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Effects of road types on road surface rill erosion after farmland size increase (FSI) in 2018. S1, S2 and S3 represent sub-watersheds 1-3 at lower, left upper and right upper watershed, respectively. Error bars are the standard error, and different letters indicate significant differences between road types within a watershed at p ≤ 0.05.
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Farmland size increase (FSI), which is an increase in operational size and consolidation of fragmented croplands, is considered an effective scheme to improve agricultural productivity and reduce fertilizer use with environmental protection benefits. But FSI involving road extension can enhance rill formation on road surfaces, and increase road ero...
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Context 1
... of the road surface rill erosion were in the order of S1 > S2 > S3 in both 2017 and 2018. The annual increase of 176 %, 42 %, and 85 % was obtained for road surface rill erosion in S1, S2 and S3, respectively, in 2018 as compared to 2017 (Fig. 4). Comparing the road types, rill erosion on new and old-new roads increased by 33-410 % than old roads (Fig. ...
Context 2
... of the road surface rill erosion were in the order of S1 > S2 > S3 in both 2017 and 2018. The annual increase of 176 %, 42 %, and 85 % was obtained for road surface rill erosion in S1, S2 and S3, respectively, in 2018 as compared to 2017 (Fig. 4). Comparing the road types, rill erosion on new and old-new roads increased by 33-410 % than old roads (Fig. ...
Context 3
... of the road surface rill erosion were in the order of S1 > S2 > S3 in both 2017 and 2018. The annual increase of 176 %, 42 %, and 85 % was obtained for road surface rill erosion in S1, S2 and S3, respectively, in 2018 as compared to 2017 (Fig. 4). Comparing the road types, rill erosion on new and old-new roads increased by 33-410 % than old roads (Fig. ...
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Citations
... Conventionally farmed landscapes also imply the expansion of road networks for car and mechanical mobility (Li et al., 2020). While most bat species are repelled by artificial illumination at night, some bat species concentrate foraging activity near lights to feed on insects lured by light (Rydell, 1992;Stone et al., 2009Stone et al., , 2012Stone et al., , 2015Barré et al., 2021;Salinas-Ramos et al., 2021b;Voigt et al., 2021). ...
Conventional agriculture occupies a substantial portion of Earth's terrestrial surface and adversely affects biodiversity through pesticide spread, mechanisation, and loss of spatial and temporal heterogeneity of farmed landscapes. Consequently, conventional agriculture has become a primary target of many restoration projects operating at various scales, from habitat to landscape. While these restoration efforts aim to increase farmland biodiversity and promote the delivery of associated ecosystem services, unintended consequences may arise when important threats are not mitigated. For instance, animals may be led to make maladaptive choices, and lured to attractive sites with poor habitat quality (ecological traps), resulting in adverse effects on individual fitness and demography. We focus our review on European farmland as a case study because of its extensive presence on the continent and the particularly articulated legal framework regulating agriculture and biodiversity within the European Union. Europe's policy framework is dual-faced: one promotes farmland development regardless of management practices, while the other advocates for biodiversity protection measures that sometimes lack strong supporting evidence or overlook critical management aspects. Insectivorous bats contribute significantly to ecosystem service delivery through insectivory in agricultural landscapes, consuming large numbers of pest arthropods. However, when restoring habitats for bats in conventional farmland, potential unintended outcomes must be considered, particularly if restoration actions are not accompanied by mitigation of key threats. These threats include the persistent and widespread use of pesticides, road networks, the siting of wind turbines in farmed landscapes, and opportunistic predators, especially domestic cats. We argue that installing bat boxes and enhancing habitat and landscape features, such as increasing connectivity and diversity, potentially trap bats in attractive yet unsuitable environments if such threats are not mitigated. While environmental restoration in farmland is highly valued for supporting bat populations, it is crucial to avoid neglecting factors that could have the opposite effect, turning 'improved' farmland into a sink. Research is urgently needed to understand such potential unintended effects and inform farmland management and policymakers.
