A lack of research on sediment displacement has led to a corresponding lack of understanding regarding the movement of insoluble N and P. In this study, we used field simulated rainfall experiments and discovered the following: first, the regulatory effects of the two planting methods on the runoff detachment rate was greater than that on the runoff sediment transport rate, and the influence of rainfall intensity was greater than that of slope. Outside the threshold, the regulatory effects of the two planting methods on runoff detachment and sediment transport on different slope gradients were diametrically opposed. Second, N loss was 10 times higher than P loss during rainfall events. N and P losses were highest on bare slopes, and lowest on slopes on which the Prunella vulgaris combined with earthworms planting method was used. N and P loss during rainfall events increased as rainfall intensity increased, and decreased as slope increased. The rate of change increased under high rainfall intensity or slope gradient. Third, regulation of insoluble N loss under the P. vulgaris-only planting method was achieved through regulation of runoff detachment and sediment transport, with contribution rates of 23.89% and 31.98%, respectively. Regulation of insoluble N loss under the P.vulgaris combined with earthworms planting method was achieved by regulating runoff detachment, with a contribution rate of 66.92%. Regulation of insoluble P loss under the two planting methods was achieved by regulating both the runoff detachment and sediment transport rates.

：In order to explore the impact of ecological planting pattern on runoff sediment transport rate(T 2), this study in two planting modes with a single planting of Prunella vulgaris (A) and P. vulgaris and earthworms (B) were investigated through simulated rainfall experiments in the field. The results showed that: 1) T 2 decreased first and then stabilized with the rainfall duration,which is dominated by the composition of soil particle size and runoff depth;2) T 2 under gentle slope and steep slope conditions is greatly affected by rainfall intensity and slope, respectively; 3) T 2 ,which has a good correlation with runoff separation rate (D 2), needs to be explained in conjunction with soil properties or raindrop kinetic energy. The main controlling factors of T 2 in bare slope, B, A are raindrop kinetic energy, D 2, and organic matter, which explain 93.10%, 95.76%, and 98.65%.Compared with B, A has obvious economic and ecological value.

Grassland runoff is related to soil and water conservation, but there are few related studies. In this study, a simulated rainfall experiment was carried out, and the results showed that: 1) The runoff depth increases with the increase of rainfall intensity and decreases with the increase of slope or cover, all of which can be described by linear equations; 2). Soil specific gravity, root fractal dimension and grass dry weight can explain 5.00%, 31.08%, and 6.64%, respectively;3). The NSE of the grassland erosion model established by rain intensity, flow discharge and cover is 0.700, which is 0.142 larger than that of the grassland erosion model established by rain intensity and flow discharge.The research conclusions will help prevent and control floods, improve water resource utilization and strengthen grassland erosion monitoring.

In order to elucidate the regulatory effects of the two planting patterns on the soil migration of raindrops and runoff, the planting period and idle period of dry land with a single planting of Prunella vulgaris (traditional planting method) and P. vulgaris and earthworms (ecological planting method) were investigated through simulated rainfall experiments in the field. The results showed that: 1). The regulation effect of the two planting modes on soil migration indicators (raindrop separation rate, raindrop sediment transport rate, runoff separation rate, and runoff sediment transport rate) showed an overall decreasing trend with the increase of rainfall intensity or slope, which can be described by a binary function；2). Compared with the planting mode of Prunella vulgaris, the regulation effect of raindrop sediment transport rate was significantly affected by rainfall intensity, and the regulation effect of raindrop separation rate, runoff separation rate and runoff sediment transport rate was significantly affected by slope under Prunella vulgaris combined with earthworm planting mode. The effects of rainfall intensity or slope on the regulation effects of runoff separation rate and runoff sediment transport rate are similar and the difference is not obvious; 3). Due to the special effect of earthworms on soil ecology, Prunella vulgaris combined with earthworms can improve the best impact index and inhibit soil migration in a short time, and the contribution rate is more than 45%.However, only planting Prunella vulgaris could not improve the soil properties in a short period of time, which also caused the influence index of Prunella vulgaris slope soil migration to be different from the regulation index of Prunella vulgaris.

The erosion mechanism on steep grass slopes is the basis and difficulty of grassland erosion model, but few related studies.The erosion mechanism on steep slopes covered by grass was studied by artificial rainfall experiments. Results showed the following: (1) The contributions of the Rω(reduction of stream power) and RK(reduction of soil erodibility) to the decreasing erosion modulus (REM) are 61.02% and 33.55%, respectively, totalling to 94.57%. This finding indicates that herbaceous vegetation decreases the interrill erosion mainly by decreasing the stream power.(2) The relationship between the Rω and grass cover, and phytyl cover can be described with logarithmic equations.The calculation under different rainfall intensities or slopes showed contribution rates of 82.86%-97.51% or 86.36%-97.51%, and 1.48%-14.82% or 1.48%-20.44%. (3) The relationship between the RK androot volume (RV), and soil bulk density (SD) can be described with binary logarithmic equations.The calculation showed contribution rates of 73.61%-97.94, and 0.04%-0.22%. (4) In-depth analysis found the regulation effect of grass on stream power is mainly achieved by grass cover, and the regulation effect of grass on soil erodibility is mainly achieved by root volume. The research focus should be on the impact of vegetation layout, vegetation types, vegetation density, and soil properties on soil erosion under large-scale conditions.

