eChapters

Introduction

Climate change refers to change of weather variables over a long period of time. The Inter-Governmental Panel on Climate Change (IPCC) defined climate change as a “change in the state of the climate that can be identified by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer”. This may occur due to natural variability or as a result of human activity. The change may be in the form of magnitude or variability of a single or multiple weather variables or weather phenomena. Global shift in temperature and precipitation pattern as well as increasing frequency of extreme weather events are consequence of climate change which is perceived over several decades. Climate change is indeed increasingly recognized as a considerable risk to agriculture particularly with respect to direct impact on crop production and yield stability (Barzman, 2015).

Effect of Climate Change in Global Warming and Greenhouse Gases

Global warming as the resultant of climate change has become an issue of serious concern worldwide for existence of life on the earth. Over past hundred years, the global temperature has increased by 0.8⁰C and is expected to reach 1.1-5.4⁰C by the end of next century. Major factors affecting the global warming and the climate change is the concentration of greenhouse gases like carbon dioxide, methane and nitrous oxide. On the other hand, CO₂ concentration in the atmosphere has increased drastically from 280 ppm to 370 ppm and is likely to be doubled in 2100 (IPCC, 2007).

Introduction

The Indo-Gangetic Plain is one of the world’s major foodgrain producing regions. The Indian states falling under this region, viz. Punjab, Haryana, Uttar Pradesh, Himachal Pradesh, Bihar and West Bengal, are also the major rice-wheat growing states spread over 10.5 million hectares in the country. During the past 30 years, agricultural production growth in this region has been able to keep pace with population demand for food in the country mainly due to adoption of green revolution technologies inducing yield growth, followed by area expansion. But this opportunity is ceasing very fast due to limited scope for increasing the availability of arable land and natural resources. The other issue is the conservation of the basic resources of land and water for sustainability of agriculture in the Indo-Gangetic Plain. It is generally believed that the rice-wheat system has strained the natural resources in this region and more inputs are required to attain the same yield levels (Swarup and Singh, 1989; Kumar and Yadav, 1993; Lal et al., 2004). It is, therefore, imperative now to promote alternative technologies that would help conserve the much needed but gradually depleting natural resources while boosting productivity growth in the long-run by maintaining soil health and production environment. As a part of this strategy, conservation agriculture and resource conserving technologies play a major role in sustaining and enhancing the productivity of the rice-wheat system at a lower cost of production.

Introduction

The Indian agriculture is very complex and carrying out multi-functionalities of providing food, nutrition and ecological security besides employment and livelihood for over 700 million people. Indeed, India has made a marvelous achievement in attaining self-sufficiency in food grain production after the induction of Green Revolution which eventually resulted in maintaining all-time high buffer stock in warehouses of our country. Such rosy picture in production trends turned to be bleak in the past few years. There are various reasons behind this. Shrinking resources of prime lands, deforestation and accelerated erosion, deterioration of soil physical environment, increasing waterlogging and salinity in canal irrigated areas, declining water table in well-irrigated areas, poor management of rainwater, lower efficiency of inputs such as water, fertilizers and agrochemicals, rapid industrialization coupled with pollution and environmental degradation and hazards have aggravated the problem. At the same time, increase in atmospheric concentrations of greenhouse gasses (GHG), of which the most common is carbon dioxide (CO₂), is the primary cause of global warming and the Intergovernmental Panel on Climate change (IPCC) estimates that the current greenhouse gases (GHGs) concentrations are 30% more than the pre-industrial level. C is accumulating in the atmosphere at a rate of 3.5 Pg (Pg = 1015 g or billion tons) per annum, the largest proportion of which resulting from the burning of fossil fuels and the conversion of tropical forests to agricultural production. Under such circumstance, there is an imperative need to produce more from less arable land and water through meticulous management of basic agricultural resources such as soil, water and biological inputs.

Introduction

Persistent use of conventional farming practices based on extensive tillage, especially when combined with removal or in-situ burning of crop residues, has magnified soil erosion losses and swiftly degraded soil resource base. One of the glaring examples for the aforementioned statement is the ‘Dust Bowl’ in the U.S during 1930s in Great plains, where 91 M ha of land was degraded by severe soil erosion (Hobbs, 2007).

One of the primary challenges of our time is to feed growing and more demanding world population with reduced external inputs and minimal environmental impacts (nature paper). Conservation Agriculture (CA) is a set of management practices for sustainable agricultural production without excessively disturbing the soils, while protecting it from the processes of soil degradation like erosion, compaction, aggregate breakdown, loss of organic matter, leaching of nutrients, and processes that are accentuating due to anthropogenic interactions in the presence of extremes of weather and management practices. The organic materials conserved through this practice are decomposed slowly, and much of materials are incorporated into the surface soil layer, thus reducing the liberation rate of carbon as CO₂ into the atmosphere. In the total balance, carbon is sequestered in the soil, and turns the soil into a net sink of carbon. So, CA enhance soil health by improving soil aggregation, reducing compaction through promotion of biological tillage, increasing surface soil organic matter and carbon content, and moderating soil temperature and weed suppression. CA reduces cost of cultivation, saves time, increases yield through timelier seeding/planting, reduces pest and diseases through stimulation of biological diversity, and reduces green house gas emissions.

Machinery development, refinement and adoption for a range of soil and cropping situations will be fundamental in any success to promote conservation agriculture practices. Agricultural machinery or tools, which support conservation agriculture generally refer to the cultivation systems with minimum or zero tillage and in-situ management of crop residues. Minimum tillage is aimed at reducing tillage to the minimum necessary that would facilitate favorable seedbed condition for satisfactory establishment of crop. Zero tillage is however an extreme form of minimum tillage. With the development of direct drilling machines, almost all research work was attempted to define the responses of direct-drilled seeds in relation to soil micro-environments. Different designs of direct drilling machines viz. zero till drill, no till plant drill, strip till drill, and rotary slit no till drill have been developed with controlled traffic measures for energy efficient and cost-effective seeding of crops without tillage. In this paper various issues, challenges and prospects of conservation agriculture in India has been discussed.

Introduction

Climate change is a statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer). Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures. Eleven years from 1995-2006 rank among the twelve warmest years in the instrumental record of global surface temperature (since 1850). The 100-year linear trend (1906-2005) of 0.74 [0.56 to 0.92] °C is larger than the corresponding trend of 0.6 [0.4 to 0.8] °C (1901-2000) and over the 21st century average temperature of earth surface is likely to go up by an additional of 1.8-4°C (IPCC, 2007). This temperature increase can be attributed to the altered energy balance of the climate system resulting from changes in atmospheric concentrations of the green house gases (GHGs). Among the principal components of radiative forcing of climate change, CO₂ has the highest positive forcing leading to warming of climate. CO₂ has the least global warming potential among the major green house gases but due to its much higher concentration in the atmosphere; it is the major contributor towards global warming and climate change. Agriculture sector in India contributes 28% of the total GHG emissions (NATCOM, 2004). The global average from agriculture is only 13.5% (IPCC, 2007). In future, the percentage emissions from agriculture in India are likely to be smaller due to relatively much higher growth in emissions in energy-use transport and industrial sectors. The emissions from agriculture are primarily due to methane emissions from rice fields, enteric fermentation in ruminant animals and nitrous oxides from application of manures and fertilizers to agricultural soils (NATCOM, 2004).

