Rainfall simulators(RS)have been used,above all,to evaluate hydrological processes related to soil water infiltration,surface runoff and soil erosion.They allow repeatability of rain application with different precipi...Rainfall simulators(RS)have been used,above all,to evaluate hydrological processes related to soil water infiltration,surface runoff and soil erosion.They allow repeatability of rain application with different precipitation intensities in field and/or laboratory conditions and should produce events with physical characteristics similar to natural rain.In this manuscript,we carried out a bibliometric and scientometric analysis of studies with simulated rainfall in Brazil to assess the temporal evolution of publications,the main topics addressed and the degree of technological development of the equipment.We searched for the terms“rainfall simulator”OR“simulated rainfall”AND“Brazil”in the Scopus,Web of Science,SciELO and Google Scholar databases.We found 143 articles published in the last 37 years(1985-2022).Our findings indicate that the main research areas covered in papers are soil erosion(57.34%),soil water infiltration(24.47%),nutrient losses(9.8%)and RS development and calibration/assessment(8.39%).In recent years,the number of published papers in international high-impact factor journals has increased.Most of the papers(49.65%)refer to studies carried out by institutions located in the south and southeast regions of Brazil.Moreover,there is a large gap of studies on simulated rainfall in other regions of Brazil,where important biomes such as the Cerrado,Amazon,Caatinga,and their transitions are located.This study informs research priorities on soil erosion under simulated rainfall and provides a bibliographic database that can assist in more detailed future analyses.展开更多
In the last decades,in some Mediterranean areas,pedodiversity decreased mainly due to pedotechnique application in large-scale farming that transformed original soils into Anthrosols.Supporting the consideration that ...In the last decades,in some Mediterranean areas,pedodiversity decreased mainly due to pedotechnique application in large-scale farming that transformed original soils into Anthrosols.Supporting the consideration that soils can be considered as living systems,the original concept of'soil genetic erosion'is re-proposed.Data,extrapolated and modeled from a Soil Information System in a study case representative of a Mediterranean landscape,predicted that most of the soil types would disappear in few years leading to a decrease of the soil diversity and originating soil genetic erosion.This circumstance is intentionally here told in form of a story where the fairy tale characters are some roils facing extinction in the landscape.Soil genetic erosion could result in a negative impact on the environment because it reduces the soil's security through a drastic reduction of the soil ecosystem services with a decrease of the immaterial benefit for the environment.The conviction that soils,as well as animals and plants,are living bodies,and pedodiversity is equally important as biodiversity in maintaining sustainability and ecosystem services,might truly attract the attention of the public opinion.Besides,focussing more on the soil economic dimension and strengthening the assignation of'economic value'to the soil ecosystem services,also politicians and administrators could increase their interest in soil security.展开更多
Nutrient loss from agricultural fields is one of the main factors influencing surface-and ground-water quality.Typical fertilizer nitrogen(N)consumption rates in vegetable production systems and horticultural crops in...Nutrient loss from agricultural fields is one of the main factors influencing surface-and ground-water quality.Typical fertilizer nitrogen(N)consumption rates in vegetable production systems and horticultural crops in Puerto Rico fluctuate between 112 and 253 kg N/ha.The nitrogen use efficiency of vegetable crops is low,increasing the potential for nitrogen losses and high residual soil nitrate content.Quantification of residual soil N and N losses to the environment can be a difficult task.Simulation models such as the USDA-ARS N Index can be used to identify the relative magnitude of varying N-loss pathways and to identify best management practices.Field studies were conducted to quantify residual soil N and crop N removal,and to validate the Nitrogen Index in onion,tropical pumpkin and tomato production systems in the Lajas Valley in southwestern Puerto Rico.Relationships between observed and simulated values were determined to examine the capability of the model for evaluating N losses.There was good correlation between observed and predicted values for residual soil N(r=0.88)and crop N removal(r=0.99)(p<0.05).In the production systems evaluated,the N volatilization losses ranged from 1 to 4 kg N/ha,the denitrification losses ranged from 18 to 46 kg N/ha,the leaching losses ranged from 155 to 779 kg N/ha,and the residual soil nitrate ranged from 64 to 401 kg N/ha.The N use efficiency ranged from 15% to 39%.The results obtained showed that the Nitrogen Index tool can be a useful tool for evaluating N transformations in vegetable production systems of Puerto Rico's semi-arid zone.展开更多
The study planed to identify a suitable alternative to the FAO 56 Penman-Monteith(FAO56PM)equation for calculating reference evapotranspiration(ET_(0))from chosen te mperature and radiation based models utilizing mont...The study planed to identify a suitable alternative to the FAO 56 Penman-Monteith(FAO56PM)equation for calculating reference evapotranspiration(ET_(0))from chosen te mperature and radiation based models utilizing monthly meteorological data from 30 destinations in diverse agro-ecologial regions of the Northeast(NE)India ie,Assam Bengal Plain(ABP),eastern Himalaya(EH),and the northeastern hilly(NEH)region.Radiation-based IRMAK3 most appropriate in the ABP(weighted root mean square deviation,WRMSD=0.17 mm d^(-1),r^(2)=0.98,for Nagrakata),and TURC model being in the first three rank of most of the sites,with the lowest error and highest correlation in NEH(WRMSD=0.10 mm d^(-1),r^(2)=0.92,for Shillong),and EH(WRMSD=0.23 mm d^(-1),r^(2)=-0.95,for Gangtok).Findings reveal that IRMAK3 and TURC models performed equally well and were observed to be the best among selected modets for the majority of stations followed by FAO24 Blaney-Criddle(FAO24BC),and 1957MAKK Pair-wise regession equations were developed for preferred FAO56PM ET_(0) estimates to ET_(0) estimates by alternative methods.Cross-correlation of eighteen chose methods demonstrated that the five equations(i.e.four radiation-and one temperature-based)performed eceptionally well when contrasted with the FAO56PM model,thus being advised for assessing ET_(0)。under limiting data conditions as have yielded a better estimate of ET_(0) with a small error.展开更多
There is an urgent need to match food production with increasing world population through identification of sustainable land management strategies.However,the struggle to achieve food security should be carried out ke...There is an urgent need to match food production with increasing world population through identification of sustainable land management strategies.However,the struggle to achieve food security should be carried out keeping in mind the soil where the crops are grown and the environment in which the living things survive.Conservation agriculture(CA),practising agriculture in such a way so as to cause minimum damage to the environment,is being advocated at a large scale world-wide.Conservation tillage,the most important aspect of CA,is thought to take care of the soil health,plant growth and the environment.This paper aims to review the work done on conservation tillage in different agro-ecological regions so as to understand its impact from the perspectives of the soil,the crop and the environment.Research reports have identified several benefits of conservation tillage over conventional tillage(CT)with respect to soil physical,chemical and biological properties as well as crop yields.Not less than 25%of the greenhouse gas effluxes to the atmosphere are attributed to agriculture.Processes of climate change mitigation and adaptation found zero tillage(ZT)to be the most environmental friendly among different tillage techniques.Therefore,conservation tillage involving ZT and minimum tillage which has potential to break the surface compact zone in soil with reduced soil disturbance offers to lead to a better soil environment and crop yield with minimal impact on the environment.&2015 International Research and Training Center on Erosion and Sedimentation and China Water and Power Press.Production and Hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).展开更多
