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1.
Land‐use dynamics in drylands are complex processes. In the context of a typical agropastoral village in northwestern Syria Im Mial, the effects of demographic and social changes, reduced soil productivity, changes in agricultural technologies and historical events on land use and land productivity are examined. Decreasing yields, mainly the result of reduced fallow periods and low investments in the land, and the deterioration of the grazing resources are the two main signs of the loss of land productivity in the area. The growing population forces the villagers to practise continuous rainfed barley cultivation with no or only occasional fallow, and without any application of plant nutrients. Also, technological changes, from the use of donkey ploughs and hand harvesting to less labour‐intensive and time‐consuming cultivation practices with tractors and combine harvesters, and the increased importance of stubble in the livestock diet have contributed to the reduction of the fallow periods. The villagers attribute the yield decreases mainly to the low rainfall in the area. The high rainfall variability discourages the fallowing of fields because continuous cultivation maximizes the chances for good harvests in years with high rainfall. There is also an expansion of cultivation into the less fertile and sloping traditional grazing areas. Population growth, increased numbers of livestock and the expansion of cultivated land into grazing areas has also put pressure on the grazing resources of the village. The possession of livestock is seen as a sign of wealth and the villagers aim to have large flocks of animals. For them, livestock is also an important means for investment of cash earned from off‐farm work, which is the main source of income for most of the households in the village. There is a recent trend of increasing levels of crop‐livestock integration with less free grazing that produces higher return to the land users. This may also have a positive effect on the restoration and conservation of the degraded natural traditional grazing grounds. The stabilization and productive use of the land resources in this dry environment requires the combined and interdisciplinary effort from both the land‐users and the policy‐makers. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

2.
The question of increasing fallow land assumes significance at national and international levels due to the decline in net cultivated area and increasing population. Biophysical characteristics of farmland and socio‐economic conditions of farmers are responsible for the increasing fallow. This study was carried out to assess the extent of permanent fallow and identify causes for its increase. High‐resolution remote sensing data were used to identify fallow land in two identified blocks of south India, viz. Nanguneri and Kangeyam. The land resources were characterized, and the specific biophysical and socio‐economic factors responsible for the increasing fallow land were assessed. Multiple regression analysis was carried out to identify the factors responsible for increasing fallows. Soil parameters such as erosion, soil texture, soil depth and available nitrogen contributed significantly (P > 0.05) to the increase in fallow land. The size of farm holding, number of farm fragments, distance from the road in Nanguneri and farm size and the distance to the nearest town in Kangeyam were socio‐economic factors that had a strong effect (P > 0.01) on increasing the fallow land. Variable importance rankings in random forest analysis indicated that soil erosion and soil pH had the largest impact on the decision to fallow land in Nanguneri and Kangeyam blocks, respectively. Based on biophysical and socio‐economic constraints, the land resources of fallow land were evaluated for other alternate land use options and policy measures were suggested.  相似文献   

3.
The strongly incised mountain landscape of northern Thailand has changed dramatically during the last few decades due to increased population pressure, agricultural commercialization, limitation to use old fallows and reforestation of upper catchments. The traditional shifting cultivation with fallow periods of 7 years and longer was gradually replaced by 1 to 4 year fallow periods. As a result, in high population areas the landscape became dominated by fields planted to rainfed upland crops, wetland rice terraces, fallow vegetation, and patches of secondary forest. This new land-use system seems to have triggered new land degradation processes that are easy to observe when travelling through this landscape.  相似文献   

