The European Soil Erosion Model (EUROSEM) is a dynamic distributed model, able to simulate sediment transport, erosion and deposition over the land surface by rill and interill processes in single storms for both individual fields and small catchments. Model output includes total runoff, total soil loss, the storm hydrograph and storm sediment graph. Compared with other erosion models, EUROSEM has explicit simulation of interill and rill flow; plant cover effects on interception and rainfall energy; rock fragment (stoniness) effects on infiltration, flow velocity and splash erosion; and changes in the shape and size of rill channels as a result of erosion and deposition. The transport capacity of runoff is modelled using relationships based on over 500 experimental observations of shallow surface flows. EUROSEM can be applied to smooth slope planes without rills, rilled surfaces and surfaces with furrows. Examples are given of model output and of the unique capabilities of dynamic erosion modelling in general.

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The leaching of soil particles and surface applied 14C-labeled glyphosate and pendimethalin from intact soil columns (height: 50 cm; diameter: 30 cm) were investigated, and the relative significance of particle-facilitated pesticide transport was quantified. Investigations were performed with a recently plowed (four columns) and an untilled (five columns) sandy loam soil. Leaching was driven by three irrigation events (15 mm h(-1); 2 h each). Samples of the leachate were filtered immediately (within 1.5 minutes) using 20 nm filters, and the 14C-pesticide content was determined for filtered and unfiltered samples. Pesticide leaching was driven by preferential water flow in macropores. For the plowed structure, 68+/-10% of the leached glyphosate (average of 6 events+/-std.) was bound to particles whereas significantly less glyphosate was bound to particles in leachate from minimally disturbed columns (17+/-12%). Thus, the results suggest that soil structure affected the mode of transport of glyphosate. It is likely that glyphosate sorbed strongly when applied on recently plowed soil (Kd=503 L kg(-1) for the soil), and that it could be mobilized and transported independently of soil particles more easily when applied on the minimally disturbed soil covered in part with crop residues (Kd<1 L kg(-1) for straw). Significantly less amounts of soil particles were leached from minimally disturbed (119-247 mg) than from recently plowed (441-731 mg) columns. The significance of particle-facilitated pendimethalin leaching could not be accurately quantified due to disagreement between control measurements based on both 14C-activity and chemical analyses.

This study examined the number, distribution, and connectivity of biopores (>1 mm) in a sandy loam till with tile drains located at 1.2‐m depth. Two areas (6.5 by 1 m, 10 m apart) were irrigated within 6 to 8 h with 50 mm of water containing the dye Brilliant Blue (2.2 g L−1) using a field sprayer. Groundwater was initially below drain depth. The distribution of stained and unstained biopores was examined in 15‐ and 30‐cm‐wide horizontal terraces in 0.5‐m‐long sections along the 6.5‐m irrigated transect at up to eight depths (15–175 cm), for a total investigated area of 14 m2 This extensive data set showed that the number of biopores were of similar magnitude at both study sites in and outside the drain trench, ranging from 0 to 1114 m−2 in the 14‐m2 examined section. The number of stained biopores (0–833 m−2) was unevenly distributed in the horizontal direction and seemed unaffected by distance to the drain trench (0–5.5 m), while in vertical sections with numerous dyed biopores at 150‐cm depth, staining continued farther down in fractures. Staining in the drain trench was associated with biopores, voids, fractures, and the soil along the pipe, which may indicate that the tile drain took over the role of fractures in the till. Consequently, the connectivity of biopores with fractures or drains may have an important impact on staining patterns and on preferential flow phenomena.

This paper presents a modelling approach where the entire land-based hydrological and nitrogen cycle from field to river outlet was included. This approach is based on a combination of a physically based root zone model (DAISY) and a physically based distributed catchment model (MIKE SHE/MIKE11). Large amounts of data available from statistical databases and surface maps were used for determination of land use and management practises to predict leaching within the catchment. The modelling approach included a description of nitrate transformations in the root zone, denitrification in the saturated zone, wetland areas and the river system within the catchment. The modelling approach was applied for the Odense Fjord catchment which constitutes one of the pilot river basins for implementation of the European Water Framework Directive. The model simulated overall nitrogen fluxes in the river system consistent with the observed values but showed some discrepancies between simulated and observed daily discharge values The results showed significant differences of denitrification capacities between larger areas such as sub-catchments. This approach has great potential for optimal planning of the establishment of wetlands and further land use legislation with respect to high denitrification rates.