Conservation practices are encouraged to improve soil health and sustain agronomic crop production.Mehlich-3 is often used as a multi-nutrient extractant to determine soil fertility status.A study inves-tigated the im...Conservation practices are encouraged to improve soil health and sustain agronomic crop production.Mehlich-3 is often used as a multi-nutrient extractant to determine soil fertility status.A study inves-tigated the impacts of the conservation practices of gypsum,cover crops,and crop rotation on 28 Mehlich-3 extractable elements,of which 11 were considered plant nutrients,from soil at three mid-western US locations.Soil was collected from 0 to 15 and 15-30 cm depths 5 years after implementing the conservation practices.Treatments consisted of(1)with and without cereal rye(Secale cereale L.)winter cover,(2)continuous soybean[Glycine max(L.)Merr.]vs.soybean-corn(Zea mays L.)rotation,and(3)annual gypsum application(0,1.1,and 2.2 Mg ha-1).Differences were observed by site,depth,and conservation practice depending on the element evaluated.Minimal interactive effects were observed among treatments.The most consistent effect was observed for crop rotation across sites.Gypsum only affected the site with the greatest clay content,where more Ca and S were retained,and Mg and Mn displaced.Cover crop only affected elements at this high clay site,where different elements were positively or negatively affected.Results suggest that not one practice fits all,and optimum conservation practices must be tailored for the site.展开更多
During the International Workshop on Soil Erosion and Riverine Sediment in Mountainous Regions held in November 2022,scientists from many countries shared their state-of-the-art knowledge and brainstormed to improve s...During the International Workshop on Soil Erosion and Riverine Sediment in Mountainous Regions held in November 2022,scientists from many countries shared their state-of-the-art knowledge and brainstormed to improve scientific understanding for coping with climate change and anthropogenic impacts.Information summarized in this discussion includes proposed key scientific questions and suggested joint actions to reduce soil erosion and riverine sediment problems in mountainous regions.展开更多
Water scarcity threatens global food security and agricultural systems are challenged to achieve high yields while optimizing water usage.Water deficit can be accentuated by soil physical degradation,which also trigge...Water scarcity threatens global food security and agricultural systems are challenged to achieve high yields while optimizing water usage.Water deficit can be accentuated by soil physical degradation,which also triggers water losses through runoff and consequently soil erosion.Although soil health in cropping systems within the Brazilian Cerrado biome have been surveyed throughout the years,information about soil erosion impacts and its mitigation are still not well understood;especially concerning the role of cropping system diversification and its effects on crop yield.Thus,the aim of this study was to assess whether ecological intensification of cropping systems-inclusion of a consorted perennial grass and crop rotation-could promote soil coverage and consequently decrease water erosion and soil,water,and nutrient losses.This work studied the effects of crop rotation and consorted Brachiaria,along with different levels of investment in fertilization on soil physical quality and on soil,water,and nutrient losses,and crop yields.Results proved that soybean monoculture(SS)is a system of low sustainability even under no-till in the Brazilian Cerrado conditions.It exhibited high susceptibility to soil,water,and nutrient losses,causing low crop yields.Our results showed that water losses in SS cropping system were approximately 10%of the total annual rainfall,and total K losses would require an additional 35%of K application.Conversely,ecological intensification of cropping systems resulted in enhanced soil environmental and agronomic functions,increased grain yield,and promoted soil and water conservation:high soil cover rate,and low soil,water and nutrient losses.Ecological intensification proved to be an adequate practice to boost crop resilience to water deficit in the Brazilian Cerrado.展开更多
There are 239,100 gullies in southern China,which cause the degradation of ecological system.However,studies on gully development at the regional scale is relatively lack.The purpose of this study is to analyze the re...There are 239,100 gullies in southern China,which cause the degradation of ecological system.However,studies on gully development at the regional scale is relatively lack.The purpose of this study is to analyze the regional gully dynamics and explore how land use and topographic factors affect gully development.Input data consists of land use maps derived from high-resolution images from 2004 to 2014,and topography maps from a digital elevation model with a pixel size of 8 m×8 m in two 25-km2 study sites of Anxi(AX)and Xingning county(XN).The following results were obtained:(1)AX gullies decreased from 2006 to 2014 while XN first increased from 2004 to 2009,and then decreased from 2009 to 2014.Both AX and XN gully area in percentage of the total area ranged from 1%to 3%,which was higher than the average 0.25%of the whole southern China by the artificial survey in 2005.(2)Most of AX and XN gullies occurred along the ridgeline and had the close relationships with the upstream contributing area and slope gradient.(3)New gullies developed on the exposed land and forestland.The lost gullies were converted into forestland and grassland.In fact,most of these gullies were only covered by vegetation,not real disappearance.These results proved that gully decreased,but construction of roads and buildings intensified gully development.Consequently,these findings reveal that vegetation protection and ecological restoration should be adopted in southern China.展开更多
Payments for Environmental Services(PES)are relatively novel mechanisms whereby the adoption of sustainable management practices by a stakeholder is rewarded by incentives linked to external markets.Adoption of PES fo...Payments for Environmental Services(PES)are relatively novel mechanisms whereby the adoption of sustainable management practices by a stakeholder is rewarded by incentives linked to external markets.Adoption of PES for conservation agricultural practices(CAPS)by smallholder farmers may provide opportunities to increase household income or cover the technology costs of adoption if the carbon sequestration benefits of CAPS are quantifiable,adoption rates are accelerated and maintained,a mechanism exists whereby carbon sequestration services can be compensated,and carbon offset exchange markets are viable.This research suggests a methodology to examine a PES market for carbon offsets generated by the adoption of CAPS by farmers in Mozambique.Assuming a cumulative adoption of 60%over a 20-year period,revenue from PES market participation to CA adopters was two times higher than revenue earned when disadoption occurred midway through the simulation.Lower adoption targets are associated with higher per household returns when fertilizer rates typical to the region are increased.Establishing and maintaining a sustainable PES system in the study region would require significant investment in time and resources.The lack of on-the-ground institutions or local support for such a program would also challenge successful implementation.Finally,the programs where participant success depends on external markets,such as the hypothetical one suggested here,are subject to the ebb and flow of foreign demand for carbon offsets.Addressing these three broad constraints to a PES/CAPS program in the region would require grass-roots driven policy initiatives with buy-in at multiple social,economic,and political levels.展开更多
