Straw mulch can induce greater soil losses from loess slopes than no mulch under extreme rainfall conditions

Zhang

et al. 2018

Hydrological Processes

Water erosion on hillslopes is a worldwide environmental problem, which is a rainfall‐induced process, especially extreme rainfall. The great intensity of extreme rainfall strongly enhances the power of overland flow to detach soil and transport sediment. Plant litter is one of the most important constituents of ecosystems that often covers the soil surface and can be incorporated into topsoil. However, little attention has been paid to its effect on flow hydraulics owing to the veiled nature. This study aimed to examine the effects of incorporated litter on the hydraulic properties under extreme rainfall condition. To reach this goal, six litter rates of 0, 0.05, 0.10, 0.20, 0.35, and 0.50 kg m−2 and four litter types collected from deciduous trees, coniferous trees, shrubs, and herbs were incorporated into topsoil. Then, simulated rainfall experiments were performed on five slope gradients (5°, 10°, 15°, 20°, and 25°) with an extreme rainfall intensity of 80 mm h−1. The results showed that Froude number and flow velocity of the overland flow decreased, whereas flow resistance increased exponentially with litter incorporation rate. Litter type had an influence on flow hydraulics, which can mainly be attributed to the variations in surface coverage of the exposed litter and the litter morphology. Flow velocity and Darcy–Weisbach coefficient increased markedly with slope gradient. However, the variation of slope gradient did not modify the relationships between flow hydraulics and incorporated litter rate. The random roughness, resulting from heterogeneous erosion due to the uneven protection of surface exposed litter, increased linearly with litter incorporated rate. As rainfall proceeded, flow hydraulics varied with incorporated litter rate and slope gradient complicatedly due to the increases in flow rate and coverage of the exposed litter and the modification of soil surface roughness.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Hydraulics of overland flow influenced by litter incorporation under extreme rainfall

Zhang

et al. 2018

Hydrological Processes

“…When addressing land degradation issues such as soil erosion by water, the understanding of spatial aspects is a key element, as it can support the application of appropriate management techniques as well as support related disciplines (Schmiedel, Kruspe, Kayser, & Oettlé, ; Pereira et al, ; Govers, Roel Merckx, van Wesemael, & Van, ; Bodoque et al, ). This is particularly the case when analysing land use patterns and their effect on erosion rates (Haregeweyn et al, ; Pacheco, Varandas, Sanches Fernandes, & Valle Junior, ; Valle Junior, Varandas, Sanches Fernandes, & Pacheco, ; Zhang, Fan, Li, & Yi, ), or when selecting appropriate conservation measures (Rahma et al, ).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the new soil erosion map of Hungary—A semiquantitative approach

et al. 2018

Soil erosion by water is one of the most significant forms of soil degradation globally, especially in Europe. A new soil erosion risk map of Hungary has been compiled and published recently, using the combined outputs of the Universal Soil Loss Equation and Pan‐European Soil Erosion Risk Assessment models. Our study aimed at providing evaluation of the map by using semiquantitative validation data obtained from the Hungarian Soil Degradation Subsystem of the National Environmental Information System. The Soil Degradation Subsystem database contained information at farm level as well as indicators based on laboratory data for 5‐ha representative plots. On the basis of the semiquantitative analysis, the map results align well with the farm‐based degradation data and provide viable information not only at the regional scale but also at the farm scale. However, indicators from representative plots did not support model results, indicating possible conflict between farm‐ and plot‐level data. Cross‐comparison of these indicators showed only limited correlation between farm‐ and plot‐level indicators.

“…Similarly, Rahma et al (2017) reported that crop straw mulched in the topsoil reduced the amount of soil erosion from hillslope croplands under extreme rainfall events. Shi and Schulin (2018) reported that crop straw application resulted in a decrease in organic carbon (C) loss through an artificial rainfall experiment.…”

mentioning

confidence: 92%

Leaching is the dominant route for soil organic carbon lateral transport under crop straw addition on sloping croplands

Hua¹,

Zhu²

2018

PLANT SOIL ENVIRON

Few field data sets are available that systematically measure soil organic carbon (SOC) transport via surface runoff, leaching and soil erosion under crop straw applications. Therefore, organic carbon (C) loss fluxes via the three routes were simultaneously observed from 2010 to 2012 based on a crop straw addition experiment. This study included three treatments: CK (no fertilizer); RSD (crop straw addition) and RSDNPK (crop straw addition combined with mineral fertilizers). As compared with CK treatment, annual dissolved organic C (DOC) loss caused by surface runoff under RSD and RSDNPK treatments decreased significantly (P < 0.05) by 302.8% and 294.2%. Similarly, corresponding organic C loss caused by soil erosion reduced sharply by 638.8% and 1227.3%. In contrast, corresponding annual DOC leaching fluxes increased significantly (P < 0.05) by 133.3% and 109.3%. Overall, the total fluxes of SOC transport under RSD and RSDNPK treatments decreased significantly (P < 0.05) by 132.3% and 184.1% compared with CK treatment (4975.7 ± 1207.8 mg/m<sup>2</sup>). DOC leaching accounted for 70% and 77% of SOC transport under RSD and RSDNPK treatments. These results clearly show that leaching is the dominant route of SOC lateral transport under crop straw applications. Therefore, reduced DOC leaching is the crucial link to enhance SOC sequestration when crop straw is returned to sloping croplands.