Soil is a highly significant resource for human survival, and agglomerates, as the basic unit of the soil structure, not only enhance the soil fertility and control the biological validity of nutrients but also strengthen the soil’s erosion resistance. The mass application of fertilizers may significantly affect crop growth and the soil structure, and the rational application and dispensing of fertilizers will be an urgent issue to be addressed. Therefore, the effect of fertilizer application on the stability of water-stable soil aggregates needs to be studied under different meteorological and soil conditions to draw more general and feasible conclusions. Our meta-analysis of data from 220 independent observations from 56 published studies found that fertilizer application increased the mean weight diameter (MWD) by an average of 18% compared to the no-fertilizer treatment. Among the nitrogen (N), phosphate (P), and organic (OM) fertilizer treatments, the organic fertilizer treatment had a more significant stimulatory effect on the MWD (26%). Among the different fertilizer levels, a low level of phosphorus (120 kg·ha⁻¹·yr⁻¹), and a low level of organic fertilizer (<5000 kg·ha⁻¹·yr⁻¹) increased the MWD by 19%, 14%, and 41%, respectively. Across the soil types and land use types, the response to the MWD was positive for red soils and paddy fields, and the organic fertilizer’s stimulatory effect was more significant than that of the chemical fertilizer. The correlation analysis showed that the response rate of the MWD was negatively correlated with the response rate of the soil pH and bulk density (BD) and positively correlated with the response rate of the soil organic carbon (SOC) and microbial mass carbon (MBC). Meanwhile, the partial least square structural equation model (PLS-SEM) showed that the meteorological factors were the main factors affecting the stability of the soil aggregates, while the secondary factors were the soil’s physical and chemical properties. Therefore, this study found that the long-term use of organic fertilizer instead of partial fertilizer is better than the use of chemical fertilizer alone, while more attention should be paid to the influence of temperature and rainfall on the stability of fertilizer in aggregate soil in the future.

The occurrence and development of rill erosion depends on the hydraulic characteristics of water flow and underlying soil surface features. Our experiments include one-rainfall-intensity treatments (2.0 mm min⁻¹) and various microtopographic levels based on different tillage practices with smooth slope (CK), artificial digging (AD), and ridge tillage (RT) on a 15° slope. The results indicate the following: (1) The soil roughness index values were in the order of CK < AD < RT, and the spatial variability of different tillage practices had strong autocorrelations during different rill erosive stages. The codomain values decreased with the increase in microtopography. (2) The multifractal dimension values of tillage practices in various erosive stages were in the order of RT > AD > CT. The microtopography of different tilled slopes showed strong multifractal characteristics, and the multifractal characteristics were stronger as the microrelief heterogeneity increased. For the CK slope, the generalized fractal dimension span (ΔD) ranged between 0.0019 and 0.0058. For the AD slope, ΔD was between 0.2901 and 0.5112. And, for the RT slope, ΔD was between 0.4235 and 0.7626. (3) With the evolution of rill erosion, the flow pattern on different tilled slopes changed from subcritical transition flow to supercritical transition flow. (4) Soil roughness index and ΔD had good correlations with hydrodynamic parameters. The stronger the erosive energy of runoff was, the higher the spatial heterogeneity of microtopography was. This study is expected to provide a theoretical basis for revealing the hydrodynamic mechanism of rill erosion in slope farmland.

Limited by water and heat conditions, the southwest alpine valley area has a dry climate, complex terrain, low vegetation coverage, and a very fragile ecological environment. The runoff plots of different slope gradients (10°, 15°, and 20°), slope lengths (2, 5, and 10 m) and reverse slope terrace (RST) in the Lancang River arid valley were taken as the objects. Through in situ observation of the slope runoff and sediment yield of six natural erosive rainfalls, the contribution rate of different factors was quantified, and the effect mechanism was revealed. The main results were as follows: (1) Sediment yields of different rainfalls were closely correlated with rainfall type and duration. Under the conditions of heavy rain (rain II and III), there was a critical slope gradient, and the maximum sediment yield was achieved when the slope gradient was 15°. (2) The runoff and sediment reduction benefits of horizontal terraces were 24.88% and 46.25%, and these benefits were increased by 1.47 times and 1.30 times after setting the RST, and the sediment reduction benefits increased significantly with the increase in the number of RSTs (p < 0.05). (3) In this study, rainfall intensity contributed the most to the runoff yield rate (34.5%), followed by slope length (15.1%) and horizontal terrace (7.2%). Slope length, rain intensity, and horizontal terrace order contributed 25.9%, 18.0%, and 11.4% to the sediment yield rate, respectively. (4) There was a significant linear correlation between sediment yield and runoff yield on different slopes (p < 0.05). The critical runoff yield rate decreased with the increase in slope length, the RST significantly increased the critical runoff yield rate (2.91 times), and it increased with the increase in RST numbers. This study can provide a scientific basis and reference for the prevention and control of soil and water loss and ecological restoration on the slope of the arid valley in the southwest alpine and canyon area.

Temporary vegetation measures are the most common methods for reducing soil erosion of spoil heaps during construction; however, their regulatory mechanisms on soil and water loss have not been sufficiently studied. This study compared the impacts of five temporary vegetation measures (turfing 300 cm (TF-300 cm), turfing 75 cm (TF-75 cm), grass seeding 300 cm (GS-300 cm), grass seeding 75 cm (GS-75 cm), and synthetic turf (ST)) on the dynamic processes of runoff and sediment yield as well as hydraulic parameters under simulated rainfall experiments. A 30° bare slope (BS) was set up as the control. The results indicated that (1) all measures delayed the onset of runoff by 57–233%, effectively decreasing the runoff rate and the average erosion rate by 45–49% and 91–99%, respectively; (2) these measures reduced the average Reynolds number by 45–52% and diminished both the average runoff shear force and runoff power by 44–60%; and (3) the effectiveness in reducing runoff and sediment loss ranked as follows: turfing > synthetic turf > grass seeding, When these measures are applied locally to the bottom 25% of the slope, the efficiency of runoff and sediment reduction can exceed 89% for the entire slope. Our findings provide valuable insights for designing temporary vegetation measures in construction.