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India shares 17.4% of the world population, while its land is only 2.4% of the total geographical area of the world. Naturally, the pressure on the land is often beyond its carrying capacity. Therefore, the productive lands, especially the farmlands in India are in the constant process of various degrees of degradation and are fast turning into wastelands. At present, approximately 63.85 million hectare area of the land is lying as wastelands in India (NRSA, 2005). Out of these lands, about 50% lands are such non-forest lands, which can be made fertile again if treated properly. In the last 50 years India’s lush green village forests and woodlots have been deforested to the maximum. To restore this ecological imbalance by developing the degraded non-forest wastelands, Government of India had created the Department of Wasteland Development during July, 1992 under the Ministry of Rural Development, which has been subsequently reorganized and renamed Department of Land Resources, with a broader mandate.

National Wasteland Development Board was established in 1985 mainly to tackle the problem of degradation of lands, restoration of ecology and to meet the growing demands of fuelwood and fodder at the national level. The Board was reconstituted in August, 1992 and was made responsible for development of wastelands mainly in non- forest areas in totality by involving local people at every stage of development. It aims at creating a scenario where the Government acts as a facilitator and the people at the grass root level become the real executioner of the programme. The degradation of environment in the fragile Indian subtropical ecosystem is basically attributed to the following factors.

A watershed is a geohydrological unit or all the land and water area bounded by a divide which contributes runoff to a common point. Watershed is considered to be synonymous with ‘catchment basin’ and ‘drainage basin’. In watershed management approach, development is not only confined to agricultural lands but also covers the area, starting from the highest point of the land to the outlet of the natural stream. Watershed management becomes increasingly important as a way to improve livelihood of people while conserving and regenerating their natural resources.

Watershed management is the process of creating and implementing plans, programmes and projects to sustain and enhance watershed functions that affect the plant, animal and human communities within a watershed boundary. It implies the judicious use of all the resources i.e. land, water and vegetation in an area to prevent soil erosion, improve water availability and increase food, fodder, fuel and timber on sustained basis.

Ecology of a place is influenced by a number of biotic and abiotic factors. An agroecological zone is broadly homogeneous in climatic and edaphic factors, but not necessarily contiguous, where a specific crop exhibits roughly the same biological expression. On the other hand, the characteristics of an agroecological zone influence the crops and cropping patterns of the zone. Thus, there are considerable variations in the types and management practices of agroforestry systems being followed in different agroecological zones.

AGROFORESTRY FOR HUMID AND SUBHUMID TROPICS

Humid and subhumid tropical regions have much variation in biological, social and economical parameters. The characteristics of humid tropics include high mean annual rainfall of more than 1500 mm, dry season of less than four months in a year and mean annual temperature of more than 22oC. Rainfall usually exceeds the evapotranspiration. However, demographic pressure has caused excessive deforestation and overgrazing which developed soil related problems like low soil fertility, low organic matter, high acidity and high rainfall erosivity. The agroforestry practices designed for this region should aim for improved fallows, soil fertility improvement and conservation, food production, etc. Thus, the common agroforestry systems in this zone are taungya, homegardens, alley cropping, plantation-crop combination, windbreaks, silvipastoral systems and various intercropping systems. Shifting cultivation is a common practice in tropics which should be discouraged as it causes environmental degradation and ecological imbalance, soil erosion and soil nutrient loss.

Agroforestry is a land use system that involves two or more plant species at least one of which must be a woody perennial. When perennial woody and herbaceous components are grown together on the same piece of land their performance would largely depend on their ability to share various growth resources in a given environmental situation. Due to difference in growth pattern and resource requirement of the components in agroforestry situation, a close interactive relation is obvious. Thus, careful management practices for the components are required to establish a successful agroforestry system. The characteristics of the trees and crops, and their interactions, can be modified with good management practice in order to take advantage of the positive characteristics and minimize the effects of the negative ones. Effective and efficient agroforestry management may be divided into two groups - tree management and agricultural crop management.