Introduction

Climate smart agriculture (CSA) refers to the incorporation of adaptation and mitigation practices in agriculture that enhances the system-resistance and recovery-mechanism against climatic hazards. Climatic hazards / disturbances include drought, flood, heat / cold wave, erratic precipitation, sudden dry spell etc. In nutshell, CSA is the ability of the system to bounce back. It can also be explained as an approach to build-up resilience of agricultural systems, to increase adaptive capacities of farming communities to climate change and variability, and to ensure food security (Prasad et al., 2015).

Climate change can be defined as a statistically significant variation in either the mean state of the climate or in its variability, persisting of an extended period, typically three decades or longer (Pathak et al., 2014; NAAS, 2013, Bhattacharyya et al., 2016). The surface air temperature, sea level rise, occurrence of extreme events (heat wave, cyclone, flash flood) is the direct evidences of climate change. The annual average surface temperature has increased by 0.87^°C in 100 years (IPCC, 2018). Recent report revealed that more than 90% of Northern Hemisphere land areas outside the tropics showed at least 1^°C above average, whereas temperatures were less extreme in Southern Hemisphere. Importantly, temperatures were above normal over most of the ocean areas. Global sea level rose to about 15 mm, in between November (2014) and February (2016), as a result of ElNino, which was well above the post-1993 trend of 3.0-3.5 mm year^-1. However, Indian summer monsoon rainfall since 1901 to 2012 showed no long-term trends, with some regional changes. Importantly, night temperatures have increased sharply during recent years, which couple with erratic precipitation could significantly affect agricultural production. The fifth IPCC (IPCC, 2014) reports clearly brought out global and regional impacts of climate change on Agriculture, Forestry and Other Land Use (AFOLU). South Asia has been characterized as one of the most vulnerable regions. Impacts of climate change witnessed all over the world; however, countries like India is more vulnerable because of its huge population primary dependent on agriculture for livelihood, predominance of small and marginal farmers, and fragmented land holding.

Introduction

Water and food security are the key challenges under climate change as both are highly vulnerable to continuously changing climatic patterns. Climate change has resulted in increases in globally averaged mean annual air temperature and variations in regional precipitation and these changes are expected to continue and intensify in the future. The projected changes in climate patterns over India include increase in surface temperature, variations in rainfall, increasing occurrence of extreme weather events like floods and droughts, rise in sea levels and impact on the Himalayan glaciers. Sectors of the Indian economy are most likely to be impacted by such changes in climate are those dependent on natural resources, namely agriculture, water and forestry. The likely impacts such as reduction in food production, water scarcity, loss of forest biomass Climate change is expected to bring more intense and more frequent extreme weather events including droughts and floods in India. The global atmospheric concentration of carbon di-oxide CO₂ for increased from preindustrial value of about 280 ppm to about 410 ppm at the present (2021). The global increase in CO₂ concentration is primarily due to fossil fuel use and land use change. Atmospheric methane was 1803 ppb in 2011, this is 150% greater than before 1750. Atmospheric nitrous oxide (N₂O) was 324 ppb in 2011, this is 150% greater than before 1750 (Table 1). These increase in GHGs have resulted in warming of the climate system by 0.74°C between 1906 and 2005.

14.1. Introduction

Environmental pollution primarily deals with five types of pollution: soil pollution, water pollution, air pollution, sound pollution and light pollution. However, soil, water and air pollutions are considered very important as the pollutants from the environmental compartments may be cycled within themselves, enter the food web and interfere the biological processes adversely of any living species. Soil supplies nutrients and water to plants which, in turn, act as the nutrient supplier to animals and humans. Thus, maintenance of soil quality is considered prerequisite for growth of plants, animals and humans. If soil, water and air are polluted through various mechanisms, living components in the environment are suffered adversely. Soil, water and air pollutions are associated with the build-up of soil contaminants such as toxic organic and inorganic compounds, petroleum hydrocarbons, radioactive materials, salts, disease causing agents etc. above the permissible limit, so that their presence will cast adverse effects on physicochemical and biological properties of soil which in turn exert negative impact on crop growth and on any non-targeted organisms. Common soil contaminants include heavy metals, pesticides, petroleum hydrocarbons, fertilizers if used in excessive amount, and many others. Contamination of the soil, air and water results from intensification of farming activities. Primarily nutrients (particularly nitrogen and phosphorus), sediment, wastes, pesticides and salts are regarded as agricultural nonpoint source pollutant. Realistically, most of the pollutants originate from anthropogenic activities, although there exists many naturally occurring mineral components that may exhibit toxicity towards living system at higher concentration. Land disposal of municipal and industrial wastes, automobile emissions, mining activity, and application of fertilizers and pesticides to agricultural field cause a continuous accumulation of heavy metals and other pollutant components in soils. These pose threats of environmental degradation via soil erosion, loss of biodiversity, climate change etc.

13.1. Introduction

Water is chemically benign. However, its interference in free gas exchange in soil becomes detrimental to crop growth when soils are subjected to waterlogging or plants are submerged with water.Waterlogging of soil refers to a soil condition when the soil attains a moisture regime to such an extent that oxygen is not available in the pore space in enough quantity for plant roots to respire adequately. On the contrary, detrimental gases such as carbon dioxide, methane, hydrogen sulphide, ethylene etc. accumulate in the root zone and adversely influence the growth of plants. Thus, anaerobic condition prevails in waterlogged soil causing depletion of oxygen and increase of CO₂ in root zone, which severely affects aerobic micro-organisms while harmful organisms proliferate and restrict the plant growth. Waterlogging leads to nutrient deficiencies or nutrient toxicities, root tip decomposition and eventually, reduced growth or death of the plant. Physical, chemical and biological activities in the soil are also disturbed due to low temperature. However, this is important to note that plants differ among themselves in their demand for oxygen. Even oxygen demand for same plants differs with its growth stage. Therefore, it is well understood that there is no universal level of soil oxygen that can identify waterlogged conditions for all plants. Mostly waterlogging prevails in the land due to non-permeability of the soil material, the presence of an impervious layer in soil horizon, or a high-water table.

12.1. Introduction

All soils invariably contain soluble salts. However, physico-chemical and biological soil properties start degrading when excessive amount of salts are accumulated in soil, particularly in rhizosphere, due to several anthropogenic activities and environmental conditions, and crop production is severely affected. Then we refer those soils as salt-affected soil.

The need of intensive agriculture to keep pace with the increasing world population for their food requirement necessitates to bring more agricultural land area under irrigation. However, irrigation system without taking enough drainage provision and poor water quality and its poor management may make the situation worst due to the development of salt-affected soils that ensue unproductive soil and low crop yield. Crops grown on salt-affected soils suffer from high osmotic stress, nutritional disorders due to nutrient (N, Ca, K, P, Fe, Zn) deficiency, specific ion toxicities, poor soil physical conditions and as a consequence, a reduced crop productivity.