4.
Adoption of input‐responsive varieties enhanced food production during the second half of the 20th century. However, even bigger challenges lie ahead because of the growing societal demands. For example, the global population of 7.2 billion in 2013 is projected to reach 9.2 billion by 2050 and stabilize at 10 billion by 2100. The growing and increasingly affluent population, with preference towards more and more meat‐based diet, is likely to jeopardize the finite, fragile, and dwindling soil and water resources which are already under great stress in densely populated countries in Asia and elsewhere. Economic growth and increase in gross domestic product also lead to generation of waste or by‐products, along with contamination and eutrophication of water resources. International trade in food/feed products also involves transfer of virtual water, which is a serious issue when water‐scarce countries export virtual water to water‐endowed countries. The problem is confounded by the present and future climate change driven by the growing energy demands of the carbon civilization. Thus, adaptation to climate change represents both a threat and an opportunity for sustainable development. Adaptive strategies must be sustainable socially and environmentally and advance the Millennium Development Goals, while buffering agroecosystems against extreme climate events (e.g., pedologic, agronomic, and ecologic drought). Thus, recognizing and addressing the water‐soil‐waste nexus is important to achieving climate‐strategic agriculture. Sustainable intensification of agroecosystems, producing more per unit consumption of essential resources, must consider judicious management of hydrological and biogeochemical cycles (C, N, P, S). The soil C pool must be managed and enhanced to offset anthropogenic emissions, and mitigate/adapt to the climate change. The pace of adoption of recommended land use and soil‐/plant‐/animal‐management practices can be kept at par with advances in scientific knowledge through continuous dialogue between scientists on the one hand and policy makers / land managers on the other to translate research data into policy and action plans.  相似文献   

5.
A survey was carried out in 136 farm‐households from seven villages in 1995 and 1996 to analyse the traditional fallow cultivation system in Niger. Farmers were asked to give information about land use on their fields, focusing on cropping and fallow periods as well as on cultivation changes compared to the past. In addition, they were interviewed about their management strategies to maintain or improve soil fertility. Millet‐based systems clearly dominate at all sites, either in pure form or intercropped with cowpea, groundnut, sorghum or roselle. At present, almost half of all farmers cultivate their fields on average up to 5 years until it is left fallow. About one‐third use their fields permanently. Most farmers use short fallow periods of 1 to 5 years. Moreover, there was a decrease in the cropping area left fallow, and the fallow period also decreased steadily in the past years. In the mid‐1970s the average fallow period was about 8 years, decreasing to 2.5 years in 1996. The actual fallow periods are too short to allow sufficient positive effects on soil fertility and farmers are aware of this problem. Consequently, farmers employ different fertilization techniques which aim at maintaining or restoring the soil nutrient pool of the fields while providing physical protection against wind and water erosion. Most farmers use animal manure to improve soil fertility and apply mulch from different sources, millet stalks and branches, for soil regeneration. Few farmers employ other strategies such as mineral fertilizer or planting pits. The farmers try to optimize the use of internal and external resources resulting in a mixture of different fertilization and soil protection methods. Internal resources play by far the most important role. Due to the generally limited resource availability farmers concentrate their management efforts on certain areas within each field or on selected fields only. This means a decreased crop production for the individual household and a higher risk of soil degradation because of soil mining or increased erosion risk on the field area where soil fertility management cannot be practised. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

6.
《Soil Use and Management》2018,34(2):249-257
Shifting cultivation involves a cycle of forest clearing, cultivation and a fallow phase. As the practice involves clearing forest, it is considered unsustainable and leads to soil fertility loss and erosion. While several variations of the practice exist, traditional communities undertake the practice systematically with relatively long fallow periods and are often knowledgeable about their landscape in terms of soil and its management. To better understand one such system, we quantified soil recovery following cultivation in terms of macronutrients and documented the traditional knowledge of the Adi community in a remote site in the Eastern Himalaya. We collected soil samples from three replicates, each from currently cultivated sites, uncut forest sites and successional sites 3, 12 and 25 yr following cultivation. Available nitrogen and phosphorus significantly increased, and there was an increasing trend in soil organic matter following cultivation. The Adi differentiated nine types of soil and preferred specific soil types for shifting and settled cultivation. We documented soil management and methods of soil fertility retention practised by the Adi. Their location of different crops in the field was based on the effect of the crop on soil fertility. Our research indicated that soil nutrient recovery was considerable following cultivation and that traditional shifting cultivators in the landscape were knowledgeable about their landscape in terms of soil diversity, undertaking practices to manage soil erosion and fertility. Future policies that will affect shifting cultivation in the region should acknowledge such systematic use of a landscape by traditional farming communities.  相似文献   

