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1.
《The Professional geographer》2013,65(3):275-287
Given steadily increasing federal expenditures to manage surplus crop production, it would seem to make economic and environmental sense to concentrate production on the best acreage and to retire marginal crop acreage to alternate uses. A major obstacle constraining adoption and implementation of cropland retirement programs in the past has been the fear that cropland retirement threatens the viability of rural communities. Regression of change in population and retail establishments on changes in farm structure, nonfarm employment, and agricultural land-use in the rural Southern Plains between 1930 and 1970 provides only weak evidence to support this fear. In fact, short-term cropland idling under post-1960 price-support programs appears to pose more of a threat to rural communities than does cropland retirement. 相似文献
2.
JOHN FRASER HART 《Geographical review》2003,93(2):153-170
ABSTRACT. Census data do not support the widespread popular perception that urban encroachment on cropland in California is serious enough to justify programs of farmland preservation. Between 1949 and 1997 the acreage of harvested cropland declined near Los Angeles, in the San Francisco Bay area, and near Sacramento, but the high‐value specialty agricultural production displaced from these areas has been relocated to more distant areas, where it has replaced lower‐value field crops, and specialized agricultural production has increased steadily in the state. Vegetable production in the Salinas Valley and dairying near Los Angeles illustrate the twin processes of relocation and replacement. Urban encroachment actually has been a boon to California agriculture, because it has transferred massive amounts of urban capital to cash‐strapped farmers and enabled them to develop efficient modern operations. Much of the concern about loss of farmland really is concern about loss of open space and amenities, and urban demand for water probably will be a greater constraint on California agriculture than will urban demand for land. 相似文献
3.
河南省粮食生产与耕地变化的分析及预测 总被引：16，自引：0，他引：16
运用Excel软件,在分析河南省改革开放以来耕地、人口、粮食动态变化的基础上,分析了最小人均耕地面积和耕地压力指数的变化特点;运用预测理论对未来15年耕地、人口、粮食、最小人均耕地面积和耕地压力指数进行了预测.研究结果显示:1978年以来,虽然河南省人均耕地面积持续减少,但由于耕地生产率不断提高,粮食产量和人均占有量却在持续增加,最小人均耕地面积和耕地压力指数呈现降低的趋势.未来15年最小人均耕地面积和耕地压力指数将进一步降低.可见,依靠增加投入和科技进步从而不断提高耕地生产率,是减轻耕地压力、保证粮食安全生产的根本途径. 相似文献
4.
T. Miyasaka T. OkuroH. Zhao X. ZhaoX. Zuo K. Takeuchi 《Journal of Arid Environments》2011,75(11):1155-1163
We examined changes in soil properties, crop biomass, and weed communities in the Horqin Sandy Land of China to elucidate cropland degradation. We studied three local cropland types having periods of cultivation of up to 20 years: maize cropland on lowlands without irrigation (nonirrigated lowland), maize cropland on flat sandy lands with irrigation (irrigated flatland), and bean-centered cropland on sand dunes without irrigation (nonirrigated dunes). Soil properties and crop biomass were more degraded in nonirrigated lowland and nonirrigated dunes than in irrigated flatland. Weed communities in the nonirrigated croplands were the type that become established in drier conditions, whereas wetland weeds were more abundant on irrigated flatland. Trends of change in each indicator did not always occur in parallel and differed statistically among the cropland types. Monitoring these indicators within the context of local land-use systems can provide scientific evidence on which to base local management practices or recommendations for change. 相似文献
5.
