氮肥在農(nóng)業(yè)生產(chǎn)中具有重要作用。氮肥的大量施用導(dǎo)致氮(NH3,NO3,NO,N2O,N2)的損失增加。氮(N)可以顯著地提高作物的產(chǎn)量和品質(zhì)。為滿(mǎn)足作物生長(zhǎng)需求,農(nóng)業(yè)生產(chǎn)中氮肥的投入增加,進(jìn)而造成N的額外損失。為此,相關(guān)農(nóng)業(yè)部門(mén)修訂了氮肥的使用標(biāo)準(zhǔn)。但由于N的固有損失,特別是硝酸鹽淋溶,導(dǎo)致氮肥利用效率仍低于50%。近幾十年來(lái),由于采用現(xiàn)代施肥技術(shù),中國(guó)農(nóng)業(yè)生產(chǎn)能力大幅提高。然而,中國(guó)高產(chǎn)區(qū)的氮肥利用效率仍低于35%,硝酸鹽的淋溶損失是氮素?fù)p失的主要途徑之一。硝酸鹽和粘土顆粒都攜帶負(fù)電荷,因此粘土顆粒不能長(zhǎng)時(shí)間吸附硝酸鹽,硝酸鹽被根際區(qū)域以外的水溶解并隨之移動(dòng),即為硝酸鹽的淋溶。大量的研究表明硝酸鹽淋溶對(duì)地下和地表水質(zhì)有負(fù)面的影響。氮肥的增施還造成蔬菜中硝酸鹽濃度的增加,從而對(duì)人類(lèi)健康產(chǎn)生不利影響。許多專(zhuān)家指出,硝酸鹽的淋溶以及蔬菜中硝酸鹽的積累引起人類(lèi)對(duì)健康問(wèn)題的擔(dān)憂(yōu)。硝酸鹽與高鐵血紅蛋白血癥有關(guān),還有許多目前尚無(wú)定論的人類(lèi)健康問(wèn)題,如癌癥(通過(guò)細(xì)菌產(chǎn)生N-亞硝基化合物)、高血壓、中樞神經(jīng)系統(tǒng)出生缺陷、糖尿病、自然流產(chǎn)、呼吸道感染和免疫系統(tǒng)異常變化等。此外,在少數(shù)情況下,硝酸鹽的大量消...

【文章頁(yè)數(shù)】：148 頁(yè)

【學(xué)位級(jí)別】：博士

【文章目錄】：
摘要
abstract
Abbreviations
CHAPTER-1 INTRODUCTION
    1.1 FACTORS AFFECTING NITRATE LEACHING
        1.1.1 Soil Properties
        1.1.2 Land Management
        1.1.3 Climatic Factors
        1.1.4 Management Practices
    1.2 NITRATE LEACHING MEASUREMENT METHODS
        1.2.1 Model Application
        1.2.2 Suction Cup and Lysimeter
        1.2.3 Repeat Soil Core Method
        1.2.4 Nitrate Leaching Measurement Approaches
    1.3 STAPLE ISOTOPIC TECHNIQUES
    1.4 RESEARCH BASIS
        1.4.1 Literature Review
        1.4.2 Problem Statement
        1.4.3 Research Targets
        1.4.4 Research Aims
        1.4.5 Purpose of the Study
        1.4.6 Significance of Study
CHAPTER-2 EXPERIMENTS DESIGN SPECIFICATIONS
    2.1 INTRODUCTION
    2.2 EXPERIMENT DESIGN
    2.3 EXPERIMENT PROCEDURE
    2.4 LYSIMETER DESIGN SPECIFICATIONS
    2.5 SOIL COLLECTION AND SAMPLING
    2.6 MOISTURE CONTENT SENSOR CALIBRATION
    2.7 LABORATORY ANALYSIS
        2.7.1 Soil pH
        2.7.2 Soil EC
        2.7.3 Soil Bulk Density
        2.7.4 Flow Injection Analysis
        2.7.5 ¹⁵N Nitrate Analysis
        2.7.6 ¹⁵N Ammonia Analysis
CHAPTER-3 MINERAL N IN SOIL PROFIL
    3.1 EXPERIMENT PROCEDURES
    3.2 SITE SPECIFICATIONS
    3.3 STATISTICAL ANALYSIS
    3.4 RESULTS
        3.4.1 Soil pH Variations
        3.4.2 Soil EC Variations
        3.4.3 Soil Nitrate Variations
        3.4.4 Soil Ammonium Variations
        3.4.5 Total Plant Available Nitrogen
        3.4.6 Total Yields
    3.5 DISCUSSIONS
CHAPTER-4 VEGETABLE PLANTATION AND NITRATE LEACHING
    4.1 EXPERIMENT DESIGN AND SPECIFICATIONS
    4.2 SITE DETAILS
    4.3 EXPERIMENT PROCEDURE
    4.4 LABORATORY ANALYSIS
    4.5 STATISTICAL ANALYSIS
    4.6 RESULTS
        4.6.1 ¹⁵N Recovery in Dry Matter
        4.6.2 ¹⁵N in Leachate
        4.6.3 ¹⁵N in Soil
        4.6.4 Evapotranspiration and Inches Per Feet
        4.6.5 Total Nitrogen and Tracer Uptake
        4.6.6 Total Leachate Volume Total and Tracer N in Nitrate
        4.6.7 Total and Tracer Ammonia in Leachate
        4.6.8 Water Use Efficiency ¹⁵N and ¹⁴N Uptake
        4.6.9 Plant Growth Curve
        4.6.10 Total Mineral and ¹⁵N Leached
        4.6.11 Soil Properties
        4.6.12 ¹⁵N Balance
    4.7 DISCUSSIONS
CHAPTER-5 NITRATE LEACHING IN NORTH CHINA PLAIN FROM VEGETABLE CROPS
    5.1 FACTORS AFFECTING NITRATE LEACHING
    5.2 NCP SOIL PROPERTIES
        5.2.1 Soil Physical Properties
        5.2.2 Soil Chemical Properties
    5.3 CLIMATIC FACTORS
    5.4 LAND USE MANAGEMENT
        5.4.1 Vegetable Crops in Open Field
        5.4.2 Vegetable Crops in Protected Greenhouses
    5.5 RECOMMENDATIONS
CHAPTER-6 CONCLUSION
REFERENCES
APPENDIX
ACKNOWLEDGEMENTS
RASHEED AHMED(RESUME)



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