*3.2. Phase Composition*

The main phase of the NdFeB magnet scrap is Nd2Fe14B [54,57], which accounts for 96–98%. Herbst et al. indicated the unit cell structure of Nd2Fe14B. The space group is *P*42/*mnm*, and there are four Nd2Fe14B units (68 atoms) per unit cell. All the Nd and B atoms, but only four of the 56 Fe atoms, reside in the z = 0 and z = 0.5 planes. Between these, the other Fe atoms form puckered, yet fully connected, hexagonal nets [58]. Apart from Nd2Fe14B, NdO, Nd2O3, and the minor NdFe4B4 may appear in the grain boundary [51,55].

## *3.3. Microstructural Morphology*

The coercivity of the NdFeB magnets is closely related to the interface microstructure between main phase (Nd2Fe14B) and the grain boundary phase (Nd-rich) [59]. Figure 5 shows the SEM images of the NdFeB magnet. Grain sizes of the NdFeB magnet are very small (Figure 5 left), and small agglomerates of the Nd-rich phase are also observed. The field emission gun scanning electron microscope image (Figure 5 right) shows a uniform continuous coating of Nd2Fe14B grains, where the thickness of the Nd-rich grain boundary phase is a few nanometers, separating the individual grains. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis was carried out to identify the compositional variation in the NdFeB magnets, and the results are listed in Figure 6. The results indicate that the Nd is concentrated in the grain boundaries instead of within the grains, and the Fe is concentrated within the grains.

**Figure 5.** SEM images of NdFeB permanent magnets [59]; published by Elsevier, 2004.

**Figure 6.** SEM-EDS analysis of NdFeB permanent magnets [54]; published by Elsevier, 2014.

The distribution of Nd, Dy, C, Al, Si, Fe, Ce, and Pr in the NdFeB magnet scrap was analyzed using energy dispersive X-ray spectroscopy (EDX) mapping. As shown in Figure 7, the Fe is most abundant in the matrix, while Nd and Pr are located in the grains and concentrated on the grain boundaries. Dy and Ce are nearly evenly distributed over the surface [60]. According to Önal et al., the area dominated by Fe indicates the Nd2Fe14B phase and the area highlighted by Nd and O represent the grain boundary phase. An area with a high B concentration represents the presence of Nd1Fe4B4 phase. They also concluded that all target metals are distributed over the entire microstructure of the magnet and the structure needs to be completely destroyed to recover valuable metals from the NdFeB magnet [61].

**Figure 7.** High-resolution EDX mapping of the NdFeB magnet scrap [60]; published by Elsevier, 2020.


2.2.3. Statistical Analyses

For multiple data points, mean and standard deviation were calculated. Statistical analyses were performed by one-way analysis of variance (Anova) and pair wise multiple comparison procedure (*t* test), carried out using the statistical software SigmaStat 2.0 (Jandel Scientific, San Jose, CA, USA).


*4.2.2. Aden city*

Low visibility range in Fig. 23 extends from 0.05 to 6 km for Aden city. Scattering coefficient at low visibility 0.05 km is 44.8, 43.8 and 37.6 km-1 for wavelengths of 780, 850 and 1550 nm, respectively. The scattering coefficient of 6 km low visibility is 0.45, 0.41 and 0.22 km-1 for wavelengths 780, 850, and 1550 nm, respectively.

**Figure 23.** Scattering coefficient (km-1) versus low visibility (km) for Aden city.

Figure 24 shows that the atmospheric attenuation versus low visibility for Aden city. At low visibility of 0.05 km, atmospheric attenuation is 194.4, 190.2 and 163.5 dB for wavelengths 780, 850 and 1550 nm, respectively. For 6 km low visibility, the atmospheric attenuation is about 1.95, 1.8 and 0.94 dB for wavelengths of 780, 850 and 1550 nm, respectively.


**Meet the editor**

Dr. Amanullah is currently working as Associate Professor in the Department of Agronomy, The University of Agriculture Peshawar, Pakistan. He did his PhD in Agronomy from The University of Agriculture Peshawar & his Post Doctorate from Dryland Agriculture Institute, WTAMU, Canyon Texas, USA. Dr. Amanullah has published more than 100 papers in impact factor jour-

nals. He as published many books. He is the co-author of two recent books UN-FAO (1): *Soil and Pulses: Symbiosis for Life (2016)* and (2): *Unlocking the Potential of Soil Organic Carbon (2017)*. Dr. Amanullah has been awarded with three Research Productivity Awards by the Pakistan Council for Science and Technology (PCST), Islamabad in 2011-12, 2012-13, and 2015-16.

