Search

The effective control of cropland soil erosion is urgent for all countries because of its threat to global food security. Cropland soil erosion is caused by agricultural production and driven indirectly by consumption. Analyzing the causes and preventive strategies from the consumption side is essential for soil erosion control. However, there is not yet sufficient research or practice. In this study, we estimated global cropland soil erosion with the revised universal soil loss equation, allocated it to specific types of crops, and quantified the cropland soil erosion footprint of the economies with a multiregional input-output analysis model. Our results showed that developed economies, usually importing cropland soil erosion from developing or agriculturally developed economies, are the beneficiaries in the current crop trading system. The European Union is the largest net importer, while Brazil is the largest exporter. The indirect and induced sectors are the main contributors, consuming approximately 70.48% of the total cropland soil erosion. Our results revealed the region- and product-specific contributors that could inform the reduction of global cropland soil erosion for sustainable food production and consumption.

Soil erosion on cropland is a result of the interaction between nature and human activities. The socioeconomic influencing factors of soil erosion have been less studied than the biophysical processes and previous studies have mainly focused on the impacts of local socioeconomic factors on soil erosion in the same region. However, since agricultural activities are densely connected to other socio-economic activities, the need for agricultural products from distant regions could potentially drive local soil erosion accompanying agricultural production. To the best of our knowledge, these telecoupling effects have not been studied. Here, we combined the Revised Universal Soil Loss Equation (RUSLE) and multiregional input-output analysis (MRIO) models to quantify the contribution of China's cross-provincial economic demand to local soil erosion at the provincial, sectoral, and supply chain levels. Our results show that a large amount of soil erosion in the southwest, northeast, and central regions is linked to the economic needs across provinces. Agriculture and food processing are the most important distant driving sectors. The driving effect of household consumption on soil erosion mainly occurs on shorter supply chains, while exports and capital formation drive soil erosion through longer chains. Our results indicate that local soil erosion management must consider the impact of distant agricultural product needs and coordinate food production and supply on a national scale to protect the ecological function of the land., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Purpose: Tillage practices and crop growth play important roles in the soil erosion of sloping farmland. This study aims to investigate the effects of tillage practices on soil erosion in response to different crop growth stages and to determine the primary factors that affected the runoff reduction benefit of tillage practices among different growth stages. Methods: A field study was carried out under natural rainfall conditions, and 12 runoff plots (20 m × 5 m) were established, including four treatments, i.e., flat planting (FP), flat planting with hedgerow intercropping (HG), longitudinal ridge (LR) and bare land (CK). Runoff and soil losses after each rainfall event were monitored during the peanut seasons of 2021 and 2022 and the effects of tillage practices and peanut growth stages on runoff and sediment yields were evaluated. Results: The total surface runoff depth and sediment yield decreased in the following order: CK > LR > FP > HG. As peanuts grew, the seedling, needling, podding, and full fruit stages contributed approximately 71.5%, 20.4%, 6.4%, and 1.7% of the total runoff depth, respectively, which could be attributed to the synergistic impact of rainfall, crop growth, and antecedent soil moisture. During the seedling stage of peanuts, which did not provide sufficient surface cover, concentrated rainfall in large amounts resulted in high soil moisture and consequently high runoff losses. As peanuts grew, the S-shaped growth curve for peanut aboveground parts and root systems and reduced rainfall depth and frequency resulted in less runoff loss and increased runoff reduction benefits of tillage practices. Conclusions: The early growth stage of peanuts, generally accompanied by high antecedent soil moisture and heavy rainfall, should attract more attention to improving water erosion conditions on sloping farmland with only longitudinal ridges. [ABSTRACT FROM AUTHOR]

Soil erosion in cropland areas is mainly influenced by agricultural activities and natural conditions. Previous studies have largely focused on the biophysical processes or economic drivers of soil erosion. There have been few attempts to balance the impacts of population, agricultural production, and soil erosion to address the global socioecological predicament facing cropland. We combined the coupling coordination degree model (CCDM) with the Shapley additive explanations (SHAP) method to evaluate the coupling coordination level between population demand, agricultural production, and soil erosion as well as the influence of socioeconomic factors in 281 Chinese cities for the period from 1995 to 2010. Coupling between population, crop yield, and soil erosion was generally moderate across China during 1995–2010. Cities with a GDP in the range of 4.42–241.54 billion could fall into different coupling coordination phases that were identified by K-means clustering. The SHAP results showed that GDP and population density were the most important factors influencing the coordination level, while industrial structure was the key determinant that distinguished the different phases in cities with a similar economic status. Building on research on the evolutionary aspects of system coupling coordination, our study reveals for the first time the probable causes of changes in system coupling coordination via machine learning algorithms, providing a reference for future investigations. Our findings also provide a basis for developing policy recommendations to balance social demands, agriculture, and environmental protection. ● Nexus between population, crop yield, and soil erosion have a spatial zonality. ● Economic growth and coupling coordination are significant positively correlated. ● Economic structure is vital for breaching the phase change threshold. ● Development policies should target to different coupling phases. [ABSTRACT FROM AUTHOR]