7.
代表性国家和地区耕地休耕补助政策及其对中国的启示   总被引:8,自引:5,他引:3  
为保证耕地休耕制度的顺利实施和成效的长久保持,中国近年来不断探索制定科学合理的耕地休耕补助政策.美国、日本、欧盟、中国台湾等国家和地区已经具有多年的休耕实践经验,且都十分重视对休耕农民的补助问题.该文采用文献资料法、对比分析法及归纳总结法,在分析美国、日本、欧盟、中国台湾等代表性国家和地区休耕补助实践的基础上,对休耕补助目的、实施模式、补助形式、补助依据及资金来源等进行了梳理和归纳.针对中国休耕补助政策中可能存在的问题,提出今后应从补助目的动态化、补助效益最大化、补助类型差异化、资金来源多样化、配套措施制度化等方面完善补助政策的改进建议,并尝试构建了中国耕地休耕补助政策的初步框架.  相似文献   

8.
Understanding the mutual influences between cropland use and soil characteristics is important in anticipating and planning for food production, environmental protection and resource sustainability. Numerous studies focus on the relationship between crop rotations and soil characteristics at a microscale, but fewer studies focus on the relationships between soil capability and cropland use and change at a medium scale. We explore how soil capability has influenced cropland changes over 22 yr, using statistical and land use transition analysis. Landsat images from the years 1988, 2002 and 2010 were used to map cropland changes by soil capability class within a pilot site in Alberta, Canada. Between the late 1980s and 2010: (i) the area of annual crops increased substantially while that of forest and summer‐fallow decreased; (ii) changes in cropland use among annual crops, perennial crops and summer‐fallow differed substantially depending on soil capability; and (iii) a transition from annual crops and summer‐fallow to perennial crops was more likely on land of poorer soil capability, whereas the transition from perennial crops and summer‐fallow to annual crops was more likely on land with higher soil capability. The changes in land use practices identified in this study indicate that producers are actively intensifying production on their best land to optimize profitability while simultaneously reducing the intensity of production on poorer land for either financial or environmental reasons, or both.  相似文献   

9.
In the Sudano–Sahelian zones of West Africa, cultivated land is degraded due to reduced fallow periods and Striga hermonthica (Del.) Benth. infestation, and poses a serious threat to sustainable food production. To provide options for addressing these problems, we investigated the possibility of replacing the short fallow periods with food legume cultivation. We tested this in two farming communities within the Sudan savannah zone of Ghana. In the 1997 and 1998 cropping seasons, selected farmers within each community planted soybean [Glycine max. (L.) Merr.] or bambara groundnuts [Vigna subterranea (L.) Verdc.] on continuously cropped, Striga‐infested farmlands, whereas lands that were maintained under two or three years of bush fallowing were planted to millet [Pennisetum glaucum (L.) R. Br.] or sorghum [Sorghum bicolor (L.) Moench]. Analysis of soil sampled from 0–15 cm (plough layer) revealed that contents of major plant nutrients were inadequate to support long‐term crop production. Within each farming community, total nitrogen content at initial sampling showed significant negative correlation with the number of Striga seeds in the plough layer. Under legume cultivation, soil organic carbon content increased and the number of Striga seeds per square metre decreased in both communities from a mean value of 28 183 seeds m−2 to 8185 seeds m−2. Under cereal cultivation Striga seed density increased from 9383 seeds m−2 to 16 696 seeds m−2. The study provides evidence that introduction of food legume cultivation on farmlands with high S. hermonthica infestation as an alternative to bush fallow system could help achieve sustainable crop production in the Sudan savannah zones of sub‐Saharan Africa. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

10.
When farmers migrate yearly to a village to carry out intense farming during the rainy season, and thereafter return to a more permanent place of abode this is referred to as seasonal migration. The impact of such migration on land‐use/land‐cover change in an area within the Volta Basin of Ghana was examined using satellite image analysis and socioeconomic surveys. The most drastic land‐cover change involved the conversion of woodland to agricultural land, while there was also a general transition to less vegetation cover. Socioeconomic surveys revealed that most of the migration occurred during the post‐structural adjustment period in Ghana with declining soil fertility accounting for the highest per cent of causes of migration. Multiple regression results highlighted the role of population size and distribution, marketing of agricultural produce and technological evolution of the household in determining agricultural land‐use change. Policy initiatives that could lead to environment conservation are suggested. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