Dr. Shah Fahad was born in Dargai (Malakand Division) - Pakistan. He studied in Pakistan at Agricultural University Khyber pakhtunkhwa and Quiad-I-Azam University Islamabad where he successfully completed two degrees: a BSC (HONS) in Agronomy and Mphil. in Plant Physiology. As a scholar he continued for another degree, in graduate studies at Huazhong Agricultural

University pursuing Ph.D. in Agronomy which was achieved with honors in 2015. Mr. Shah Fahad is now doing Post Doctorate at Huazhong Agricultural University. He is a contributor to many international journals with focuses on global warming and their influences on rice crop attributes in his articles. He is a member of the Editorial Board and a Critic of seven international journals.

Contents

**Preface VII**

**Section 1 Nitrogen and Environment 1**

**Agricultural Soils 17** Ling Zhang and Xiaojun Liu

**Recent Advances 73**

**Production Systems 95**

Chapter 1 **Inter‐ and Intra‐Annual Variability of Nitrogen Concentrations**

Chapter 2 **Nitrogen Transformations Associated with N2O Emissions in**

Chapter 3 **Controlled-Release Fertilizers as a Means to Reduce Nitrogen**

Chapter 4 **An Overview of the Effects of Heat Treatments on the Quality of Organic Wastes as a Nitrogen Fertilizer 53**

Chapter 5 **Nitrogen-Fixation by Endophytic Bacteria in Agricultural Crops:**

Akshit Puri, Kiran Preet Padda and Chris P. Chanway

M. Anowarul Islam and Albert Tetteh Adjesiwor

M. Luz Rodríguez‐Blanco, M. Mercedes Taboada‐Castro, Ricardo

**Leaching and Runoff in Container-Grown Plant Production 33**

**in the Headwaters of the Mero River 3**

Arias and M. Teresa Taboada‐Castro

Jianjun Chen and Xiangying Wei

Naoki Moritsuka and Kaori Matsuoka

Chapter 6 **Nitrogen Fixation and Transfer in Agricultural**

## Contents

**Preface XI**

#### **Section 1 Nitrogen and Environment 1**

#### **X** Contents

## **Section 2 Nitrogen and Crops 111**

Chapter 7 **Field Scale Simulation of Nitrogen Dynamics Using LEACHN and OVERSEER® Models 113** Babar Mahmood

Preface

**NITROGEN** is an essential nutrient for plant and microbial growth, and one of the key limit‐ ing nutrients in many natural ecosystems all over the world. Globally, the nitrogen cycle is perhaps the most altered of the major biogeochemical cycles, with serious implications for human health, biodiversity, and air and water quality. Recent studies have reported that the productivity and quality but also reduce the cost of production and environmental pollution. In many developing countries, the use of nitrogen is highly imbalance which results in nitrous oxide (N2O) release from the N-fertilized fields is much stronger greenhouse gas than carbon dioxide. Efficient use of nitrogen for field crops production is therefore very important for increasing grain yield, maximizing economic return, and minimizing nitrous oxide (N2O) emission from the fields and nitrate (NO3) leaching to ground water. The use of adequate nitrogen sources, rates and time of application (split) are very important, which can not only increase nitrogen use efficiency but also reduce environmental problems due to nitrogen. In order to maintain optimum crop yields and at the same time to reduce nitrogen losses, it is important to utilize applied nitrogen as efficiently as possible. Recent studies indicated that the integrated use of chemical and organic N-fertilizers can improve plant growth, increase yield and yield components, grain quality and reduce environmental pollution. Nitrogen-rich organic manures (animal manure, poultry manure, and plant residues etc.) can be served as an effective substitute to chemical N-fertilizers (urea, ammonium sulphate, nitrate etc.) to re‐ duce the costs of chemical fertilizers, reduce environmental pollution and increase grower's income. Integrated nitrogen management (combined use of chemical + organic + bio-fertiliz‐

ers) in field crop production is therefore more resilient to climate change.

The purpose of the book: **Nitrogen in Agriculture – Updates** is an attempt to present a com‐ prehensive picture of the importance of nitrogen globally. This book is intended to satisfy to the needs of students, researchers, technologists and policy makers. The book comprises of eight chapters.  We are also extremely grateful to **Ms. Martina Usljebrka** (Publishing Process Manag‐ er) of InTech for helping us to publish the book in an excellent form in the shortest possible time. We owe our sincere thanks and irreparable gratitude to our families whose consistent encouragement and love have been a tremendous impetus for the completion of this book.

