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Soil conservation is of global importance, as accelerated soil erosion by human activity is a primary threat to ecosystem viability. However, the significance and role of soil conservation in reshaping landscape carbon (C) accounting has not been comprehensively integrated in the terrestrial C sink. Here, we present the first integrated assessment of the modified terrestrial C sink and aquatic C transport due to soil conservation for the semiarid Chinese Loess Plateau (CLP), the world's most vulnerable region to soil erosion. We show a surprisingly low terrestrial‐aquatic C transfer that offset the terrestrial net ecosystem productivity by only 7.5%, which we attribute to the effective implementation of soil conservation practices. Despite the highest soil erosion, the semiarid CLP acts as effective C sink at 43.2 ± 22.6 g C m−2 year−1, which is comparable to temperate forest in absorbing atmospheric CO2. Moreover, C burial in reservoirs has created an additional anthropogenic C sink of 2.9 ± 1.1 g C m−2 year−1. Our findings indicate that effective soil conservation can significantly increase landscape C sequestration capacity. The co‐benefits of soil conservation in erosion control and C sequestration have important implications for policy makers in other regions undergoing increasing erosion intensity to pursue environmental sustainability. Plain Language Summary: Aquatic export of terrestrial carbon (C) plays a significant role in modulating the magnitude of terrestrial C sink. Previous estimates of terrestrial C sink may be overestimated because not all C losses across heterogeneous landscapes are accurately determined and properly accounted for. This is particularly possible for catchments with high erosion and terrestrial‐aquatic C transfer potential. Meanwhile, soil conservation can greatly modify landscape C sequestration capacity. Thus, a more comprehensive assessment of net landscape C budget is needed that integrates aquatic export of terrestrial C while considering the role and significance of soil conservation. For the Chinese Loess Plateau in semiarid climates that once characterized the world's high soil erosion rate, we show a surprisingly low aquatic C transfer that offset the terrestrial C sink by only 7.5%, due largely to successful soil conservation in the past decades. Our findings suggest that effective implementation of soil conservation practices can substantially reduce terrestrial‐aquatic C transfer and enhance the landscape C sequestration capacity. Key Points: The magnitude of terrestrial‐aquatic C transfer in influencing landscape‐scale C balance on the Chinese Loess Plateau (CLP) is assessedThe low reduction of terrestrial C sink by terrestrial‐aquatic C transfer on the CLP is largely due to soil conservationEffective implementation of soil conservation can substantially reduce terrestrial‐aquatic C transfer and enhance landscape C sink capacity [ABSTRACT FROM AUTHOR]

Sediment source fingerprinting provides an effective and reliable way for targeted control of soil erosion. However, the accuracy of source contribution predictions of different fingerprinting methods has not been well verified, which affects the further application of these methods. Here, compared with the real sediment sources measured by indoor simulated scouring experiments, we verified the accuracy of two tracers (geochemical elements and n‐alkanes) and three mixing models (Walling model, MixSIAR, and Landwehr model). The results showed that geochemical properties have high accuracy in identifying sediment sources, with the mean absolute error (MAE) ranging from 3.5%–5.9%, while poor results were shown for n‐alkanes (MAE values 7.5%–45.7%). The Walling model and MixSIAR showed higher accuracy of contribution prediction, and the MAE was 3.5%–5.9% and 0.7%–3.5%, respectively. Although Landwehr also presented high accuracy of model output, it was relatively less robust compared with the former two mixing models (the MAE range was 3.8%–9.7%). Furthermore, the mixing model with three correction factors (particle size, organic matter (OM), and particle size with OM) showed poor output results for scouring experiments. This study provides a reference for the selection and determination of tracers, mixing models, and correction factors in field experiments. [ABSTRACT FROM AUTHOR]