Although it is considered that the rocks and minerals on weathering lead to salt accumulation in the soil, but the salt-affected soils are not truly originated from the accumulation of such salts in situ. On the contrary, occurrence of salt-affected soils is due to receiving salts that come from other locations with water. Sea water inundation in coastal belt, irrigation with poor quality water including saline groundwater, poor drainage system, irrigation adopting unscientific ways leading to waterlogging, shallow water table etc. contribute heavily toward development of salt-affected soils. Salt-affected soils may occur under almost all climatic conditions. Their distribution, however, is relatively more extensive in the arid and semi-arid regions compared to the humid regions because of poor precipitation to leach soluble salt adequately. Since evapotranspiration greatly exceeds precipitation in these climatic conditions, the soluble salts move upward with water due to capillary action and are left behind on the surface soil and the rhizosphere, once water is evaporated. The commanding ions of accumulated salts in affected soil are sodium, potassium, magnesium, calcium, chlorides, sulphates, carbonates and bicarbonates. The nature and properties of salt-affected soils are so diverse that they require specific approaches for their reclamation and management. Therefore, it is necessary to know their origin, formation, nature, chemistry and properties in detail to classify them into groups for their proper management to maintain sustainable agriculture.

11.1. What is acid soil?

Acid soils refer to those soils that are characterized with the presence of higher concentration of H⁺ in soil solution and at exchangeable sites or characterized with its high proton donating capacity such as aluminium (Al³⁺) on hydrolysis gives rise to proton. Both H⁺ and Al³⁺ are responsible to contribute soil acidity. Al³⁺ causes soil acidity indirectly by generating H⁺ through its hydrolysis, while H⁺ contributes directly. Therefore, due to more abundance of H⁺, they exhibit low soil pH and low base saturation (Ca²⁺, Mg²⁺, Na⁺ and K⁺). Such soil is considered as problematic soil because plant growth is affected adversely under acidic conditions and they suffer root injuries when grown in acid soils. Besides, soil acidity interferes in the soil nutrients availability to plants, making them either deficient to plants (such as phosphorus, calcium, magnesium, molybdenum) or toxic to plants for their more availability. Under acidic condition, Al, Mn and Fe are found in more soluble form. Thus, they are taken up by the plant in such a higher level that they become toxic to plants. Phosphorus becomes immobile due to the formation of insoluble compounds with aluminium and iron under acidic conditions. Ca, Mg and Mo also become unavailable in acid soil and show their deficiency symptoms. Soil acidity also affects soil microbial growth and thus, in turn, affects the nutrient dynamics in soil. Soil acidification is induced heavily under intensive agricultural practices such as increasing leaching due to more irrigation practices, addition of fertilizers, build-up of soil organic matter and many other possible ways.

10.1. Introduction

The soils possessing characteristics that are not suitable and economical for crop growth are termed as Problem soils. These characteristics may be of physical, chemical and biological. For cultivation of crops in these soils, it is necessary to follow specific management interventions and proper reclamation measures. Frequently we come across another term, ’degraded soil’. Degraded soil is also a problem soil. However, there exists a hair-line difference between problem and degraded soil. Problem soils refer to the soils in which the inherent soil characteristics, obtained from its genesis, pose problems for their optimal use, while degraded soils are developed due to anthropogenic activities by unwise management interventions.

10.2. Types of problem

Mainly there are four types of problem that may exist in soils: physical problems, chemical problems, biological problems and nutritional problems as a result of physical, chemical and biological constraints in soils.

9.1. Introduction

Soil biology is a branch of science that studies the soil inhabiting organisms in relation to their ecology, functions, behaviour and impact on various soil processes and plant growth. Soil fertility is directly dependant on humus content as well as the presence of microorganisms in soil, although surface soil does not contain more than 0.5% by weight of living organisms. However, such a small portion of soil constituent as compared to other organic and inorganic constituents plays a significant and major role in transformation of plant nutrients from their unavailable to available form from organic wastes, soils and fertilizers. They have a direct role in improving soil tilth, providing an appropriate environment for root growth, decomposing organic residues to form humus and in turn releasing nutrients for plants use, releasing many plant growth promoters, fixing inert atmospheric nitrogen in plant usable forms and they promote many other important processes without which plants cannot survive. Absence of living organisms in soil leads to its infertility. An understanding of microbial processes in soil environment, keeping in view of soil nutrient status, carbon sequestration, soil health and quality, overall sustainability in agriculture and also global warming in respect of greenhouse gas emissions (nitrous oxide and methane) through agricultural practices, is very important in regulating nutrient release at different plant growth stages. If we are in a state to understand how various biological processes influence various changes in soil environment or in the opposite way that how different soil conditions alter the soil biota in number as well as in their functions and diversity, it is easier to implement soil management practices that promote to gain more benefits.

Microorganisms are ubiquitous in nature. Possessing a diverse habitat, they are found everywhere in soil, air and water at a varied temperature and pH. One may find the highest genetic diversity of life within the domain of microorganisms. But unfortunately very few are known to us, so far only 1% of the microbial species on the earth are culturable. However, it is believed that soil of one gram may contain hundreds of millions to billions of microbes which may represent several thousand microbial species. In respect of the population, bacteria top the list followed by actinomycetes, fungi, algae and protozoa in accordance with a decreasing numerical order. Out of three important soil fertility components viz. physical, chemical and biological; the biological component is least understood due to its wide complexity.

8.1. What is an ion exchange reaction and its application in soil system

Ion exchange is a reversible chemical reaction between two substances, either between two electrolytes or between an electrolyte solution and a solid complex as well as between two solid phases (if in close contact with each other), where ions of equal charge may be interchanged in equivalent proportion.

Organic colloids and inorganic micelles (clays) are sites of ion exchange. Soil contains silicate clay minerals which exhibit charges due to isomorphous substitution as well as due to the pH dependant charges for ionisation of hydrogen and hydroxide functional groups. Organic matter present in soil also contributes to the pH dependent charges due to the presence of various active functional groups. Thus, the organic and inorganic colloids present in soil bear positive or negative charges. Electric charge on soil particles is neutralized by equivalent amount of oppositely charged exchangeable counter ions, held by coulomb forces and van der Waals forces. Ca⁺², Mg⁺², H⁺, K⁺, Na⁺, NH₄ ⁺, Al⁺³, Fe⁺³, Fe⁺², Mn⁺², etc. are the common cations present in soil where Ca⁺² serves as the dominant ion. However, Na⁺ and Al(OH)₂ ⁺ are the dominant cations found in the exchangeable phase in strong alkali and strong acid soils, respectively. SO₄ ^- 2, Cl^-, HCO₃ ^-1, NO₃ ^- etc. are the most common anions found in soil to neutralize positively charged soil colloids.

7.1. Introduction

Like all other living organisms such as humans, animals, and microorganisms, plants also need elemental nutrients for their growth and development. They assemble the nutrients from soil, water and air. However, to obtain economical crop yield, nutrients are also supplied to the crops from external sources such as chemical fertilizers and manures and using biofertilizers. It is the present-day need to handle the soil fertility status in a more realistic and careful way to obtain maximum crop harvest. Under poor management practices, soil may become infertile and loose its importance in agricultural use. In modern days, huge food demand for the burgeoning human population does not permit to show luxury to use only fertile soil. Moderately fertile soil or even degraded soil should also be managed properly so that they may be used to grow crops. For this, plant nutrients status of the soil plays a significant role along with other soil properties. For sustainable soil fertility management, parameters such as crop to be raised, its nutrient demand at various growth stages, current nutrient status of the soil, amount of nutrient application based on the soil testing results etc are important to be considered. Balanced nutrition to the plants is the prerequisite to obtain maximum benefit. If nutrients supplied to the plants are low in quantity than their requirement, crop production is lowered down. Similarly, if the nutrients are provided in more amount in the soil or unbalanced way through fertilizer or manure applications, total crop yield is suffered. It is a very common example that excess of phosphorus leads to zinc deficiency in most crop plants and it has been observed that excess N is responsible for potassium starvation in potato. Again, excess of iron, manganese, zinc, copper shows plant toxicity. Addition of nutrients to soils in excess also causes environmental pollution when the excess nutrients are lost from soil by leaching, surface run-off and volatilization. Unscientific way of soil fertilization leads to increasing cost of cultivation and imparts adverse effect to the environment instead of doing any good. Therefore, one should have a clear knowledge on soil fertility to obtain a sustainable productivity.