Trees that provide materials for propagation are called mother trees. Selection of mother trees is important because the young trees will be expected to inherit the favourable characteristics from the mother tree, such as fast growth, upright or spreading shape of the tree crown, good flowering and fruiting, and tolerance of diseases or pests. There may be sexual propagation by seed or vegetative propagation by using other parts of the tree. The genetic make-up of the seeds differs due to recombination of the genes, resulting in seedling variation. Thus, all the seedlings may look like the mother tree in some respects, but no two seedlings are the same. In case of vegetative propagation through cutting, layering, grafting or budding, the genetic make-up of the young tree is exactly the same as that of the mother tree. Consequently, all new trees grown vegetatively from one mother tree have the same set of gene pairs and therefore the same characteristics; they form a so called clone. Differences between plants of a clone can only be caused by different growing conditions.

Farmers have been growing trees for different purposes for thousands of years. Tree species that are grown to provide more than one significant function are called multipurpose trees. These functions may be productive such as producing fuelwood, timber, fibre, fodder, food, medicine, etc. and/or protective such as soil conservation, shade, shelterbelt, microclimate amelioration, land sustainability, biodiversity preservation, etc. All trees are multipurpose; some, however, are more multipurpose than others. Tree species can be multipurpose in two ways.

1. A single tree can provide more than one function. For example, Gliricidia sepium is grown as living fences that provide fuel, fodder and green manure for agricultural crops - all at the same time.
2. Trees of the same species, when managed differently, can provide different functions. For example, Leucaena leucocephala is managed so that some trees will mainly yield wood while others mainly produce leaf fodder.

Farmers can grow multipurpose trees (MPT) in various combinations with other crops, as in agroforestry, in block plantations of trees or in naturally regenerating tree farms. In certain cases, multipurpose trees are grown and managed for only one purpose. For example, Gliricida sepium is grown only to provide shade in coffee plantations. The same species may be planted in some other places and is managed differently for a very different use.

Agroforestry systems are not simply systems where trees and crops or animals give useful products to the farmers, rather systems where trees and crops and/or animals interact. Interaction literally means influence or mutual or reciprocal action. So component interaction refers to the influence of one component of a system on the performance of other component as well as the system as a whole.

In agroforestry systems, trees are grown in close proximity to crops and pasture. Their performance would largely depend on their ability to share various growth resources in a given environmental situation. Various interactions take place between the woody trees and herbaceous plants (crops or pastures) which is referred to as tree-crop interface. These interactions take place through the media of soil and microclimate and may exert favourable or adverse effects on the crop. Study of interaction helps to know how the components of agroforestry utilize and share the resources of the environment, and how the growth and development of any of the components will influence the others. Interaction occurs both above and below the ground and includes a complex set of interactions relating to radiation exchange, the water balance, nutrient budget and cycling, shelter and other microclimatic modifications.

The success of an agroforestry system relies heavily on exploitation of the component interactions. In an ideal relationship, production of trees as well as crops or grasses in combination could be comparable to their sole performance. Agroforestry could be even more advantageous if the production of associated components is increased due to influence of trees. This is possible because trees are capable of improving productivity of soil in many ways. A large number of trees are known to fix nitrogen symbiotically. Nevertheless, instances of crop inhibition in association of trees are not uncommon. Such inhibitions are primarily caused by shade effect as well as competition for belowground resources such as nutrients and water. In some cases inhibitory effect may also result from allelochemicals secreted by some of the tree species.

Management approaches to soil, including problems of soil degradation and low soil fertility, have recently undergone major changes. The earlier concept was to concentrate on achieving high levels of production from the more fertile areas, leaving the marginal lands for extensive use only. Steeply sloping and highly drought-prone areas were mostly left without any cultivation as production from these areas was hardly cost effective. Soil constraints were to be overcome by inputs like improved crop varieties, fertilizers, chemical control of pests and diseases, and the use of irrigation.

The approach of use of newly developed high yielding crop varieties, improved agronomic management practices, use of chemical fertilizers, efficient water management and timely plant protection measures has been successful in achieving large increases in crop productivity in recent years. On the other hand, continuous application of fertilizers at higher rates leads to environmental problems. Yield responses to fertilizers have declined because of soil physical degradation and micronutrient deficiencies. Above all, large numbers of poor farmers simply can neither afford high levels of fertilizers and other purchased inputs, nor do they have the capital to take on the risk involved in their use. Increasing the area under irrigation has also run into severe constraints in the form of limits to available freshwater resources.