Cropland soil erosion is primarily caused by agricultural production and indirectly altered by consumption patterns. A well-developed grain trade system transfers grain products to distant locations, away from their place of origin where soil erosion may have occurred. Evidence-based policies to control soil erosion can be developed by holding consumers responsible for the soil erosion caused by their consumption. However, there have been few systematic studies on cropland soil erosion that is embodied in grain trade. In this study, we estimated the soil erosion intensity (SEI) of grain production in each province of China from 1990 to 2020 by combining the Revised Universal Soil Loss Equation and socio-economic statistics. We also constructed an interprovincial grain trade network using linear programming techniques and analyzed the cropland soil erosion associated with the interprovincial grain trade. The results showed a rise in national cropland soil erosion attributed to grain production from 5.36×108 t in 1990 to 7.56×108 t in 2020. In particular, those embodied in interprovincial grain trade increased from 0.94×108 t in 1990 to 3.52×108 t in 2020. Nationally, about 10.72% of soil erosion exports in 2020 was from provinces with lower-than-average SEI, compared to 18.42% in 1990, indicating that current patterns of grain production and consumption are unfavorable for erosion control. Accordingly, measures have been proposed to build a soil erosion control system that includes consumers, such as changing farming practices, optimizing agricultural layout, promoting technology export and establishing a provincial compensation mechanism. [Display omitted] • Trade was prominent and insufficiently explored driver for cropland soil erosion. • RUSLE and grain trade network were utilized to estimate embodied soil erosion. • Mismatch between production and consumption increased embodied soil erosion. • Soil erosion burden mainly shifted from south with high SEI to north with low SEI. • Current provincial grain trade patterns were not conducive to soil erosion control. [ABSTRACT FROM AUTHOR]

In China, sloping farmland accounts for one-third of its total farmland, supporting ~330 million mountain people's livelihoods. Despite its long history of using soil conservation measures for reducing soil loss on sloping farmland, no comprehensive evaluation has ever been performed on their effectiveness. In this study, we reviewed the soil conservation measures on sloping farmland in China from ~2500 years ago to the present and examined their effectiveness under current and projected climate change scenarios based on 6909 plot-scale observations. For the sloping farmland across China, the average soil loss rate is 14.47 Mg ha−1 yr−1, with a quarter of the observed values exceeding the maximum tolerable soil loss rate (10 Mg ha−1 yr−1). Soil conservation measures can reduce soil loss by ~80%, with the highest effectiveness for the combination of biological and engineering measures (reduced by ~86%), followed by biological measures (reduced by ~84%) and engineering measures (reduced by ~82%) separately. However, the effectiveness of soil conservation measures shows a significant decrease in the farmland with a slope above 15° or a single rainfall event >25 mm. The effectiveness of currently applied soil conservation measures was also compared under the Shared Socioeconomic Pathways (SSP) 1, 2, and 5 in 2050, and their effectiveness is expected to decrease on over 27% of the sloping farmland. In particular, under the SSP1 scenario, the effectiveness of soil conservation measures is projected to diminish in 70%, 54%, and 54% of sloping farmland in Northeast China, Sichuan Basin and surrounding regions, and Yunnan-Guizhou Plateau, respectively, due to changes in rainfall, highlighting the need to consider the impact of climate change when implementing soil conservation measures. Overall, this study provides useful information for scientific strategies on the construction, management, and maintenance of soil conservation measures to control soil loss on sloping farmland. [ABSTRACT FROM AUTHOR]

[Display omitted] • Accurate quantification of soil erosion sub-process by remote sensing and check dam. • Vegetation restoration significantly reduced soil erosion modulus. • Check dams effectively reduce sediment delivery on the watershed scale. • The variation of erosion and deposition changes the sediment delivery ratio. China has implemented a series of ambitious soil and water conservation (SWC) projects on the Chinese Loess Plateau, which have significantly changed the erosion, transport, and deposition of sediment. As a result, the sediment flux of the Yellow River, once the largest carrier of fluvial sediment worldwide, has been reduced by approximately 85 % in the past 60 years. However, the effects of SWC measures on erosion, transport, and deposition of sediment are still difficult to quantify, which greatly limits the further planning and adjustment of SWC measures. Here, we determined soil erosion, sediment deposition, and sediment yield at different historical stages in a 187 km2 hilly and gully watershed on the Chinese Loess Plateau using the unmanned aerial vehicle (UAV) photogrammetry technology combined with check dam surveying and hydrologic monitoring. The results show that the construction of check dams and vegetation restoration significantly reduced the soil erosion rate, from 21,144 t km−2 yr−1 at Stage-1 (1960–1969) to 13,819 ± 3,622 t km−2 yr−1 at Stage-2 (1970–1999) and further to 4,723 ± 1,278 t km−2 yr−1 at Stage-3 (2000–2018). The sediment deposition rate was estimated to be 5,989 and 2,582 ± 351 t km−2 yr−1 at Stage-2 and Stage-3, respectively. The variation in the erosion and deposition of sediment led to a significant change in the sediment delivery ratio, from 1 at Stage-1 to 0.57 at Stage-2 and 0.45 at Stage-3. Our research results provide an important reference for further SWC planning. [ABSTRACT FROM AUTHOR]