6.1. What is colloid and colloidal system?

A colloidal particle may be defined as a substance which is microscopically dispersed evenly throughout another phase and is possessing a size of 10^-7 to 10^-3 mm and representing a larger surface area per unit mass. Thus, a colloidal system refers to a two-phase system in which small particles of one phase which might be of solid, liquid or gas is suspended evenly in the second phase of solid, liquid or gaseous material. These colloidal systems may be of solid in liquid or solid in gas or liquid in liquid or liquid in gas. Unique examples of liquid in liquid colloidal system includes the fat droplets dispersed in water of milk. When you put floor disinfectant liquid in water, it forms a white emulsion. Thus, emulsion becomes a colloidal system of liquid in liquid. Likewise, in fog, water droplets are suspended in gaseous air. So, fog is an example of a colloidal system, constituting of liquid dispersed in gas. When we refer smoke, it contains carbon particles (solid) suspended in air (colloidal system of solid and gas). However, smog is composed of smoke and fog. In case of soil colloidal system, soil colloids, which are of tiny particles (<0.001 mm size) and may be of organic and inorganic nature, are suspended in soil solution (water) and referred to as sol. Colloidal chemistry, which involves in the surface reactivity and charge characteristics of colloids, plays a pivotal role in total soil chemistry.

5.1. What is soil organic matter?

Plant and animal residues which are not yet added to the soil are considered as organic materials. However, once they are added to soil, they become soil organic matter. Therefore, organic materials contributing to the soil matrix are referred as Soil Organic Matter (SOM). Sometimes SOM is also used to highlight only the non-living organic materials produced by living organisms. But SOM should be regarded as a broad term that includes biomass, partially decayed residue, and highly decomposed and transformed organic substances, humus. Agricultural soil contains nearly 1-5% of SOM, which is regarded as least amount in soil as compared to other three soil components, minerals (45%), air (25%) and water (25%). However, it contributes enormously to soil productivity. Soil productivity and fertility exhibit direct positive relationship with SOM content in soil. Plants and animals are considered as primary and secondary sources of soil organic matter, respectively. Plant residues and application of organic manures e.g., farmyard manure, compost or green manuring help to build up organic matter in soil and thus, enrich the soil with organic carbon and other plant nutrients. Under natural conditions, roots of grasses in grasslands, the leaves including shoot portion of the large trees in forest lands and after harvesting the crop remnants in agricultural field provide enough incorporation of organic materials in soil. SOM plays a vital role to maintain sustainability in agricultural production through producing healthy soils and thus, healthy crops.

4.1. What is pH?

pH is used to classify substance as acidic, neutral and alkaline, based on the prevalence of free H⁺ ions. Water molecules on autoionization dissociate to produce H⁺ and OH^- in equal number, although degree of dissociation is very small because of its stability (about one molecule in 10 million is ionized at any one time). H⁺ ions later attached to un-ionized water molecule to give rise hydronium ions, (H₃O)⁺

3.1. What is weathering?

Weathering may be defined as the transformation process of solid rocks, involving the disintegration and decomposition of rocks and minerals, into soil.

There are different types of weathering: physical, chemical and biological.

3.1.1. Physical weathering

In physical weathering the chemical composition of the weathered products remains same as that of the parental rocks. It is involved in fragmentation of rocks into comparatively smaller sizes. It does not transform the parental rock into a newer one that may differ from the parental rock in chemical composition. The process is totally physical in nature. But this is also true that physical weathering encourages chemical weathering, and both may be carried out simultaneously because physical weathering promotes more surface area of parental rocks for more interaction with agents of chemical weathering.

2.1. Minerals

Primarily, minerals are usually inorganic substances possessing a definite chemical composition and a definite molecular arrangement which is usually expressed in geometric form. The mineral matter is made up of various elements, combined to form compounds. Usually, minerals consist of more than one constituent elements. Quartz contains two elements, silicon and oxygen. Other minerals may contain many elements, such as amphibole consists of several elements that include sodium, calcium, magnesium, iron, aluminium, silicon, and oxygen. Some elements exist as such without forming compounds. They contain exceptionally one element. Graphite (C), diamond (C), and Sulphur (S). Minerals are naturally occurring crystalline solid where the atoms are arranged in a regular three-dimensional array. A crystal is a solid, formed by a repeating three-dimensional pattern of atoms, ions, or molecules & possessing fixed distances between the different parts. Minerals that do not grow in these regular or crystalline patterns are called amorphous solids. When we talk about ‘naturally occurring’, we exclude the laboratory-synthesized crystalline solids. Glass and amber are also naturally occurring solid, but they are not crystalline and thus, they are not considered as minerals, rather they are referred as amorphous solids.

1.1. What is Earth?

The Earth is a layered body consisting of three parts: core, mantle, and crust. The radius of the Earth is nearly 6370 km of which crust, mantle and core share a depth of 40, 2850 and 3480 km, respectively (Figure 1.1). Exterior of the Earth contains the outer lithosphere which is surrounded (70% of surface) by water (hydrosphere). Solid and liquid sphere are surrounded by gas (atmosphere). The atmosphere is of 320 km above the lithosphere / hydrosphere. It is believed that there is a progressive increase in temperature with depth, if one goes to the core from the Earth crust. There is a rise of approximately about 1°F for every 64 feet depth on an average. Therefore, one could imagine that the interior of the earth is in molten condition.

Milk revolution with change in technology is gaining attention in India. Robotic milking reduces labour and increases efficiency irrespective of large dairy farms. A typical system requires a large camera- and spray-system robot. When activated to apply the disinfectant, the robot sends a six-foot- long pipe with the sprayer under the cow. These floor-mounted robots require expensive installation into the floor of the milking parlour, as well as fencing for employee protection.

15.1 Introduction

Mechanical draining has increased broad acknowledgment, especially in Western Europe, as an approach to lessen labor on dairy ranches, increment creation per cow, and improve the way of life of dairy ranch families draining 40 to 250 cows (De Koning, 2010). The developing ubiquity of this innovation is obvious in its fast pace. In 2009, the evaluated number of automated dairy ranches overall was 8,000 (De Koning, 2010). Only 6yr later, Barkema et al. (2015) proposed that this number had dramatically multiplied to 25,000 dairy ranches around the world. The level of groups utilizing this technology is most noteworthy in Scandinavian nations and the Netherlands (Barkema et al., 2015). Broad selection in these nations proposes in any event a proportion of accomplishment in helping dairy ranchers accomplish more noteworthy work productivity and a superior way of life, yet field experience recommends that wide variety exists in the measure of work spared and in the general fulfilment of early adopters.