The word 'social forestry' was coined by Westoby and used in the ninth Commonwealth Forestry Conference at New Delhi in 1968. In India the term was first used by the National Commission on Agriculture, Government of India in 1976, to denote tree raising programmes to supply firewood, small timber and minor forest products to rural population. Prasad (1985) defined social forestry as forestry outside the conventional forests which primarily aims at providing continuous flow of goods and services for the benefit of people. This implies that the production of forest goods for fulfilling the needs of the local people is social forestry. Thus, conceptually it deals with the people to produce goods such as fuel, fodder, small timber, etc. to meet the needs of local community particularly the underprivileged section (Shah, 1988).

The words ‘system’, ‘sub-system’ and ‘practice’ are commonly used in agroforestry literature. In a broad sense, a system is defined as a group of associated elements forming a unified whole and working together in a well defined regular relation for a common goal. An agroforestry system refers to a type of agroforestry land-use that extends over a locality to the extent of forming a land utilization type of the locality. Sub-system and practice are lower-order terms in the hierarchy with lesser magnitudes of role, content and complexity. However, these terms are used loosely, and almost synonymously.

Classification of agroforestry systems is necessary in order to understand and provide a practical framework for evaluating systems and developing action plans for their improvement. Any classification scheme should satisfy the following criteria (Nair, 2008).

Agroforestry is a new name for a set of old practices. The general concept of agroforestry is to integrate trees and agriculture so as to create a more diversified landscape, while providing the producers with new environmental and economic benefits. In other words, agroforestry is a method of farming that allows trees and shrubs to grow along with crops and/or livestock, therefore blending agriculture and forestry in the same production system. In fact, man's association with forest is much older than with agriculture. First man was a food gatherer and hunter in forests. Then he realized that the seeds of the fruits he collected germinated, grew into plants and bore the fruits again and thus man started to cultivate foods. Man's desire to live in a community created settled agriculture.

The pressure on the agricultural lands has increased manifolds due to the increasing population, expansion of urban area and the industrialization process. The environment has also been disturbed. Soil is losing its productivity and the biodiversity is threatened. Farming community is trying all means to increase the land productivity. Chemical fertilizers and pesticides are applied in higher proportion, causing environmental pollution hazards. Under all these circumstances agroforestry has shown that besides sustainable agriculture it can also help promote a better environment. Trees have always played an important role in mankind's survival. This relatively young science known as agroforestry was brought from the realm of indigenous knowledge into the forefront of agricultural research three and half decades ago and was promoted widely as a sustainability-enhancing practice that combines the best attributes of forestry and agriculture.

Abstract

Anaerobic microorganisms occur in oxygen-free environments as they possess biomolecules and metabolic processes that have adapted to sustain them in the stressed environments. These biomolecules and metabolic processes are harnessed and employed in various biotechnological applications. Anaerobes are abundant in various ecological niches such as freshwater or marine sediments, subsurface aquifers, deep thermal vents etc. where, in the absence or limitation of oxygen, they utilise reduced ions such as nitrate, sulphate, ferric, carbonate and certain organic compounds like degrading organic matter, fatty acids or alcohols as electron acceptors during respiration/fermentation to produce more or fewer reduced products such as, alcohols, ammonia, organic acids, hydrogen and carbon dioxide as the oxidised product. Diversity of substrates that can be fermented and the wide range of products that can be formed make anaerobic processes useful in biotechnological applications. Their substrate versatility and flexibility, for example, they can utilize simple sugars as well as many of them can utilise complex renewable biomass make their biotechnological applications sustainable and environment friendly. Anaerobes have been employed in food, chemical and material industries for the production of food items, preservative, additives, chemical intermediates, solvents, catalysts and polymers. They find widespread usage in energy sector for generation of various kinds of biofuels that can mitigate our reliance on non-renewable sources for fuel production. An emerging aspect of anaerobic biotechnology is waste valorization that involves treatment of any kind of waste (industrial, municipal, agricultural, pharmaceutical), where organic fraction of the waste is converted into valuable products. Anaerobes play key role in maintaining the global cycles of carbon, nitrogen, and sulfur, and also facilitate bioremediation by breakdown of persistent compounds. Lately, role of anaerobes in medicine and health care sector is widely explored as they are found to produce several bacteriocins, antibiotics, immunomodulators, vitamins and anti-tumor compounds. Some of the anaerobes have also been employed as probiotics. In the present chapter, we discussed these and many more biotechnological applications of anaerobes in white, green, red and blue biotechnology.