The application of fallout radionuclides in soil erosion investigations and related sediment budget studies has provided a widely used tool for improving understanding of soil erosion and sediment transfer processes.H...The application of fallout radionuclides in soil erosion investigations and related sediment budget studies has provided a widely used tool for improving understanding of soil erosion and sediment transfer processes.However,most studies using fallout radionuclides undertaken to date have focussed on small areas.This focus on small areas reflects both the issues addressed and practical constraints associated with sample collection and analysis.Increasing acceptance of the important role of fine sediment in degrading aquatic habitats and in the transfer and fate of nutrients and contaminants within terrestrial and fluvial systems has emphasised the need to consider larger areas and the catchment or regional scale.The need to upscale existing approaches to the use of fallout radionuclides to larger areas represents an important challenge.This contribution provides a brief review of existing and potential approaches to upscaling the use of fallout radionuclides and presents two examples where such approaches have been successfully applied.These involve a national scale assessment of soil erosion rates in England and Wales based on 137Cs measurements and an investigation of the sediment budgets of three small/intermediate-size catchments in southern Italy.展开更多
Soil loss by water erosion is one of the main threats to soil health and food production in intensively used agricultural areas.To assess its significance to overall sediment production,we applied the Water and Tillag...Soil loss by water erosion is one of the main threats to soil health and food production in intensively used agricultural areas.To assess its significance to overall sediment production,we applied the Water and Tillage Erosion Model/Sediment Delivery model(WaTEM/SEDEM)to the Luoyugou catchment,a sub-catchment of the Yellow River Basin within the Chinese Loess Plateau.WaTEM/SEDEM considers rill and interrill erosion and deposition rates to calculate the sediment yield rates leaving the catchment.Ter-races were established in the 1990s to reduce soil loss in this area,but no soil erosion modeling has been published regarding the effect of this mitigation measure.Therefore,we applied 1000 Monte Carlo simulations of the WaTEM/SEDEM,and the modeled average soil loss by rill and interrill erosion for 2020 was 12.2±0.5 t ha^(-1)yr^(-1),with a sediment yield at the outlet of 53,207.8±11,244.1 t yr^(-1).The results indicated that the terracing reduced gross soil loss rates(from 51.8t ha^(-1)yr^(-1)in 1986 to 12.2±0.5 t ha^(-1)yr^(-1)in 2020),while land cover changes,mainly the conversion of forests and grassland,partly coun-teracted the mitigation(combined effect:76%reduction).Modeled sediment loads by rill and interrill erosion accounted for 22.8%of the total long-term sediment production recorded by flow discharge measurements.Other processes not considered by the model,such as landslides,gully erosion,riverbank erosion,and sediment production by construction,seem to predominantly influence the overall sedi-ment yield.Considering years with baseline sediment production only,the measured and modeled sediment yields compared favorably,indicating that the latter processes primarily contribute during extreme events.展开更多
Alternate partial root-zone drying(APRD)is a water-saving method but can regulate crop physiological responses.A pot experiment has been conducted to study the efficiency of partial and fixed root-zone drying on the g...Alternate partial root-zone drying(APRD)is a water-saving method but can regulate crop physiological responses.A pot experiment has been conducted to study the efficiency of partial and fixed root-zone drying on the growth and production of maize(Zea mays L)in addition to the water use efficiency in soils with different gypsum content.The experimental treatments include three irrigation treatments,i.e.Conventional Irrigation(CI),Alternate Partial Root-zone Drying(APRD)and Fixed Partial Root-zone Drying(FPRD),and three soils with different gypsum content"(60.0[G1],153.7[G2],and 314.2[G3]g kg^(-1))".The vegetative growth,root dry mass and physiological indices(leaf relative water content,carotenoid concentration,proline)have been studied during three stages of maize plant growth(jointing,tasselling,and maturing).The Results showed that compared to CI,APRD and FPRD increased water use efficiency by 38.93 and 14.94%based on dry seed yield.In addition,compared to CI,APRD increased maize seed yield by 4.62-20.71%,while FPRD decreased yield by 19.24-5.28%for the gypsiferous soils G2 and G3,respectively.APRD has a slight effect on leaf water potential,leaf relative water content,carotenoid and proline activities from jointing to maturing stages at the three gypsiferous soils.Results suggest that APRD could make maize plants use water even more productively with better adaptation to water shortages in the gypsiferous soils.展开更多
Soil erosion disturbs not only the global carbon cycle,but it is a complex environmental problem.Revegetation could reduce carbon emission by controlling soil erosion and increase carbon sequestration and accumulation...Soil erosion disturbs not only the global carbon cycle,but it is a complex environmental problem.Revegetation could reduce carbon emission by controlling soil erosion and increase carbon sequestration and accumulation by fixing carbon in vegetation and soil.The Grain for Green Program(GFGP)of China is the largest ecological restoration program in the world closely related to land-use/land-cover change(LUCC).Systematically assessing the carbon sequestration benefit of GFGP is crucial for a better understanding of the effects of implementing GFGP and providing reasonable vegetation management.Therefore,we selected the hilly red soil region(HRSR)of southern China as a study area,which is one of the main ecologically vulnerable areas in China.We assessed the carbon sequestration in the GFGP area of the HRSR using the InVEST(Integrated Valuation of Environmental Services and Tradeoffs)model based on land-use/land-cover datasets during 2000e2015.Our results show that implementing GFGP is conducive to the enhancement of carbon sequestration services.Total carbon sequestration showed an increasing trend at a rate of 15.43%from 2000 to 2015.The most significant change mainly happened in Hunan Province with the shortest implementation time.The carbon sequestration of each carbon pool(namely aboveground biomass,belowground biomass,soil,and dead organic matter)also increased slightly.Additionally,for carbon sequestration,unused land converted to forest land is the most effective LUCC.This study can provide scientific support for the management and implementation of GFGP in the HRSR of China.展开更多
A field experiment was conducted for two consecutive years at North Eastern Indian Himalayan region to assess the effect of soil moisture conservation measures on soil and water productivity of different rainfed maize...A field experiment was conducted for two consecutive years at North Eastern Indian Himalayan region to assess the effect of soil moisture conservation measures on soil and water productivity of different rainfed maize(Zea mays L.)-based cropping sequences.Results revealed that double mulching with in-situ maize stover mulch(MSM)+fresh biomass of white hoary pea(WHP-Tephrosia candida)and MSM+fresh biomass of ragweed(RW-Ambrosia artemisiifolia)improved soil moisture content(SMC)and leaf relative water content of crops during dry season.The soil organic carbon(SOC)content and stocks under MSM+WHP and MSM+RW mulches were significantly higher than that under no mulch at 0-15 cm depth.The soil microbial biomass carbon and dehydrogenase activity were maximum under MSM+WHP/RW.The highest system productivity was obtained from maize-French bean(Pole type-PT)sequence under MSM+RW followed by MSM+WHP.The water productivity was the highest under MSM+WHP.While SOC content was the highest under maize-French bean(PT),the maximum plant available nitrogen and phosphorus were obtained under maize-black gram sequence.Thus,double mulching technology involving MSM and RW(available in plenty)is a viable option for improving soil,crop and water productivity under rainfed hill ecosystems of eastern Indian Himalayas.展开更多