The development of the civilisation humans have tried to domesticate the animals. Initially dogs were known to be the first pet domesticated by humans followed by the domestication of other animals like cattle, horses, sheep etc.

14.1 Introduction

When humans started to domesticate the animal, they have tried several ways to control them. Generally these animals are released in free space to graze and one of the known problems is to prevent them from overgrazing. So building a fence is one of the ways to limit their movement is one viable solution, but building a fence is limited to a smaller area. Since these animals are locked in a large number, so building a bigger fence and moving it every time for grazing is not viable. It can be observed in the history of humankind as that civilisation progressed the use of Shepherd dogs has been one of the widely accepted. Shepherd dogs not only help in shepherding and herding but also prevents these livestock from wolves

The incorporation of robotics will not only automate the process intelligently but also keep a vigil on various aspects of livestock management. In recent years there has been a substantial development in this regard. The development of robotic dogs for shepherding and herding purposes has found a lot of increment developments. SPOT developed by Boston dynamics and SwagBot developed by University of Sydney, are well-known robots developed in recent times for the purpose.

These robots are equipped with multiple sensors like LiDAR, gas and heat sensors, high-resolution cameras etc. The array of sensors are used to capture the data in real-time and is then used for decision-making processes. Also these reports are built to be rugged and can navigate on a variety of terrains.

Harvesting is one of the most labour intensive jobs in agriculture, and by implying the robotics in harvesting, the quantity of the harvested yield can be readily increased, thus saving a lot of time and human resources. This also aids in reducing the farm to market transportation times. The use of robotics can also reduce the seasonal requirement of the manual labour and thus reduce the recurring costs.

13.1 Introduction

The incorporation of robotics in agriculture has proved to be advantages for the farmers and thus for the economy. The automation of various agricultural processes led to the reduction of the operational costs and also in the reduction of the labour required. A possible solution to address the problems of labour availability and scaling up the harvesting of the crop is the incorporation of robotics.

To cater the increased demand of food, it will be required that farmers are equipped with tools and methods to improve their yields and make informed decisions [1]. Also, with the increase in population, the agricultural land is decreasing by 1 lakh hectares per year and it is required to double the agricultural produce in the next 30 years to sustain the global food requirements.

The improvements in various technological fields like machine learning, navigation, robotics etc. and their applications in agriculture is required to meet this increasing need. One of the factors is to make the farmland ready for sowing the crops, spraying, etc. and this has to be done in a precise and faster manner to address the latter issues. So, the uses of autonomous tractors for such jobs offer accurate, precise and timely preparation of the fields for the cultivation.

12.1 Introduction

Autonomous tractors or driverless tractors are unmanned ground vehicles mainly employed in agriculture for various purpose like preparation of land for the crops, harvesting, spraying, and other agricultural purposes. They are equipped with GPS, autopilot, cameras, lasers (LiDAR), and other wireless technologies navigation and mutual coordination and offer saving of both the manpower and time. These autonomous tractors can be programmed to navigate their paths through the fields and are designed to avoid the obstacles while doing their jobs. These tractors automate various laborious field jobs and also minimize human intervention in the process.

These autonomous machines are regarded to revolutionize the agriculture industry and offer safety, sharing of resources, economical solutions per square area of land, etc. Several industries like Jhon Dheere, AgraBots, EcoRobotix, RowBot, etc.

In the wild (forests) plants grow by their own, but in agriculture because of limited space they don’t have freedom to grow in a much natural way. This can lead to structural irregularities in their growth, and can hamper the overall plant’s development and this will impact the produce or crop yield. To deal with such constraints and to boost the crop production, the methods of thinning and pruning provide efficient ways to train the growth of young plants and maintain the health of grown-up plants.

11.1 Introduction

In agriculture, thinning means the removal of some plants or some parts of plants that show inconsistent growth and or are damaged by some pest or disease, without removing the whole tree or plant. The selective removal of branches, buds or roots is termed as pruning [1]. If the plants are overcrowded in a confined space, the overall health of the crop decreases due to the competitive stress from the neighbouring plants. Thinning and pruning is done to improve the growth rate or health of the plants by decreasing the competitive stress. Thinning and pruning in agriculture is the sensible removal of plant parts such as flowers, shoots, its branches or other parts to correct or maintain that structure of the tree and control be directed growth of the crop. This practice covers the precise removal of the unhealthy and obstructive part of the plant branch, leaves, fruits, buds, fruits, etc. Pruning improves the quality and longevity of the crop, leading to quality produce and increased yield of the field. This also helps in increasing the size of the fruit as it increases the availability of nitrogen required for growing and stimulating growth of the crop. There are several factors that influence the amount of pruning to be done, i.e., age of the plant, condition of the bark and wood, growth characteristics, whether cup crop/plantation is permanent or seasonal [2]. Pruning is done for controlling the size of the plant, controlling the structure makeup of the plant, controlling and improving the light distribution of the plants by the selective removal of leaves to improve the quality of the fruits, removing the diseased parts of the plant and to regulate the fruit crop and increase the life of the tree.

The principle behind thinning and pruning is to admit more sunlight to the branches that bear fruit by the selective removal of the unproductive branches which obstruct the sunlight to fall on the productive branches to increase the productivity white and vitality of the plant to obtain optimum healed of good quality crop [3]. Young trees are pruned so that they acquire the desired shape. In old trees it is done to stimulate flowering. In plants bearing fruits or crops, pruning is done to allow adequate sunlight to fall on fruit bearing branches, so that quality crop is produced. Very old plants heavy pruning is done to restore the vigour of the plant. It is also done so that the loss of nutrients being shared by the diseased peak or shading branches is reduced. The use of robotics and other automated systems can aid in the precise pruning and thinning of the crop. This will also automate the whole process and will save their requirement on the extensive manpower which ultimately saves time.

In the wild (forests) plants grow by their own, but in agriculture because of limited space they don’t have freedom to grow in a much natural way. This can lead to structural irregularities in their growth, and can hamper the overall plant’s development and this will impact the produce or crop yield. To deal with such constraints and to boost the crop production, the methods of thinning and pruning provide efficient ways to train the growth of young plants and maintain the health of grown-up plants.

11.1 Introduction

In agriculture, thinning means the removal of some plants or some parts of plants that show inconsistent growth and or are damaged by some pest or disease, without removing the whole tree or plant. The selective removal of branches, buds or roots is termed as pruning [1]. If the plants are overcrowded in a confined space, the overall health of the crop decreases due to the competitive stress from the neighbouring plants. Thinning and pruning is done to improve the growth rate or health of the plants by decreasing the competitive stress. Thinning and pruning in agriculture is the sensible removal of plant parts such as flowers, shoots, its branches or other parts to correct or maintain that structure of the tree and control be directed growth of the crop. This practice covers the precise removal of the unhealthy and obstructive part of the plant branch, leaves, fruits, buds, fruits, etc. Pruning improves the quality and longevity of the crop, leading to quality produce and increased yield of the field. This also helps in increasing the size of the fruit as it increases the availability of nitrogen required for growing and stimulating growth of the crop. There are several factors that influence the amount of pruning to be done, i.e., age of the plant, condition of the bark and wood, growth characteristics, whether cup crop/plantation is permanent or seasonal [2]. Pruning is done for controlling the size of the plant, controlling the structure makeup of the plant, controlling and improving the light distribution of the plants by the selective removal of leaves to improve the quality of the fruits, removing the diseased parts of the plant and to regulate the fruit crop and increase the life of the tree.

