Preface

Nitrogen (N) is the most abundant gas in the Earth's atmosphere, although it is exceptionally unreactive. Biological nitrogen fixation (BNF), the process by which gaseous N2 is converted into ammonia (NH3) via the enzyme nitrogenase, is crucial for the availability of nitrogen in the terrestrial ecosystem. Some bacteria have the remarkable capacity to fix atmospheric nitrogen to ammonia under ambient conditions, a reaction only mimicked on an industrial scale by a chemical process. This microbiological process converts atmospheric nitrogen into a plant-usable form, thus decreasing the necessity of the use of chemical fertilizers in crop production. In many systems, N fixers have driven the accumulation of fixed N on long time scales, bringing N supply dose to equilibrium with other potentially limiting resources.

BNF includes symbiotic (nodule formation) and free-living bacteria N fixation, defined as N fixation occurring without formal plant–microbe symbioses. The ability of microorganisms to use nitrogen gas as the sole nitrogen source and engage in symbioses with host plants confers many ecological advantages. However, it also incurs physiological penalties. BNF is highly regulated at the transcriptional level by sophisticated regulatory networks that respond to multiple environmental cues.

The present book chapters in this volume cover approaches different aspects related to of this fantastic phenomenon, such as biofertilizer, organic nitrogen in agricultural systems, nitrogen fertilization for sustainable crop production, and others.

I would like to thank my wife Fernanda, my daughter Maria Eduarda and my son João Henrique for making my life happier. I also thank my deceased father Angelo Sidney Rigobelo, who lives in my mind and in my heart every day of my life.

> **Everlon Cid Rigobelo** Universidade Estadual Paulista – FCAV – Jaboticabal SP – Department of Plant Production, Brazil

**Ademar Pereira Serra** Brazilian Agricultural Research Corporation - EMBRAPA – Campo Grande MS – Department of Plant Production, Brazil

**II**

**Chapter 8 137**

**Chapter 9 147**

**Chapter 10 155**

**Chapter 11 173**

N-Fertilization Adjustment in Sugarcane Crop Cultivated

Effects of Pesticides, Temperature, Light, and Chemical

Distribution and Characterization of the Indigenous Soybean-Nodulating Bradyrhizobia in the Philippines

Phylogenomic Review of Root Nitrogen-Fixing Symbiont Population Nodulating Northwestern African Wild Legumes *by Mokhtar Rejili, Mohamed Ali BenAbderrahim and Mohamed Mars*

*by Maria Luisa Tabing Mason and Yuichi Saeki*

Constituents of Soil on Nitrogen Fixation *by Shweta Nandanwar, Yogesh Yele, Anil Dixit, Dennis Goss-Souza, Ritesh Singh, Arti Shanware* 

*by Sérgio G. Quassi de Castro and Henrique C. Junqueira Franco*

in Intensive Mechanization

*and Lalit Kharbikar*

**1**

**Chapter 1**

**Abstract**

biological nitrogen fixation

**1. Introduction**

Role of Biofertilizers in Plant

*Murugaragavan Ramasamy, T. Geetha and M. Yuvaraj*

**Keywords:** biofertilizers, microorganisms, diazotrophics, bioinoculants,

One of the present day challenges in agriculture is eco-friendly practices. Though the benefits of Green revolution has been reaped by us in terms of production, the other side of it, i.e., over usage of chemical fertilizers and its subsequent deterioration of soil health has been realised these days [1]. Hence awareness of practicing organic agriculture has been taken to various spheres and products of organic agriculture are fetching up huge market. One of the organic agriculture practices includes usage of biofertilizers in farming. Biofertilizers are likely called as bioinoculants as they are the preparations containing living or latent cells of microorganisms that facilitate crop plants uptake of nutrients by their interactions within the rhizosphere once applied through seed or soil. It accelerate bound microorganism processes within the soil that augment the extent of convenience of nutrients in a very type simply assimilated by plants [2]. Use of biofertilizers has several other advantages as well like they are cost effective, eco-friendly and renewable source of plant nutrients hence forms one of the important components of integrated nutrient management. As of now we could not claim bio-inoculants as a right alternative to chemical fertilizers but in near future the scientific understanding of the same will pave way for its right use and reap full benefits [3]. In addition to this in global scale, recent published works on biofertilizers states about the varied role of bioinoculants viz., other than nutrient transformations in different crops. To mention few, increase in root growth has been observed in wheat due to inoculation of bioinoculant consortia. Likewise *Rhizobium* inoculation increases deaminase

Biofertilizers nowadays have been realised for shifting fortunes in agriculture. It has been proven successful technology in many developed countries while in developing countries exploitation of bioinoculants is hampered by several factors. Scientific knowledge on bioinoculants and its usage will pave way for its effective usage. At the same time overlooking the significance of ensuring and maintaining a high quality standard of the product will have negative impact. Hence a proper knowledge of bioinoculants and its functioning will pave way to tape the resources in a better way. Thus the chapter provide overview knowledge about different bacterial, fungal and algal biofertilizers, its associations with plants and transformations of nutrients in soil. Adopting a rational approach to the use and management of microbial fertilizers in sustainable agriculture thrive vast potential for the future.

Growth and Soil Health

#### **Chapter 1**