Nutrient management, water quality protection, and irrigation efficiency top the list of on-farm resource concerns indicating a need to address them through conservation strategies. A suite of Best Management Practice...Nutrient management, water quality protection, and irrigation efficiency top the list of on-farm resource concerns indicating a need to address them through conservation strategies. A suite of Best Management Practices (BMPs) has been identified and recommended, through several outlets, to farmers to ameliorate these concerns. This research examines the adoption of strategies that ameliorate the resource concerns as a joint decision, using a bivariate model. Data from the 2016 Nutrient Management Survey, conducted by the Louisiana Master Farmer Program, are used to examine the factors affecting adoption of these conservation practices. A bivariate probit regression found significant results for explanatory variables and emphasize the effect of perception regarding the role of on-farm practices, ownership of land, participation in conservation programs in the past, and producers educational attainment on the like-lihood of adopting the conservation practices. Implications for policy development and educational programs are discussed.展开更多
The adoption of no till was a major turning point in the transformation of agriculture in Argentina.This paper describes the process of adoption of no till,and the impacts of this on agricultural production.Whereas pr...The adoption of no till was a major turning point in the transformation of agriculture in Argentina.This paper describes the process of adoption of no till,and the impacts of this on agricultural production.Whereas previously,soil erosion was so extreme and pervasive as to threaten the economic viability and survival of the industry,today with the majority of production under no till,Argentina produces more than ever in the past.The paper also illustrates how,after first focusing on technology adoption(no-till),the system in Argentina has now broadened to include the concepts of Conservation Agriculture(CA)and Sustainable Land Management(SLM).These strategic moves have contributed to an agricultural industry in Argentina that is more economically and environmentally sustainable than that of the past.展开更多
Soils are key natural resources for the Earth's system;however,human impacts,especially,soil erosion are considered serious threats.Therefore,identifying and assessing effective factors to understand erosion hot s...Soils are key natural resources for the Earth's system;however,human impacts,especially,soil erosion are considered serious threats.Therefore,identifying and assessing effective factors to understand erosion hot spots at different scales is critical to developing effective land management plans and ensuring the sustainability of the territory.This study was conducted to determine and prepare an erosion risk map,but to prioritize the survey at different scales,such as sub-basin and watershed ones.To achieve this goal,geographic information system(GIS)and remote sensing data(RS)were used combining the analysis network process method(ANP)and ICONA model(Institute for the Conservation of Nature).As study case,we selected the degraded areas of the Gorganrood watershed located in the north of Iran.The study area was obtained for very low,low,medium,high,and very high-risk classi-fications of 14.0,21.4,17.9,31.3,and 15.4%,respectively.Results from the ICONA model also indicated that 12.8,28.8,22.1,27.9,8.5,and 0.03%belong to very low,low,medium,high,very high,and without risk of erosion,respectively.According to the validation results,it was found that the accuracy of ANP and ICONA models are 0.83 and 0.80,respectively,which indicates the suitability of the models for preparing the erosion map of the region is appropriate and useful for designing land management plans.We conclude that both models can be used to develop the erosion map potential and to prioritize sub-basins if a complete database of geomorphological characteriscs and human activities are accurate previously defined.展开更多
Global climate change and overgrazing are driving shifts in the plant composition of grassland com-munities,which may profoundly affect the function of grassland ecosystems in regulating runoff and soil erosion.Here,w...Global climate change and overgrazing are driving shifts in the plant composition of grassland com-munities,which may profoundly affect the function of grassland ecosystems in regulating runoff and soil erosion.Here,we examined the shift effects of normal hillslope alpine meadow to shrub and severely degraded meadow states on runoff and sediment generation under natural rainfall conditions,and determined the contributions of plant and soil properties changes to soil erodibility,runoff and sediment generation by in situ rainfall experiment and monitoring on the hillslope of Qinghai-Tibetan Plateau.The results showed that normal meadow shift into severely degraded meadow state,mean weight diameter,soil saturated hydraulic conductivity,soil cohesion and soil erodibility K-factor at the topsoil decreased by 70.3%,73.1%,80.3%and-13.1%,respectively,and when normal meadows shift into shrub meadow state,they reduced by 49.1%,-1.3%,49.4%,and-8.3%,respectively.Runoff and soil loss significantly changed by-40.0%and 177.8%when normal meadow shifted into a severely degraded meadow state,while runoff and soil loss significantly changed by+65.0%and+77.8%when normal meadow shifted into a shrub meadow state.Our findings highlight that the two divergent shifts both increased soil loss compared to the normal hillslope alpine meadows.Overall,our results indicate that the divergent shifts of normal alpine meadows exacerbated soil erodibility and soil loss of hillslope alpine meadows.These results obtained here offer a novel perspective on the regulation of runoff and soil erosion in the alpine meadow ecosystem.展开更多
To date the roles of raindrop impact in sediment entrainment and transport processes of interrill soil erosion are not yet fully quantified.The objectives are to 1)evaluate the effects of raindrop impact on sediment e...To date the roles of raindrop impact in sediment entrainment and transport processes of interrill soil erosion are not yet fully quantified.The objectives are to 1)evaluate the effects of raindrop impact on sediment entrainment,2)systematically quantify the relative importance of raindrop-driven and flow-driven transport,and 3)characterize sediment size distributions in different sediment transport re-gimes.A loam soil with 48.4%sand and 23%clay was packed into flumes(L×W×H:1.8×0.5×0.1 m)and subjected to intensities of 60,90,120 mm h^(-1)at gradients of 5,10,and 16°.Air filter and tarp covers were used to vary impact energy and flow length.Results show that sediment is largely entrained by raindrop impact and transported by raindrop-impacted flow.Interrill erosion consists of two composite processes:raindrop-induced detachment/entrainment and raindrop-impacted flow transport.The former includes direct detachment by raindrop impact and'flow detachment'.The latter includes raindrop-driven and flow-driven transports.The proportions between the two transports vary with slope steepness,slope length,flow depth(or flow discharge),rainfall intensity,and sediment characteristics.Raindrop-driven transport is competent but inefficient,while the opposite is true for flow-driven transport.Because raindrop impact plays dual roles in detaching soil(and/or entraining sediment)and enhancing sediment transport,a drop energy factor must be included in interrill erosion models to adequately simulate the dual roles.More studies are required to derive a drop energy function that takes into consideration the rainfall energy dissipation by canopies of various plants under natural conditions.展开更多
基金The authors would like to thank the Brazilian Agencies Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(CAPES)(Finance code 001)Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)(Processes 140335/2021-8 and 305919/2022-9)for funding the training of highly qualified human resources through research grants and for funding the projects that resulted in the referenced publications and the present paper.
