| ABSTRACT | 第8-9页 |
| 摘要 | 第10-19页 |
| CHAPTER 1. INTRODUCTION AND REVIEW OF LITERATURE | 第19-28页 |
| 1.1 Background and problem statement | 第19-21页 |
| 1.2 Justification and significance of the research | 第21-22页 |
| 1.3 Review of literature | 第22-26页 |
| 1.4 Research objectives and hypothesis | 第26页 |
| 1.5 Research approach | 第26-28页 |
| CHAPTER 2. MATERIALS AND METHODS | 第28-40页 |
| 2.1 Study region | 第28-29页 |
| 2.2 Field experiment | 第29-36页 |
| 2.2.1 Characteristics of research sites | 第30-31页 |
| 2.2.2 Ammonia volatilization measurement | 第31-32页 |
| 2.2.3 Soil analysis | 第32-35页 |
| 2.2.4 Plant analysis | 第35-36页 |
| 2.3 Incubation experiment | 第36-39页 |
| 2.3.1 Soil collection and experimental design | 第36-37页 |
| 2.3.2 Characteristics of soil sample collection areas | 第37-38页 |
| 2.3.3 Ammonia volatilization measurement | 第38页 |
| 2.3.4 Soil analysis | 第38-39页 |
| 2.4 Major equipments | 第39页 |
| 2.5 Statistical analysis | 第39-40页 |
| CHAPTER 3. MITIGATION OF AMMONIA VOLATILIZATION WITH THE APPLICATION OF UREASE AND NITRIFICATION INHIBITORS FROM SUMMER MAIZE CROP GROWN AT THREE DIFFERENT SITES OF LOESS PLATEAU | 第40-59页 |
| 3.1 Introduction | 第40-42页 |
| 3.2 Materials and Methods | 第42-45页 |
| 3.2.1 Research site description | 第42-43页 |
| 3.2.2 Experimental design | 第43页 |
| 3.2.3 Soil sampling and analysis | 第43-44页 |
| 3.2.4 Calculations and statistical analysis | 第44-45页 |
| 3.3 Results | 第45-55页 |
| 3.3.1 Climatic and soil conditions | 第45-48页 |
| 3.3.2 Changes in soil NH_4~+-N and NO_3~--N | 第48-51页 |
| 3.3.3 Daily ammonia volatilization | 第51-53页 |
| 3.3.4 Cumulative ammonia loss | 第53-55页 |
| 3.4 Discussion | 第55-59页 |
| 3.4.1 Ammonia volatilization loss | 第55-56页 |
| 3.4.2 Effect of inhibitors on ammonia volatilization | 第56-57页 |
| 3.4.3 Factors affecting on ammonia volatilization loss | 第57-59页 |
| CHAPTER 4. EFFECT OF UREASE AND NITRIFICATION INHIBITORS ON SOIL NITROGEN TRANSFORMATION AND NITROGEN USE EFFICIENCY OF SUMMER MAIZE GROWN IN THE LOESS PLATEAU | 第59-81页 |
| 4.1 Introduction | 第59-61页 |
| 4.2 Materials and Methods | 第61-65页 |
| 4.2.1 Research site description | 第61-63页 |
| 4.2.2 Experimental design and field management | 第63页 |
| 4.2.3 Soil sampling and analysis | 第63-64页 |
| 4.2.4 Plant sampling and measurements | 第64页 |
| 4.2.5 Calculations and statistical analysis | 第64-65页 |
| 4.3 Results | 第65-76页 |
| 4.3.1 Changes in soil p H and EC | 第65-68页 |
| 4.3.2 Changes of mineral-N in soil | 第68-71页 |
| 4.3.3 Plant height, seed index, and SPAD values | 第71-73页 |
| 4.3.4 Plant dry weight and grain yields | 第73-74页 |
| 4.3.5 N uptake and N use efficiency indicators | 第74-76页 |
| 4.4 Discussion | 第76-81页 |
| 4.4.1 Effect of NBPT on N transformation and NUE | 第76-78页 |
| 4.4.2 The combined effect of NBPT and DCD on N transformation and NUE | 第78-81页 |
| CHAPTER 5. UREASE INHIBITOR (NBPT) APPLICATION AS A MITIGATING STRATEGY OF AMMONIA VOLATILIZATION FROM UREA APPLIED DIFFERENT SOILS OF LOESS PLATEAU | 第81-99页 |
| 5.1 Introduction | 第81-83页 |
| 5.2 Materials and Methods | 第83-85页 |
| 5.2.1 Soil sampling | 第83-84页 |
| 5.2.2 Incubation study and analysis | 第84页 |
| 5.2.3 Statistical analysis | 第84-85页 |
| 5.3 Results | 第85-96页 |
| 5.3.1 Changes in soil p H and EC | 第85-89页 |
| 5.3.2 Changes in soil NH_4~+-N and NO_3~--N | 第89-93页 |
| 5.3.3 Ammonia volatilization | 第93-96页 |
| 5.4 Discussion | 第96-99页 |
| 5.4.1 Ammonia volatilization as a key N loss pathway | 第96-97页 |
| 5.4.2 Effect of NBPT on ammonia volatilization | 第97-99页 |
| CHAPTER 6 SUMMARY OF RESEARCH | 第99-101页 |
| 6.1 Main conclusions | 第99-100页 |
| 6.2 Innovative points of study | 第100页 |
| 6.3 Suggestions and recommendations | 第100-101页 |
| REFERENCES | 第101-115页 |
| NOMENCLATURE | 第115-118页 |
| ABOUT THE AUTHOR | 第118-119页 |
| RESEARCH PUBLICATIONS | 第119-121页 |
| CONFERENCES | 第121-122页 |
| ACKNOWLEDGEMENT | 第122页 |