... Considerando os artigos selecionados, observa-se uma diminuição de trabalhos acerca da temática nos últimos anos. Apesar dos primeiros trabalhos sobre estradas terem surgido na década de 1960 (Dieseker;Richardson, 1961Richardson, , 1962, e evoluído bastante a partir da década de 2000, com o emprego de novas metodologias de análise, ainda há uma preocupação em melhor compreender a dinâmica das estradas e dos processos erosivos associados (Xiao;Yang;Cai, 2017;Nosrati et al., 2018;Farias et al., 2019;Li et al., 2020). Isso justifica a necessidade de se produzir mais conhecimento sobre o tema, a fim de favorecer o entendimento de toda a dinâmica e fatores que contribuem para a ocorrência dos processos de produção de sedimentos. ...
As estradas, embora fundamentais para o desenvolvimento econômico, podem apresentar diversos impactos ambientais vinculados, por exemplo, à produção de sedimentos e erosão dos solos. Essas investigações são importantes a fim de encontrar soluções e novas maneiras de promover os avanços de forma aliada à proteção ambiental. A fim de melhor compreender esse campo de estudo, esta investigação apresenta como objetivo identificar os estudos recentes acerca da influência das estradas na produção de sedimentos e erosão dos solos. Para tanto, foi realizada uma revisão sistemática de literatura com o auxílio do Methodi Ordinatio. Ao total 51 estudos foram avaliados. Os resultados mostraram que houve uma redução no número de trabalhos sobre a temática nos últimos anos, sendo observada uma concentração de estudos em países equatoriais, especialmente asiáticos. Também é observada uma predominância de estudos direcionados às estradas florestais e estradas não pavimentadas de uma forma geral, com ênfase na produção de sedimentos na superfície destas vias. Os estudos empregam metodologias tradicionais e avançadas como sensoriamento remoto, monitoramento de campo e modelagem hidrossedimentológica. Nesse sentido, a pesquisa contribuiu com o fornecimento de uma base de conhecimento sobre a erosão do solo e produção de sedimentos em estradas, além de apontar para as lacunas de pesquisa que podem fornecer orientações aos avanços futuros da área.
... Eliminating some natural and semi-natural types to increase farmland area is mainly undertaken to maximize the production function of farmland, but this itself has certain risks, which will lead to the reduction in ecological functions, including SOC loss and biodiversity decline. Li et al. highlighted the negative impacts of increased farmland area, such as road erosion and associated nutrient losses, while reducing the average farmland size may have a positive impact on biodiversity within farmland (i.e., the crop-grown portion of the landscape) [66], which was more strongly dependent on the presence of semi-natural farmland boundary habitats [67]. The farmland landscape pattern is largely controlled by humans and is susceptible to landscape management policies [68]. ...
Accurate digital mapping of farmland soil organic carbon (SOC) contributes to sustainable agricultural development and climate change mitigation. Farmland landscape pattern has changed greatly under anthropogenic influence, which should be considered an environmental variable to characterize the impact of human activities on SOC. In this study, we verified the feasibility of integrating landscape patterns in SOC prediction on Lower Liaohe Plain. Specifically, ten variables (climate, topographic, and landscape pattern variables) were selected for prediction with Random Forest (RF) and Support Vector Machines (SVMs). The effectiveness of landscape metrics was verified by establishing different variable combinations: (1) natural variables, and (2) natural and landscape pattern variables. The results confirmed that landscape variables improved mapping accuracy compared with natural variables. R² of RF and SVM increased by 20.63% and 20.75%, respectively. RF performed better than SVM with smaller prediction error. Ranking of importance of variables showed that temperature and precipitation were the most important variables. The Aggregation Index (AI) contributed more than elevation, becoming the most important landscape variable. The Mean Contiguity Index (CONTIG-MN) and Landscape Contagion Index (CONTAG) also contributed more than other topographic variables. We conclude that landscape patterns can improve mapping accuracy and support SOC sequestration by optimizing farmland landscape management policies.
... The FSI has changed land use patterns, which has exacerbated soil erosion and nutrient losses in agricultural watersheds and, making them (the farmlands) the primary source of non-point source pollution in rivers and lakes around the world (Mateo-Sagasta et al., 2017;Li et al., 2020a;Li et al., 2020b). Previous studies have shown that FSI can cut fertilizer use while increasing agricultural output globally (Tilman et al., 2020;Wu et al., 2018;Ren et al., 2019) and decreasing environmental pollution (Zhu et al., 2022). ...
