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In 1965, Urist demonstrates that the implantation of demineralized bone at extra skeletal sites induced de novo formation of cartilage and bone and proposed that the decalcified bone matrix possess high osteoinductive property and the inductor is a unique chemical that differentiates mesenchymal type cells (pericytes) into new bone. Urist and Starates (1971) reported that the inductor is a protein and termed it bone morphogenetic protein (BMP) . BMP is the bone induction principle.

Sources: Bone morphogenetic protein isolate from bovine as well as human bone and designated as bBMP and hBMP respectively. The molecular cloning of the bone morphogenetic proteins and their subsequent expression in recombinant system, resulted recombinant bone morphogenetic protein designated as rhBMP. BMP has been extracted from dentin and bone matrix, as well as from bone tumours, by enzymatic and nonenzymatic methods. The sources of BMP, thus far explored are rabbit dentin, rat, rabbit and bovine bone, human bone, mouse or human osteosarcoma and human placenta.

BMP circulates in the blood and it can be detected by BMP-radioimmunoassay. BMP levels higher in growing children (20-72 ng/ml) and patients with Paget’s disease (over 259 ng//ml) than in normal adults (14-18ng/ml). Crude and partially purified BMP has been extracted with the aid of collagenase, ethylene glycol, calcium chloride urea and Guanidine hydrochloride (GuHCL) solution. Wang et al (1988) purified BMP factor that induces bone formation> 300,000 fold from Guanidine chloride extracts of demineralized bone. As littlie as 50ng of this factor can induce the formation of cartilage and bone in an in vivo assay, though only 40µg could be obtained from 400kg of bovine bone powder.

Fracture in animals occur frequently and is a concern of economic importance to the owner. The practice of keeping them as pets in households rather than in sheds or in confinements have increased the chance of encountering accidents like fall from coat, terrace, limbs being trapped in drains, being hit by vehicles, dog bites etc. leading to fracture. Fracture management in small animals/small ruminants can be successfully achieved owing to their light weight; they tolerate external coaptation relatively well and can ambulate in three limbs well in order to spare the injured limb. Fracture can be repaired successfully with regional anaesthetic techniques which they can tolerate very well. The constraint of cost effectiveness can be balanced by carefully selecting the appropriate technique according to the weight and limb involved. Many economical skeletal fixation technique have been evolved which can well fit into the budget of the owner. Knowledge of simple techniques can enhance healing in cases of bone loss and management of infection.

Fracture site stabilization

Fracture repair is usually elective, hence initial support and care of the fracture is necessary to prevent further trauma and complications like communication of fracture site to the exterior through wound or sinus and chances of infection. Initial support to splint the bone not only limits the movements but also supports the soft tissues from untoward consequences. Limb splinting reduces edema and pain, preserves neurovascular supply to the limb till the day of operation and helps to transport the animal safely. Fracture to limbs caudal to mid radius ulna/ tibia can safely be stabilized by splints or full limb casts. Wood, pliable bamboo or split poly vinyl chloride pipes positioned on the caudal and lateral aspects of the limbs and supported firmly with tapes or bandages can serve the purpose. Fracture proximal to mid radius ulna or tibia should not be stabilized using splits since the fulcrum effect created due to this can augment soft tissue injury. Careful assessment of the viability of the structures caudal to fracture site should be assessed prior to a decision regarding surgery, devitalized tissue hamper healing and is a subject to be considered for amputation.

Repairing fractures in small animal’s presence challenges to the veterinarians in their day to day service. These challenges include properly repairing fractures, each of which is unique, choosing the right fixation device, keeping an extensive inventory of costly instruments, and providing high standards of care for fracture repair. But fracture repair also gives veterinarians the opportunities to do something a little unusual in daily practice and to experience the immediate gratification of easing pain and promoting activity in injured animals.

Successful management of fractures mainly depends upon early diagnosis, type of fracture, timing of surgery and selection of proper method of fixation. The fixation of fractures can be achieved either by external or internal fixation methods. An ideal method of fracture fixation is one that can maintain early anatomical reduction, minimal soft tissue trauma, rigid stability and early motion of bone and joint. Restoring a fractured bone’s normal shape is important for return to function because it contributes to normal alignment of adjacent joint surfaces. Whereas, rigid stability of fracture fixation eliminates fragment movement and reduces pain. Soft tissue trauma adjacent to fractured bone should be minimum, which play a vital role in early vascularisation and prevents infection. Finally, early return to function maintains muscular tone of the limb allows normal weight mobility and joint nutrition and uses normal weight bearing forces to maintain bone density. These can be achieved with use of internal fixation devices.

1. Bone grafts

Bone grafting represents one of the earliest devised reconstructive approaches to the musculoskeletal system and remains among the most commonly used orthopedic procedures. Bone is the second most frequently transplanted tissue. The first recorded attempt to use bone graft is by the Dutch surgeon Job Van Meek’ren in 1668.

Definition

A graft is a living tissue that is transplanted to another site either within the same individual or into another individual for repair of a defect. An implant is a non viable material placed in a living system. Implants are composed of bone cement, metal or ceramic material. Grafts are structurally important for mechanical stability, but their use evolved to include the stimulation and enhancement of bone in response to injury.

Indications

Bone grafts are used, in general as framework, both to provide stability and to augment healing. It is used in the management of non union, delayed union, treatment of pseudoarthrosis, filling of osseous defects or cavities, arthrodesis, stabilization of spinal segments and addition of bone stock in total joint displacement.

Fracture healing is a specialized type of a wound healing response in which the regeneration of bone leads to a restoration of skeletal integrity. Because healing of a fracture in a living organism is accomplished by cells, it can be modified by almost any endogenous or exogenous factors like nutrients, vitamins, hormones, growth factor etc. that has an influence on the metabolic function of bone cells. Fracture healing may be induced by malnutrition that involves certain nutrients, notably calcium (Ca), phosphorus (P) and vitamin D, but also iodine (I), copper (Cu), zinc (Zn), manganese (Mn), fluorine (F), silicon, vitamin A and perhaps vitamin C as well as different endocrines. The number of these nutrients and their interaction is so large that dietary intervention in fracture management is likely to be the most effective if directed at consumption of a good diet that is completely balanced for growth, maturity, old age or stress. Substitution of a good diet for a bad one is also likely to be more convenient and safer than most attempts at partial supplementation of a faulty diet in order to bring it into balance. Underfeeding a good diet decreases size-for-age of bones during growth and delayed fracture healing. Underfeeding may engender osteoporosis in older animals. Underfeeding of Ca, P and vitamin D, causes delayed fracture healing. Over feeding a balanced diet induces rapid growth of newly formed bone and sometimes-accelerated fracture healing but it also causes obesity in adults.