In the mountainous area of China, the rock fragments in top soils are often removed by farmers because of their side effects on tillage. To understand hydrological processes and to assess the risk of soil erosion in purple soil areas with sloping farmlands, this study investigated the effects of rock fragment cover on surface runoff, infiltration, subsurface runoff, and erosion under field conditions using a portable rainfall simulator. Experimental twin plots (two subplots, 1 m wide by 2 m long, 32% slope) with different rock fragment covers ranging from 0 to 42% were exposed to four rainfall intensities: (I1), (I2), (I3), and (I4). Surface runoff, subsurface runoff, soil moisture, and sediment were measured. The results show that the hydrological response was influenced by the rock fragment cover and rainfall intensity. The rate of surface runoff in bare soils was affected by the rainfall intensity and increased with increasing rainfall intensity. The values of the surface runoff rates in bare soils were lower than under the I1, I2, and I3 rainfall intensities. As the rock fragment cover increased, the surface runoff rate decreased while the infiltration rate, the subsurface runoff rate and the deep percolation coefficient increased. On the other hand, when the surface runoff rates in the bare soils were higher than (in rainfall of I4), there were no significant differences in these hydrological variables among soils with different rock fragment covers. The differences in hydrological variables among soils with varying rock fragment covers decreased with increasing rainfall intensity. The rock fragment cover determined the erosive response. As the rock fragment cover increased, the sediment concentration decreased. The presence of surface rock fragments significantly reduces soil erosion, and the relationship between the soil erosion rate and rock fragment cover can be expressed by an exponential function with a high degree of reliability for different rainfall intensities. However, the effectiveness of the rock fragment cover in reducing soil erosion decreased with increasing rainfall intensity. [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]

Soil erosion affects the redistribution of soil and associated soil organic carbon (SOC) from different landforms, and it has significant implications regarding the fate of eroded SOC and terrestrial carbon sequestration. Despite the importance of soil erosion, few studies have evaluated the sources and budget of eroded SOC in the Loess Plateau region, which suffers from severe soil erosion. Based on an 11.3 m check dam sediment profile, we used the 137 Cs activity and extreme rainfall events as dating methods to date sediment sequences. In addition, the natural abundance levels of the stable carbon isotope (δ 13 C) of bulk organic matter and a two-end-member mixing model were used to discriminate the sources of eroded SOC from different siltation stages retained by the check dam in an intensive agricultural catchment of the Loess Plateau, China. The eroded SOC captured by the check dam was compared to potential source materials from different landscape units, which included sloping cropland and gully surface soils (0–5 cm). The results showed that the check dam intercepted 98.5 Gg of eroded soil and 172.6 Mg of SOC. The eroded SOC was primarily sourced from sloping cropland, which contributed to 81.3% of the total SOC retained by the check dam, whereas the gully soils contributed to 18.7% during the entire siltation stage. Additionally, the contribution of sloping cropland to eroded SOC increased from 1960 to 1990 as a result of rainfall and anthropogenic activities. A total of 89.7 Mg SOC was lost during soil erosion processes at a rate of 0.17 Mg ha −1 yr −1 and accounted for approximately 30% of the total eroded SOC exported from the eroding areas. Our results indicate that the soil erosion process has been an important net source of SOC in the study catchment. The check dam served as a carbon storage and sequestration structure for the hilly loess region due to its beneficial conditions for carbon sequestration over broad temporal and spatial distributions. [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]