JOHN FRASER HART 《Geographical review》2001,91(3):525-543
ABSTRACT. The census concept of total cropland is a better measure of effective agricultural land than is total farmland, which includes extensive areas of woodland owned by farmers. The cropland area of the United States dropped from 478 million acres in 1949 to 431 million acres in 1997, for a net loss of less than 1 million acres, or roughly one‐fifth of 1 percent, per year. In the midwestern agricultural heartland most counties changed less than 5 percent in the half‐century, and more counties gained than lost. The West was a crazy quilt of change, and in the East most counties lost more than 10 percent. Major metropolitan counties lost a few percentage points more than did adjacent areas, but at a lower rate per capita than the nation as a whole. Most of the loss of cropland was in marginal agricultural counties with soils of low inherent fertility and topography unsuited to modern farm machinery. The loss of cropland to suburban encroachment may be cause for intense local concern, but attempts to thwart development cannot be justified on grounds of a net national loss of good cropland. 相似文献
6.
The changing patterns of cropland conversion to built-up land in China from 1987 to 2010 总被引：2，自引：0，他引：2
Hongrun Ju Xiaoli Zhao Xiao Wang Wenbin Wu Ling Yi Qingke Wen Fang Liu Jinyong Xu Shunguang Hu Lijun Zuo 《地理学报(英文版)》2018,28(11):1595-1610
Over the past few decades, built-up land in China has increasingly expanded with rapid urbanization, industrialization and rural settlements construction. The expansions encroached upon a large amount of cropland, placing great challenges on national food security. Although the impacts of urban expansion on cropland have been intensively illustrated, few attentions have been paid to differentiating the effects of growing urban areas, rural settlements, and industrial/transportation land. To fill this gap and offer comprehensive implications on framing policies for cropland protection, this study investigates and compares the spatio- temporal patterns of cropland conversion to urban areas, rural settlements, and industrial/ transportation land from 1987 to 2010, based on land use maps interpreted from remote sensing imagery. Five indicators were developed to analyze the impacts of built-up land expansion on cropland in China. We find that 42,822 km2 of cropland were converted into built-up land in China, accounting for 43.8% of total cropland loss during 1987–2010. Urban growth showed a greater impact on cropland loss than the expansion of rural settlements and the expansion of industrial/transportation land after 2000. The contribution of rural settlement expansion decreased; however, rural settlement saw the highest percentage of traditional cropland loss which is generally in high quality. The contribution of industrial/transportation land expansion increased dramatically and was mainly distributed in major food production regions. These changes were closely related to the economic restructuring, urban-rural transformation and government policies in China. Future cropland conservation should focus on not only finding a reasonable urbanization mode, but also solving the “hollowing village” problem and balancing the industrial transformations. 相似文献
7.
农户生计非农化对耕地流转的影响——以福建省长汀县为例 总被引：13，自引：2，他引：11
针对农户生计非农化对耕地流转的影响,采用Logistic回归分析方法,对福建省长汀县358户农户生计非农化对耕地流转的影响进行了实证分析。研究结果表明:①农户生计非农化与耕地流出之间是一种正反馈关系,农户生计非农化有效促进了农户耕地的流出;②生计非农化诱致的农业劳动力缺乏以及较高的务农机会成本是农户耕地流出的直接原因;③生计非农化总体上对耕地流入起到抑制作用,其中,务农机会成本对农户耕地流入起到主导的抑制作用,而地租下降等因素对耕地流入起到促进作用,一定程度上缓解了高务农机会成本对耕地流入的影响。 相似文献
8.
From Rural Dilution to Multifunctional Countryside: Some pointers to the future from South Australia 总被引：1，自引：0，他引：1
Peter J. Smailes 《The Australian geographer》2002,33(1):79-95
Rural dilution, a term originally used in the UK in the 1950s, refers to change in the social composition of rural populations: those elements engaged in primary production (and its necessary servicing) are thinned out by agricultural restructuring and labour shedding, while at the same time in-migration of new elements (retirement, long-distance commuting, lifestyle migration) is occurring. The extent to which such dilution occurs is influenced by a number of factors, including distance in travel time from the nearest metropolitan or other large city, location with respect to the coast/perceived environmental amenity, and rural population density. This paper explores changes in traditional rural communities in Southern Yorke Peninsula, South Australia, which lie 2½-3 hours' drive from Adelaide and have been subject to substantial rural dilution. Drawing on two detailed surveys of the strictly rural (dispersed) population of the region carried out in 1984 and replicated in 2000, some important social impacts of the recent migration flows are identified, including changes in perceived community identity and allegiance, shopping and business patterns, and the very recent impact of the uptake of electronic communication innovations. The paper concludes with an assessment of the extent to which the trends identified are likely to continue, and mould future communities in similar distance and amenity situations over the next 10-20 years, changing the nature of rurality in Australia. 相似文献
9.
