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N_2O emissions from regional agricultural lands——A case study of Guizhou Province, southwestern China

Science China Earth Sciences 2000年第1期43卷 103-112页

作者：徐文彬洪业汤陈旭晖 C.S.Li State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China Institute of Environment and Resources Chemistry Zhejiang University Hangzhou 310027 China Soil and Fertilizer Institute Guizhou Academy of Agricultural Sciences Guiyang 550013 China Institute for the Study of Earth Oceans and Space University of New Hampshire Durham USA.

To preliminarily study N2O emissions and the importance of environmental parameters on N2O flux from subtropical agroecosystem in China, N2O flux measurements were made at three cultivated agricultural lands in Guizhou Province, southwestern China. Based on the test and validation of daily N2O flux and its several associated variables between DNDC model and field measurements, DNDC model has been employed to estimate total N2O emissions from entire agricultural lands and its spatial distribution at county scale in Guizhou in 1995, and to assess the contributions of cropping practices on N2O emissions.

关键词： N_2O emission agricultural lands DNDC model

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Urban Sprawl and Fertile agricultural lands in Iranian Cities Case Study： Tehran and Karaj

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Journal of Civil Engineering and Architecture 2012年第2期6卷 204-210页

作者： Saeed Zanganeh Shahraki Faranak Seifolddini Ahmad Pourahmad Department of Human Geography University of Tehran Tehran Iran

The phenomenon of disproportional expansion of urbanized areas into undeveloped area or ＂urban sprawl＂ has become a very a remarkable characteristic of urban development worldwide in the last decades. Urban sprawl is the popular media as the source of numerous social, environmental, and economic ills. One of the most evident consequences of urban sprawl is destroying agricultural lands around cities. One of the extreme expanded cities in Iran is Tehran megalopolis and cities around it. Tehran is expanding in all dimensions especially toward western side where Karaj city is located. The area of study for this research is Tehran and Karaj cities where the event of urban sprawl is happening. Materials used for achieving goal are aerial photographs, satellite images, thematic map of degree of soil and GIS software. The result of analysis shows that Tehran area has expanded from 10000 in 1956 to 80835 hectares in 2006. Area of Karaj city increased from 125 to 26000 hectare in the same period and the population density of two cities together decreased from 116 to 43 people per hectare. Sixty five percent of areas of these two cities are consisted of good fertile agricultural lands with irrigation potential. Twenty four percent of this land （14900 hectares） is classified as rank or class 1, 38.1 percent （23725 hectares） has rank 2, and 37.9 percent （23605） has rank 3 in terms of fertile land. Based on soil class and potential of production of wheat, it is estimated that if urban sprawl and expansion of these cities decreased or the direction of expansion changed to unfertile lands （class 4, 5 and 6）, and the cultivation of land had continued, 270,000,000 kilos of wheat could be produced yearly. So, urban sprawl is seen as one of the potential challenge to urban sustainable development and cannot be urban sustainable form.

关键词： Urban sprawl sustainable development agricultural lands land productivity urban sustainable form.

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GIS-based soil maps as tools to evaluate land capability and suitability in a coastal reclaimed area(Ravenna,northern Italy)

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International Soil and Water Conservation Research 2021年第2期9卷 167-179页

作者： Mauro De Feudis Gloria Falsone Massimo Gherardi Maria Speranza Gilmo Vianello Livia Vittori Antisari Department of agricultural and Food Sciences Alma Mater Studiorum-University of BolognaVia Fanin4040127BolognaItaly Boreal Mapping Via Casella23/a40030Grizzana MorandiItaly Centro Sperimentale per lo Studio e l’Analisi Del Suolo(CSSAS) Alma Mater Studiorum-University of BolognaBolognaItaly

Land capability and suitability maps are useful tools for soil resource *** study aimed to build land capability and suitability maps using a multi-thematic approach by GIS in a salt-affected coastal area of ***,morphological,geological,pedological delineations and land cover maps,remote sensing image and climate data were acquired and the main physical and chemical properties,including electrical conductivity(EC)and available water capacity,were analysed on the soil samples collected in the study *** acquired information were elaborated through QGIS software to obtain the land capability and suitability *** suitability map showed that most of the area(80%)is suitable for cultivation and,therefore,can be addressed for agricultural purposes without risk of *** fact,the land capability map showed that 42%of the investigated area belongs to class I and II indicating that they can be used for a wide range of *** 44%of the investigated area clustered in class III and *** these latter the cultivation should be allowed to a limited range of crops due to the high sand content,which does not allow a good water retention,and due to a strong intrusion of sea water with consequent increase of the soil *** our study area,where agricultural productivity and environmental impact are in conflict,to classify the lands on base the land capability and suitability could help to define the best agricultural practices to apply in order to preserve soil functions.

关键词： agricultural lands Salt affected soils Geographic information system Land capability map Land suitability map

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Studies of Nitrous Oxide Emission from Farmlands in North China

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Advances in Atmospheric Sciences 1993年第4期10卷 489-496页

作者：王少彬苏维瀚宋文质曾江海张玉铭 Research Center for Eco-environmental Sciences Chinese Academy of Sciences Beijing 100085 Institute of agricultural Modernization Chinese Academy of Sciences Shijiazhuang 050021 Hebei Province

Measurements of nitrous oxide emission from agricultural lands were conducted. The results show that nitrous oxide fluxes on several soils are at the range of 2-60 μg . N / m2 h. Factors influencing the production rates of nitrous oxide from the soils, such as soil temperature, soil moisture and fertilization, are discussed. The calculated amount of nitrous oxide emission from China farmlands is 9.8 × 107 Kg . N per year, which accounts for about 10% of the total source strength in China areas.

关键词： Nitrous oxide agricultural lands

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