Three major component of bone are osteogenic cells, organic matrix and inorganic matrix (mineral). The osteogenic cells include osteoblasts, osteocytes and osteoclasts, while the matrix consists predominantly of collagen and proteoglycans and constitutes approximately one-third of bone mass (on dry basis). The inorganic/mineral component that makes up approximately two-third of bone and it performs two essential functions : it serves as an ion reservoir and it gives bone most of its stiffness and strength. Bone is a reservoir for 99% of body calcium, 85% of body phosphorus and 40-60% of body sodium and magnesium. The main mineral composition of a long bone is: 85% calcium phosphate as hydroxyapatite, 12% calcium carbonate and 3% magnesium phosphate, calcium fluoride and magnesium carbonate and trace amount of chloride, potassium and sodium. For collagen synthesis, hydroxylase enzymes requires ferrous ion and vitamin C. Impaired collagen synthesis also occurs during deficiencies of vitamin D and E and zinc. The organic intercellular bone matrix is rich in mucoplysaccharide. Their synthesis involves enzymes that require manganese, zinc and vitamin A.

A. Definition

A fracture is a break in the continuity of hard tissues like bone, cartilage, etc.

B. Etiology

(a) Extrinsic causes

Direct violence

Indirect violence

Bone is an integral part of musculo-skeletal system of body. In the living animal it is bluish pink, whereas, fresh dead bone is yellowish-white in colour. It is hard and resistant to pressure but also have certain amount of elasticity. Its tensile strength is equal to the cast iron, though bone three times lighter and ten times flexible to cast iron.

Number of bones: The number of bones of the skeleton varies with age and species. Number of bones in cattle-210; Horse-208; Dog-271; Fowl-166 and human-208 (207-212)

Composition of bone: Bone contains different bone cells, organic and inorganic matrix and water. Organic matrix is about one-third and Inorganic matrix is two-third weight by volume. The organic material consists of 90% collagen [type-I (maximum), type V and type XII] and 10% non-collagenous glycoprotein and bone specific proteoglycans (osteocalcin, osteonectin, sialoprotein, bone phosphoproteins and small proteoglycans) and bone growth factors [TGF-beta family; Insulin-like growth factor-1, 2; bone morphogenetic protein (BMP); platelet derived growth factor (PDGF); Interleukin -1 (IL-1); Interleukin-6 (IL-6); colony stimulating factor]. Organic matrix of bone resembles the matrix of dense fibrous tissues such as tendons, ligament and joint capsule. It is not certain whether all of these proteins are synthesized by bone cells or whether they are synthesized by cells outside of the bone and then incorporated into the bone matrix. However, their presence within bone and their potential to affect the activity of bone cells suggests they have important role in controlling bone cell functions. Inorganic matrix of bone or mineral component of bone serves as an ion reservoir and gives bone of its stiffness and strength. It reserves 99% of body calcium, 85% body phosphorus and 40-60% body sodium and magnesium. Inorganic matrix of bone is composed of 85% calcium phosphate, 12% calcium carbonate, 3% of magnesium phosphate, calcium fluoride and magnesium carbonate. It also contains traces of chlorine, sodium, potassium. These minerals remain as hydroxyapatite crystal form within bone. However, bone mineral crystal is not pure hydroxyapatite, instead they contain both carbonate and acid phosphate groups (HPO₄) and bone crystal does not contain OH groups. Bone matrix has such great durability and stability that it can remain essentially unchanged and retain much of its strength for centuries after death. Removal of organic matters renders the bone fragile, brittle and shattered, whereas, decalcification renders bone soft and pliable and resistant to fracture.

11.1 Performance of Farm Irrigation Systems

The performance of farm irrigation systems is determined by the efficiency with which water is delivered to the field and utilized to the fullest amount possible with minimum losses due to seepage and percolation, runoff, evaporation and other operational losses. The efficiency of the irrigation system will increase if the conveyance losses, application losses and other losses are reduced to a great extent.

11.1.1 Overall Efficiency

The overall efficiency of a farm irrigation system is defined as the percent of water applied to the farm that is used for irrigation on the farm. Irrigation efficiency otherwise called as overall system efficiency is defined.

10.1 Application Efficiency and Irrigation Uniformity

All irrigation systems have some non-uniformity. This non-uniformity influences yields and irrigation efficiency especially application efficiency. If the net amount of water applied during irrigation is the same as that required to fill the soil water deficit, then because the distribution of water is never perfect, half of the field will receive too much water while the other half will receive too less water. In such a context, a farmer will try to apply more irrigation water to his field so that a larger fraction of the field has an adequate amount. This will tend to have higher percolation and runoff and thereby declining the application efficiency. An alternative to adding extra water is to improve the uniformity of water application. A major advantage when the uniformity is improved is that the amount of deficit in the area under irrigation is reduced and the potential for water logging and salinization is also reduced.

9.1 Introduction

After knowing when to irrigate and how much to irrigate, next important thing is how to irrigate the crop field. Methods of irrigation plays a very crucial role in deciding how to irrigate the crop fields since all the crops do not require same methods of irrigation. Depending on the sources of water available for irrigation, type of crop to be irrigated, quantity and quality of water to be applied and other economic considerations, methods of irrigation will vary. Irrigation water may be applied to the crops by flooding it on the field surfaces as surface irrigation, by applying it beneath the soil surface as sub irrigation, by spraying it under pressure as sprinkler or overhead irrigation or by applying it in drops around the root zone of the crop as trickle irrigation. The commonly used methods of irrigation are described in schematic diagram as follows

8.1 Introduction

For maximization of yield of crops, it is essential to provide irrigation to crops. When either the natural sources like rainfall, dew, snowfall and other forms of precipitation or when the capillary rise of groundwater is not sufficient to meet the crop water demand, then there is need to supply irrigation. This irrigation water is a precious resource and need to be used cautiously. There are three important things need to be understood for optimum utilization of irrigation water with basic purpose to maximize the yield and returns. 

7.1 Introduction

The entire amount of water that is diverted at the canal head regulator does not reach at the field for use of irrigation. Major amount of it is lost on way during its movement in the canal systems. During the passage of water from main canal to outlet at the head of the water course, water may be lost either by evaporation from the surface or by seepage through the peripheries of the channel. These losses are sometimes very high, and may go up to 50 % of the total water diverted into the main canal. Evaporation losses are low and may go to a maximum of about 7 percent of total losses. The major loss of water in the conveyance system is the seepage loss. Seepage loss depends on the channel geometry and evaporation loss is proportional to the area of free surface. In determining the designed channel capacity, a provision of these water losses must be made. The provision for the water lost in the watercourses and in the field however, already made in the outlet discharge factor, and hence no extra provision is made on that account. However, excluding the above two losses, there is operational loss which when added to the evaporation and seepage losses, the total losses goes up the maximum 50 percent level. The operational loss includes spillage, over-toping, leakage through rodent holes, dead storage, initial infiltration and evapotranspiration from the vegetation along the watercourse. Evaporation and seepage losses of the canals are discussed below.

6.1 Introduction

In order to increase the production and productivity of crops, provision of irrigation system is highly essential. A project that makes use of weir or a barrage for providing irrigation to fields is called as direct irrigation system. On the other hand, a storage irrigation system makes use of storage reservoir by construction of dams. In order to provide irrigation by both the schemes, it is necessary to have a network of canal systems. A canal is an artificial channel, generally trapezoidal in shape constructed on the ground to carry water to the fields. The canal systems that provide water to the fields include main canals, branch canals, distributaries, minors and watercourses. It is imperative to design the canal systems properly for a certain realistic value of peak discharge that must pass through them so as to provide sufficient irrigation to the command areas. The flow irrigation that provides irrigation water to the fields may be of two types i.e. Inundation irrigation and Perennial irrigation.