This study was conducted to collect historical land use information that would help explain the historical patterns in accumulation
of sediment and phosphorus in Lake Pepin documented by Engstrom et al. (J Paleolimnol, this issue). A wide range of historical factors including cropping systems, phosphorus applications from fertilizer and manure, human
and animal populations, river flows and phosphorus discharges from waste water treatment plants were studied using statistical
methods. Results showed that sediment losses from the Minnesota River basin are significantly correlated with historical increases
in river flows, row crop production acreage and basin population. Total phosphorus accumulations in the sediments of Lake
Pepin are significantly correlated with increased phosphorus discharges from metropolitan area wastewater treatment plants,
and increases in row crop acreage and river flows. Total phosphorus inflows to Lake Pepin are significantly correlated with
increases in river flows, row crop acreage and phosphorus fertilizer applied to agricultural lands.
This is one of eight papers dedicated to the “Recent Environmental History of the Upper Mississippi River” published in this
special issue of the Journal of Paleolimnology. D. R. Engstrom served as guest editor of the special issue. 相似文献
10.
Historically land reserve programs have been used to reduce soil erosion. Slippage, which occurs when the number of acres enrolled in a reserve program is not met by an equivalent reduction of acreage in production, has limited reserve success, however. This study addresses the effect of slippage on conservation reserves in southwestern Kansas from 1988–1994. Slippage has varied considerably on both spatial and temporal bases. At one extreme the programs were 100% successful in removing land from production, but at the other extreme, slippage rendered reserve programs nearly useless. Overall, slippage in the study area has greatly reduced conservation reserve effectiveness. 相似文献
11.
Rural Social Networks along Amazonian Rivers: Seeds,Labor and Soccer among Communities on the Napo River,Peru 
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下载免费PDF全文 Christian Abizaid Oliver T. Coomes Yoshito Takasaki J. Pablo Arroyo‐Mora 《Geographical review》2018,108(1):92-119
Research on Amazonian communities has focussed more often on rural‐urban linkages than on links among rural communities. This is unsurprising, given the low density of population, limited intercommunity commerce, and importance of direct city‐market relations. Social relations among rural communities are also important in shaping rural livelihoods and lifeways. We report on the findings of a large‐scale census of communities in the Napo River basin in northeastern Peru (n=174). Data were gathered on intervillage crop seed acquisition and cooperative labor sharing as two key inputs in agriculture, and on intervillage soccer matches, which are integral to rural social life. We analyze the socio‐spatial networks of each practice, paying attention to settlement patterns, community ethnicity, and differential access to the uplands. We find that seeds and labor flow along soccer network lines. Rural social networks appear to be structured strongly by ethnicity (homophily) and reflect important complementarities between upland and lowland communities (weak ties). 相似文献
12.
