Soil tillage is usually considered as a process having only an indirect influence on soil erosion. This paper describes the results of field experiments carried out with a mouldboard and a chisel plough showing that an important net downslope soil movement can be associated with soil tillage. Available experimental evidence suggests that the soil redistribution by tillage can be described by a diffusion-type equation, which allows the intensity of the process to be characterized by a single number, which may be called the diffusion constant. The experimentally determined values of the diffusion constant vary between 100 and 400 kg mpl apl. This implies that erosion and sedimentation rates associated with tillage may be more important than those associated with water erosion on much of the hilly arable land in western Europe. A comparison of recent hillslope evolution with model simulation results corroborates this conclusion. Therefore, tillage should be considered as a soil degradation process per se, rather than a process which makes the soil more sensitive to erosion.

This study uses evidence for the long-term (35 years) pattern of soil redistribution within two agricultural fields in the UK to identify the relative importance of tillage and overland flow erosion. Spatially distributed long-term total soil redistribution data for the fields (Dalicott Farm and Rufford Forest Farm) were obtained using the caesium-137 (I3'Cs) technique. These data were compared with predicted patterns of soil redistribution.Recent studies have demonstrated that the redistribution of soil by tillage may be described as a diffusive process. A two-component model was, therefore, developed which accounts for soil redistribution by both overland flow and diffusive processes. Comparison of the predicted patterns of overland flow erosion alone with the observed ('37Cs-derived) data indicated a poor agreement (rZ = 0.17 and 0.11). In contrast, a good agreement exists between the predicted pattern of diffusive redistribution and the observed data (3 = 0.43 and 0.41). These results give a clear indication that diffusive processes are dominant in soil redistribution within these fields. Possible diffusive processes include splash erosion, soil creep and tillage. However, the magnitude of the diffusion coefficients for the optimum predicted pattern (c. 350-400 kgm-' a-I) demonstrates that tillage is the only process capable of explaining the very significant soil redistribution which is indicated by the I3'Cs data. Consideration is given to the implications of these results for both soil erosion prediction and landscape interpretation.

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A suite of methods to interpolate a digital elevation model from a ground survey was evaluated with respect to precision and ability to maintain the shape of the original height data. This shape reliability was evaluated by comparing the spatial patterns of secondary terrain parameters derived from the interpolated elevation data. The best interpolation method for this study area was found to be a spline interpolation, which is somewhat contradictory to findings in the literature. The error and uncertainty found in the results for terrain analysis and modelling tools is important and sometimes distressingly high, even for some frequently used local or context operations on altitude. Positional operations, in which the output is determined more by the position in the topographic structure, seem to give more reliable results. Therefore, the results obtained by terrain analysis and spatial modelling need careful interpretation.

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This study investigates the effect of two attention-enhancing techniques on L2 students' learning and processing of novel French words (i.e., target words) through video with L2 subtitles or captions. A combination of eye-movement data and vocabulary tests was gathered to study the effects of Type of Captioning (full or keyword captioning) and Test Announcement, realized by informing (intentional) or not informing (incidental) learners about upcoming vocabulary tests. The study adopted a betweensubjects design with two independent variables (Type of Captioning and Test Announcement) resulting in four experimental groups: full captioning, incidental; full captioning, intentional; keyword captioning, incidental; keyword captioning, intentional. Results indicated that learners in the keyword groups outperformed the other groups on the form recognition test. Analyses of learners' total fixation and second pass time on the target words revealed a significant interaction effect between Type of Captioning and Test Announcement. Results also suggest that second pass as well as total fixation duration and word learning positively correlated for learners in the full captioning, intentional group: The longer their fixations on a given word, the more likely correct recognition became. Results are discussed in relation to attention and word learning through video.