Weed control in agriculture disturbs the farming. Weed management and control essentially increase productivity of the farm. Autonomous robots for weed control systems are gaining a lot of attention. Adaptability of effective weed control robots has the potential to bring evolution in the areas of weed species, genetics and climate conditions. Weed control is one of the major challenges in agriculture. Removal of weeds from farming land required a lot of human effort. To minimize the weed growth pesticides and chemicals are used which is very harmful. In order to make this process easy and reliable robots are used nowadays. Robots are specially designed to detect the weeds and remove them within a stipulated time period. Robots are programmed using various algorithms to do this task in an efficient way without human efforts. This chapter illustrates the use of modern robots in weed control to help the farmers to gain maximum profit and healthy concerns without using chemicals to do so.

10.1 Introduction

Over the time, weed control in a farming land has been an issue. Evolution in technologies in the area of agriculture brought a lot of innovations. Among these robots are one of the innovations to be implemented in agriculture to enhance profitability and reliability with minimum human resource. The robots are deployed to monitor the farming land from weeds and try to remove these. Due to which uses of agrochemicals reduced down the timeline. When precision farming came into the picture robots are the best use cases. An autonomous mechanical robot was used to remove the weed from farming land. Robots are equipped with sensor modules, actuators and IoT enabled which makes the things very easy to control from remote area with commands [4].

Agriculture irrigation is a crucial part of precision farming. An irrigation system required a lot concentration to grow the plant healthy. A smart irrigation system in an agriculture farm leads to maximum profits in terms of yield. Integrating technologies like IoT (Internet of Things), AI (Artificial Intelligence) in irrigation accomplish to the human efforts. Controlling of water pumps, sprinklers seamlessly draws the kind attention of farmer to adapt these technologies in their day today farming schedules. This chapter illustrates a wide variety of robots used in irrigation to achieve maximum yield and minimizing water loss. The high scalability and reliabilities of these autonomous robots replicates the potential of agriculture 4.0 in coming future. Advanced robots deployed on the field to monitor the land and pass the information to the controllers and further to the water pumps. Here case study of robots is highlighted to reduce water losses by using nozzles mechanisms.

9.1 Introduction

Agriculture faces many environmental challenges. As far as the irrigation in agriculture is concerned it is very essential to maintain soil hydrated and water level in the field. Robotic irrigation enables autonomous irrigation from remote access [3]. Smart irrigation technique enables a lot of water saving. So robotic in agriculture plays a very crucial role in it [2]. In order to avoid water losses agro robots adapt smart irrigation techniques like droplet irrigation and sprinkling. To maintain sustainability, water resource management is required. Technologies like drones, smart sprinkler based on IoT, smart droplet irrigation used across the globe. These technologies have the greatest impact on productivity and sustainability of the environment as well. As far as the country India is concerned, due to diversity in geographical infrastructures rainfall changes from state to states. So, a wide range of water diversity is found to grow agricultural foods. For example northeast and southern part of India due to heavy rainfall paddy cultivation is preferred since it requires a lot of water. Whereas the northern part of India observe a moderate rainfall, so vegetables and other agriculture foods get cultivated. At the same there are certain states like Rajsthan, Gujrat where very less rainfall occurs through varieties of crops related to dal.

Precision Agriculture is fulfilled by adapting suitable monitoring and analysis mechanisms. Autonomous monitoring is getting a new dimension using robots. Agriculture is the trending area to attract new professionals, investors and new companies. The technology in agriculture is not only increasing the yields but the time and labour. This chapter illustrates the use of robotics in crop monitoring and analysis.

8.1 Introduction

Monitoring of agriculture farm enhance the productivity. Evolution in technologies in the era of agriculture brought a lot of innovations. Among these innovations robots are one of them to be implemented in agriculture to enhance profitability and reliability with minimum human resource. At the same robots were deployed to monitor the farming land from weeds and try to remove these. Due to which uses of agrochemicals reduced down the time line. When precision farming came in to the pictures robots are the best use cases. In fig. 8.1 autonomous mechanical robots are shown, which are used to remove the weed from farming land. Robots are equipped with sensor modules, actuators and IoT enabled which makes the things very easy to control from remote area with commands.

Agriculture is the backbone of India. Evolution in technology is bringing new dimensions of conventional agriculture. Looking towards the current food demands it is very crucial to maintain the food supply. According to UN (United Nations), by 2050 the world population will be increased to around 9.3 billion which increases the food need. As the technology in agriculture evolving it seems that we could be able transform conventional farming to unconventional and traditional to modernization by the help of agriculture robots. Agri-bots can be autonomous with human intervention that could perform the task precisely. Chapter illustrates the applications in agriculture seeding. These robots are efficiently used in crop seeding.

7.1 Introduction

The very first agriculture robots were used in the early 1920s along with autonomous vehicle development.

Agro robots are becoming an ongoing pattern in farming with lots of research advancement and business models [1]. Agrarian robots have huge focal points as far as adaptability, flexibility and ecological advantages contrasted with customary horticultural apparatus and speak to an extraordinary resource for cutting edge precision agribusiness. Numerous advances in machine vision with imaging and otherworldly cam-periods for distinguishing weeds, vermin and infections, supplement inadequacies in soil or plant leaves have given profound applications to be mounted on independent vehicles for exploring soil and crops and for additional downstream choice help and control [2]. The mechanical network has additionally made earth shattering upgrades and advancements as far as utilizing a far reaching working framework, the Robotic Operating System (ROS), just as applying strong stages and route calculations.

Comparable to horticultural robots, the attributes of the central framework of robots are the lightweight, little size and lively self-governance [3]. Lightweight implies that the vehicle requires lower impetus vitality and incites less soil compaction while simultaneously the vehicle must be little for security reasons, for accomplishing more noteworthy accuracy during execution of assignments and having more maneuverability inside the field to limit turning delays.

Robots can replace human efforts in the future. Discovery of robots in agriculture is going to accelerate the growth of agriculture 4.0. Nursery planting needs robust and profitable solutions. Nursery plants deals with the direct consumer, which is the primary stage of agriculture. An intensive care is required to look after the nursery plant before going to be planted. Now a days robots are used to monitor the plants, essentially to maintain the health standard of a plant. This chapter illustrate the applications of the robots in nursery planting.

6.1 Introduction

Nursery is the primary stage where seeds are grown in to the young plants. Nursery planting involves many activities like seeding, potting and monitoring. The process required high attention to look after at this stage [1]. As the food demand is increasing day by day, it is necessary to adapt unconventional way of farming. Bringing robots in to the farming will bring a lot of changes in the traditional agriculture. The robotics in agriculture is not new, it has started with evolution of autonomous vehicles [2]. The usage of robots are increasing exponentially. So the researcher and scientist also started use of robots in agriculture. They found a phenomenal result in term of easy to handle the agro tasks, seeding, weeding, automatic irrigation and harvesting. It draws the farmer attention down the line [3].

The communication module is a device which is used to control the communication between the stations. This chapter explores the different communication modules and their specifications.