Cropland soil erosion is a major threat to global agricultural sustainability. Compared with the well-studied natural factors of soil erosion, socioeconomic factors have just begun to be considered. The major obstacle is that the soil erosion of different crops has not been accounted for and connected to socioeconomic activities. This study adopted the revised universal soil loss equation (RUSLE) and the environmentally extended multiregional input-output (EE-MRIO) model to account for soil erosion on cropland from the production, consumption, and income perspectives at the provincial and sectoral levels in China. The results showed the major responsible agents in a synthetic view. On the production side, the Yunnan-Kweichow Plateau and surrounding hills of the Sichuan Basin, the Chinese grain bases located in northeastern and central China, and the Loess Plateau were the major regions that caused the most cropland soil erosion. On the consumption side, the national final demand for Sichuan, Yunnan, Shandong, Henan, and other provinces with high production-based cropland soil erosion (PBE) values per se pulled remarkable cropland soil erosion. On the income side, the crucial provinces into which the national primary input enabled notable cropland soil erosion were still those areas with serious cropland soil erosion. From the industrial perspective, the direct effects of human primary inputs into agriculture and the demand for agricultural products played the dominant role. In addition, Cereal and BOP (beans, oil and potatoes) were the most important among the agricultural sectors. The effects of the nonagricultural sectors, especially the manufacture of foods and tobacco (MFT) and the chemical industry (CI), on cropland soil erosion also cannot be ignored. Our results indicated that accounting from multiple perspectives could inform the better management of cropland soil erosion from a more comprehensive perspective. To the best of our knowledge, this study is the first to consider the accounting of cropland soil erosion in China from multiple perspectives. Tailored packages of measures should be established based on different patterns of areas with serious cropland soil erosion. [Display omitted] • Cropland soil erosion accounting was based on a multi-regional input-output table. • Multiple perspectives' accounting shows the major responsible agents for soil loss. • Crops in different regions also were the key to tackle cropland soil erosion. • Cropland soil erosion control cannot just narrow down to four agricultural sectors. • Cropland soil erosion is not a local phenomenon but a macroscopic problem. [ABSTRACT FROM AUTHOR]

• A UAV-based method estimating sediment deposited behind check dams was developed. • Errors of the optimal model for single and regional check dams are 12–13% and 2–3%. • This method avoids limitations of tedious field surveys and historical records. • This method can evaluate sediment retained by check dams in areas as large as 211,800 km2. The estimation of sediment deposited behind dams and reservoirs is of great significance for quantifying soil erosion rate and sediment flux. However, existing methods of sediment volume estimation often require detailed field measurements and historical topographic data, limiting the broader application of these methods. In this paper, focusing on the region that suffers the world's most severe soil erosion, we combine unmanned aerial vehicle (UAV) photogrammetry and simulate submerging analysis to propose a novel method for estimating sediment silted by check dams under complex topography. We obtained 1339 groups of topographic factors and ascertained the corresponding volumes of sediment deposited behind check dams in the loess hilly region of China (LHRC), and established five different models combined with regression analysis. Two different sets of data were used for method validation and optimal model determination. The results showed that the error of the optimal model in the volume estimation of single check dam and regional check dams is 12–13% and 2–3%, respectively. Additionally, the area-volume model has the potential to evaluate the sediment retention capacity of check dams (in the order of billions of cubic meters) in the whole LHRC, because the variables are easy to obtain and the model accuracy is relatively high. The further application of this method will help to evaluate the watershed sediment yield and regional soil and water conservation benefits, and is of great significance for explaining the future changes in water and sediment in the Yellow River basin. [ABSTRACT FROM AUTHOR]