... Zhu et al. (2022) reported that 1% increase in farm size resulted in 0.2% increase in fertilizer use efficiency and thus reduce environmental pollution. However, in an agricultural watershed, FSI can increase hydrological connectivity, resulting to an increase in road erosion, hillslope gully erosion, and channel erosion (Gómez et al., 2014;Li et al., 2020a;Li et al., 2020b;. With an increased hydrological connectivity, it could be argued that contaminant transfer to river networks increases (Didone et al., 2021). ...
... However, these studies ignore the increased soil erosion caused by the expansion of farmland, accelerating the loss of nutrients from farmland into rivers, and aggravating the pollution of agricultural nonpoint sources. Our study, published in 2020, was the first to focus on soil erosion after FSI (Li et al., 2020a). Our results showed that 1% of increase in sugarcane plantation and channel sizes resulted in significant increase in contribution to river sediment by over 2% and 0.3%, respectively. ...
Farm size increase (FSI) accelerates soil erosion and sediment loss into the river. However, it is not clear how large-scale management, including FSI, changes the proportion of sediment from different land use types (LUTs) into rivers in intensive agricultural catchments. Thus, the aim of this study is to quantify and elucidate the contribution of different LUTs to river sediment before and after FSI using compound-specific stable isotopes (CSSI). The study was conducted in three parallel sub-watersheds in the sugarcane plantation region of subtropical southern China, each of which included four different LUTs (eucalyptus plantation, road, sugarcane plantation and channel). Following FSI, the contribution of sediment entering the river from the four LUTs was significantly different from that before FSI. The contribution per unit area of the road, sugarcane, and river channel to river sediment was significantly higher (P < 0.05) after FSI than before FSI. Overall, 1% increase in sugarcane farm size and stream channels caused > 2% and 0.3% increase contribution to river sediment, respectively. Field and road densities significantly correlated with river sediment sources. The FSI had a significant impact on the contribution of sediment entering the river from different LUTs within the watershed. Our results demonstrate that the increase river sediment depends on the increased hydrological connectivity of the watershed due to decreased field density and increased road density. Therefore, it is important to pay attention not only to the agricultural/economic benefits of FSI, but also the negative impacts on increasing erosion and ecological/environmental degradation.
... To improve agricultural production and environmental outcomes in these regions, reducing farm size may be a helpful strategy, particularly in countries like the United States, where large farm sizes are already prevalent. Meanwhile, large-scale farming has certain negative consequences, such as biodiversity loss and soil erosion [28][29][30] . Large-scale farms, especially industrial farms, would put negative pressure on the economy and food security when facing economic crisis 31,32 . ...
Maintaining food production while reducing agricultural nitrogen pollution is a grand challenge under global climate change. Yet, the response of global agricultural nitrogen uses and losses to climate change on the temporal and spatial scales has not been fully characterized. Here, using historical data for 1961–2018 from over 150 countries, we show that global warming leads to small temporal but substantial spatial impacts on cropland nitrogen use and losses. Yield and nitrogen use efficiency increase in 29% and 56% of countries, respectively, whereas they reduce in the remaining countries compared with the situation without global warming in 2018. Precipitation and farm size changes would further intensify the spatial variations of nitrogen use and losses globally, but managing farm size could increase the global cropland nitrogen use efficiency to over 70% by 2100. Our results reveal the importance of reducing global inequalities of agricultural nitrogen use and losses to sustain global agriculture production and reduce agricultural pollution.
... Rill erosion intensity is determined by many factors, such as rainfall intensity, frequency, and duration (Wemple et al., 2018), road features (Seutloali and Beckedahl, 2015), vegetation (Olsen et al., 2021), soil and lithology (Dymond et al., 2014), traffic (Li et al., 2020), and maintenance practices (Dymond et al., 2014). In this study, different road hydrological constituents (road surface, cutslope, and upslope catchment) were used as factors that influence the REI and morphological characteristics. ...