The role of drought among agro-pastoral communities in a semi-arid environment: The case of Botswana
Agro-pastoral livelihoods in semi-arid Botswana have evolved and adapted to recurrent droughts endemic to the region. Droughts, more than any other phenomena, have shaped and influenced rural communities' interaction with their environment on which they eke a living. The physical aspect of droughts and their effects are well known, but the often subtle and complex dynamics emanating from drought outbreaks are less understood among communities. A study was conducted during the 2009/2010 season to investigate how communities in Kgalagadi North and Bobonong Sub-districts perceive droughts, anticipate droughts and which sections of the respective communities were most vulnerable to drought shocks. An extensive agro-ecological knowledge base, in form of environmental indicators, was used by communities to predict imminent droughts. Preparations included storing excess crop harvests during good years, storing crop residues for livestock, buying commercial feed to supplement livestock and seeking alternative sources of income outside the agricultural sector. In spite of these efforts, drought still affected the communities negatively mainly through increased livestock mortalities and crop failure-especially among poorer households. Subsequently, it is recommended that any effective aid interventions ought to understand and appreciate these dynamics to enhance resilience to future droughts and ensure sustainable rural development. 相似文献
13.
《The Professional geographer》2013,65(1):127-140
Abstract This article provides an analysis of a wetland site in southern Illinois from presettlement to the present. The study area is part of the Cache River-Cypress Creek Wetland, which has international importance, as recognized by the Ramsar Convention on Wetlands. Land-cover data for 1807, 1938, and 1993 were created and analyzed with a geographic information system (GIS). Land-use change by topographic setting (uplands, transitional, and bottomlands) and soil productivity was quantified and studied. Interviews with local experts informed this analysis. Results illustrate the complexity of environmental change and its driving forces. First, notable forest and swamp acreage was converted to cropland between 1807 and 1938 and, to a lesser degree, from 1938 to 1993. Second, there were land-use variations by topographic region. Between 1807 and 1938, the largest transformation occurred in the uplands, with substantial acreage converted from forest to cropland. Between 1938 and 1993, however, agriculture decreased in the upland areas as hilly areas reverted to forest cover. At the same time, agriculture expanded in the bottomlands as this land was drained for farming. Third, there are interesting patterns within these categories of land-use change, as soil productivity is an indicator of what lands were taken out of cropland and converted back to grassland and forest. 相似文献
14.
三江平原近50年耕地面积动态变化序列重建 总被引：2，自引：0，他引：2
基于1950-2000年三江平原23个县市和3个农垦管理局耕地面积的统计数据,利用空间插值和线性时间内插方法对统计缺失数据进行插补,重建其50年耕地面积时空变化序列。重建的耕地面积变化序列显示,1950年该区域耕地面积仅有88.7万hm2,到2000年增至269.6万hm2,增加了203.9%,除20世纪60年代后期外,该区域耕地基本表现为持续增加。在空间变化方面,近50年三江平原耕地面积增加的重心表现为由早期的平原西部逐渐向中东部转移。耕地面积变化的主要原因在于该区域3个农垦管理局所辖的农场对自然湿地的大规模垦殖,其108.8万hm2的耕地面积几乎全部源于近50年的湿地垦殖。 相似文献
15.
中国城市化和工业化进程所带来的粮食安全问题一直是政府和学术界关注的焦点。中国近25年来快速的城市化与工业化导致耕地资源减少和环境污染加剧,对国家粮食安全和农业可持续发展产生一定影响。本文基于中国土地利用/覆盖变化最新解译结果和中国分县粮食产量数据,重建了中国1 km分辨率的粮食产量空间数据,分析了中国1990-2015年工矿用地扩张及其对粮食产能的影响。结果表明：中国工矿用地面积在1990-2015年间增长了326%,扩张速率从1990-2000年的288 km2/a增加到2000-2010年的1482 km2/a,近5年(2010-2015年)扩张速率最快,达2600 km2/a。过去25年间工矿用地扩张导致耕地面积减少1.7×104 km2,直接导致粮食产能损失约6.49 Mt(106 t),因工矿用地扩张可能会对周边耕地污染等间接影响的粮食产量达83.20 Mt。经评估,国家工矿用地扩张对粮食产能潜在影响总体上是当前粮食总产能的17%。在空间分布特征方面,工矿用地扩张对粮食产能的直接影响呈现由东部沿海地区向西北地区逐渐减小趋势;间接影响在中部和西部地区相对较大。 相似文献
16.