5.1 Soil

Soil and water are the two most important natural resources required for crop production. Without soil, no crop can be produced even if there is availability of plenty of water. It is vital not only for agriculture but also very vital for sustenance of life. No building can stand on any place without soil. Soil gives foundation support for any building. The term ‘soil ’is defined in various ways depending on the general professional field in which it is used. However to an agriculturist, soil is the substance existing on the earth surface, which grows and develops plant life. It contains all vital elements including its inherent fertility contents that support the growth of plants. For an engineer, soil is the unaggregated deposits of mineral and organic particles covering major part on the earth crust. It includes widely different materials like boulders, sand, gravel, clays and silts. Soil is produced by the weathering of solid rocks. The formation of soil is due to geologic cycle continuously taking place on surface of the earth. The geologic cycle comprises weathering or denudation, transportation, deposition and upheaval, again followed by the above mentioned processes. Weathering may be natural or artificial. In natural weathering, physical processes like temperature changes, flow of water, ice, wind and rain play the role. In artificial weathering animals especially human beings interference causes soil erosion and formation. It is obvious that it takes hundreds of years to form one inch of soil.

4.1 Introduction

A reservoir that collects and harvests in-situ rainfall as well as runoff from the catchment area can be used for many purposes: the most important of which is the supply of water to crops as supplemental irrigation. The water of the reservoir can be used for domestic and industrial uses. It is also a good source for recreational use. Total water demand of the reservoir including irrigation to different crops in different seasons, domestic and other non-agricultural uses are to be assessed. While estimating the crop water requirement and irrigation requirement, various crops to be grown in the service area of the reservoir, their water requirements, crop duration, extent of coverage and water management practices followed are to be taken into consideration. Multiplying the irrigation requirement with crop coverage area, volumetric irrigation water requirement of crop can be found out. Summation of irrigation requirement of all crops grown in service area of the reservoir gives total irrigation demand of the reservoir.

4.2 Water and Irrigation Demand of Crops

Of the various demand of water from the reservoir, irrigation demand of crops grown in the command area of the reservoir is very important. Most of the crop water demand is met from rainfall. However, when the rainfall is deficient to meet the crop water demand, then the deficit is met from the stored water of the reservoir in the form of irrigation, more commonly called as supplemental irrigation. The irrigation to the crops is required mostly to meet the evapotranspiration requirement of the crop. Before discussing the water and irrigation demand/requirement of crops, it is essential to know some commonly used terms frequently used.

3.1 Introduction

Irrigation water that is supplied to crop fields is defined by a term commonly called as discharge which is also called as rate of flow. Discharge is defined as the volume of water flowing through a cross section in a unit time. It can be expressed as cubic metre per second (cumec), cubic feet per second (cusec), litre per sec (lps) etc. one cumec is equivalent to 35.5 cusecs or 1000 lps. The measurement of discharge is very important in everyday life starting from deciding the amount of irrigation to be supplied to a crop at a particular growth stage, or amount of water supply for domestic and industrial uses, for flood control and power generation etc. It plays a vital role in water resources planning.

3.2 Methods of Discharge Measurement

The various methods of discharge measurement can be broadly classified into the following types: (i) volume method of discharge measurement (ii) flow measuring structures such as orifices, mouthpieces, flumes and weirs.

2.1 Introduction

Rain and snow are the two chief sources of water of the earth. In-situ conservation of rainwater helps the plants to meet some of their consumptive uses directly. Not all the amount of rainwater that falls at a point is conserved by the soil reservoir to support the plant growth. Some part of it flows over the soil surface as surface runoff and some seeps down as infiltration and finally adds to the underground reservoir. Therefore, rain or snow, which is not used directly by the plants, becomes a potential source of either surface or ground water for irrigation. In areas with extreme low temperature, snow contributes major source of water supply wherever, in humid and sub humid regions, rain is the principal source. Precipitation, rain or snow, is the first stage of the continual cycle of water in its round from atmosphere to the earth and return by evaporation from water bodies, snow surfaces and land surfaces. The continual cycle of distribution of water is governed by the process called as hydrologic cycle. Thus, precipitation or atmospheric water is the first form of water above the earth’s surface, the second form being the surface water on earth and the third form is the subsurface water or underground water. The study of occurrence, distribution and circulation of precipitation through the unending hydrologic cycle forms the basic part of study of hydrology. As mentioned above, the part of precipitation that is not used by the plants in-situ flows over the soil surface as runoff and contributes to either surface or ground water supply.

Engineering hydrology is the science that deals with the estimation of runoff and its transmission from one place to the other, besides dealing with the properties of water in nature. For, an engineer, surface and groundwater are the two most important components to deal with. But due to lack of data of stream flow, it is usually necessary to study precipitation, evaporation and percolation to indirectly determine the availability of surface and groundwater. For planning and management of water resources systems, an engineer has to estimate (i) water resources potential of a basin, (ii) dependable yield for irrigation and hydel power generation and industrial water demand (iii) probability of occurrence of floods with their magnitude, (iv) sediment yield and transportation (v) hydrometeorology (vi) new sources of water for irrigation (vii) stream flow forecasting by use of precipitation data (viii) water control, navigation, control of soil erosion and control of pollution of water bodies and (ix) operation and maintenance of river valley projects. For estimation of the above mentioned parameters, it is important to understand the hydrologic cycle properly.

1.1 Importance of Water for Agriculture

All animals and plants require water for their survival. Animals cannot prepare their own food. They depend on plants for their food. Plants need water for preparation food by the process of photosynthesis. Majority of this water requirement of the crops is met from different forms of precipitation. However, when the water requirement is not fully met from precipitation, then growth of the crops is affected. Water requirement of crops depend on many factors. It depends on the type of crops, irrigation schedules practiced, soil texture, position of groundwater table below effective root zone of the crop and management practice followed in crop cultivation. The dry land crops need less water compared to rice which is a water loving crop. The perennial crops like sugarcane, banana etc. need more water than other crops like cereals, pulses, oilseeds etc. Water requirement of crops is partly met by the upward flux of groundwater. The capillary rise of shallow water table in the form of upward flux helps in meeting the water requirement of crops to some extent. The upward flux depends on the type of the soil, effective root zone depth of the crop, depth of water table below effective root zone depth of the crop and potential gradient of soil moisture suction. If the soil is heavy like clay, effective root zone depth of the crop is more (deep rooted crop) and position of ground water table is near to ground level (shallow water table), then the upward flux is more.

Due to rainfall or application of irrigation water, some amount of water is recharged to soil reservoir. This recharged water is stored in the soil as soil moisture content. The stored moisture or called as water in the soil reservoir helps in supporting water requirement of crops also. The heavy soil like clay has more moisture retention capacity than the light soils like sandy soil. The residual soil moisture held in clay soil is released slowly and supports more soil moisture to the crops for a longer period than the sandy soil which has less soil moisture retention capacity. After meeting the water requirement of crops from all sources including different forms of precipitation, ground water contribution by capillary rise and residual soil moisture, if there is any shortage of water, then this shortage should be met from other sources which are called as irrigation. It is to be noted that irrigation is not the natural phenomenon of supply of water; rather it is the artificial means of supply of water to the crops. Irrigation may, therefore, be defined as the science of artificial application of water to the crop in accordance with the crop requirement for better nourishment of the crops.