... followed by cutslopes (30.83%). These results are consistent with Cao et al. (2014), Li et al. (2020), and Wang et al. (2022), which demonstrated that greater available catchment area can generate more runoff, resulting in the greater erodibility, thus increasing rill morphological parameters. When runoff converges into a concentrated flow on road surface, it increases the rate of rill development. ...
Forest roads are a major source of and transport pathway for eroded sediments in mountainous watersheds. When rills develop on these roads' surfaces, they amplify sediment erosion. Best management practices can decrease sediment erosion, but in order to efficiently implement these practices it is necessary to determine which factors have the most influence on rill development on forest roads. Despite this need, there is scarce literature on rill development on forest roads. To fill this gap in knowledge, based on field survey and multivariate statistical methods including redundancy analysis (RDA) and variation partitioning analysis (VPA), we investigated unpaved forest roads in the Xiangchagou watershed in China and quantified the extent to which various factors influenced rill formation. Specifically, we studied how rill erosion intensity (REI) and rill morphological characteristics (like rill length, mean width and depth, density, and severity of fragmentation) varied along the slope of a forest road. We also introduced the concept of a road's hydrological constituents (its upslope catchment, surface, and cutslopes), and determined how much each constituent contributed to REI. We found that REI and morphological characteristics decreased moving from the upper portion of road segment downward, implying that rills developed more intensely uphill. Additionally, REI increased exponentially with rill width, density, and severity of fragmentation, and increase linearly with length and depth. Conversely, REI decreased exponentially with rill width-depth ratio. These relationships suggest that the morphological characteristics of rills could be used to predict the REI of a given road segment. Finally, we found that the road characteristics that best predicted rill formation included catchment area, cutslope area, and gravel bareness. Correspondingly, the upslope catchment, cutslopes, and road surface contributed 11.56%, 30.83%, and 8.23% of the variation in REI and morphological characteristics. The interaction between upslope catchment and road surface explained 19.89% of the variation. These results suggest that when best management practices are implemented to decrease erosion caused by forest roads in mountainous watersheds, they should integrate these hydrological constituents of a road.
... Landscape simplification is occurring all over the world, for example, soybean expansion and intensive production in the Amazon basin (Fearnside, 2001;Gasparri and Grau, 2009), oil palm cultivation in Southeast Asia (Wicke et al., 2011), and agricultural intensification in Europe (Stoate et al., 2001). Previous studies have focused on the effects of intensive production on vegetation coverage (Neill et al., 2013), slope erosion (Li et al., 2020a;Li et al., 2021a,b), soil quality (Yi et al., 2022) and irrigation demands (Salmoral et al., 2020). However, although arable land resources in mountainous areas are scarce, research on effects of intensification on watershed hydrology and sediment processes is relatively lacking. ...
... Thus, promoting an effective increase in farm size, thereby increasing agricultural productivity and achieving more sustainable N management is of great significance. It is worth noting that there are also some negative effects of large-scale farming including biodiversity loss, soil erosion and nutrient loss, typically in hilly areas (Marcacci et al., 2020;Li et al., 2020aLi et al., , 2020b. The risk of large-scale farms facing would increase when tackling market fluctuations, which may exert negative pressure on the economy (Ritchie and Ristau, 1986;Levins and Cochrane, 1996). ...
Synthetic nitrogen (N) fertilizers support global food production and feed over half of the global population. However, more than half of the N fertilizers applied to croplands are not absorbed by crops, but lost to the environment, leading to low N use efficiency (NUE) globally. Identifying and overcoming socioeconomic barriers to achieve an improvement of NUE and a reduction in N loss is thus key for N management and to attain agricultural and environmental sustainability. In this paper, we compiled the global cropland N budgets at a national scale (1961–2018) and developed robust econometric models to explore the relationship between cropland N use with socioeconomic factors. The results demonstrate that economic development and farm size are the key drivers to improve NUE for agricultural and environmental sustainability. In less developed countries, it is difficult for farmers to access chemical fertilizers, leading to croplands receiving too little N input and at a high NUE, but suffering from soil N depletion. As economic development progresses, more fertilizer is produced and applied, but smallholder farming typically leads to over-fertilization and consequently N losses to the environment. Large-scale farming improves NUE, reduces N loss and benefits agricultural production and environmental protection. Also, interactions between farm size and economic development, international trade, crop and livestock systems, and related policies are important causes for changes in the NUE of the whole agricultural system. Overcoming these socioeconomic barriers especially combining large-scale farming could effectively reduce excessive N inputs and sustain agricultural and environmental N management, while maintaining food production, resulting in a triple-win for food security, poverty alleviation, and environmental protection.