文摘Rainfall simulators(RS)have been used,above all,to evaluate hydrological processes related to soil water infiltration,surface runoff and soil erosion.They allow repeatability of rain application with different precipitation intensities in field and/or laboratory conditions and should produce events with physical characteristics similar to natural rain.In this manuscript,we carried out a bibliometric and scientometric analysis of studies with simulated rainfall in Brazil to assess the temporal evolution of publications,the main topics addressed and the degree of technological development of the equipment.We searched for the terms“rainfall simulator”OR“simulated rainfall”AND“Brazil”in the Scopus,Web of Science,SciELO and Google Scholar databases.We found 143 articles published in the last 37 years(1985-2022).Our findings indicate that the main research areas covered in papers are soil erosion(57.34%),soil water infiltration(24.47%),nutrient losses(9.8%)and RS development and calibration/assessment(8.39%).In recent years,the number of published papers in international high-impact factor journals has increased.Most of the papers(49.65%)refer to studies carried out by institutions located in the south and southeast regions of Brazil.Moreover,there is a large gap of studies on simulated rainfall in other regions of Brazil,where important biomes such as the Cerrado,Amazon,Caatinga,and their transitions are located.This study informs research priorities on soil erosion under simulated rainfall and provides a bibliographic database that can assist in more detailed future analyses.
文摘In the last decades,in some Mediterranean areas,pedodiversity decreased mainly due to pedotechnique application in large-scale farming that transformed original soils into Anthrosols.Supporting the consideration that soils can be considered as living systems,the original concept of'soil genetic erosion'is re-proposed.Data,extrapolated and modeled from a Soil Information System in a study case representative of a Mediterranean landscape,predicted that most of the soil types would disappear in few years leading to a decrease of the soil diversity and originating soil genetic erosion.This circumstance is intentionally here told in form of a story where the fairy tale characters are some roils facing extinction in the landscape.Soil genetic erosion could result in a negative impact on the environment because it reduces the soil's security through a drastic reduction of the soil ecosystem services with a decrease of the immaterial benefit for the environment.The conviction that soils,as well as animals and plants,are living bodies,and pedodiversity is equally important as biodiversity in maintaining sustainability and ecosystem services,might truly attract the attention of the public opinion.Besides,focussing more on the soil economic dimension and strengthening the assignation of'economic value'to the soil ecosystem services,also politicians and administrators could increase their interest in soil security.
文摘Nutrient loss from agricultural fields is one of the main factors influencing surface-and ground-water quality.Typical fertilizer nitrogen(N)consumption rates in vegetable production systems and horticultural crops in Puerto Rico fluctuate between 112 and 253 kg N/ha.The nitrogen use efficiency of vegetable crops is low,increasing the potential for nitrogen losses and high residual soil nitrate content.Quantification of residual soil N and N losses to the environment can be a difficult task.Simulation models such as the USDA-ARS N Index can be used to identify the relative magnitude of varying N-loss pathways and to identify best management practices.Field studies were conducted to quantify residual soil N and crop N removal,and to validate the Nitrogen Index in onion,tropical pumpkin and tomato production systems in the Lajas Valley in southwestern Puerto Rico.Relationships between observed and simulated values were determined to examine the capability of the model for evaluating N losses.There was good correlation between observed and predicted values for residual soil N(r=0.88)and crop N removal(r=0.99)(p<0.05).In the production systems evaluated,the N volatilization losses ranged from 1 to 4 kg N/ha,the denitrification losses ranged from 18 to 46 kg N/ha,the leaching losses ranged from 155 to 779 kg N/ha,and the residual soil nitrate ranged from 64 to 401 kg N/ha.The N use efficiency ranged from 15% to 39%.The results obtained showed that the Nitrogen Index tool can be a useful tool for evaluating N transformations in vegetable production systems of Puerto Rico's semi-arid zone.
文摘The study planed to identify a suitable alternative to the FAO 56 Penman-Monteith(FAO56PM)equation for calculating reference evapotranspiration(ET_(0))from chosen te mperature and radiation based models utilizing monthly meteorological data from 30 destinations in diverse agro-ecologial regions of the Northeast(NE)India ie,Assam Bengal Plain(ABP),eastern Himalaya(EH),and the northeastern hilly(NEH)region.Radiation-based IRMAK3 most appropriate in the ABP(weighted root mean square deviation,WRMSD=0.17 mm d^(-1),r^(2)=0.98,for Nagrakata),and TURC model being in the first three rank of most of the sites,with the lowest error and highest correlation in NEH(WRMSD=0.10 mm d^(-1),r^(2)=0.92,for Shillong),and EH(WRMSD=0.23 mm d^(-1),r^(2)=-0.95,for Gangtok).Findings reveal that IRMAK3 and TURC models performed equally well and were observed to be the best among selected modets for the majority of stations followed by FAO24 Blaney-Criddle(FAO24BC),and 1957MAKK Pair-wise regession equations were developed for preferred FAO56PM ET_(0) estimates to ET_(0) estimates by alternative methods.Cross-correlation of eighteen chose methods demonstrated that the five equations(i.e.four radiation-and one temperature-based)performed eceptionally well when contrasted with the FAO56PM model,thus being advised for assessing ET_(0)。under limiting data conditions as have yielded a better estimate of ET_(0) with a small error.
