers, on 18 different slopes ranging from 2 to 43% and 15 strip plots marked with 10 l of aqueous sodium chloride solution on the same slopes. Two working directions, up–down and along the contour, were analysed and compared. After tilling the plots, the positions of the aluminium tracers were recorded and samples were taken from the FFM plots. FFM redistribution was determined by measuring electrical conductivity of extract solutions. A statistical analysis revealed that there were no significant differences between the two methods. Soil loss and accumulation were calculated for one of the trial sites. Maximum soil loss values for contour tillage, were almost nine times less than for up and down tillage.