Introduction

Plants are considered as immobile organisms with poor sensitivity and limited ability to respond. Within the plant kingdom, Mimosa pudica (also called the sensitive plant), Drosera (sundews), Dionea muscipula (flytraps) and tendrils of climbing plants which showed rapid and purposeful movements were considered as exceptions. These sensitive plants attracted attention of outstanding pioneer researchers like Pfeffer (1845-1920), Burdon-Sanderson (1828-1905), Darwin (1809-1882), Haberlandt (1854-1945) and Bose (1858-1937). Stahlberg, 2006 reported the presence of various mechanoreceptors in such species which could trigger action potentials (APs) which activated these sudden movements.

The first extracellular recording of a plant action potential (AP) development was initiated by Charles Darwin; later, the animal physiologist Burdon-Sanderson in 1873 performed similar studies on leaves of the Venus flytrap (Dionea muscipula Ellis). Haberlandt (1884) demonstrated that phloem strands were the actual paths for excitation by destroying the external, non-woody part of vascular bundles. This notion was confirmed in Mimosa and other plant species by a number of recent studies. Houwink (1935) carried out experiments with two species of Vitis (grape) and obtained electrical fluctuations which was similar and comparable with the action potentials he obtained with Mimosa. In 1907, Bose, used a D’arsonval galvanometer to demonstrate propagating electrical effects in different genera of plants such as Ficus, Artocarpus, Cucurbita, Corchorus, “fern” etc. APs have their largest amplitude in phloem sieve cells and cells adjacent to this area (Sibaoka, 1969). Other studies found that AP-like signals are propagated with equal rate and amplitude throughout the cells of vascular bundles.

Introduction

Plant architecture is defined as a three-dimensional organization of plant body in terms of its size, shape position of leaves, flower organs and branching pattern. Earlier this was the only criterion for systematic and taxonomic classification of plant species and the best means of identifying them (Stecconi, 2006). Study of plant architecture emerged as a new scientific discipline some 30 years ago. The subject derives its base from earlier works on plant morphology (Halle and Oldeman, 1970) but currently it is integrated with several disciplines of plant sciences ecology and engineering. Modification in plant architecture causes alteration in primary and secondary growth. This occurs due to differences in phyllotactic arrangement, branching pattern and floral differentiation. Plant architecture can be modulated by various parameters like climate, agronomic practices and human interventions. Manipulation of plant architecture is a major area in plant science which is currently adopted for productivity improvement by breeders, agronomists, horticulturists and landscape managers. However, the basis for such manipulation lies in the knowledge of the basic architecture of plants and its significance.

Introduction

Clean and renewable energy is a basic requirement for developmental activities. Global energy crisis is caused by increasing world population, escalating demand due to urbanisation, and continued dependence on fossil-based fuels. Non-renewable energy sources like coal, natural gas oil contribute 79 per cent of world electricity generation; only 21 per cent comes from renewable energy sources. Promoting the use of existing renewable energy sources and identifying new environment-friendly technology is gaining importance. Switching to renewable energy sources like wind energy, ocean energy and solar energy is gaining a lot of importance. These green technologies emit less greenhouse gases into the atmosphere and hence are pollution free and immensely available. Recently, investigators have identified plants as weak energy sources. Plants are versatile organisms capable of communicating with each other with a number of signaling mechanisms. It was observed that plants generate electronic signals inside their system. The concept of utilising electronic signals for studying various physiological plant processes was first put forth by Sir Acharya J. C. Bose, an eminent biophysicist, botanist, archaeologist and polymath from India (Fromm and Lautner, 2007). His ideologies and concepts of movements of plants laid the foundation for modern electrophysiology-a branch of physiology that deals with electrical phenomena associated with metabolic functions. Attempts have been made to harvest electricity from free electrons available in plant leaves produced during photosynthesis and from rhizosphere of plants formed as a result of bacterial activity. Currently, a lot of attention is being given to improvise and develop this technology. To proceed forward in this direction, it is very critical to understand the mechanism of electrical signaling in plants.

Introduction

Earth’s magnetic field (MF) is a natural component of environment and is an inescapable factor for all living organisms including plants. Earth has an inner core made of molten iron which rotates at a fairly high speed creating a magnetic field just like a dynamo. This Geo Magnetic Field (GMF) extends from the earth’s interior into outer space. It interacts with the solar wind, which is actually a stream of charged particles emanating from the sun. As earth is engulfed in a GMF, all living organisms, both plants, animals and all biological processes are under its influence. However, local differences in strength and direction of the geomagnetic field have been detected. The vertical component of GMF is maximum at the magnetic poles, which is around 67 μT, and the horizontal component is zero there. Conversely, at the magnetic equator the vertical component is zero and the horizontal component is maximum, about 33 μT (Kobayashi et al., 2004).

Turbulent flows of the fluid metallic inner core of earth mainly contribute to GMF and the effect of external MFs located in the ionosphere and the magnetosphere is very meagre (Qamili et al., 2013). As GMF extends beyond the earth’s surface it is this force along with magnetosphere that protects the earth and its biosphere, from the solar wind by deflecting most of its charged particles (Occhipinti et al., 2014).

Introduction

The ultimate aim of agricultural research or any other related activity is to increase yield. Yield improvement could be obtained mainly through the enhancement of photosynthetic efficiency. Photosynthesis is a process in which plants convert light energy to chemical energy. Sun is the ultimate source of energy for photosynthesis. However only half of the total solar radiation (51%) reaches the earth’s surface of these only 1.2% reaches the plant canopy. Solar spectrum contains an array of other radiations which can be harmful for plant and human life. With increasing global climatic change amount of harmful radiation reaching the earth’s surface has increased and this is found to influence plant productivity. Under this scenario, protected cultivation is gaining popularity in many countries as it helps to reduce harmful effects of undesirable radiation, to allow cultivation of crops irrespective of seasons and also expand cultivation to non-traditional areas by artificially manipulating crop environment. In this context, spectral manipulation for crop production has emerged as an important area in crop production system

Introduction

Plants possess complex, systematic and specific mechanisms to cope up with abiotic as well as biotic stresses in the existing environment. ‘Do plants respond to sound ? How can plants perceive sound without a hearing organ?’- are interesting queries among the scientific community. Responses of plants to different factors such as temperature, moisture, light, wind, pests and microbes are well understood. However, information on the effects of audible sound frequencies on plants are still lacking. Recent evidences suggest that audible sound stimulation can contribute to better plant growth and improved quality of plant produce. It also represents a new trigger for plant protection. Sound is an acoustic energy in the form of a mechanical wave which transmits through gases, liquids and solids. Acoustic spectrum consists of three regions, infra sound (less than 20 Hz), audible region (20-20,000 Hz) and ultrasound (greater than 20,000 Hz). Infra sound and ultrasound are used in clinical diagnosis and therapeutics.