Abstract

Hundreds of bacterial taxa makes up human gut microbiota and it is comprised primarily of anaerobes belonging to four main phyla which are Firmicutes, Bacteriodetes, Actinobacteria, and Proteobacteria. Anaerobes colonizes the human body, including oral cavity, small intestine, vagina, skin but the majority of them are housed in the colon. The composition and distribution anaerobes varies along the length of gastrointestinal tract because of variation in oxygen gradient, anatomy of intestinal tract and other host physiological factors. Human gets colonized by anaerobes during the birth and these initial colonizers have impact on infant’s health status. The colonization and development of the gut microbiome is responsive to variety of factors including the mode of delivery, feeding methods, environment etc. The human gut microbiota plays an important role in healthy status of host. It plays an important role in nutrient metabolism and absorption, synthesis of vitamins and production of short-chain fatty acids (SCFAs). In turn these metabolites have positive effect on host immunity and overall host fitness. Studying, the anaerobes using culturing method remains critical in microbiology. However, culturomics approach, combined with sequencing technology, provides new insights in studying anaerobes of human gut microbiota. In this chapter we have discussed that, how human gut is an ideal habitat for the colonization and growth of anaerobes and their impact on host health. We also tried to shed light on latest technical advancement in sequencing culturing technology and their application in studying gut anaerobes.

Abstract

Gastrointestinal tract (GIT) harbors mixed microbial community, these are highly diversified, as revealed by molecular and phylogenetic studies. It is also estimated that microbiota of the GIT is composed of over 35,000 species and play a crucial role in human health and diseases. Thus are now of great interest to both the industrial and scientific communities. The microbes exhibit health benefits are known as probiotics. Anaerobic bacteria dominate in the GIT environment and genera like Bifidobacterium, Clostridium, are strict anaerobes while Lactobacillus, Lactococcus, is facultative anaerobes implicated in the probiotic effects.

For developing anaerobic bacterial based bio-products, it is necessary to cultivate large-scale biomass production that could be done using a modern manufacturing practice. Information on detailed understanding of the perfect growth medium and other bioprocessing parameters for the growth and viability is must. Also high cell viability is a prerequisite during downstream processing and storage of probiotic formulation. In this work we review the latest information about the history, mechanism of action, benefits of probiotic, selection criteria, sources of anaerobic probiotic bacteria, industrial cultivation medium along with biomass production, downstream processing.

Abstract

The normal human microbial flora comprises of both aerobes and anaerobes at various sites. Anaerobes are recognised as pathogens causing simple abscesses to life threatening human infections like gas gangrene. They are also incriminated in a large number of mixed bacterial infections and their diagnosis and specific therapy is important for better patient outcomes. The emergence of Clostridioides difficile as an important pathogen causing antibiotic associated diarrhoeas and its emerging resistance to antimicrobial agents has brought anaerobic microbiology into the forefront. Unfortunately, anaerobic clinical microbiology is difficult to practice with long turnaround time, difficult to grow pathogens, new genera and species being discovered based on 16S rRNA sequencing methods and increasing incidence of antimicrobial resistance being reported in anaerobes. This chapter delves into the important aspects required to improve utilization of anaerobic microbiology services and the variety of human infections we encounter in clinical practice due to anaerobic bacteria.