Abstract: Controlling soil hydrological processes and combating soil erosion on agricultural fields are high priorities for crop production and ecological environments. In this research, the effect of land application of rock fragments on surface runoff, subsurface runoff, infiltration and soil loss on Regosols had been investigated under field conditions using a portable rainfall simulator. Experimental twin-plot (two subplot with 1-m wide by 2-m long, 32% slope) with different rock fragment covers ranging from 0–40% were exposed to three rainfall intensities, low (57±2mmh-1), medium (91±3mmh-1), and high (122±5mmh-1). Fifteen treatments were conducted in the experiments in duplicates. Surface runoff, subsurface runoff, soil moisture and sediment were measured. Results show that surface rock fragment cover retarded surface runoff, increased infiltration and subsurface runoff, and diminished sediment concentration and soil loss. The final infiltration rates, which increased with increasing rock fragment covers, were 16.5–42.7mmh-1 at low intensity, 19.7–50.8mmh-1 at medium intensity and 23.8–56.4mmh-1 at high intensity. Compared with bare soils, surface runoff rates were reduced to 24%, 51% and 64% in soils with 40% rock fragment cover at low, medium and high intensity rainfall, respectively. Subsurface runoff volume was significantly higher and time to start subsurface runoff was shorter as surface rock fragment cover increased. Compared with bare soils, subsurface runoff coefficients increased to 3.5, 3.3 and 2.9 times in soils with 40% rock fragment cover at low, medium and high intensity, respectively. Sediment concentrations increased from 9.8gL-1 for 40% rock fragment cover under high intensity rainfall to 51.5gL-1 for bare soils with rain falling at high intensity. The erosion rate was <12gm-2 min-1 for soils with 40% rock fragment cover, even when rainfall intensity was high, while it was >15gm-2 min-1 for bare soils under low intensity. The relationship between rock fragment cover and soil loss ratio can be expressed by an exponential function with a high degree of reliability, regardless of rainfall intensities. Overall, results indicate the surface rock fragments can be influential in shaping hydrological processes and soil loss from sloping farmland. [Copyright &y& Elsevier]

Abstract: Soil thickness exerts a first-order control on the hydrological processes of the hillslopes. However, from a hydropedological perspective, the knowledge of soil thickness effect on hydrological and erosion characteristics under sloping lands is limited. Based on a comprehensive survey of an experimental watershed in the Three Gorges Area of China, five typical sloping land plots (2m×1m) with different soil thickness were selected along a hillslope to investigate their hydrological processes and erosion response under three rainfall intensities (60, 90 and 120mmh−1) using a portable rainfall simulator. The results can be summarized as follows: (1) The surface flow coefficient was increased with increasing soil thickness, especially under the event of 60mmh−1. (2) The subsurface flow of the 23, 31 and 45cm plots mainly took the form of preferential flow. Conversely, the 59 and 76cm plots mainly took the form of matrix flow. (3) A prolonged low intensity rainfall is much more likely to facilitate deep percolation and subsurface flow than a short high intensity rainfall regardless of soil thickness. (4) Soil thickness and rock fragment cover were the most important factors than other soil properties in determining the hydrological and erosion behaviors. Thin soils showed higher infiltration capacity than thick soils due to their more distinct hydrological processes of subsurface flow and deep percolation. Rock fragment cover enhanced infiltration and served as a shield to protect the soil surface from detaching. Due to the synergies between thin soil thickness and high rock fragment cover, thin soils displayed significantly lower erosion rates than thick soils in all rainfall events, which increased from 211gm−2 h−1 for the 23cm plot with rainfall of 60mmh−1 to 4220gm−2 h−1 for the 76cm plot with rainfall of 120mmh−1. Our study suggested that the emerging interdisciplinary field of hydropedology promotes synergistic integration of pedology (e.g. watershed scale soil thickness investigation and soil profile description) and hydrology (e.g. rainfall simulation, subsurface flow and deep percolation) to enhance the holistic study of soil–water interactions in the sloping lands with different soil thickness. [Copyright &y& Elsevier]

Agricultural production in China is mainly decentralized, small in size, and involved by independent single households. Farmers are the main implementers of soil erosion control projects. Their willingness and abilities, which are crucial to the effectiveness of these projects, are closely related to their social networks. However, the relationship between farmers' social networks and soil erosion control remains unclear. Hengxi, a typical village in Jiangxi Province, China, was used as a case study. Traditional- and new-type of farmers' social networks were built according to the planting structures based on survey data. The results showed that both types of networks had the characteristics of small-world network and scale-free network. The ability to obtain and dispense information was the significant distinction between the two networks. The dealer was an influential key node in both networks. The government agencies were key nodes in the new-type network but not in the traditional-type network, which made it difficult for traditional farmers to obtain indispensable information about soil erosion control. The characteristics of farmers and their corresponding networks had significant influences on their awareness of soil erosion. Soil erosion management projects could be deployed smoothly by the key farmers and government agencies in the new-type social network, but difficultly in the traditional-type social network. To improve the effectiveness of soil erosion control projects, cooperation with dealers is important for government agencies. • Characteristics of farmers' social networks are distinct based on planting structure. • Information diffusion is more efficient in new-type social network. • Betweenness centrality affects farmers' awareness of soil and water conservation. • Government agencies should undertake proper roles in traditional-type social network. [ABSTRACT FROM AUTHOR]