eChapters

Managing soil organic matter is of paramount importance in sustainable crop production. Human interventions always lead to a decrease in soil organic matter content and biological activity. Therefore, even for maintaining moderate levels of organic matter in soils, sustained efforts should be in place. Such sustained efforts should include adopting high-residue crops in rotation and ensuring regular return of residues to soils.

It is all the more difficult to maintain the organic matter content in well aerated soils and soils of hot and arid regions, because in these soils added materials decompose rapidly. However, in comparison, it may not be so difficult to maintain the organic matter levels in fine-textured soils with restricted aeration and in soils of cold temperate regions.

19.1. Measures that Decrease Soil Organic Matter Content

Abstract

Microorganisms are potential tool for the production of large amount of potent and effective health care, food products and biofertilising agents. Recently, the marine microorganisms are considered as good sources of such products which may possess novel properties. There is a high scope for the exploration of marine microbes in order to search new product of economic importance from marine resources. Mangrove habitat is also part of marine habitat with the plant community having unique adaptation in their morpho- physiological and reproductive behavior. The high level of organic content in mangrove rhizosphre also leads to the colonization of degradative microorganisms and make them responsible for the creation of diverse and potential microbial community. Hence, mangroves are also considered as untapped resources of microbial metabolites and products. Several microorganisms including bacteria, fungi, algae, cyanobacteria, lichens are documented from mangrove habitats. These inhabitant microbes are the good source of secondary metabolites, therapeutic enzymes, food protective agents and mineral solubilisers. However, information on these aspects is very meager and thus the present review is an attempt to compile informations on the sources, properties and application of important microbes from mangrove ecosystems.

Genetic Mapping

Perhaps one of the most powerful applications of markers is genetic mapping. This technology allows researchers identify markers located within or very close to genes of interest. With this it is possible to trace these genes through generations of crosses.

If the trait in question is complex and multigenic, mapping will also be of tremendous help to dissect the various genes or loci that contribute to the overall characteristic. Determining the amount of impact each locus delivers is a process called Quantitative Trait Loci or QTL mapping.

ABSTRACT

The world ocean with a coastline of approximately 3,50,000 km is the largest ecosystem on earth. Marine organisms are the major, sustaining components of ecosystem processes and are responsible for biogeochemical reactions that drive our climate changes. Despite this, many marine organisms are poorly described and little is known of broad spatial and temporal scale trends in their abundance and distribution. With new molecular and analytical techniques we can advance our knowledge of marine biodiversity at the species level to understand how marine biodiversity supports ecosystem structure, dynamics and resilience. We can then interpret environmental, ecological and evolutionary processes controlling and structuring marine ecosystem biodiversity. In biotechnology applications marine microbes represent a potential source for numerous commercially important biomolecules and their bioremediation capabilities are also remarkable. They also play a crucial role in decomposition of organic matter and cycling of nutrients. Microbes also serve as food for some bottom-living organisms. Understanding and preserving biodiversity was one of the most important global challenges for the past 20 years and will continue to be an important scientific issue into the new millennium. Our knowledge of marine microbial diversity has, however, been severely limited by relying on microorganisms that have been cultured which are less than 1%.

Introduction

India being a developing nation is trying to reach a balance in ever increasing population with marginal increase in crop production. There occurred a bigbang in crop production during the green revolution era however this also resulted in creation of infertile, barren lands with low chemical nutrient input responsive soils. Soil fertility is the major constraint among resource poor Indian farmers as lesser benefits are harnessed by use of newer agricultural protocols/tools/products viz improved varieties, productive technology from less fertile soils. There is dire need for looking for the alternative technologies of food or crop production to satiate the hunger of burgeoning Indian population. Today there is enormous emphasis on the conservation facets of soil fertility and crop productivity which are the instrumental philosophies in sustainable agriculture. Biofertilizers are the cost effective, ecofriendly and renewable resource of plant nutrients that could well supplement the use of already functional and popular chemical fertilizers for obtaining increase in crop yield without over hazardous impacts on various facets of soil chemistry, fertility and microbial diversity to attain sustainable agricultural system.

Microbial inoculants in agriculture, horticulture and forestry can be defined as preparations containing strains of microorganisms which can augment the microbiological process such as nitrogen fixation, phosphate mobilization, excretion of growth promoting substances, decomposition of organic wastes, biocontrol of insect pests and diseases etc. Thus they become an important component of sustainable agriculture. Microbial inoculants are based on renewable sources available in soil and nature and are low cost input and eco-friendly. These inoculants carrying the microorganisms when applied to soil/plant promote plant growth and productivity.

Mass Production of Bacterial Inoculants

Strain Selection and Improvement

In biofertilizer technology, strain selection occupies the foremost criteria, so as to explore its biological potentialities for the beneficiary crop. The selected strain used in biofertilizer production must be efficient to grow fast besides retain desirable potentialities of biological activities, which should be present in desired high numbers and must be stable. The strain must be improved periodically so as to sustain the productivity.