11.
The forest cultivation system (slash‐and‐burn or shifting cultivation) has contributed to the transformation of social systems since the early Neolithic period. Despite being considered by conservationists and public policymakers as a system of low productivity that generates environmental degradation and contributes to the maintenance of rural poverty, the shifting cultivation system (SCS) is being declared a practice that is highly ecologically and economically efficient. Such dichotomy of opinions is the consequence of the disparate results of studies assessing the effects of SCS on soil properties of rainforests throughout the last three decades. To circumvent this apparent inconsistency, we used a systematic quantitative review method (meta‐analysis), with the objective of integrating and synthesizing the data published in the literature to assess the overall effects of SCS on soil chemical properties. Four variables traditionally assessed in primary studies were chosen for the meta‐analyses: pH, cation exchange capacity (CEC), total carbon (Total C) and total nitrogen (Total N). Our results show that pH values increase under SCS conditions, while Total N and C content are significantly reduced under SCS. No significant impacts are observed on CEC. Our results on pH and CEC support the position from researchers who argue for the sustainability of SCS and highlight the importance of evaluating the soil system as a soil/vegetation complex. Also, our results indicate that soil chemical properties under SCS scenarios are better conserved and more readily recoverable, provided there is a rather longer fallow period than has been traditionally employed.  相似文献   

12.
In the Gilgel Gibe catchment in Ethiopia, local farmers intensify land use on Planosols by adjusting a traditional soil burning practice known as guie. The burning practice used to be applied in a cycle of shifting cultivation. However, more recently, farmers burn small plots to make fertile seedbeds for Eucalyptus seedlings in the first year before these trees are transplanted to larger plots. The purpose of this research was to assess the physico‐chemical properties of Planosols that have been subjected to burning over the last 10 yrs and evaluate the contribution of guie to land‐use intensification of these soils. Transect studies and interviews of local farmers, followed by chemical, physical and micromorphological analyses of samples from selected plots were used to compare the soil properties of recently (0–2 yrs) and formerly (3–10 yrs) burnt Planosols with those of unburnt Planosols. The analytical results show that the burning practice improved nutrient availability in the first 2 yrs after guie. Increased amounts of exchangeable aluminium (Al) were reported in the long term. Charge fingerprints illustrate that the nutrient‐buffering capacity of the soil was high shortly after the practice but subsequently decreased with time. Given the population pressure on the formerly extensively used Planosols, it is argued that the current application of guie on small, localized plots for raising Eucalyptus seedlings is well adapted to the local socio‐economic context and promotes land‐use intensification on the Planosols. The increased exchangeable Al content of former Eucalyptus seedbeds merits further in‐depth research into the biophysical sustainability of the burning practice.  相似文献   

13.
In the Gadarif Region of Sudan, destruction of the natural vegetation for agricultural expansion is one of the major causes of the degradation of renewable resources and the environment. This study identifies and analyses the farmers' attitudes and perceptions towards agricultural land degradation and abandonment. The cross‐sectional data collected from ten key informants and 41 large‐scale farmers focussed on the degradation and abandonment of mechanized agricultural land. The results of the study show that the respondents are well aware that soil degradation is in various forms are taking place on their cultivated agricultural land. This is based on their perception and interpretation of indicators such as weed infestation, poor soil fertility and soil compaction. Continuous cropping, mono‐cropping, rainfall shortage and the use of inferior seeds are the main reasons of land degradation as indicated by farmers. The main measures acknowledged to maintain and improve land productivity are repeated soil ploughing, abandonment/fallow periods and crop rotation. The study adduces evidence of widespread land degradation. The mitigation measures followed by the farmers may though not be sufficient to restore the soil fertility. The application of appropriate chemical fertilizers, sound crop rotation and long fallow periods can be recommended. Any management and research intervention regarding the problem of land degradation should; however, be concerted with the farmers' knowledge. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