This article provides an analysis of a wetland site in southern Illinois from presettlement to the present. The study area is part of the Cache River‐Cypress Creek Wetland, which has international importance, as recognized by the Ramsar Convention on Wetlands. Land‐cover data for 1807, 1938, and 1993 were created and analyzed with a geographic information system (GIS). Land‐use change by topographic setting (uplands, transitional, and bottomlands) and soil productivity was quantified and studied. Interviews with local experts informed this analysis. Results illustrate the complexity of environmental change and its driving forces. First, notable forest and swamp acreage was converted to cropland between 1807 and 1938 and, to a lesser degree, from 1938 to 1993. Second, there were land‐use variations by topographic region. Between 1807 and 1938, the largest transformation occurred in the uplands, with substantial acreage converted from forest to cropland. Between 1938 and 1993, however, agriculture decreased in the upland areas as hilly areas reverted to forest cover. At the same time, agriculture expanded in the bottomlands as this land was drained for farming. Third, there are interesting patterns within these categories of land‐use change, as soil productivity is an indicator of what lands were taken out of cropland and converted back to grassland and forest. 相似文献
17.
全国农情监测与估产的运行化遥感方法 总被引：105，自引：3，他引：102
农作物遥感估产包括农作物的长势与产量趋势监测及产量的早期预报。在总结１５年来国内遥感估产成果的基础上,提出了以充分利用已有成果为基础的全国范围农作物估产运行化遥感方法。建成了ＮＯＡＡ ＡＶＨＲＲ数据实时预处理系统,并利用每旬的ＡＶＨＲＲ最大ＮＤＶＩ图像与上年同期数据对比实现全国范围的家作物遥感长势监测。在高精度耕地数据库的支持下,通过提取不同作物种植成数估算作物种植面积。种植成数可以用ＴＭ和多时相 相似文献
18.
科尔沁沙地农田玉米耗水规律研究 总被引：12，自引：5，他引：7
首先采用波文比-能量平衡法分析了科尔沁沙地农田玉米(Zeamays L.)不同发育阶段晴天的能量分配特征,在此基础上估算了玉米的蒸散量,并对估算结果和蒸渗仪测定结果进行比较,最后运用作物蒸散量和参考作物蒸散量计算了玉米的作物系数。结果表明:①在玉米的整个生长过程中,能量交换以水分蒸散耗热为主;②根据试验年份的降雨分布情况,该地区的自然降水不能满足玉米对水分需求,玉米各生育阶段水分亏缺比较严重;③科尔沁地区玉米4个生长阶段(苗期、营养期、生殖期、成熟期)的作物系数分别为0.52、0.90、1.13和0.64;④波文比能量平衡法可以较准确的估算玉米农田晴天时的蒸散量。 相似文献
19.
劳动力非农转移对农户耕地撂荒的影响 总被引：3，自引：0，他引：3
以福建省长汀县农区为研究区域,依据1978-2008年社会统计资料和农户调查数据,构建农业劳动力非农转移对农户耕地撂荒影响的多项式回归分析模型,采用社会统计和比较分析方法,研究长汀县农业劳动力非农转移对于农户耕地撂荒的影响．结果表明：近30年来,长汀县农业劳动力非农转移与农户耕地撂荒之间存在非线性关系,即自改革开放至20世纪90年代中后期,农业劳动力非农转移程度虽逐渐提高,而农户耕地开垦面积却呈现上升趋势;但自2000年以来,农户从耕地净开垦转向耕地净撂荒,农业劳动力非农转移推动着农户耕地撂荒面积的不断增加．同时发现,与外出务工以及本地雇佣劳动相比,从事传统农业较高的务农机会成本是农户耕地撂荒的根本原因,也是农业劳动力非农转移对耕地撂荒产生影响的主要中介． 相似文献