Research on plant responses towards different stimuli started during 1880s by Charles Darwin. In 1848, Dr. Gustav Theodor Fechner, a German experimental psychologist, suggested that plants are capable of feeling emotions and that one could promote healthy growth of plants with talk, attention, attitude and affection. Later, J. C. Bose (1926), famous Indian botanist and physicist, made several studies on the effect of sound vibrations on plants. According to him, a plant treated with care and affection gives out a different vibration than a plant subjected to torture. In addition, Bose found that plants grew more quickly in pleasant music and more slowly in loud noise or harsh sounds. He also noticed that plants can “feel pain and understand affection” based on variation of cell membrane potential under different sound frequencies. Retallack (1973) also described several experiments involving plants and music.

Introduction

Plasticity is a unique attribute by which the otherwise sessile plant species are capable of adjusting to environmental vagaries by changing their phenotypic and morphological characters. Any plant population will be able to survive only if it can respond to an extremely variable environment by becoming more plastic and more genetically variable. To achieve this, plants should be able to suitably change their morphology anatomy and physiology or any one of these parameters based on environmental changes so as to improve their adaptability and survival in the altered environment. When such changes are genetically heritable, then they lead to species evolution.

Plasticity helps plants to adapt to new environmental conditions, after migration to new geographical areas, by genetic assimilation of traits that can help to improve their performance under a new set of conditions. Understanding plasticity is important for predicting and managing the effect of climate change on native species as well as crop plants. Response of plants to modified environmental conditions is critical for their persistence.

Phenotypic plasticity has been defined as the ability of an individual genotype to produce different phenotypes when exposed to different environmental conditions (Pigliucci et al., 2006). This includes the ability of a plant to modify its development in response to environmental cues and also its ability to bring about changes in its metabolism which increases the chances of survival of an organism under a specific condition.

The biofertilizer technology has paved way for the manufacturers and entrepreuners to establish a biofertilizer production unit due to an increasing demand and awareness among farmers. Biofertilizer production units have already been started with most of them in the southern states of India. The biofertilizers can be produced using different kinds of carrier materials (peat, coal, lignite, clays, inorganic soil), organic materials (composts, soybean meal, wheat bran, sawdust, etc.), or inert materials (e.g., vermiculite, perlite, kaolin, bentonite, silicates). Natural carriers like peat, plant waste materials, composts, sawdust, sludge lignite, clays, coal, vermiculite, perlite and bentonite and mixture of organic and inorganic materials may also be used.

The Government of India is also encouraging a low cost technology by providing a subsidy to establish a biofertilizer production unit . The major equipment’s and other materials required for a biofertilizer production unit with the capacity of 150 metric tonnes/annum are given below

There are many manufacturers of biofertilizers in both government and private sectors. Only some of them have been listed here for the information

The soil fertility is depleting in the current scenario of gap between nutrient removal from soil and supplies. Moreover, increase in the fertilizer prices has become unaffordable to small and marginal farmers. There is also a growing concern about the environmental hazards and its threat to sustainable crop production. Indiscriminate use of synthetic fertilizers for intensive crop production has resulted in large quantity of nutrient (particularly P) accumulation in soils which has resulted in generating a dead soil. In this context, the long term use of biofertilizers are considered to be economical, eco-friendly, more efficient, productive and accessible to marginal and small farmers over chemical fertilizers (Subba Rao, 2001). Biofertilizers mainly consists of specific living cells which supplies nutrients to plants through their root system. Microbes in these fertilizers provide nutrients to the plants by nitrogen fixation, phosphate solubilization, phosphate mobilization, and promotion of beneficial rhizobacteria (Bhat et al., 2010). Biofertilizer application improves the supply of nutrients, organic carbon, accumulation of soil enzymes, productivity, soil fertility index, economy of farmers, and maintenance of sustainability in natural soil ecosystem and horticultural crops. The production of efficient and sustainable biofertilizers for crop plants needs to be undertaken to make the biofertilizers popular and efficient. The important and specific research in future may be focused on the following aspects.

Microbes present in the biofertilizer formulations help in microbial processes in the soil which augment the availability of nutrients to be taken up by plants. They are of different types based on their nature and function such as nitrogen fixing, phosphate solubilizing, phosphate mobilizing or biofertilizers for micronutrients. Plants use different strategies for growth promotion at different stages of plant growth and development. Biofertilizers are mass multiplied cultures of specific beneficial microbial strains which improves the fertility of soil and productivity. The nutrients are added through natural processes of nitrogen fixation, solubilization of phosphorus and synthesis of growth promoting substances to stimulate the plant growth. The main sources of biofertilizers are bacteria, fungi and cyanobacteria.

11.1. Bio-enrichment of chemical fertilizers- A new approach

Yield response of different host plant depends on the mineral fertilizer and its fertilizer use efficiency. Generally, such fertilizers are low in efficiency due to environmental and soil factors. A large portion of synthetic fertilizers are lost due to fixation, leaching, run-off, erosion, volatilization, denitrification and precipitation without reaching plants. Hence, there is an economic loss and water and environmental pollution.

Microbial inoculants applied to the soil enhances the uptake of nutrient by plants and increase the efficiency of synthetic or organic fertilizers. In this context, it is possible to impregnate mineral fertilizers with specific microbial strain. A new approach is to incorporate the microbes or microbial compositions into fertilizer compositions.

It has been well established that the biofertilizers are beneficial to plants and are cost-effective inputs for sustainable production system. However, there are some constraints with respect to its production, which are presented below:

10.1 Production constraints

10.1.1 Raw material

Eventhough there are large number of biofertilizer formulations, only few are considered as good carrier materials for biofertilizers such as peat and lignite. Moreover, its availability in India is limited and the quality is lacking for these carrier materials. Hence, a cost effective and locally available material with increased shelf-life is the need of the hour.

10.1.2 Specificity and availability of strains

As the microbial strains used as biofertilizers are specific to soil and agro-ecological conditions, availability of specific strains for the specific host and soil edaphic factors are inadequate.

Quality Control is very important in biofertilizer production, which determines the efficiency of microbial strains. Generally, the quality control based on BIS are voluntary in nature. However, some of the biofertilizers are brought under the ambit of Fertilizer Control Order 1985 (FCO) during 2006 (Yadav and Chandra, 2014). At present, biofertilizers are under the FCO with specific quality standards. Biofertilizer production and its sales can be regulated and is a mandatory requirement for registration of manufacturing unit with the State Fertilizer Controller (who is generally the Commissioner or Director of Agriculture Department) under the statutory provision of FCO. Moreover, some officers of the Agriculture Department have been declared as Fertilizer Inspectors at the district level, who are authorized to inspect production and storage facilities and draw samples for quality analysis. National Centre of Organic Farming (NCOF), Ghaziabad under the Govt. of India and its six Regional Centre’s located at Bhubaneswar, Bangalore, Jabalpur, Nagpur, Hissar and Imphal have been declared as testing laboratories. Under the provisions of the FCO act, State Governments can also develop their own quality control laboratories and notify them under the FCO (1985). Peat, lignite, peat soil, humus, wood charcoal or similar material favouring the growth of microbial strain could also be used. The FCO specifications for different biofertilizers are presented below:

Biofertilizer is already proven to be beneficial for agricultural and horticultural crops. The most important pre-requisite for the success of biofertilizer application is the presence of high population of viable cells which will show the desired effect on plants. Biotic interactions along with competition from native microflora is a major challenge to an applied strains of biofertilizers. The formulation is an important parameter for biofertilizer production containing efficient microbial strain with suitable carrier material and additives. The microbial strain needs suitable protective environment to increase their efficiency at the target site and also make it user-friendly. Performance of biofertilizers under field condition is the major requirement for inoculants. Inadequate formulations and poor inoculant quality are the major hurdles for the successful use of biofertilizers.

