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81.
Soils in a lower Hunter valley vineyard, New South Wales, Australia, were sampled and analysed for caesium‐137, an indicator of soil erosion status, in 1984–1985 and 2004. From the time of the vineyard's first establishment in 1971 to 1985, estimated soil losses were 250 tonnes (equivalent to 64.2 t ha?1 yr?1). Re‐sampling in 2004 showed that soil losses were 48 tonnes in the 19 years since 1985, equivalent to 9.7 t ha?1 yr?1. The decline in erosion rates may be explained by a change in land and soil management from intensive cultivation to one of no cultivation (sod culture) in 1998, and a lower annual rainfall and fewer rain‐days per year in the period from 1986 to 2004. 相似文献
82.
DAO KIM NGUYEN THUY BINH LE T. V. PHUONG IAN DOUGLAS NGUYEN VAN DE JULIA MCMORROW SARAH LINDLEY TRAN THI VAN LE HUU THANH NGUYEN THO 《Geographical Research》2008,46(1):17-26
Several parts of Binh Phuóc Province, southern Vietnam, suffer from degraded soils and vegetation as a result of both natural erosion of weak mud rocks and sandstones and intensive human activity, especially through land clearing for agriculture on unstable slopes, deforestation, and abandonment of poor farmland. The underlying cause of this land degradation has been the farming habits of migrants of varying ethnic groups who have settled in the area since 1980. The indigenous farming knowledge of these people and the role of that knowledge in soil erosion were examined by a series of household surveys. They enabled farming practices to be related to ground cover established from a 2002 Landsat 7 ETM (Enhanced Thematic Mapper), and erosion data from a series of erosion bridge measurements. A GIS (Geographical Information System) approach was piloted as a means of identifying areas vulnerable to erosion. This could then be combined with the understanding of farming practices to reveal the relative roles of farmer behaviour, crop cover, and slope and soil characteristics in the erosion process. Land use, local people's knowledge and economic realities are the main factors, as well as natural conditions, that drive this land degradation. 相似文献
83.
NGUYEN DAI TRUNG ANN VERDOODT MICHIEL DUSAR TRAN TAN VAN ERIC VAN RANST 《Geographical Research》2008,46(1):27-38
Ethnopedological knowledge is incorporated in a case study for sustainable land management of mountain karst areas in Vietnam. The research is based on a multidisciplinary approach, including participation of local inhabitants for identifying and classifying local indicators of soil quality, next to scientifically sound approaches to soil quality assessment based on analytical soil data and a statistical treatment of the results. The case study focuses on Bo hamlet, located in the Ngo Luong commune of the Tan Lac district, Hoa Binh province. The participatory approach reveals that local people of the Muong ethnic group distinguish seven land use types and six soil types. They also identified nine local indicators of soil quality: presence of earthworms; crop productivity; topsoil colour; presence of a humus layer; soil surface compaction; erosion; slope gradient; surface water, and soil moisture status. Based on this indigenous knowledge, 19 soil samples from nine soil profiles in Bo hamlet were analysed for fertility indicators. Laboratory results confirmed the validity of indigenous knowledge for identifying and classifying local indicators of soil fertility, compared to scientific standards of soil quality. 相似文献
84.
Martin Locock Christopher K. Currie Stephen Gray 《International Journal of Osteoarchaeology》1992,2(4):297-304
Macroscopic chemical analysis of animal bone recovered from dated excavation contexts of known pH from Castle Bromwich Hall, West Midlands, UK, allows an assessment of the rate and effects of bone decomposition, and the evaluation of current models of chemical decay. The results show great variation, and it is suggested that factors such as mechanical disturbance have a more significant effect on the differential destruction of excavated bone assemblages than chemical decay. The implications of this conclusion for the attempted reconstruction of past faunas, diet and behaviour are summarized, recommending caution in the acceptance of assemblages as unbiased samples. 相似文献
85.
室外土遗址经常因遭遇降雨、水淹等发生结皮,造成土遗址表层性能改变,影响土遗址的进一步保护。以定量纯净黄土在等降雨大小下,通过控制不同降雨时长,试验了不同降雨时长下土壤结皮发育的过程,分别测试了降雨前后的结皮厚度、密度、硬度及孔隙结构。结果表明,在降雨量未达到饱和状态时,随降雨量增大,结皮层的厚度、密度、硬度迅速增大,表皮土壤颗粒被击碎,孔隙迅速减小;在降雨量达到饱和状态时,随降雨量增大,结皮层的厚度、密度、硬度缓慢增大,但表皮土壤裂缝迅速发育,由周围向中心形成同心圆状或辐射状裂隙。研究结论可为室外土遗址的保护提供参考。 相似文献
86.
