Primary particle size distribution of eroded material affected by degree of aggregate slaking and seal development

Abstract

Primary particle size distribution (PSD) of eroded sediment can be used to estimate potential nutrient losses from soil and pollution hazards to the environment. We studied eroded sediment PSDs from three saturated soils, packed in trays (20 Â 40 Â 4 cm), that had undergone either minimal aggregate slaking (MAS) or severe aggregate slaking (SAS) prior to a 60 mm simulated rainstorm (kinetic energy, 15.9 kJ m À3 ; droplet diameter, 2.97 mm) and collected runoff at regular intervals. The degree of aggregate slaking was controlled by the rate at which soils were wetted to saturation. The PSDs of eroded materials and of parent soils were determined using a laser particle size analyser. For each soil, PSD frequency curves of eroded sediments and parent soils were generally of a similar shape but most eroded sediments had larger clay contents than their parent soils. In the SAS treatment, cumulative clay enrichment in the eroded materials was inversely related to the parent soil clay content, these being 28.5, 26.6 and 22.8% richer in clay than their parent soils for the loam, sandy clay and clay, respectively. Generally, total clay loss was greater from soils with SAS than from those with MAS because of erosion rates; however, clay enrichment of sediments, compared with parent soil clay contents, was mostly greater in samples with MAS. Greater clay enrichment took place during the early seal development stage in the loam, but could not readily be associated with specific stages of seal development for the clay. In the sandy clay, the relation between seal development and clay enrichment in the eroded material depended on the initial degree of aggregate slaking. The observed large preferential loss of clay by erosion in cultivated soils re-emphasizes the need to employ erosion control measures.

Effects of soil erosion by water under different tillage treatments on distribution of soil chemical parameters

“…These results are consistent with the results of other researchers: Burwel et al (1977), McIsaac et al (1991), Fleige and Horn (2000), Kisic et al (2002), Ali et al (2006), Malam Issa et al (2006) and Warrington et al (2009) reported higher content of OM, plant available nutrients and other chemicals in soil sediments. Gaynor and Findlay (1995) concluded that conservation tillage reduces average soil loss compared to conventional tillage.…”

Quantifying the changes of soil surface microroughness due to rainfall impact on a smooth surface

“…However, changes in roughness during a storm event have been attributed to compression and drag forces from the raindrop impact on the soil, angular displacement due to rain splash, aggregate fragmentation, and differential swelling (Al-Durrah and Bradford, 1982;Warrington et al, 2009;Rosa et al, 2012;Fu et al, 2016). Regions exhibiting different median raindrop diameters may experience different soil surface roughness evolution due to different aggregate fragmentation and rain splash effects (Warrington et al, 2009;Rosa et al, 2012;Fu et al, 2016). Future research should explore these mechanisms.…”

Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

“…For the 5 • slope level, occurrence of a higher ponding head pressure, due to the thick surface flow layer [10], may be the reason for the higher infiltration rate. However, at steeper slopes, high flow velocity increased the loss of water runoff, decreased the hydraulic gradient and reduced the infiltration rate during rainfall intensity of 94 mm·h −1 [67,68]. Similarly, comparatively lower flow velocities during rainfall intensity of 54 mm·h −1 could have promoted the maximum water absorption, thus, higher water infiltration occurred compared with that under the rainfall intensity of 94 mm·h −1 .…”