14.
The structure of fungal communities was examined in soil subjected to 5 years of different agricultural land management and tomato production practices. Length heterogeneity polymerase chain reaction (LH-PCR) of fungal rDNA internal transcribed spacer-1 (ITS-1) regions was used to create genomic fingerprints of the soil fungal communities. Three years after initiation of land management practices, univariate analysis of genetic diversity failed to detect differences among soil fungal communities in plots managed organically, conventionally or maintained free of vegetation by continuous tillage (disk fallow). Genetic diversity was significantly higher in plots maintained as a perennial pasture grass (Paspalum notatum var Argentine bahiagrass) or as an undisturbed weed fallow. The composition of soil fungal communities within organic, pasture grass or disk fallow plots were separated into unique clusters by non-parametric multivariate analysis of their Bray-Curtis similarity matrices, computed from the relative abundance of ITS-1 amplicons, while the composition of communities within disk fallow and conventional plots could not be distinguished from each other. Diversity of soil fungal communities was significantly reduced following the cultivation of tomato in year four when compared to the diversity in plots where tomato was not cultivated. Divergence in the composition of soil fungal communities was observed following the cultivation of tomato under all land management regimes except organic, where communities continued to remained clustered based upon similarities among their ITS-1 amplicons. Divergence in the composition of fungal communities became more pronounced following two major hurricanes (Francis and Jeanne, September 2004) except for communities in the organic and pasture grass plots. Following the completion of a second tomato crop in year 5, genetic diversity and richness was similar under all land management regimes except the pasture grass, where it remained significantly higher. By contrast, following two consecutive years of tomato production, unique but mutually similar compositions of fungal communities were detected only in plots subjected to the organic land management regime. This was supported by observations that fungal communities were dominated by a 341 bp rDNA amplicon fragment in all land management regimes except the organic. Cloning and sequencing indicated that the 341 bp fragment generated by LH-PCR had a sequencing size of 343 bp, which was most closely related to Fusarium oxysporum. Thus, land management practices that disturb or disrupt soil fungal communities will significantly reduce their diversity. However, the composition of soil fungal communities is more strongly influenced by land management practices and communities within an organically management system were more resistant to anthropogenic and meteorological disturbances.  相似文献   

15.
Intensification of land use can become a threat to agricultural sustainability if they lead to increased soil erosion. This study examines land‐use changes, soil and water conservation, soil erosion and soil productivity in the Highlands of Kenya. In addition, it examines farmers' perception of livelihood changes. Land‐use changes were determined from interpretations of aerial photographs taken in 1960 and 1996. Additional information on land use, soil and water conservation and livelihood changes were obtained from discussions and interviews with farmers, as well as from field verifications of the most recent aerial photographs. Soil samples were analysed and soil erosion assessed according to the PLUS classification scheme. The results indicate that substantial changes in land use, such as introduction of coffee and high‐yielding maize, and fragmentation of land holdings have taken place. Less land was conserved in 1996 as compared to 1960. Moreover, SWC practices have changed from fanya chini terraces and shifting cultivation to bench terraces and permanent cultivation. Rates of soil nutrients (organic C, N and K) and maize‐yield levels decreased significantly with increasing erosion. Farmers' perception of livelihood changes was differentiated according to farmers' off‐farm resource 60 per cent of the farmers depended on income from the land and thought livelihoods were better in the 1960s. It is concluded that more efforts to decrease soil erosion and investments in land and labour are necessary to sustain soil productivity and hence secure rural livelihoods. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

16.
Water cycle, land management, and environmental sustainability are intimately linked. Sustainable land and water management practices are vital for sustaining agricultural productivity and regional development. Unsustainable land and water management practices that violate the system's carrying capacity constraint over long periods can impose significant costs in terms of lost opportunities in farm production and regional development, say by causing waterlogging and salinity. On‐farm and regional salt and water balance dynamics are modeled as a sustainability or carrying capacity constraint, proxied by regional salt and water balance; on‐farm land and water management practices are then adjusted to meet the constraint, such that individual actions do not lead to a net change in the ground water and salt balance. Common actions across the farms would achieve the overall environmental sustainability. An irrigated area in southern Murray‐Darling Basin in Australia serves as a case study example. Integrated hydrologic, economic, agricultural, and environmental models called SWAGMAN series are used to evaluate the impacts of a range of on‐farm interventions on farm income and environmental sustainability. The results show that policies such as restrictions on area under certain crops, and tradable groundwater recharge/salinity credits both offer higher total gross margin and net present value than the business as usual scenario, specifically in the long run—win–win options for the farmers and the environment. The modeling results thus confirm the widely held view that unsustainable land and water management practices that violate the system's carrying capacity can impose significant costs on regional communities. In‐depth hydrological and economic analyses are needed to shape and guide society's vision for sustainable land and water management. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