Julie Guthman 《对极》2017,49(1):86-105
Soil fumigants have been critical to the California strawberry industry's success, but they are also highly toxic to farmworkers and nearby residents. This article traces recent regulatory debates over restrictions on their use which were cast as a contest of lives and livelihoods: activists emphasized the danger of the chemicals while industry emphasized their necessity. Activists’ claims were typical of environmental justice battles that focus on disproportionate toxic exposure to marginalized populations, but I problematize that they downplayed industry concern with farmworker jobs. Drawing on Marx, Foucault and recent literature on surplus populations and disposability, I suggest that the analytical separation of lives and livelihoods is complicit in the making of disposable workers such as California farmworkers. Strategically, upholding the separation was a missed opportunity to leverage the strawberry industry's new‐found concern with farmworker employment and push for measures that protect current and future farmworker health. 相似文献
87.
Ewa Domańska 《Journal of Genocide Research》2020,22(2):241-255
ABSTRACTThe author presents an ecological-necrological perspective on the ontology of the human dead body and remains in the context of Holocaust studies. The article examines the environmental history of mass graves and reflects on the ontological status and condition of human remains. The author proposes an approach that combines humanities and soil sciences while thinking about post-genocidal spaces and sites of mass killings in order to discuss the issue of protecting human remains from politicization and commercialization and to prefigure appropriate long-term approaches to the preservation of sites containing human remains. The article suggests focusing on humus while examining the process of dehumanization through decomposition (organic decay) and unbecoming human by “becoming-soil.” To enrich and problematize the humanities’ conception of humus, the article draws on conceptions of humus proposed by soil scientists. What is argued here is that the ecological perspective becomes a necessary and essential element in managing post-genocidal (and post-Holocaust) sites, particularly when it comes to planning their conservation and preservation. 相似文献
88.
Soil (SL) and organic carbon losses (SOCL) have increased with human population and climate change linked extreme events. While SL and SOCL are clearly associated with surface run‐off, the impact of land use is still not well understood. This article elucidates the effects of land use, surface cover, and other environmental factors on SL and SOCL using data from 55 published studies. The overall SL (12.34 ± 2.25 Mg ha?1 year?1) and SOCL (21.80 ± 0.91 g C m?2 year?1) suggests substantial losses of the fertile topsoil globally. Grasslands (4.19 ± 1.22 Mg ha?1 year?1) had 77%, 66%, and 41% lower SL than orchards, croplands, and forests, respectively, which is attributable to higher soil organic matter and surface cover. Croplands had the highest SOCL at 22.78 ± 2.22 g C m?2 year?1. Natural vegetation had 98% and 70% lower run‐off and SL than did plant residue mulched plots, indicating its great potential for surface run‐off and soil erosion control. Rainfall and slope were key drivers of soil erosion, while soil surface cover, SOC, and clay content decreased. These findings improve our knowledge on soil and organic carbon losses, which is useful for fostering sustainable management of soils and natural vegetation to enhance ecosystems functionality. 相似文献
89.
水硬性石灰改性土修复加固材料性能研究 总被引：3，自引：1，他引：3
孙延忠 《文物保护与考古科学》2015,27(Z1):27-30
针对土遗址土体坍塌、残缺等病害,为选择更好的土遗址修复加固材料,通过遗址土中添加水硬性石灰进行改性,分析检测水硬性石灰改性土修复材料的性能,并与石灰改性土材料性能进行对比分析。研究结果表明,与石灰改性土性能相比,水硬性石灰改性土修复材料夯土收缩率小、水稳定性好、抗压强度大和强度增加快、耐冻融性好;其性能优于石灰改性土材料的性能,适合土遗址土体坍塌、残损病害的修补加固,其研究成果为土遗址的保护修复加固提供科学依据。 相似文献
90.
This paper describes the design features and capabilities of a portable automated in‐situ closed chamber (ISCC) for the quantification of CO2 fluxes in dryland soils where both photosynthetic and respiratory components may be associated with a cyanobacterial crust. The processes of CO2 flux in dryland soils are briefly described in order to clarify the conditions that make quantification of these fluxes problematic. The instrumentation currently available for in‐situ soil CO2 flux measurements is then reviewed demonstrating their inadequacies for the dryland environment. The ISCC described here is a member of the closed or enrichment class of soil respiration chambers. The ISCC, however, features an optical window possessing high (>90%) transmission in the photosynthetic active region (PAR) of the solar irradiance spectrum, permitting observations of photosynthesis. The ISCC possesses automatic venting and purging so that gaseous concentrations inside the chamber do not change from ambient sufficiently to significantly affect diffusion. The ISCC features both active and passive cooling employing internal solid‐state Peltier coolers and external aluminised Mylar respectively. This avoids severe disturbance of the microclimate within the chamber due to admission of high fluxes of PAR and permits in‐situ operation under a wide range of ambient field temperatures (~ ?5 to 40°C). Sensors internal to the chamber monitor temperature, relative humidity, irradiance and pressure. In this implementation the ISCC is coupled to a portable gas chromatograph (Agilent GC‐3000) to sample the chamber atmosphere. Indicative data for Kalahari Sand soils of Botswana are presented as an illustration of the general performance characteristics. 相似文献