Formulation of biofertilizers has to be consistant during production, distribution, storage and transport to the farmer/end users. The shelf-life of inoculated microbial fertilizer depends on the formulation with suitable carrier material. If local production and distribution of an efficient native biofertilizer formulations are developed, the present problems in the field performance of biofertilizers could be significantly solved. Specific formulations of native strains for use in saline soils, acid soils, drought, high temperature and eroded soils requires specific formulations. Therefore,use of native strains of biofertilizer formulations which are tolerant to the abiotic stress is an important approach. The formulations of biofertilizers are challenging and limited success has been observed in the commercialization of new biofertilizers. Hence, the search for new formulations has been a continuous approach. However, the choice of the formulation depends on the application method, available equipment, farmer’s convenience, plant inherent characteristics and developmental stage, cost, mode of action and colonization pathway of the inoculated strain. Conventionally, solid based formulations are used, which have problems of low viability during storage and application.

Biofertilizers can directly or indirectly influence the growth of plant. The direct influence can be through production of phytohormones or making the nutrients available to plants. The indirect effect can be through management of plant pathogens through biological control. Therefore, the purposeful introduction of biofertilizer inoculants to plant microbiome represents an environmentally sound option that holds a prominent position in order to reduce the dependency on agrochemicals (Adesemoye and Kloepper, 2009; Abhilash et al., 2016; Aloo, et al., 2019).

Microbes in soil can rarely exists as single cells and survive near the plant root canopy or in bulk soils or endophytes or even on plant surfaces (Lorito, 2006). The soil microflora occurs as complex members of microbiota (Hacquard, 2015). Microbial consortia (MC) are unique mixture of organisms which respond to the environment stress and adapt to stresses due to internal beneficial interactions among the microbial community. Ecosystem’s physiological functions by microflora is carried out by more than one microbial species with the functional diversity and succession among different microbial components. The microbial balance among the different microflora of a MC will consist of a continuous shift between actively growing cells and non-dividing cells of the microbial consortia. It has been reported that different microbial populations “talk” to each other by “quorum sensing” mechanism in a given environment by exchanging specific chemical signals (Thompson, 2015). Natural microbial consortia holds many specific properties like stability, functional diversity and perform complex functions. The natural consortia have generated an interest in manpulating synthetic consortia for the benefit of application (Minty, et al., 2013).

Fruits, vegetables, ornamentals, plantation crops and spices, medicinal and aromatic plants, tubers, are the major horticultural crops contributing to the economic growth in India. Even though the horticultural sector is growing fast, with India being the second largest producer of fruits and vegetables in the world, the productivity and quality have to be improved in order to meet the demand of increasing population. Under these circumstances, ecofriendly techniques needs to be adopted which could ensure food security and sustainable production. Indiscriminate application of agrochemicals and chemical fertilizers in horticultural crops and their residues could harm the human health, soil and environment. Horticultural crops need an ecofriendly technique, as most of the horticultural products are directly consumed. Hence, there should not be any residues of agrochemicals in food products. In the current context, use of ecofriendly, cost effective and organic-based inputs like biofertilizers can maintain health of the soil and good quality in horticultural crops. The application of biofertilizers offers an attractive and sustainable means of improving the quality of food products. Biofertilizers like Azotobacter, Azospirillum and AMF and PGPRs not only supplies the required nutrients to plants, but improves the fruit quality and quantity (Pathak et al., 2017).

The inoculum dosage and method of application determines the efficacy of biofertilizers. The quantity of biofertilizers to be applied depends on the type of crop, seed rate and soil edaphic factors. There are 3 methods for inoculation of biofertilizers

Seed treatment: One packet containing inoculant (200 g) is mixed with 200 ml of rice gruel or 40 % gum arabic solution to make a slurry (Fig. 23). Then the seeds required for an acre are mixed in the slurry in such a manner that they have a uniform coating of the inoculant over the seeds. Then, the inoculated seeds are shade dried for 30 minutes. The shade dried seeds should be sown within 24 hours. One packet of the inoculant (200 g) is normally sufficient to treat 10 kg of seeds.

Benefit of biofertilizers have been extensively studied for various agricultural and horticultural crops. However, the effectiveness of inoculated biofertilizers are influenced by several factors. If the use of biofertilizers have to be popularized in horticultural crops, the major factors affecting their performance particularly in relation to soil, plant, quality of the product and application methods have to be addressed. Factors affecting the performance of biofertilizers are:

4.1 Quality of the product

4.1.1 Production process

The high quality of biofertilizers are determined by the production process (Bashan et al., 2014). At the same time, the population density of mother culture and the quality of the final products are directly related (Stephens and Raskm, 2000). As the inoculum consists of a strain, the relationship among the microorganisms interaction in the rhizosphere have to be understood. In the case of more than one microorganisms, the efficiency depends on the various mode of action by various microorganisms which might overlap with antagonistic acitivities (Vassilev et al., 2001, 2006 b). The relationship of microorganisms with plants is not based on the taxonomic diversity, but their functional diversity (Maherali and Klironomos, 2007).

The efficiency of biofertilizers could be assured by enhanced shelf life of the inoculant and biological traits which are a challenge for developing a formulation (Bashan, et al., 2014). Hence, either single or consortia of microorganisms formulation with or without additives determines the efficacy of the biofertilizers. The formulation determines shelf-life during storage and transport, which enhances the persistence of the strain in soil and get maximum benefits to the host plants after inoculation (Manikandan et al., 2010; Schoebitz et al., 2012). Different kinds of carriers are used in the formulation process which affects the overall quality and efficacy of the biofertilizers (Bashan et al., 2014; Herrmann and Lesueur, 2013). Granular inoculants showed good results under stressed soil conditions (Clayton et al., 2004; Lupwayi et al., 2006). Encapsulation of the microbial strain into polymers allow diverse compositions and structures (Vassilev et al., 2005) but, have limitations for commercial production (Bashan, et al., 2014; John et al., 2011). Use of additives might improve the shelf life of the product (Bashan et al., 2014; Malusà et al., 2012; Herrmann and Lesueur, 2013) with introduction of specific substances to enhance the efficacy of biofertilizers.

Biofertilizers improve the plant growth due to changes in the microbial community of rhizosphere by production of several substances. Normally, biofertilizers promote plant growth either by facilitating nutrient absorption or by secretion of plant hormones. Biofertilizers also cause inhibitory effects by acting as biocontrol agents on various pathogens so that the growth of plant is enhanced. The mode of action could be either direct or indirect methods

2.1 Nitrogenous biofertilizers

These biofertilizers augment nitrogen to the plants through fixation of atmospheric nitrogen, either symbiotically or asymbiotically. The major nitrogenous biofertilizers are:

2.1.1 Rhizobium

The word Rhizobium is a Greek word where “rhiza” refers to root, and “bios” refers to life. Rhizobium was first named by Frank (1889) which means ‘root living’ in Latin (Fig. 3). Some species of Rhizobium were later moved to new genera based on phylogenetic analysis. It consists of 49 rhizobial species and 11 non-rhizobial species.

