Surface-subsurface flow and soil loss indicator in different RIP patterns and SCTs

Description

Straw mulching is a common and effective method in controlling soil erosion. However, the impacts of rainfall intensity profiles (RIP) on soil erosion and surface-subsurface flow under different straw mulching types remains poorly understood. This study conducted a 5-year continuous observation in the red soil hilly region of southern China, focusing on five cover types: plowing bare (PLB), conventional farming (COF), no-tillage with straw mulching (NTSM), straw burial ditch with straw mulching (SBDM), and tillage with straw mulching (TSM). Key parameters monitored included RIP, surface runoff rate (SFR), subsurface flow rate (SSFR), sediment concentration (SC), and soil loss rate (SLR).

Steps to reproduce

The experiment was carried out with runoff plots that depended on natural precipitation. Six sloped farmland runoff plots, each 10 m long and 2 m wide, were created on a broad south-facing hillside. The slope gradient of the runoff plots was set to 8° due to the wide distribution of slope gradients in the sloping farmland of the red soil hilly area. To prevent hydrological interference, the plots were separated by 1.0 m deep retaining dikes for partition boards The soil thickness typically exceeds 100 cm, and the soil profile type is Ah-Bs-Cs . The physical and chemical properties of the soil varied significantly between the different soil layers, particularly porosity and infiltration capacity . The plow layer (A) formed through long-term cultivation was approximately 30 cm deep. It has a loose structure, receives considerable rainfall and is susceptible to severe soil erosion. Layer B, which ranges from 30 to 60 cm in depth, has a compact structure and low permeability. Soil layers below 60 cm were defined as the C layer (parent material), which features a dense structure and poor permeability. Under natural rainfall conditions, disparities in soil physical and chemical properties along the soil profile result in distinct responses of hydrological processes such as surface–subsurface flow. The surface–subsurface flow was collected separately . To accurately measure the interflow volume, an L-shaped steel plate with a 2-cm pore was inserted at the bottom of layer B in front of the plot. A 3–5 cm layer of gravel was piled up at the bottom of layer B and separated from the steel plate using porous nylon gauze. A concrete wall was constructed around the steel plate, leaving a trench below it that was connected to a collection container via a plastic pipe to collect the interflow caused by natural rainfall events . The collection of surface runoff and sediments requires supplementation.

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