文摘There is an urgent need to match food production with increasing world population through identification of sustainable land management strategies.However,the struggle to achieve food security should be carried out keeping in mind the soil where the crops are grown and the environment in which the living things survive.Conservation agriculture(CA),practising agriculture in such a way so as to cause minimum damage to the environment,is being advocated at a large scale world-wide.Conservation tillage,the most important aspect of CA,is thought to take care of the soil health,plant growth and the environment.This paper aims to review the work done on conservation tillage in different agro-ecological regions so as to understand its impact from the perspectives of the soil,the crop and the environment.Research reports have identified several benefits of conservation tillage over conventional tillage(CT)with respect to soil physical,chemical and biological properties as well as crop yields.Not less than 25%of the greenhouse gas effluxes to the atmosphere are attributed to agriculture.Processes of climate change mitigation and adaptation found zero tillage(ZT)to be the most environmental friendly among different tillage techniques.Therefore,conservation tillage involving ZT and minimum tillage which has potential to break the surface compact zone in soil with reduced soil disturbance offers to lead to a better soil environment and crop yield with minimal impact on the environment.&2015 International Research and Training Center on Erosion and Sedimentation and China Water and Power Press.Production and Hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).
基金support provided by United Soybean Board Project Number 1520-732-7226by state and federal funds appropriated to The Ohio State University and The Ohio Agricultural Research and Development Center。
文摘Conservation practices are encouraged to improve soil health and sustain agronomic crop production.Mehlich-3 is often used as a multi-nutrient extractant to determine soil fertility status.A study inves-tigated the impacts of the conservation practices of gypsum,cover crops,and crop rotation on 28 Mehlich-3 extractable elements,of which 11 were considered plant nutrients,from soil at three mid-western US locations.Soil was collected from 0 to 15 and 15-30 cm depths 5 years after implementing the conservation practices.Treatments consisted of(1)with and without cereal rye(Secale cereale L.)winter cover,(2)continuous soybean[Glycine max(L.)Merr.]vs.soybean-corn(Zea mays L.)rotation,and(3)annual gypsum application(0,1.1,and 2.2 Mg ha-1).Differences were observed by site,depth,and conservation practice depending on the element evaluated.Minimal interactive effects were observed among treatments.The most consistent effect was observed for crop rotation across sites.Gypsum only affected the site with the greatest clay content,where more Ca and S were retained,and Mg and Mn displaced.Cover crop only affected elements at this high clay site,where different elements were positively or negatively affected.Results suggest that not one practice fits all,and optimum conservation practices must be tailored for the site.
文摘During the International Workshop on Soil Erosion and Riverine Sediment in Mountainous Regions held in November 2022,scientists from many countries shared their state-of-the-art knowledge and brainstormed to improve scientific understanding for coping with climate change and anthropogenic impacts.Information summarized in this discussion includes proposed key scientific questions and suggested joint actions to reduce soil erosion and riverine sediment problems in mountainous regions.
文摘Water scarcity threatens global food security and agricultural systems are challenged to achieve high yields while optimizing water usage.Water deficit can be accentuated by soil physical degradation,which also triggers water losses through runoff and consequently soil erosion.Although soil health in cropping systems within the Brazilian Cerrado biome have been surveyed throughout the years,information about soil erosion impacts and its mitigation are still not well understood;especially concerning the role of cropping system diversification and its effects on crop yield.Thus,the aim of this study was to assess whether ecological intensification of cropping systems-inclusion of a consorted perennial grass and crop rotation-could promote soil coverage and consequently decrease water erosion and soil,water,and nutrient losses.This work studied the effects of crop rotation and consorted Brachiaria,along with different levels of investment in fertilization on soil physical quality and on soil,water,and nutrient losses,and crop yields.Results proved that soybean monoculture(SS)is a system of low sustainability even under no-till in the Brazilian Cerrado conditions.It exhibited high susceptibility to soil,water,and nutrient losses,causing low crop yields.Our results showed that water losses in SS cropping system were approximately 10%of the total annual rainfall,and total K losses would require an additional 35%of K application.Conversely,ecological intensification of cropping systems resulted in enhanced soil environmental and agronomic functions,increased grain yield,and promoted soil and water conservation:high soil cover rate,and low soil,water and nutrient losses.Ecological intensification proved to be an adequate practice to boost crop resilience to water deficit in the Brazilian Cerrado.
基金This work was financially supported by the National Natural Science Foundation of China(Grant 41301297)the One Hundred Person Project of Shannxi Province in 2017.Many thanks are given to Dr.Nicola Fohrer for greatly improving the quality of this manuscript.We also acknowledge the careful revision and suggestions of the editor and the reviewers of this article.We thank LetPub(www.letpub.com)for its linguistic assistance during the preparation of this manuscript.
文摘There are 239,100 gullies in southern China,which cause the degradation of ecological system.However,studies on gully development at the regional scale is relatively lack.The purpose of this study is to analyze the regional gully dynamics and explore how land use and topographic factors affect gully development.Input data consists of land use maps derived from high-resolution images from 2004 to 2014,and topography maps from a digital elevation model with a pixel size of 8 m×8 m in two 25-km2 study sites of Anxi(AX)and Xingning county(XN).The following results were obtained:(1)AX gullies decreased from 2006 to 2014 while XN first increased from 2004 to 2009,and then decreased from 2009 to 2014.Both AX and XN gully area in percentage of the total area ranged from 1%to 3%,which was higher than the average 0.25%of the whole southern China by the artificial survey in 2005.(2)Most of AX and XN gullies occurred along the ridgeline and had the close relationships with the upstream contributing area and slope gradient.(3)New gullies developed on the exposed land and forestland.The lost gullies were converted into forestland and grassland.In fact,most of these gullies were only covered by vegetation,not real disappearance.These results proved that gully decreased,but construction of roads and buildings intensified gully development.Consequently,these findings reveal that vegetation protection and ecological restoration should be adopted in southern China.