Culture Media and Reagents

The media used throughout the study were procured from Hi- Media Laboratories, Mumbai, India and the chemicals used were procured locally. Composition of each medium is as follows:

Introduction

All biological reactions in soil are catalyzed by enzymes. Soil enzyme activities are believed to indicate the extent of specific processes in soil and in some cases, can act as indicators of soil fertility. Biological oxidation of organic compounds is generally a dehydrogenation process and there are many dehydrogenases that carry out the following reaction:

XH₂ is an organic compound and is a hydrogen donor and A is a hydrogen acceptor. These systems are integral part of the microorganisms, so dehydrogenase activity can be correlated with active population.

Principle

Measurement of dehydrogenase activity involves determination of Triphenyl formazan (TPF) produced by the reduction of Triphenyl tetrazolium chloride (TTC). TTC is a redox indicator, a yellow coloured water soluble salt which possesses the property of being easily transformed into, methanol soluble formazan (intensely coloured, water insoluble) by reduction. 

Introduction

The major biogenic gases, which contribute to global warming, are carbon dioxide, methane and nitrous oxide. Out of these, methane is the most important gas because its thermal absorption is 30 times greater than carbon dioxide, though its atmospheric concentration is about 200 times less than carbon dioxide. Atmospheric measurements of greenhouse gases indicate that methane concentration had increased by 1 per cent annually to 1.7 ppm (by volume) during the last decade. The steady increase of atmospheric methane concentration in the past 200 years has attracted much attention.

Flooded rice soils provide an optimum environment for methane production and emission. Flooding a soil creates essential redox potential, anaerobic decomposition of organic matter and stabilizes the soil pH near neutral, thus makes the congenial environment for methane emission.

Rice is the world’s most important food crop

Introduction

The soil microbial biomass is an important component of the soil organic matter that regulates the transformation and storage of nutrients. It is a labile component of the soil organic fraction containing 1 to 3% of the soil carbon and up to 5% of the total soil N. The microbiologically mediated processes affect ecosystem functions associated with nutrient cycling, soil fertility, global C change and soil organic matter turnover. The size and activity of the soil microbial biomass must be assessed to fully understand nutrient flux in managed and natural ecosystems.

Soil microbial biomass estimations are useful in investigations that compare temporal nutrient fluctuations along natural and perturbed gradients. The effect of tillage, crop rotations and soil type on organic carbon and nutrient turnover can be assessed by following nutrient pools and activity associated with the soil microbial biomass.

Introduction

Various organic orthophosphoric mono-and di-esters in soils are hydrolyzed when incubated with toluene-treated or irradiated soils, indicative of phosphatase activity. Assays have been identified, based on the rates of release of orthophosphate. Phosphatase activities of field soils showed little or no variation with season but were influenced by the cropping system and nature of the plant cover. Activities generally increased after the addition of inorganic and organic fertilizers to soils. However, inhibition of phosphatase by phosphatic fertilizers and by liming of soils (application of ca and Mg) has been reported. Phosphatase activities were directly related to the organic-P of soils but were not consistently related to available-P contents.

Phosphatases have been used to describe a broad group of enzymes that catalyze the hydrolysis of both esters and anhydrides. These are classified into five categories

Introduction
• A cell is the most basic structural and functional unit of life. These are of two types:
i) Prokaryotic cells– Prokaryotes are those cells which lack a membrane bound nucleus and other membrane bound cell organelles. These cells are primitive cells. Examples, bacterial cells, archaeal cells.
ii) Eukaryotic cells– Eukaryotes are those cells which have distinct membrane bound organelles. These are advanced cells. Example, animal cells, plant cells, fungi.
• A microorganisms (from the Greek: mikros, “small” and organism’s, “organism”) are those small living organisms which cannot be seen with naked eyes. These are of two types:
i) Single cell– Organism made up of a single cell.
ii) Multi-cellular– Organism made up of multiple cells.
Shape and Arrangement of Bacterial Cells
• Prokaryotes display following shapes
• Spherical cells called Cocci
• Cylinders called rods or Bacilli
• Coma shaped called Vibrio
 

Mechanism of Bioinputs explains the biological processes through which beneficial microorganisms and other bioinputs influence plants, pathogens, and agricultural ecosystems. The chapter examines direct and indirect plant-growth-promoting mechanisms of rhizobacteria, mycorrhizal fungi, endophytes, and biocontrol microbes. It also covers entomopathogenic bacteria, fungi, nematodes, viruses, and the modes of action of microbial and botanical biopesticides, predators, parasitoids, and semiochemicals. Environmental factors, microbial variability, pathogen interactions, and relationships with other organisms are considered as influences on biocontrol performance. The chapter therefore connects biological mechanisms with practical application, helping readers understand why particular bioinputs work under specific agricultural conditions. across varied farming conditions.