Abstract

Anaerobes are a diverse groups of microorganisms which do not require oxygen or energy for respiration/metabolism and are one of the important components of nitrogen cycle. They are capable of using various other organic and even inorganic materials as electron acceptors during respiration. Anaerobic based wastewater treatment is a biological approach where microorganisms degrade organic contaminants (i.e. rich in carbon and nitrogen) in the absence of oxygen. In this chapter, the role of anaerobes in wastewater treatment has been discussed as it offers an alternative, cheap and eco friendly treatment technology among different biological treatment methods. Anaerobic biological treatment of wastewater is well developed, understood, and frequently used in anaerobic digesters to treat complex organic carbon and nitrogen compounds such as primary and secondary wastewater sludge. The anaerobic sludge contains diverse groups of anaerobic microorganisms that work together in association via a multistage processe consisting of the following biochemical reactions like hydrolysis, acidification, acetogenesis, and methanogenesis thereby converting the organic matter to biogas. The composition of biogas includes 70% methane (CH₄) and 30% carbon dioxide (CO₂) in addition to traces of other gases (e.g., H₂ and H₂S). The methane produced as a by-product can be used as an energy source. The potentiality of anaerobes in anaerobic based bioreactors for its maximum efficiency can be implemented in a variety of ways. The chapter discusses about the working principle, performance, treatment potential, and cost implication in the application of anaerobic treatment technology. The main bioprocess parameters such as pH, temperature, mixing, organic loading rate (OLR), and hydraulic retention time (HRT) have also been discussed in brief. Anaerobic treatment offers several benefits over aerobic treatment, including lower energy requirements, less chemicals, low capital, operation, and maintenance costs, and less sludge production. Hence, it saves money and the environment and overall simplifies the whole process.

Abstract

Solid Waste Management (SWM) has become a significant global concern, specifically for developing countries like India because of increasing population, rapid urbanization and high rate of municipal solid waste generation. Bio-composting and anaerobic digestion are the methods majorly used for solid waste management. Present chapter comprises detailed information on methods, microbiology involved and pros and cons of these methods to provide the detail information of solid waste management processes to the readers. Variable nature of substrates are available for bio-composting process. It includes sludge from effluent treatment plant (ETP), sewage treatment plant (STP) and bio-toilets, municipal solid waste, food waste and garden waste etc. Nutritional content, carbon /nitrogen (C/N) ratio of the substrate, available space and cost of the process are the main factors that affect selection method for waste management. Anaerobic digestion is the preferred method of solid waste management in comparison to other processes of composting due to methane generation as biogas and bioconversion of organic compounds to manure.

Abstract

Rise in global energy demand has led to an increase in consumption of fossil fuels. In recent years, there has been an increasing awareness about the consequences of pollution and global warming caused by burning of fossil fuels. This has led to an increased interest in the search for sustainable energy. Transportation sector is a major consumer of world’s energy resources. n-Butanol is one of the most promising alternative bio-fuels which has various advantages over other biofuels. The microbial n-butanol is produced by anaerobic conversion of the substrate to n-butyric acid and subsequently utilized to form n-butanol. The present chapter explores the scope of bacterial butanol production as need of the hour and its use as an alternative biofuel.

Abstract

Hydrogen synthesis from bioprocesses a good approach for generation clean of fuel for world's development. Throughout the ancient and current periods, most of the developmental activities are completed by consumption of non-renewable fossil fuel energy that which has resulted in multiple environmental issues or challenges (Climate change and pollution by toxic gases or byproducts formation) at global level. Biohydrogen synthesis from anaerobic bacterial fermentation could be a good effort for sustainable energy production without any toxic byproduct formation. For production of hydrogen, lignocellulosic material can be utilized as cheap raw substrates. This would help the farmers in providing surplus benefits to farmer for their agriculture residues that normally burnt and cause the serious air pollution. Utilization of agro-waste residues can help in development of sustainable biofuels for world energy need. Burning of agrowaste residues by farmer's can be discouraged via utilization as raw carbon substrates thereby reducing air pollution.

Abstract

Grazing animals have developed symbiotic relationship with anaerobic microorganisms, which survive in their rumen and help in the oxidation of complex molecules of feed containing lignocellulosic materials into volatile fatty acids. The consortium comprises anaerobic bacteria, fungi and protozoans. The rich microbial diversity of rumen remains constant after its establishment and does not get affected by intruding contaminants along with feed or water. The rumen contains a wide range of microbes such as Fibrobacter spp., Ruminococcus spp., Clostridium spp., Prevotella spp., Eubacterium spp., Methanobacterium spp., Treponema sp. Lachnospira sp., Bacterioides s pp., fungi: Anaeromyces s pp., Neocallimastix spp., and protozoa: Enoplastron sp., Eudiplodinium spp., Ostracodinium sp. They often have a variety of enzymes, glucanases, xylanase, glucuronidase, pectinase and amylase, etc. These enzymes inhabit the microbes and even break down complex molecules into simpler forms like; glucose and volatile fatty acids. The present chapter discusses on the role of microorganisms of rumen.