In modern agriculture, use of synthetic chemical fertilizers are essential in agriculture for sustainable yield but, these have resulted in environmental pollution. The use of synthetic fertilizer could result in serious human health issues and also affects the soil microflora, besides being costly due to high production cost. Further, excess use affects soil processes and result in nutrient imbalances in plants with increased susceptibility to pests and diseases and also affects the symbiotic associations. Under these circumstances, biofertilizers could be an alternative for integrated nutrient management system in horticulture. The entire crop production system depends on soil beneficial microflora and their activities, which makes them highly potential alternatives to synthetic chemical fertilizers.

Biofertilizers or microbial fertilizers are essential for eco-friendly and sustainable cultural practices. The term “biofertiliser” has been defined in several ways due to its unique relationships between the plant and rhizosphere microflora. Biofertilizers mainly include nitrogen fixing bacteria, phosphate solublizing and potash solubiling bacteria.

Introduction

The resource conservation technologies (RCTs) is primarily focussed on resource savings through minimal tillage, ensuring soil nutrients and moisture conservation through crop residues and growth of cover crops, and adoption of spatial and temporal crop sequencing. These practices have long been practised by the farmers in the Indo Gangetic Plains (IGP) but it got eroded in recent times due to various geo-socio economic- political reasons. This region (10.5 million ha) comprises of Punjab, Haryana, Uttar Pradesh, Himachal Pradesh, Bihar and West Bengal and have major share in production of rice and wheat due to adoption of green revolution technologies followed by area expansion. It has been reported that rice-wheat system has strained the natural resources of this region (Swarup and Singh, 1989; Kumar and Yadav, 1993; Lal et al., 2004). In present scenario there is little scope to meet future target by earlier approaches like area expansion and intensive use of natural resources. Therefore, RCTs can be regarded as energy, water and labour efficient system to sustain soil health and production environment and produce more at less cost (Jat et al., 2012; Gathala et al., 2011b).

Major emphasis is given upon the RCTs components like zero/reduced tillage, direct seeded rice, crop residue management and crop diversification. However, other RCTs like site specific nutrient management, leaf colour chart, laser land leveller, nutrient use efficient genotypes, integrated crop and pest management provide options to the farmers as per their resource endowment.

Introduction

Persistent income from agriculture is most important for sustaining the farming sector. Conservation agriculture (CA) is a resource-saving agricultural production system that aims to achieve production intensification and high yields while enhancing the natural resource base through compliance with three interrelated principles, along with other good production practices of plant nutrition and pest management (Abrol and Sangar, 2006). Conservation agriculture is largely promoted as one of the few win–win technologies affordable to farmers, in the sense that potentially it improves farmers’ yields (in the long term) at the same time conserving the environment. CA is described by FAO (http://www.fao.org.ag/ca) as a concept for resource saving agricultural crop production which is based on enhancing the natural and biological processes above and below the ground. As per FAO definition CA is to a.) Achieve acceptable profits, b.) High and sustained production levels, and c.) Conserve the environment. It aims at reversing the process of degradation inherent to the conventional agricultural practices like intensive agriculture, burning/removal of crop residues. Shifting from tillage-based agriculture to no-tillage CA systems removes unsustainable elements in the current tillage based systems and replaces them with CA elements that make the production systems profitable and ecologically sustainable. Conservation agriculture offers an opportunity for arresting and reversing the downward spiral of resource degradation, decreasing cultivation costs and making agriculture more resource – use-efficient, competitive and sustainable.

Introduction

Precise and continuous measurement the greenhouse gases (GHGs) fluxes/ emissions in agricultural systems are required for accounting and budgeting of carbon. Further, the long-term measurements of GHGs fluxes are equally important as precise measurement. Therefore, high frequency and long-term measurement of GHGs across the cropping systems are essential for chalking out the GHGs emissions mitigation strategies. Various technologies with definite working principles are used for estimation of GHGs emissions in agriculture.

Greenhouse Gases Estimation Techniques

Two basic principles are followed to estimate greenhouse gases in agriculture. One is the collection of GHGs from the field and subsequent analysis of the concentration of gases through gas chromatography (GC). Another principle is based on sensors measurement with the help of infrared gas analyze (IRGA). The two techniques used for the measurement are (i) ‘closed chamber method’ (manual/automatic), and (ii) ‘sensor-based method’. Generally, the GHGs fluxes in agricultural crop field are estimated by ‘closed chamber method’ for methane (CH₄) and nitrous oxide (N₂O). And for carbon dioxide (CO₂) measurement either soil respiratory chamber or canopy chamber is used that measures CO₂ with the help of infrared gas analyzer (IRGA).

Introduction

Intensive soil tillage, burning of crop residues and over use of fertilizer and irrigation water under current agricultural practices has accelerated the pace of degradation in Indian agriculture. Intensive soil tillage increases soil erosion and nutrient runoff into nearby waterways. Crop residue burning resulting in loss of plant nutrients and release of greenhouse gases (GHGs) in the atmosphere. Imbalanced use of chemical fertilizer leads to soil compaction, slows down the fertilizer utilization rate and contaminates the local environment. Increasing demand of irrigation water causes water shortage and harms the environment in several ways including increased salinity, nutrient pollution, and the degradation of flood plains and wetlands. In the face of these management and environmental challenges, there is a need to formulate such agricultural practices which improve the productivity of natural resources as well as of external inputs and help to prevent soil degradation. Conservation agriculture (CA) practices such as reduced tillage, residue retention and proper crop rotations offer such solutions. CA also helps in making agricultural systems more resilient to climate change and safeguard ecosystem services.

Introduction

Conservation of biodiversity and mitigation of global warming are two major environmental challenges today. In the context of climate change and the global carbon cycle, the relationship between plant biodiversity and soil organic carbon (SOC) sequestration has become a subject of considerable scientific interest. The Earth’s terrestrial vegetation plays a pivotal role in the global carbon cycle. Not only are tremendous amounts of carbon stored in the terrestrial vegetation, but large amounts are also actively exchanged between vegetation and the atmosphere. Anthropogenic perturbations exacerbate the emission of CO₂ from soil caused by decomposition of soil organic matter (SOM) or soil respiration (Schlesinger, 2000). The emissions are accentuated by agricultural activities including tropical deforestation and biomass burning, plowing, drainage of wetlands and low-input farming or shifting cultivation. In addition to its impact on decomposition of SOM, macroclimate has a large impact on a fraction of the SOC pool which is active. Conversion of natural to agricultural ecosystems increases maximum soil temperature and decreases soil moisture storage in the root zone, especially in drained agricultural soils (Lal, 1996). Thus, land use history has a strong impact on the SOC pool (Pulleman et al., 2000). The dynamic relationship between plant biodiversity and SOC depicts that any land use practices that increase vegetative cover, or reduce its removal, could have an influence on the global carbon budget by increasing the terrestrial carbon sink.