5.1 WiFi

ESP8266 WiFi Module is a WiFi serial transceiver module. This chip has a full TCP/IP protocol stack with the computational power onboard. This makes the board simple to use as Wi-Fi connection board. The specification of this board includes, 32-pin QFN package, Integrated RF switch, Integrated RISC processor. It has on-chip memory with external memory interfaces, integrated MAC/baseband processors, Quality of Service management, on chip regulator, Integrated WEP, TKIP, AES, and WAPI engines, 11 b/g/n. It has integrated TCP/IP protocol stack and Integrated PLLs, regulators, DCXO and power management units. It has +19.5dBm output power in 802.11b mode and Power down leakage current of <10uA

5.2 Bluetooth

Bluetooth is a wireless protocol. The recent introduction of Bluetooth with Low Energy extension is also as iBeacon. The advantage of BLE4.0 standard includes the low power consumption, which makes it a better option to be used in smart phones. This facilitates the setup of a mesh network of Bluetooth devices, with lower latency and higher range respect to standard Bluetooth.

This is a SMD BLE module based on TI cc2541 chip. It has low cost, small and easy to use. The preloaded firmware allows to build BLE communications with AT command. It supports communication with iPhone, iPad (iOS 5.0 or greater) and Android 4.3 or greater. It works on frequency: 2.4 GHz ISM band and modulation method is GFSK (Gaussian Frequency Shift Keying). It has transmission power: - DBM, 23-6 DBM, 0 DBM, 6 DBM, can be modified by the AT command. It works on baud rate 9600bps. It can operate on temperature range -40 ~ 125°C.

Another interesting board is the HC-05 Bluetooth module. Specifications of the works Master/Slave configurations. It operates on frequency of 2.4GHz ISM band with Modulation GFSK(Gaussian Frequency Shift Keying).

At this moment, the majority of energy is obtained from fossil fuels and requires switching over to alternative energy sources is the need of the hour. Fossil fuels are nonrenewable energy source and also have seriously negative impacts on the environment. The use of fossil fuels cause excessive global climate change because emissions of greenhouse pollutants and the formation of compounds CO_x, NO_x, SO_x, C_xH_y, ash and other organic compounds that are released into the atmosphere. The increase in greenhouse gas emission will result in global warming, climate change, environmental degradation and health problems.

Biofuel, any fuel that is derived from biomass - that is, plant or algae material or animal waste. Since such feedstock material can be replenished readily, biofuel is considered to be a source of renewable energy, unlike fossil fuels such as petroleum, coal, and natural gas.

Bacterial biofertilizers are supplied as carrier based inoculants. Peat or lignite is used as carrier material. Carrier based bacterial inoculants are applied by the following methods.

1. Seed treatment or seed inoculation.
2. Seedling root dip and
3. Main field application

Seed Treatment

One packet of the inoculant (200 g) 7is mixed with 200 ml of rice kanji to make a slurry. The seeds required for an acre are mixed in the slurry so as to have a uniform coating of the inoculant over the seeds and then shade dried for 30 minutes. The shade dried seeds should be sown within 24 hours. One packet of the inoculant (200 g) is sufficient to treat 10 kg of seeds.

Biofertilizers are one of the important components of organic farming and sustainable agriculture. Awareness among farmers is increasing on the biological fertilizers. But, the success of biofertilizer inoculation depends on the quality of the inoculant used. Because farmers are unable to judge the quality of the inoculants at the time of purchase or even at use. The inoculant producers are negligent to institute quality control programmes. Unfortunately much of the inoculant produced in the world today is relatively of poor quality. In such situation maintaining high quality inoculant products depend on the internal implementation of effective quality control systems by manufacturer. A major goal of a quality standard is to control the quality of inoculant to be used in any country.

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.

Chemical pesticides though extremely effective in controlling pest population suffer from disadvantages. They have a broad toxic range and potentially toxic to non target organisms. Other constraints that have emerged with the use of chemical pesticides such as development of resistance and resurgence in insects, residual toxicity, secondary outbreak of minor insect pests, etc., In this juncture, the biopesticides have proven to be effective tool in managing the devastating insect pests of various crops.

The biopesticides are types of pesticides derived from natural materials such as microorganisms, plants, animals and certain minerals. They are living organisms or their products or byproducts, which can be used for the management of pests that are injurious to crop plants. Biopesticides have a vital role in crop protection, although most commonly in combination with other tools including chemical pesticides as part of integrated pest management (IPM). Microorganisms help to regulate the abundance of many pests or potential pests without any cost to society. Microbes can be increased artificially and thereby achieve faster, higher and more consistent control of the target pests that will occur naturally. Insect pathogens that are transmissible in nature from one host to another offer an important bonus effect that chemical insecticides do not have. A pathogen will kill pests exposed and many continue killing them by natural transmission from one individual host to another through subsequent host generation.

Biopesticides generally have several advantages compared to conventional pesticides. While chemical pesticides are responsible for extensive pollution of the environment, a serious health hazard due to the presence of their residues in food and development of resistance in targeted insect pest populations, biopesticides, in contrast, are inherently less toxic to humans and the environment, do not leave harmful residues, and are usually more specific to target pests. The agents employed as biopesticides, include parasites, predetors and disease causing fungi, bacteria and viruses, which are the natural enemies of pests. Utilization of naturally occurring parasites, predators and pathogens for pest control is a classical biological control. These bio agents can be conserved, preserved and multiplied under laboratory condition for field release. Once these bio-agents are introduced in the field to build their population considerably, they are capable of bringing down the targeted pest population below economic threshold level (ETL).

For many soil borne diseases, effective and economic control methods are not available. Several soil borne pathogens have developed resistance to many fungicides. The beneficial microbes are also affected by fungicides. Many fungicides pose health hazards by polluting food and water and cause direct toxicity of heavy metals and carcinogenic risk. In the context of growing worldwide awareness of environmental pollution and development of fungicide resistant strains of pathogens, biological method of suppression of disease causing organisms have been recognized as the safest approach for plant disease management.

Biological control of plant diseases is the suppression of populations of plant pathogens by living organisms. Amongst beneficial microorganisms, isolates can be selected which are highly effective against pathogens and can be multiplied on artificial media. Application of such selected and mass produced antagonists in high densities once or several times during a growing season is called “augmentative biological control”.

Mycorrhizal symbiosis is the most prevalent and important mutualistic association in plant kingdom. ‘Mycorrhiza’- the word means fungus - root, this association was reported by A.B.Frank in the year 1885. Nearly 95% of plant species form this mycorrhizal association. This serves as critical linkage between plant roots and soil and characterized by the movement of plant produced carbon to fungus and fungal acquired nutrients to plants. Through its hyphae this fungus absorbs the available P from soil and transports directly to root cortex. Mycorrhizal associations vary widely in structure and function. There are seven types of mycorrhizae (Table 1). These are endo (arbuscular), ecto, ectendo, arbutoid, monotropoid, ericoid, and orchidaceous mycorrhizae. Among them, endomycorrhizae and ectomycorrhizae are the most abundant and widespread

Introduction

Biofertilizers are microbial preparations containing living or latent cells of efficient strains of nitrogen fixing, phosphate solubilizing and cellulose decomposing microorganisms intended for seed or soil application and designed to improve soil fertility and plant growth by increasing the number and biological activity of beneficial microorganisms in the soil.