17.
Food security is a crucial issue in sub‐Saharan Africa as a consequence of unreliable rainfall, marginal soil fertility and a low level of inputs leading to declining crop yields. As a case study, we investigated the most important variables affecting maize yield in northern Ghana. We combined a soil quality index on a continuous scale with a social data set to model maize yield using linear multiple regression. Five significant variables have been identified (P < 0.05): soil quality index, fertilizer use, household size, distance from main market, and the interaction between fallow length and soil quality index. The effect of the interaction between soil quality and fallow on maize yield is negative, suggesting the influence of litter quality and N immobilization in the soils. Research and policy should focus on the development of site‐specific, legume‐based cropping, and the integration of crop and livestock farming in Northern Ghana and similar areas in sub‐Saharan Africa.  相似文献   

18.
Maps of land‐use classes and soil series were analysed to identify areas having specific priorities with respect to agricultural land‐use analysis. Remote sensing data supported by field investigations was used to generate land‐use and soil maps. Present relationships between soils and associated land cover/use are analysed and patterns in these relationships are identified using GIS techniques. Relationships observed on the basis of a priori knowledge of the area and the available statistics are compared and these relationships in the field and through interviews with farmers are correlated. This allows three land‐use analysis objectives to be formulated: crop management improvement; crop selection; and conservation. The results can be used to focus the efforts of planning and extension services in the area. The method was tested using a participatory rural appraisal in eighteen villages in which the areas for the three land‐use analysis objectives were identified. The findings are that the areas identified for crop management improvement require knowledge about management practices for a specific crop to optimize yield and water use. Most areas identified for crop selection are occupied by smallholder subsistence farmers with insufficient water for irrigation, and a lack of contact with the extension service. In these areas, identifying suitable crops to minimize risk and allow subsistence for the resource‐poor farmers may be the priority. In areas identified for conservation the question to be addressed is whether to grow a crop at all, or to encourage alternative activities. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

19.
Sustainability of the local shifting cultivation practice in the mountainous region of Northern Laos was investigated. Due to low fertility of the soils derived from shale and its strongly weathered and acidic nature in the eastern side of the Nam Khan River watershed, shortening of the fallow period to produce enough amount of upland rice for the local population would not be sustainable any more. On the other hand, the eroded materials from limestone range were added to the soils in the western side of watershed which made the soil more fertile. Based on the calculated population capacity by Carneiro's equation, a system with 2- or 3-year fallow for 1-year cultivation can be the maximum to afford the current population. To make the shifting cultivation system more sustainable, introduction of fallow system with a tree species, paper mulberry ( Broussonetia papyrifera ) could be a good option to be proposed.  相似文献   

20.
A growing number of regions in the developing world are targeted by transnational investors who are acquiring large amounts of land and natural resources. Driven by the increasing global demand for agricultural products, such investments are often considered an opportunity for economic development in the target country. However, there are concerns about the social and environmental impacts on local communities. In this brief review, we discuss some key socio‐environmental controversies surrounding large‐scale land acquisitions (LSLAs). LSLAs often target common property systems and lead to privatization and commodification of land through long‐term land concessions. There is a debate between supporters of foreign land investments as a means to attract modern agricultural technology that would decrease the yield gap in underperforming agricultural land and those who question such a development model because it is seldom coupled with policy instruments that would ensure that the benefits improve food security in local populations. Large‐scale land investments displace a variety of systems of production ranging from small‐scale farming to (arguably) “unused” land such as forests and savannas on which local communities often depend. Moreover, LSLAs entail an appropriation of water resources that may negatively impact local farmers or downstream human and natural systems. In most cases, investors keep the land fallow but, when they put it under productive use, they typically change land cover and land use to start intensified commercial farming, often for nonfood crops. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

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