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31.
中国农业资源的可持续性分析 总被引:24,自引:0,他引:24
本文以农业资源可持续利用的三项基本约束条件为前提,从广义上(时间上的可持续约束、空间上的可持续约束、资源管理上的可持续约束)和狭义上(粮食增长速率和人口增长速率的同调对应)对于中国农业可持续发展与农业资源可持续利用,作了理论上的分析和实际上的计算。并将中同从1952~1995年划为8个时段,分别作了可持续发展分析并寻求其背景原因,作出了相应的农业可持续发展模型。最后,对于未来中国农业可持续发展的战略提出了基本的监控指标。 相似文献
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33.
1936~1937年河南旱灾述评 总被引:2,自引:0,他引:2
曹风雷 《防灾科技学院学报》2007,9(2):13-16,69
发生在1936~1937年间的大旱灾给河南农业生产造成了巨大损失,由此酿成的大饥荒导致食品奇缺、灾民遍地并大批饿死逃亡、伦理道德丧失.究其原因,除自然界气候变异的客观因素外,社会原因是主要的:农业生产力水平低下和统治者、侵略者的压榨与掠夺,致使国困民穷,无力抗灾;政府的防灾无能、救灾无力使灾情不断加重;水利长期失修、植被遭严重破坏使灾害难以抗御、亦加剧了旱灾. 相似文献
34.
本文分析了内蒙古农牧业生态环境存在的主要问题,提出了改善内蒙古农牧业生态环境的基本思路重点任务和应注意的问题。 相似文献
35.
Soil water characteristics in mountain poplar stand and its benefits to soil and water conservation in loess hilly region 总被引:2,自引:0,他引:2
SoilwatercharacteristicsinmountainpoplarstandanditsbenefitstosoilandwaterconservationinloesshillyregionWuQinxiao;LiuXiangdong... 相似文献
36.
37.
从生态环境角度论鄱阳湖区农业可持续发展 总被引:3,自引:1,他引:3
鄱阳湖区农业资源十分丰富,具有发展大农业的优越条件。本文通过对湖区农业生态环境的脆弱性分析,指出湖区农业的非良性循环特性,提出防洪、抗旱、治涝、血吸虫病治理等对策措施,为湖区农业可持续发展提供决策参考。 相似文献
38.
假日经济与发展琅琊山旅游资源的对策 总被引:1,自引:0,他引:1
文章对我国假日经济与假日旅游现状进行分析,并在对琅琊山旅游资源、区位优势进行评价的基础上,发现假日旅游发展中存在的问题,从而提出应对假日旅游的策略,为促进滁州市旅游经济的进一步发展提供理论依据。 相似文献
39.
A Sensitivity Analysis of Nitrogen Losses from Dairy Farms 总被引:2,自引:0,他引:2
International attention has focused on agricultural production systems as non-point sources of pollution affecting the quality of streams, estuaries and ground water resources. The objective of the current study was to develop a model of nitrogen management on the dairy farm, and to perform sensitivity analyses in order to determine the relative importance of manipulating herd nutrition, manure management and crop selection in reducing nitrogen (N) losses from the farm. The importance of the method of N input to the farm (purchased feed, legume fixation, inorganic fertilizer, imported manure) was investigated, and the potential to reduce N losses from dairy farms was evaluated. Nitrogen balance equations were derived, and related efficiency coefficients were set to reference values representing common management practices. Total farm N efficiency (animal product N per N input), and N losses per product N were determined for different situations by solving the set of simultaneous equations. Improvements in animal diet and management that increase the conversion of feed N to animal product by 50% would increase total farm N efficiency by 48% and reduce N losses per product by 36 to 40%. In contrast, reducing losses from manure collection, storage and application to improve the percentage of manure N that becomes available in soil by 100% would only improve total farm N efficiency by 13% and reduce total N losses by 14%. Selecting crops and management that can use soil nutrients 50% more efficiently would improve total farm efficiency by up to 59% and reduce N losses by up to 41% depending on the predominant nitrogen sources to the farm. Legume production would reduce N losses per product compared with non-legumes. There was more than a five fold difference in N losses per animal product N between the most extreme scenarios suggesting considerable opportunity to reduce N losses from dairy farms. 相似文献
40.
Paul V Bolstad Wayne T Swank 《Journal of the American Water Resources Association》1997,33(3):519-533
ABSTRACT: Water quality variables were sampled over 109 weeks along Coweeta Creek, a fifth-order stream located in the Appalachian mountains of western North Carolina. The purpose of this study was to observe any changes in water quality, over a range of flow conditions, with concomitant downstream changes in the mix of landuses. Variables sampled include pH, HCO32?, conductivity, NO3??-N, NH4+-N, PO43?-P, C1?-, Na, K, Ca2+, Mg2+, SO42?, 5iO2, turbidity, temperature, dissolved oxygen, total and fecal coliform, and focal streptococcus. Landcover/landuse was interpreted from 1:20,000 aerial photographs and entered in a GIS, along with information on total and paved road length, building location and density, catchment boundaries, hydrography, and slope. Linear regressions were performed to relate basin and near-stream landscape variables to water quality. Consistent, cumulative, downstream changes in water quality variables were observed along Coweeta Creek, concomitant with downstream, human-caused changes in landuse. Furthermore, larger downstream changes in water quality variables were observed during stormflow when compared to baseflow, suggesting cumulative impacts due to landscape alteration under study conditions were much greater during storm events. Although most water quality regulations, legislation, and sampling are promulgated for baseflow conditions, this work indicates they should also consider the cumulative impacts of physical, chemical, and biological water quality during stormflow. 相似文献