... Hillslope topography accelerates soil erosion and nutrient loss through runoff. The heterogeneity of spatial arrangement of crops in smallholder farms further aggravates soil and nutrient loss [56] . While studies have shown that consolidating smallholdings into larger ones will increase resource use efficiency and productivity and reduce fertilizer use [57] , the environmental and ecological benefits from reduced fertilizer and other agrochemical use can be negated by accelerated erosion and runoff due to increase in slope length [57] . ...
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● Cost escalation and declining profits evident in sugarcane production in China.
● Monoculture and fertilizer overuse causes poor soil health, crop productivity plateau.
● Matching crop nutrient demand and supply key to recovery of sugarcane soils.
● Inorganic inputs need to be replaced with organic sources to restore soil health and sustainability.
● Integrated multidisciplinary solution for sustainable sugarcane cropping system needed.
Demand for sugar is projected to grow in China for the foreseeable future. However, sugarcane production is unlikely to increase due to increasing production cost and decreasing profit margin. The persisting sugarcane yield plateau and the current cropping system with fertilizer overuse, soil acidification and pests and diseases remain the major productivity constraints. Sugarcane agriculture supports the livelihood of about 28 million farmers in South China; hence, sustaining it is a socioeconomic imperative. More compellingly, to meet the ever-increasing Chinese market demand, annual sugar production must be increased from the current 10 Mt to 16 Mt by 2030 of which 80% to 90% comes from sugarcane. Therefore, increasing sugar yield and crop productivity in an environmentally sustainable way must be a priority. This review examines the current Chinese sugarcane production system and discuss options for its transition to a green, sustainable cropping system, which is vital for the long-term viability of the industry. This analysis shows that reducing chemical inputs, preventing soil degradation, improving soil health, managing water deficit, provision of clean planting material, and consolidation of small farm holdings are critical requirements to transform the current farming practices into an economically and environmentally sustainable sugarcane cropping system.
... In particular, cautions are needed to manage CAPRP to adapt climate change in countries where already have large CAPRP, and reducing farm size to an optimal level may be helpful given the inverted U-shaped relationship of CAPRP with N use and loss. Meanwhile, large-scale farming favored by large CAPRP has certain negative consequences, such as biodiversity loss, soil erosion, and nutrient loss [40][41][42] . When dealing with market uctuations, the possibility of large-scale farms, especially for industrial farms, encountering unfavorable consequences would grow, putting negative pressure on the economy and causing nancial problems 43,44 . ...
Maintaining food production while reducing agricultural nitrogen pollution is a grand challenge under the threats of global climate change, which has exerted negative impacts on agricultural sustainability. How global agricultural nitrogen use and loss respond to climate change on temporal and spatial scale is rarely understood. Here we show that climate change leads to small temporal but substantial spatial changes in cropland nitrogen use and losses across global regions based on historical data for the period 1961-2018 from 150 countries. Increases of yield, nitrogen surplus and nitrogen use efficiency (NUE) are identified in 24% of countries, while reductions are observed for the remaining 76% of countries, as a result of climate change in 2018. Changes of cropland area per capita of rural population (CAPRP) further intensify the variations of nitrogen use and pollution in global croplands. Yet, improving farmers’ practices with changes of CAPRP can facilitate climate change adaptation, by which global cropland NUE could be increased by one-third in 2100 compared to 2018 under future shared socioeconomic pathways. Our results would be of great significance to sustain global agriculture as well as eliminate national inequalities on food production and agricultural pollution control.