**Dr. Amanullah**

Peshawar, Pakistan

**Dr. Shah Fahad**

Department of Agronomy,

Agriculture department, The University of Swabi,

The University of Agriculture Peshawar,

Swabi Kyhber Paktunkhwa, Pakistan

## Preface

**Section 2 Nitrogen and Crops 111**

**VI** Contents

Babar Mahmood

**and OVERSEER® Models 113**

**Azospirillum brasilense 163**

Chapter 11 **Prospects of N Fertilization in Medicinal Plants**

Chapter 12 **The Potential of Tree and Shrub Legumes in Agroforestry Systems 223**

Chapter 10 **Nitrogen Use Efficiency in Rice 187**

**Cultivation 209**

Chapter 8 **Optimization of Nitrogen in Durum Wheat in the**

**Greenhouse Gas (GHG) Emissions 131**

Chapter 7 **Field Scale Simulation of Nitrogen Dynamics Using LEACHN**

**Mediterranean Climate: The Agronomical Aspect and**

Luigi Tedone, Salem Alhajj Ali and Giuseppe De Mastro

Chapter 9 **The Effect of N Fertilization on Wheat under Inoculation with**

Marcelo Carvalho Minhoto Teixeira Filho, Fernando Shintate Galindo, Salatiér Buzetti and Eduardo Henrique Marcandalli Boleta

Shuangjie Huang, Chunfang Zhao, Yali Zhang and Cailin Wang

Ana I. Ribeiro‐Barros, Maria J. Silva, Isabel Moura, José C. Ramalho,

Felix Nchu, Yonela Matanzima and Charles P. Laubscher

Cristina Máguas‐Hanson and Natasha S. Ribeiro

**NITROGEN** is an essential nutrient for plant and microbial growth, and one of the key limit‐ ing nutrients in many natural ecosystems all over the world. Globally, the nitrogen cycle is perhaps the most altered of the major biogeochemical cycles, with serious implications for human health, biodiversity, and air and water quality. Recent studies have reported that the productivity and quality but also reduce the cost of production and environmental pollution. In many developing countries, the use of nitrogen is highly imbalance which results in nitrous oxide (N2O) release from the N-fertilized fields is much stronger greenhouse gas than carbon dioxide. Efficient use of nitrogen for field crops production is therefore very important for increasing grain yield, maximizing economic return, and minimizing nitrous oxide (N2O) emission from the fields and nitrate (NO3) leaching to ground water. The use of adequate nitrogen sources, rates and time of application (split) are very important, which can not only increase nitrogen use efficiency but also reduce environmental problems due to nitrogen. In order to maintain optimum crop yields and at the same time to reduce nitrogen losses, it is important to utilize applied nitrogen as efficiently as possible. Recent studies indicated that the integrated use of chemical and organic N-fertilizers can improve plant growth, increase yield and yield components, grain quality and reduce environmental pollution. Nitrogen-rich organic manures (animal manure, poultry manure, and plant residues etc.) can be served as an effective substitute to chemical N-fertilizers (urea, ammonium sulphate, nitrate etc.) to re‐ duce the costs of chemical fertilizers, reduce environmental pollution and increase grower's income. Integrated nitrogen management (combined use of chemical + organic + bio-fertiliz‐ ers) in field crop production is therefore more resilient to climate change.

The purpose of the book: **Nitrogen in Agriculture – Updates** is an attempt to present a com‐ prehensive picture of the importance of nitrogen globally. This book is intended to satisfy to the needs of students, researchers, technologists and policy makers. The book comprises of eight chapters.  We are also extremely grateful to **Ms. Martina Usljebrka** (Publishing Process Manag‐ er) of InTech for helping us to publish the book in an excellent form in the shortest possible time. We owe our sincere thanks and irreparable gratitude to our families whose consistent encouragement and love have been a tremendous impetus for the completion of this book.

> **Dr. Amanullah** Department of Agronomy, The University of Agriculture Peshawar, Peshawar, Pakistan

**Dr. Shah Fahad** Agriculture department, The University of Swabi, Swabi Kyhber Paktunkhwa, Pakistan

**Section 1**

**Nitrogen and Environment**


**Abstract**

No preventive vaccines are available for the treatment of AIDS. To improve therapy, combinational antiretroviral drugs are given; however some patients develop resistance to particular combinational drug. Microbubble-mediated drug delivery technology solves the problem by reducing systemic dose and toxicity. Microbubbles are bubbles smaller than one millimeter in diameter but larger than one micrometer. The general composition of microbubble is gas core. The mechanism of microbubbles through which its delivery increases is sonoporation, the formation of openings in the vasculature, induced by ultrasound-triggered oscillations and destruction of microbubbles. Rapid isolation strategy of CD4+ cells is mixing blood and glass microbubbles which then bind with the specific target cells to the microbubble carrying specific antibodies on their surface. The target cells will spontaneously float to the top of the blood vial and can be quickly separated. The microbubbles are particularly used in the diagnosis of AIDS because of their cell isolation techniques which is rapid and inexpensive and their small size to pass through capillary for perfusion in tissue This review demonstrates the problems with the current treatment of the disease and shed light on the remarkable potential of microbubbles to provide more effective treatment and prevention for HIV/AIDS by advancing antiretroviral therapy, gene therapy, immunotherapy, vaccinology, and microbicides.

**Keywords:** microbubbles, HIV/AIDS, target drug delivery