Introduction

The inevitability of detrimental effects of climate change is looming large not only on the sustenance of agriculture, but also on the survival and progress of mankind. Estimates by the Organization for Economic Cooperation and Development (OECD) reveal that the atmospheric concentration of GHG would exceed 680 parts per million (ppm) CO₂-equivalents by 2050, which is about 50% higher than baseline year 2010 (OECD, 2012). Additionally, global temperature is predicted to increase by 2°C within this period, resulting in meansea level rise and erraticweather conditions. Consequently, the catastrophic effects on food consumption pattern by the end of 2050 will create malnutrition in at least 290 million people. Agricultural crops provide 63% of the human protein, and additionally supply almost 100% protein to the livestock, which are the second major sources of protein in human diet. Altogether, the detrimental effect of climate change on agriculture would make about 300 million additional people malnourished. Add to that a 2.7 billion increase in human population by 2050, coupled with shortage of water availability that would affect 3.9 billion people by 2050, and one can easily perceive the grim scenario for our kind in not so distant future.

Introduction

The basic needs of life are food, clothing and shelter. In the 21^st century a fourth need added to mankind is energy. According to the laws of physics, energy is defined as capacity to do work. Energy, economics and the environment are mutually dependent. Also, there is very close relationship between agriculture and energy. The level and pattern of energy use in agricultural production system depends on variety of agronomic and socio-economic factors. Energy use in agriculture encouraged maximization of yields from limited available arable land, minimization of labour intensive operations and improving standard of living. Efficient and effective energy use in agriculture is one of the conditions for sustainable agricultural production, since it provides financial savings.

Introduction

India agriculture is now at turning point as we have travelled a long way after the advent of green revolution. Over the past four to five decades our strategies, policies and actions were guided by goals of ‘self-sufficiency’ in foodgrains production via green revolution. Indian agriculture has been successful in achieving increased food grains production albeit at a low level of satisfaction. While the mission of increasing foodgrains production stands somehow achieved, these gains were accompanied by widespread problems of resource degradation and high factor productivity, which now pose a serious challenge to the continued ability to meet the demand of an increasing population and lifting our people above the poverty line (Tan et al., 2010). Indian agriculture has reached a point where it must seek new directions – those by way of strategies, policies and actions which must be adopted to move forward addressing sustainable intensifications. The past strategies to increase food grains production, however, have resulted in massive exploitation of natural resources, contributing to unsustainable growth; there is need to change this approach in the future. This will call for strategies, which are different than the ones we adopted in the ‘green revolution’ era. High levels of fertilizer use and decreasing resource use-efficiency are increasingly contributing to groundwater pollution and increased emissions of green-house gases (GHGs) (Gupta, 2004). High level uses of pesticides in many areas have become a major health hazard. Thus, with continuously deteriorating resources, widespread problem of soil and water contamination and eroding ecological foundation, sustainability of agriculture is becoming highly questionable (Conway and Barbier, 1990). There is need to seriously debate on the strategies required to ensure that agriculture continues to play a critical role in the overall development.

Introduction

Conservation tillage is a model of sustainable agriculture as it leads to profitable food production while protecting and even restoring natural resources. Conservation agriculture benefits farmers because it reduces production costs and increases yields, but it also has positive impacts on the whole society: enhancement of food security thanks to a better soil fertility, improvement of water quality, reduction of erosion and mitigation of climate change by increasing carbon sequestration. Conservation agriculture (CA) systems are also less sensitive to extreme climatic events and therefore contribute to the adaption of climate change and the resilience of agricultural systems. Hence, CA becomes a fundamental element of sustainable production intensification, combining high production with the provision of environmental security.

CA is based on healthy functioning of the whole agro-ecosystem with a maximum attention and focus on the soil. The soil is the entry point and it has to be considered not only as simple physical support to roots and plants, but as a living entity with its physical, chemical and biological characteristics. The focus of CA embraces not only the nutrient contents of the soil but also its biological and structural status, which are determinants of sustained productivity.

The paradigm of CA is that an undisturbed soil has the opportunity to develop and produce healthier plants. Soil life can develop in a stable habitat in quantity and quality better than on tilled soils, the structural integrity of soil is maintained, so continuous vertical macro-pores are not destroyed and remain as drainage channels for rainwater into the soils. Seeding under conditions of minimum soil disturbance is achieved by direct seeding through the mulch cover without tillage.

Introduction

The main aim of conservation agriculture is to sustain and improve the crop productivity and to provide protection against biotic and abiotic stress, while at the same time protecting and enhancing the biological activities of the soil. The essential principles of conservation agriculture are no-tillage (and direct seeding) or reduced tillage, the maintenance of a cover of live or dead vegetative mulch on the soil surface and the wise use of crop rotations. The crop sequences are planned in such a way that which will discourage the buildup of pests or diseases and will help to optimize plant nutrient use by synergy between different crops of the rotation. While deciding the crop rotation, the locally important crops should be considered and there should be deep rooted and shallow rooted crops in the sequence so that the utilization of soil nutrients is maximized. At least one leguminous crop should be there in the crop sequence. The use of plant residues influences the soil physical, chemical and biological properties by reducing surface temperature, rate of evaporation and maintaining water content, nutrient load and rate of organic matter decay. The soils under conservation agriculture are happened to be highly active and diverse biologically and can supply plant nutrients for a longer period of time because of their higher nutrient loading capacities.

Soil biodiversity comprises of all organisms whether single-cell organisms or multi-cell animals or plants that live in the soil. Soil microbial diversity includes “genetic diversity, that is the amount and distribution of genetic information within microbial species, diversity of bacterial and fungal species in microbial communities, and ecological diversity, that is variation in community structure, complexity of interactions, number of trophic levels and number of guilds (Nannipieri et al., 2003).

Introduction

There is a widespread degradation of natural resource, e.g., soil erosion, nutrient loss, water-logging, salinity, alkalinity, acidity, decline in soil organic carbon (SOC) content, ground water depletion and micronutrient depletion. The major causes are washing away of topsoil and organic matter due to water erosion, intensive deep tillage and inversion tillage, dismally low levels of fertilizer application, mining and other commercial activities, faulty agricultural practices, no or low use of organics, indiscriminate use of herbicides, pesticides, fungicides etc. Other cause is loss of organic matter with higher temperatures, which increase rate of microbial decomposition of organic matter due to adverse effect of climate change. Climate change due to global warming as a result of increased concentration of GHGs in the atmosphere is a well-established fact. Impacts of climate change are experienced throughout the world. Increases in global mean temperature, rise in sea-level, and occurrence of extreme events are the consequences of climate change. These changes may deplete the SOC pool and soil structural stability, increase soil’s susceptibility to water runoff and erosion, disrupt cycles of water, carbon, nitrogen, phosphorus, sulphur and other elements, and cause adverse impacts on biomass productivity, biodiversity and the environment. Climate change is likely to have a variety of impacts on soil quality. In order to restore soil quality, enhance productivity, it is of utmost importance to focus on conservation agriculture practices on long-term basis. Conservation Agriculture (CA) is gaining importance as an alternative to conventional agriculture.