Size fractions resulting from an aggregate stability test, interrill detachment and transport

Abstract

Aggregate stability is a soil characteristic often linked with soil erodibility, but this relationship is generally empirical. The aggregate size distribution is a recognized factor influencing crust characteristics and transport during interrill erosion events. This parameter was used in this work in order to improve the understanding of the relationship between aggregate stability and erodibility. A second aspect of this study was to investigate the size selectivity of interrill erosion processes, i.e. breakdown, detachment by splash and transport by overland flow. This experimental work was based on rainfall simulations and aggregate stability tests which were performed using two different soils: a clay loam slightly sensitive to erosion, and a more susceptible silt loam. Size distributions of soil fragments either produced by aggregate stability tests or detached by splash or transported by runoff were measured by both wet sieving and laser diffraction sizer analysis. The clay loam is particularly stable and has coarse breakdown products with mean weight diameters larger than 1400 µm. Aggregate breakdown is more efficient for the silt loam and leads to finer soil fragments with mean weight diameters between 229 and 380 µm. For the more stable soil, the clay loam, splash rate and sediment concentration are respectively two and six times lower and less time variable than for the silt loam. For the two soils, detachment by splash and short distance transport are size-selective interrill erosion processes. This selectivity leads to the enrichment of silt and clay fractions of the eroded aggregates in comparison with the breakdown products. The low erodibility of the more stable soil is in accordance with results of aggregate stability tests.

The effect of soil type, meteorological forcing and slope gradient on the simulation of internal erosion processes at the local scale

“…These soils are common among cultivated soils. They represent a wide range of soil types and their erodibility has been widely tested in the laboratory, in the field and numerically (Elliot et al, 1989;Nearing et al, 1997;Chaplot and Le Bissonnais, 2000;Hairsine et al, 2002;Leguédois and Le Bissonnais, 2004;Nord and Esteves, 2007). The approach followed in this study was to propose a combination of realistic parameters for each type of soil based on various studies of infiltration, detachment and redetachment by rainfall impact, detachment by runoff and sediment size and density.…”

“…The parameters for infiltration (K s ,  s  i and h f ) were selected on the basis of the results of Rawls et al (1983), Elliot et al (1989) and Nord and Esteves (2007). The parameter for detachment by rainfall impact (˛) was selected on the basis of the findings of Leguédois (2003) and Leguédois and Le Bissonnais (2004). The parameter for redetachment by rainfall impact (˛d) was set one order of magnitude greater than˛, following the observations of Proffitt et al (1991), although there are very few references on this question in the literature.…”

Long‐lasting impact of biowaste‐compost application in agriculture on soil‐quality parameters in three different crop‐rotation systems

“…Besides a substitution of energy and nutrients, and a stimulation of the internal processes in soil governed by the microbial community, the application of biowaste compost in agricultural soils may positively affect soil organic-matter (SOM) content and soil-aggregate stability (Balesdent et al, 2000;Wahlen et al, 2003) and thus may reduce the potential risk of soil erosion (Barthès and Roose, 2002;Leguédois and Le Bissonais, 2004;Cantón et al, 2009). …”

Concentrated flow erosion as a main source of sediments in Galicia, Spain

“…This parameter is a recognized factor infl uencing crust characteristics and transport during interrill erosion events (Leguédois and Le Bissonnais, 2004).…”