文摘Payments for Environmental Services(PES)are relatively novel mechanisms whereby the adoption of sustainable management practices by a stakeholder is rewarded by incentives linked to external markets.Adoption of PES for conservation agricultural practices(CAPS)by smallholder farmers may provide opportunities to increase household income or cover the technology costs of adoption if the carbon sequestration benefits of CAPS are quantifiable,adoption rates are accelerated and maintained,a mechanism exists whereby carbon sequestration services can be compensated,and carbon offset exchange markets are viable.This research suggests a methodology to examine a PES market for carbon offsets generated by the adoption of CAPS by farmers in Mozambique.Assuming a cumulative adoption of 60%over a 20-year period,revenue from PES market participation to CA adopters was two times higher than revenue earned when disadoption occurred midway through the simulation.Lower adoption targets are associated with higher per household returns when fertilizer rates typical to the region are increased.Establishing and maintaining a sustainable PES system in the study region would require significant investment in time and resources.The lack of on-the-ground institutions or local support for such a program would also challenge successful implementation.Finally,the programs where participant success depends on external markets,such as the hypothetical one suggested here,are subject to the ebb and flow of foreign demand for carbon offsets.Addressing these three broad constraints to a PES/CAPS program in the region would require grass-roots driven policy initiatives with buy-in at multiple social,economic,and political levels.
基金support of the International Atomic Energy Agency Coordinated Research Programme D1.20.11,and associated Technical Contract 15478 for the work reported in this contribution is gratefully acknowledgedThe work on the UK National Soil Erosion Inventory was funded by DEFRA contracts SP0411 and SP0413.
文摘The application of fallout radionuclides in soil erosion investigations and related sediment budget studies has provided a widely used tool for improving understanding of soil erosion and sediment transfer processes.However,most studies using fallout radionuclides undertaken to date have focussed on small areas.This focus on small areas reflects both the issues addressed and practical constraints associated with sample collection and analysis.Increasing acceptance of the important role of fine sediment in degrading aquatic habitats and in the transfer and fate of nutrients and contaminants within terrestrial and fluvial systems has emphasised the need to consider larger areas and the catchment or regional scale.The need to upscale existing approaches to the use of fallout radionuclides to larger areas represents an important challenge.This contribution provides a brief review of existing and potential approaches to upscaling the use of fallout radionuclides and presents two examples where such approaches have been successfully applied.These involve a national scale assessment of soil erosion rates in England and Wales based on 137Cs measurements and an investigation of the sediment budgets of three small/intermediate-size catchments in southern Italy.
文摘Soil loss by water erosion is one of the main threats to soil health and food production in intensively used agricultural areas.To assess its significance to overall sediment production,we applied the Water and Tillage Erosion Model/Sediment Delivery model(WaTEM/SEDEM)to the Luoyugou catchment,a sub-catchment of the Yellow River Basin within the Chinese Loess Plateau.WaTEM/SEDEM considers rill and interrill erosion and deposition rates to calculate the sediment yield rates leaving the catchment.Ter-races were established in the 1990s to reduce soil loss in this area,but no soil erosion modeling has been published regarding the effect of this mitigation measure.Therefore,we applied 1000 Monte Carlo simulations of the WaTEM/SEDEM,and the modeled average soil loss by rill and interrill erosion for 2020 was 12.2±0.5 t ha^(-1)yr^(-1),with a sediment yield at the outlet of 53,207.8±11,244.1 t yr^(-1).The results indicated that the terracing reduced gross soil loss rates(from 51.8t ha^(-1)yr^(-1)in 1986 to 12.2±0.5 t ha^(-1)yr^(-1)in 2020),while land cover changes,mainly the conversion of forests and grassland,partly coun-teracted the mitigation(combined effect:76%reduction).Modeled sediment loads by rill and interrill erosion accounted for 22.8%of the total long-term sediment production recorded by flow discharge measurements.Other processes not considered by the model,such as landslides,gully erosion,riverbank erosion,and sediment production by construction,seem to predominantly influence the overall sedi-ment yield.Considering years with baseline sediment production only,the measured and modeled sediment yields compared favorably,indicating that the latter processes primarily contribute during extreme events.
文摘Alternate partial root-zone drying(APRD)is a water-saving method but can regulate crop physiological responses.A pot experiment has been conducted to study the efficiency of partial and fixed root-zone drying on the growth and production of maize(Zea mays L)in addition to the water use efficiency in soils with different gypsum content.The experimental treatments include three irrigation treatments,i.e.Conventional Irrigation(CI),Alternate Partial Root-zone Drying(APRD)and Fixed Partial Root-zone Drying(FPRD),and three soils with different gypsum content"(60.0[G1],153.7[G2],and 314.2[G3]g kg^(-1))".The vegetative growth,root dry mass and physiological indices(leaf relative water content,carotenoid concentration,proline)have been studied during three stages of maize plant growth(jointing,tasselling,and maturing).The Results showed that compared to CI,APRD and FPRD increased water use efficiency by 38.93 and 14.94%based on dry seed yield.In addition,compared to CI,APRD increased maize seed yield by 4.62-20.71%,while FPRD decreased yield by 19.24-5.28%for the gypsiferous soils G2 and G3,respectively.APRD has a slight effect on leaf water potential,leaf relative water content,carotenoid and proline activities from jointing to maturing stages at the three gypsiferous soils.Results suggest that APRD could make maize plants use water even more productively with better adaptation to water shortages in the gypsiferous soils.
基金This research was funded by the National Key Research and Development Program of China(2017YFC0505401).
文摘Soil erosion disturbs not only the global carbon cycle,but it is a complex environmental problem.Revegetation could reduce carbon emission by controlling soil erosion and increase carbon sequestration and accumulation by fixing carbon in vegetation and soil.The Grain for Green Program(GFGP)of China is the largest ecological restoration program in the world closely related to land-use/land-cover change(LUCC).Systematically assessing the carbon sequestration benefit of GFGP is crucial for a better understanding of the effects of implementing GFGP and providing reasonable vegetation management.Therefore,we selected the hilly red soil region(HRSR)of southern China as a study area,which is one of the main ecologically vulnerable areas in China.We assessed the carbon sequestration in the GFGP area of the HRSR using the InVEST(Integrated Valuation of Environmental Services and Tradeoffs)model based on land-use/land-cover datasets during 2000e2015.Our results show that implementing GFGP is conducive to the enhancement of carbon sequestration services.Total carbon sequestration showed an increasing trend at a rate of 15.43%from 2000 to 2015.The most significant change mainly happened in Hunan Province with the shortest implementation time.The carbon sequestration of each carbon pool(namely aboveground biomass,belowground biomass,soil,and dead organic matter)also increased slightly.Additionally,for carbon sequestration,unused land converted to forest land is the most effective LUCC.This study can provide scientific support for the management and implementation of GFGP in the HRSR of China.