The artificial simulated rainfall test method is used to deeply analyze the mechanism of the change of sediment concentration on the grassland slope .Under the experimental condition, the results show the following. 1). The addition of root volume can increase the accuracy of the expression of the sediment concentration variability and reduction of sediment concentration by 0.5% and 1.12%, respectively; 2).The relationship between the vegetation characteristics and the sediment concentration on the grassland slope is best expressed by the coverage and root volume; 3).The slope plays a larger role than the rain intensity in the change of sediment concentration on grassland slopes .

Few data are available for estimating the sediment transport rate on a steep slope of grass with different covers. In this study, the artificial simulated rainfall test is used to investigate how rainfall intensity, slope and cover affect the sediment transport rate. Simultaneously, the study establishes a model for the sediment transport rate using shear stress, stream power, unit stream power and unit energy on steep grassland slopes. Results show that the sediment transport rate decreases as the vegetation cover increases, as described by linear or logarithmic equations under different rainfall intensities or slopes. The sediment transport rate increases as an exponential function equation with rainfall intensity, slope and cover with a Nash–Sutcliffe model efficiency (NSE) value of 0.864. The effects of slope steepness are stronger than the effects of rainfall intensity and cover. Regression analyses show that the sediment transport rate can be predicted from the power function equations of shear stress, stream power and unit energy. In addition, the sediment transport rate can be fit to unit stream power with linear equation (NSE = 0.840). Further analysis shows that the sediment transport rate is best modelled by a power function equation that includes three factors, i.e. rainfall intensity, vegetation cover and slope.The measurements and calculations of the sediment transport rate, the calculations of the surface roughness and characteristic considerations of the vegetation for sheet flow should be explored in future research, which are important in improving experimental accuracy and sediment transport rate modell

Few data are available for estimating the sediment transport rate on a steep slope of grass with different covers. In this study, the artificial simulated rainfall test is used to investigate how rainfall intensity, slope and cover affect the sediment transport rate. Simultaneously, the study establishes a model for the sediment transport rate using shear stress, stream power, unit stream power and unit energy on steep grassland slopes. Results show that the sediment transport rate decreases as the vegetation cover increases, as described by linear or logarithmic equations under different rainfall intensities or slopes. The sediment transport rate increases as an exponential function equation with rainfall intensity, slope and cover with a Nash–Sutcliffe model efficiency (NSE) value of 0.864. The effects of slope steepness are stronger than the effects of rainfall intensity and cover. Regression analyses show that the sediment transport rate can be predicted from the power function equations of shear stress, stream power and unit energy. In addition, the sediment transport rate can be fit to unit stream power with linear equation (NSE = 0.840). However, shear stress, stream power and unit energy perform poorly (NSE = 0.394, NSE = 0.498 and NSE = 0.330, respectively). Further analysis shows that the sediment transport rate is best modelled by a power function equation that includes three factors, i.e. rainfall intensity, vegetation cover and slope. Moreover, unit stream power results in the best model for the sediment transport rate among the different hydrodynamic parameters. The soil erodibility parameter and critical unit stream power of this experiment are 113.59 and 0.216 m·s-1, respectively, which are six times more than those in the bare slope. The measurements and calculations of the sediment transport rate, the calculations of the surface roughness and characteristic considerations of the vegetation for sheet flow should be explored in future research, which are important in improving experimental accuracy and sediment transport rate modelling

Sediment transport rate is greatly important in establishing reliable strategies to manage environmental changes. However, few data are available for estimating the sediment transport rate on a steep slope of grass with different covers. In this study, the artificial simulated rainfall test is used to investigate how rainfall intensity, slope and cover affect the sediment transport rate. Simultaneously, the study establishes a model for the sediment transport rate using shear stress, stream power, unit stream power and unit energy on steep grassland slopes. Results show that the sediment transport rate decreases as the vegetation cover increases, as described by linear or logarithmic equations under different rainfall intensities or slopes. The sediment transport rate increases as an exponential function equation with rainfall intensity, slope and cover with a Nash–Sutcliffe model efficiency (NSE) value of 0.864. The effects of slope steepness are stronger than the effects of rainfall intensity and cover. Regression analyses show that the sediment transport rate can be predicted from the power function equations of shear stress, stream power and unit energy. In addition, the sediment transport rate can be fit to unit stream power with linear equation (NSE = 0.840). However, shear stress, stream power and unit energy perform poorly (NSE = 0.394, NSE = 0.498 and NSE = 0.330, respectively). Further analysis shows that the sediment transport rate is best modelled by a power function equation that includes three factors, i.e. rainfall intensity, vegetation cover and slope. Moreover, unit stream power results in the best model for the sediment transport rate among the different hydrodynamic parameters. The soil erodibility parameter and critical unit stream power of this experiment are 113.59 and 0.216 m·s-1, respectively, which are six times more than those in the bare slope. The measurements and calculations of the sediment transport rate, the calculations of the surface roughness and characteristic considerations of the vegetation for sheet flow should be explored in future research, which are important in improving experimental accuracy and sediment transport rate modelling. These results provide a basis for establishing process-based erosion models on steep grassland slopes.