The objects behind the application of biofertilizers /microbial inoculants to seed, soil is to increase the number and biological / metabolic activity of useful microorganisms that accelerate certain microbial processes to augment the extent of availability of nutrients in the available forms which can be easily assimilated by plants. The need for the use of biofertilizers has arisen primarily due to two reasons i.e. though chemical fertilizers increase soil fertility, crop productivity and production, but increased / intensive use of chemical fertilizers has caused serious concern of soil texture, soil fertility and other environmental problems.Use of biofertilizers is both economical as well as environment friendly. Therefore, an integrated approach of applying both chemical fertilizers and biofertilizers is the best way of integrated nutrient supply in agriculture.

Biofertilizers, thus include i) Symbiotic nitrogen fixers- Rhizobium sp. ii) Non-symbiotic, free living nitrogen fixers- Azotobacter, Azospirillum etc. iii) Blue Green Algae (BGA) inoculants- Azolla-Anabaena, iv) Phosphate solubilizing microorganisms (PSM)- Bacillus, Pseudomonas, Penicillium, Aspergillus etc. v) Mycorrhiza vi) Cellulolytic microorganisms

Silage is preserved pasture. Fresh forage crops such as maize, grasses, legumes, wheat and lucerne can be preserved by ensiling. Silage is the green material produced by controlled fermentation of the green fodder crop retaining the high moisture content, which contain 20-40% dry matter.

Silage can be prepared from plants having thick stems and are generally not very suitable for hay making like sorghum, maize. Weeds can also be utilized along with main fodder crops for silage making. Silage making kills majority of weed seeds. It is highly palatable. The organic acids produced in the silage are similar to those normally produced in the digestive tract of the ruminants and therefore are used in the same manner.

Industrial microbiology is an important area of applied microbiology. In a broader sense, industrial microbiology is concerned with all aspects of business that relate to microbiology. It refers to the use of microorganisms in commercial enterprise. Cheap raw materials are converted to valuable products through the metabolism of microbes. Microbes for this purpose could be exploited in different ways.

Various commercial products of economic value made by microbes are :

Soil is the largest terrestrial ecosystem where a wide variety of relationships exists between different types of soil organisms. The associations existing between different soil microorganisms, whether of a symbiotic or antagonistic nature, influence the activities of microorganisms in the soil. Microflora composition of any habitat is governed by the biological equilibrium created by the associations and interactions of all individuals found in the community. In soil, many microorganisms live in close proximity and interact among them-selves in a different ways. Some of the interactions or associations are mutually beneficial, or mutually detrimental or neutral.

Plant Growth Promoting Rhizobacteria (PGPR) are root-colonizing bacteria that form symbiotic relationships with many plants. The name comes from the Greek rhiza, meaning root. Though parasitic varieties of rhizobacteria exist, the term usually refers to bacteria that form a relationship beneficial for both parties (mutualism). They are an important group of microorganisms used in biofertilizer. Biofertilization accounts for about 65% of the nitrogen supply to crops worldwide. The term PGPRs was first used by W. Kloepper in the late 1970s and has become commonly used in scientific literatures. PGPRs have different relationships with different species of host plants. The two major classes of relationships are rhizospheric and endophytic. Rhizospheric relationships consist of the PGPRs that colonize the surface of the root, or superficial intercellular spaces of the host plant, often forming root nodules. Endophytic relationships involve the PGPRs residing and growing within the host plant in the apoplastic space.Some common examples of PGPR genera exhibiting plant growth promoting activity are: Pseudomonas, Azospirillum, Azotobacter, Bacillus, Burkholdaria, Enterobacter, Rhizobium, Erwinia, Mycobacterium, Mesorhizobium, Flavobacterium, etc.An ideal PGPR should possess high rhizosphere competence, enhance plant growth capabilities, have a broad spectrum of action, be safe for the environment, be compatible with other rhizobacteria, and be tolerant to heat, UV radiation, and oxidizing agent.

Microbes that live inside plant tissues without causing disease are termed as endophytes. Endophytes have been found in all parts of plant viz., seeds, roots, stems, leaves, fruits etc. Within these organs, there is evidence of endophytes living in apoplastic intercellular space within parenchyma tissues and xylem vessel apoplast. Endophytic bacteria have been isolated from both monocotyledonous and dicotyledonous plants, ranging from woody tree species to herbaceous crop plants. Further, a single plant may be a host for several different bacterial species. They are consistently present in the root, stem, leaf, fruit and tuber tissues of a wide range of agricultural, horticultural and forest species. All plants in nature harbor a diverse community of endophytic bacteria which can positively affect host plant growth.

The potential of endophytic bacteria to fix nitrogen, promote plant growth and suppress plant diseases has renewed interest in such associations. It is advantageous to have the endophytic plant growth promoting organisms safely inside the plant, which could supply substantial amounts of nitrogen and other nutrients, growth hormones and other beneficial effects to the crop plants without the interference of the rhizosphere soil environment. Furthermore, plant growth promotion is often greater when it is induced by endophytes rather than by rhizosphere bacteria.

The spermosphere represents a short-lived, rapidly changing, and microbiologically dynamic zone of soil surrounding a germinating seed. It is analogous to the rhizosphere, being established largely by the carbon compounds released into the soil once the seed begins to hydrate. These seed exudations drive the microbial activities that take place in the spermosphere, many of which can have long-lasting impacts on plant growth and development as well as on plant health.

Rhizosphere

The term Rhizosphere was introduced by the German scientist, Hiltner in 1904. It is region of the soil, which is subjected to the influence of plant roots. It is the unique environment under the influence of plant roots. The roots of plants are not only involved in the uptake of mineral nutrients and water for plant growth, but they also release a wide range of organic compounds in the surrounding soil.

Pesticides are the chemical substances that kill pests and herbicides are the chemicals that kill weeds. In the context of soil, pests are fungi, bacteria, insects, worms, and nematodes etc. that cause damage to field crops. Thus, in broad sense pesticides are insecticides, fungicides, bactericides, herbicides and nematicides that are used to control or inhibit plant diseases and insect pests. Although wide-scale application of pesticides and herbicides is an essential part of augmenting crop yields; excessive use of these chemicals leads to the microbial imbalance, environmental pollution and health hazards. An ideal pesticide should have the ability to destroy target pest quickly and should be able to degrade nontoxic substances as quickly as possible.

The ultimate “sink” of the pesticides applied in agriculture is soil. Soil being the storehouse of multitudes of microbes, in quantity and quality, receives the chemicals in various forms and acts as a scavenger of harmful substances. The efficiency and the competence to handle the chemicals vary with the soil and its physical, chemical and biological characteristics.

Bioconversion refers to the recycling and reprocessing of organic waste materials using the system of biological decomposition or biodegradation into value added products. Composting is one way of conversion of organic waste into manures. It is defined as a method of solid waste management whereby the organic component of the solid waste stream is biologically decomposed under controlled conditions to a state in which it can be handled, stored or applied to the land without adversely affecting the environment.

Composting provides a partial solution to an issue of great concern in many communities. All around the world, landfills are filling up, garbage incineration is becoming increasingly unpopular, and other waste disposal options are becoming ever harder to find. Composting provides a way not only of reducing the amount of waste that needs to be disposed of, but also of converting it into a product that is useful for agriculture. Composting reduces waste, makes us less dependent on landfills, and decreases greenhouse gas emissions. Composting recycles essential nutrients back into the soil and promotes a prolific soil ecosystem.