文摘A field experiment was conducted for two consecutive years at North Eastern Indian Himalayan region to assess the effect of soil moisture conservation measures on soil and water productivity of different rainfed maize(Zea mays L.)-based cropping sequences.Results revealed that double mulching with in-situ maize stover mulch(MSM)+fresh biomass of white hoary pea(WHP-Tephrosia candida)and MSM+fresh biomass of ragweed(RW-Ambrosia artemisiifolia)improved soil moisture content(SMC)and leaf relative water content of crops during dry season.The soil organic carbon(SOC)content and stocks under MSM+WHP and MSM+RW mulches were significantly higher than that under no mulch at 0-15 cm depth.The soil microbial biomass carbon and dehydrogenase activity were maximum under MSM+WHP/RW.The highest system productivity was obtained from maize-French bean(Pole type-PT)sequence under MSM+RW followed by MSM+WHP.The water productivity was the highest under MSM+WHP.While SOC content was the highest under maize-French bean(PT),the maximum plant available nitrogen and phosphorus were obtained under maize-black gram sequence.Thus,double mulching technology involving MSM and RW(available in plenty)is a viable option for improving soil,crop and water productivity under rainfed hill ecosystems of eastern Indian Himalayas.
文摘Nutrient management, water quality protection, and irrigation efficiency top the list of on-farm resource concerns indicating a need to address them through conservation strategies. A suite of Best Management Practices (BMPs) has been identified and recommended, through several outlets, to farmers to ameliorate these concerns. This research examines the adoption of strategies that ameliorate the resource concerns as a joint decision, using a bivariate model. Data from the 2016 Nutrient Management Survey, conducted by the Louisiana Master Farmer Program, are used to examine the factors affecting adoption of these conservation practices. A bivariate probit regression found significant results for explanatory variables and emphasize the effect of perception regarding the role of on-farm practices, ownership of land, participation in conservation programs in the past, and producers educational attainment on the like-lihood of adopting the conservation practices. Implications for policy development and educational programs are discussed.
文摘The adoption of no till was a major turning point in the transformation of agriculture in Argentina.This paper describes the process of adoption of no till,and the impacts of this on agricultural production.Whereas previously,soil erosion was so extreme and pervasive as to threaten the economic viability and survival of the industry,today with the majority of production under no till,Argentina produces more than ever in the past.The paper also illustrates how,after first focusing on technology adoption(no-till),the system in Argentina has now broadened to include the concepts of Conservation Agriculture(CA)and Sustainable Land Management(SLM).These strategic moves have contributed to an agricultural industry in Argentina that is more economically and environmentally sustainable than that of the past.
文摘Soils are key natural resources for the Earth's system;however,human impacts,especially,soil erosion are considered serious threats.Therefore,identifying and assessing effective factors to understand erosion hot spots at different scales is critical to developing effective land management plans and ensuring the sustainability of the territory.This study was conducted to determine and prepare an erosion risk map,but to prioritize the survey at different scales,such as sub-basin and watershed ones.To achieve this goal,geographic information system(GIS)and remote sensing data(RS)were used combining the analysis network process method(ANP)and ICONA model(Institute for the Conservation of Nature).As study case,we selected the degraded areas of the Gorganrood watershed located in the north of Iran.The study area was obtained for very low,low,medium,high,and very high-risk classi-fications of 14.0,21.4,17.9,31.3,and 15.4%,respectively.Results from the ICONA model also indicated that 12.8,28.8,22.1,27.9,8.5,and 0.03%belong to very low,low,medium,high,very high,and without risk of erosion,respectively.According to the validation results,it was found that the accuracy of ANP and ICONA models are 0.83 and 0.80,respectively,which indicates the suitability of the models for preparing the erosion map of the region is appropriate and useful for designing land management plans.We conclude that both models can be used to develop the erosion map potential and to prioritize sub-basins if a complete database of geomorphological characteriscs and human activities are accurate previously defined.
基金funded by the National Natural Science Foundation of China(NSFC41930755,NSFC32230068)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB40000000)the Opening Project of State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau(A314021402-202105).
文摘Global climate change and overgrazing are driving shifts in the plant composition of grassland com-munities,which may profoundly affect the function of grassland ecosystems in regulating runoff and soil erosion.Here,we examined the shift effects of normal hillslope alpine meadow to shrub and severely degraded meadow states on runoff and sediment generation under natural rainfall conditions,and determined the contributions of plant and soil properties changes to soil erodibility,runoff and sediment generation by in situ rainfall experiment and monitoring on the hillslope of Qinghai-Tibetan Plateau.The results showed that normal meadow shift into severely degraded meadow state,mean weight diameter,soil saturated hydraulic conductivity,soil cohesion and soil erodibility K-factor at the topsoil decreased by 70.3%,73.1%,80.3%and-13.1%,respectively,and when normal meadows shift into shrub meadow state,they reduced by 49.1%,-1.3%,49.4%,and-8.3%,respectively.Runoff and soil loss significantly changed by-40.0%and 177.8%when normal meadow shifted into a severely degraded meadow state,while runoff and soil loss significantly changed by+65.0%and+77.8%when normal meadow shifted into a shrub meadow state.Our findings highlight that the two divergent shifts both increased soil loss compared to the normal hillslope alpine meadows.Overall,our results indicate that the divergent shifts of normal alpine meadows exacerbated soil erodibility and soil loss of hillslope alpine meadows.These results obtained here offer a novel perspective on the regulation of runoff and soil erosion in the alpine meadow ecosystem.
文摘To date the roles of raindrop impact in sediment entrainment and transport processes of interrill soil erosion are not yet fully quantified.The objectives are to 1)evaluate the effects of raindrop impact on sediment entrainment,2)systematically quantify the relative importance of raindrop-driven and flow-driven transport,and 3)characterize sediment size distributions in different sediment transport re-gimes.A loam soil with 48.4%sand and 23%clay was packed into flumes(L×W×H:1.8×0.5×0.1 m)and subjected to intensities of 60,90,120 mm h^(-1)at gradients of 5,10,and 16°.Air filter and tarp covers were used to vary impact energy and flow length.Results show that sediment is largely entrained by raindrop impact and transported by raindrop-impacted flow.Interrill erosion consists of two composite processes:raindrop-induced detachment/entrainment and raindrop-impacted flow transport.The former includes direct detachment by raindrop impact and'flow detachment'.The latter includes raindrop-driven and flow-driven transports.The proportions between the two transports vary with slope steepness,slope length,flow depth(or flow discharge),rainfall intensity,and sediment characteristics.Raindrop-driven transport is competent but inefficient,while the opposite is true for flow-driven transport.Because raindrop impact plays dual roles in detaching soil(and/or entraining sediment)and enhancing sediment transport,a drop energy factor must be included in interrill erosion models to adequately simulate the dual roles.More studies are required to derive a drop energy function that takes into consideration the rainfall energy dissipation by canopies of various plants under natural conditions.