ABSTRACT

Heavy metal contaminated soils are biologically inactive and extremely poor in soil fertility status. These metals are highly resistant and cannot be easily degraded by either chemical reactions or amendments. Microorganisms are biological softwares capable of degrading the metals efficiently. Among microorganisms, mycorrhizas are known to circumvent metal toxicities through a series of processes that assist in immobilization in biological systems which converts toxic metals into less or nontoxic forms. There are five mechanisms such as biosorption, solubilization, hyphal transport, detoxification and dilution are involved in promoting tolerance of host plants to heavy metal toxicities. These processes are strategies that can be exploited to phytoremediate the contaminated soils. The phytoremediation strategies encompass tolerance of mycorrhizal fungi, phytostabilization (preventing entry of heavy metals into plants), phytoextraction (luxuriant uptake and transport to shoots) and intercropping or crop rotation with mycorrhizal dependent hyperaccumulators or non-hyperaccumulators. Despite mycorrhizas are natural, the indigenous population is not sufficient enough to induce tolerance of host plants to abiotic and biotic stress conditions. This necessitates adopting recommended agronomic practices to promote mycorrhizal colonization in natural agro-ecosystem or to derive full benefits from phytoremediation strategies. Thus mycorrhizas are important naturally occurring microorganisms capable of withstanding highly contaminated metal sites and offer protection against phytotoxicities caused by heavy metals.

Traditional media channels have served as the backbone of agricultural communication in India for decades, playing a crucial role in disseminating information about farming practices, government schemes, and technological innovations to rural communities. These conventional platforms, including radio, television, print media, and community-based communication methods, continue to remain relevant and effective for promoting natural farming practices, despite the emergence of digital technologies. Understanding the strengths, limitations, and optimal utilization strategies for traditional media is essential for developing comprehensive communication programs that can reach diverse farming populations across various geographical and socio economic contexts. Radio broadcasting represents one of the most successful and enduring traditional media platforms for agricultural extension in India. All India Radio (AIR) has been actively playing a unique role in bridging the digital divide and supporting agricultural extension programmes in India since the experiment in 1952-53 with ‘An Indian Experiment in Farm Radio Forums’ at Poona (now Pune). The effectiveness of radio stems from its accessibility, affordability, and ability to reach illiterate farmers who may face barriers with text-based information sources. Radio programs dedicated to agriculture have evolved significantly from simple one-way

SEX IS VERY COSTLY

Large amounts of energy required to find a mate and do the mating: specialized structures and behavior required

Intimate contact provides route for infection by parasites (AIDS, syphillis, etc.)

Genetic costs: in sex you pass on only half your genes to your children

Males are an expensive luxury- in most species they contribute little to rearing offspring

But There are Some Advantages

More genetic diversity: more potential for survival of species when environmental conditions change

Shuffling of genes in meiosis (random separation of homologous chromosomes)

Crossing-over in meiosis (see below)

Fertilization (genes from 2 individuals brought together)

ALL MOLECULES MOVE CONTINUOUSLY BY SIMPLE DIFFUSION

Heat energy causes molecules to move randomly (sometimes called Brownian motion)

If the concentration of molecules is different in 2 regions (this produces a concentration gradient), diffusion will cause molecules to move from a region of high concentration to one of low concentration

The higher the concentration gradient the more rapid the net diffusion

Diffusion evens out the concentrations so they are equal everywhere (maximum entropy)

If 2 different substances have the same concentration gradient, usually one will move faster than the other

Differences in speed between molecules with the same concentration gradient are given in terms of diffusion constants

A substance with a high diffusion constant moves faster than one with a low diffusion constant

In general, large molecules move slower than small molecules

Diffusion across a membrane is called permeability, and membrane diffusion constants are called permeability constants

A fair number of practical breeding experiments were done in ancient times

People knew there was a connection between sex and reproduction

The idea had developed that “like begets like”

By selecting certain plants and animals and breeding them many domestic varieties of plants and animals had been developed

Example: corn was developed from a wild grass in Mexico and Central America, probably about 5000 years ago

149 of the top 150 plant crops were domesticated by primitive man

Mentoring represents a developmental relationship between a more experienced individual and a less experienced person, characterized by guidance, support, and knowledge transfer that facilitates personal and professional growth. The word “mentor” originates from Homer’s epic poem “The Odyssey,” where Mentor serves as a wise counselor and guide to Telemachus during Odysseus’s absence. This classical reference captures the essence of mentoring as a relationship built on wisdom sharing, guidance provision, and developmental support that extends beyond mere instruction or supervision.

Contemporary definitions of mentoring emphasize its multifaceted nature as both a relationship and a process that serves developmental functions for mentees while often providing reciprocal benefits for mentors. Kram’s seminal work defines mentoring as a relationship between a young adult and an older, more experienced adult that helps the younger individual navigate the adult world and the world of work. This definition highlights the developmental and navigational aspects of mentoring while recognizing the experience differential that typically characterizes these relationships