eChapters

In this method, plant available sulphur (S) is extracted with 0.15% CaCl₂ and the soluble sulphate is estimated on a colorimeter.

Introduction

Agricultural lands in India have mostly low native soil fertility. On these soils there must be a regular application of nutrient inputs through chemical fertilizers and/or organic manures for a successful and sustained crop production to replenish soil nutrient reserves depleted by crop removal and other losses. It is essential to recognize that even in agricultural production systems with relatively low productivity level, the quantity of nutrients available for recycling through plant and animal residues is not enough to compensate the amount being removed by crops. Under these circumstances mineral fertilizers play a key role in those areas having low fertile soils by increasing agricultural production to meet out growing food demand. Chemical fertilizers are the major contributors as source of plant nutrients to enhance crop production and also to maintain soil productivity.

The influence of water quality on the soil and plant growth is related to the chemical and physicalproperties of the soil, the salt tolerance of the crop, the climaticregime of the area and the method,frequencyand the amount of irrigation water applied. Irrigation water quality refers to its suitability and sustainability for use in agricultural crops. The problems thatresultfrom the use of a particular irrigation water, vary both in kind and degree, and are modified by soil, climate and crop as well as by the skill and knowledge of the water user. As a result there is no set limiton water quality, rather itssuitability for use is determined by the conditions of use which affects the accumulation of water constituents andwhichmayrestrictcrop yield.The soilproblems mostcommonlyencountered and used as a basisto evaluate water quality are those related to salinity, water infiltrationrate,toxicityanda group of other miscellaneous problems. Numerous guidelines are available for evaluation of water quality. Time to time some of theseguidelines has been updated with modification of some criteria like SAR to Adj. SAR and the Adj. R_Na and development of new concepts like water qualityIndex (WQI) whichhave increasedour predictability. Thenewguidelines are relied heavily on old ones.The modified guideline by Ayers and Westcot (1985) was foundto be themost reliabletopredict thewaterqualityforirrigation.

Irrigated agriculture is playing a major role in enhancing food and livelihood security of a country. Supply of fresh water which is an importantinput for the sustainable and economic development of agriculture are not enough to meet the requirement of all sectors of economy. Reduced water availability to agriculture from the present share of 85% of country’s water resources to about 70-75% by 2020AD wouldaffect the capacity of the country to meet the food production target, unless supplies are augmented from unconventional sources. For future agriculture there are no alternatives but to rely on non conventional sources for partial alleviation of the forecasted water scarcity. Amongthese sources extraction of marginal quality groundwater and the waste water generatedfromurban and industrial activities have thepotential to augment the water supplies. Many associatedsoil, plant and environmental problems come up when these sources of water are directly used for irrigation. For addressing theseproblems and to get more benefit from thesesourcesof water, the first step is to understand how an irrigation water source affects the soil plantsystem.Thereforeknowledge of irrigationwaterqualityiscriticaltodevelop appropriate site and crop specific comprehensive short term and long term management programs.

The basic philosophy of nutrient management should be to apply fertilizers at rates to ensure high fertilizer use efficiency so that the amount of unutilized fertilizers is reduced to environmentally acceptable levels. Leaching of nitrate into public drinking water supplies has become a national problem. There is no realistic alternative but to use increasing quantities of inorganic fertilizers for maintaining food supplies in order to feed the increasing population. Used properly, fertilizers can, in fact, lead to better environment because greater vegetative growth and higher crop yields leave large quantities of residues in the soil, thus reducing erosion; absorb more carbon dioxide, a major source of green house effect and lessen the need to bring marginal and forest land into cultivation. The declining or stagnating yield trend in India has been attributed to multiple nutrient deficiencies and imbalance of nutrients. Therefore, the most widely recognized alternative is integrated nutrient management (Trehan et al., 2008).

Soil test based fertilizers is the maintenance of soil fertility and plant nutrient supply to an optimum level for sustaining the desired productivity through optimization of the benefits from fertilizers, organic manures, green manures, bio-fertilizers, non-conventional sources and crop residues. Soil test based fertilizers  aims at maximization of the use efficiency and minimization of the avoidable losses of nutrients from all the sources such that triple objective of maximization of crop yields, sustenance of soil, water and air quality and improvement of socio-economic conditions of farming community is accomplished.

Instrumental methods of chemical analysis are the quantitative methods of analysis that use, as principal measuring devices, instruments other than those employed in conventional gravimetric and volumetric determinations.

The main basis for this method of analysis is the physical property of any particular element or compound being analyzed. These properties include:

Soil chemical properties determine the availability, retention and movement of nutrients and strongly influence plant growth under irrigated conditions. This chapter introduces the fundamental chemical characteristics of soils, with particular emphasis on exchangeable bases, cation exchange and anion exchange. Cation exchange capacity (CEC) is discussed as an important indicator of the soil's capacity to retain and exchange nutrient cations. The chapter explains the principles and reactions involved in cation exchange, cation selectivity and the determination and expression of CEC. Relationships between CEC, soil pH and particle size are also considered, together with the concept of base saturation. These properties are important for understanding nutrient availability and fertilizer management in different soil types. The chapter further introduces the mechanism of nutrient uptake by plant roots, linking soil chemical reactions with plant nutrition. Understanding these processes provides an essential basis for managing soil fertility, improving nutrient-use efficiency and maintaining productive irrigated soils.

Microbiology is the scientific study of microorganisms, including bacteria, fungi, algae, protozoa and viruses, and their interactions with plants, animals and the environment. Microorganisms are microscopic in size but have enormous importance in agriculture, food production, environmental management and biotechnology. In agricultural systems, microorganisms contribute to decomposition of organic residues, nutrient cycling, soil fertility, plant growth and suppression of harmful organisms. Beneficial microorganisms also form associations with plant roots and improve nutrient availability and plant health. At the same time, certain microorganisms cause plant diseases, food spoilage and environmental contamination. Agricultural microbiology applies the principles of general microbiology to understand these beneficial and harmful activities in farming systems. This chapter introduces the scope and importance of microbiology, major groups of microorganisms, basic laboratory concepts and their applications in agriculture. An understanding of microbial structure, metabolism, diversity and ecological functions provides the foundation for studying soil microbiology, plant–microbe interactions, biotechnology and environmental remediation.

6.1 Soil

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. 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.

Introduction

In chemical laboratories, the use of acids, alkalis and some hazardous and explosive chemicals is unavoidable. In addition, some chemical reactions during the analysis process may release toxic gases and, if not handled well, may cause an explosion. Inflammable gases are also used as a fuel/heating source. Thus, work safety in a chemical laboratory calls for special care both in terms of the design and construction of the laboratory building, and in the handling and use of chemicals.

For chemical operations, it is also necessary to provide special chambers. The air temperature of the laboratory and work rooms should be maintained constant at 20–25°C. Humidity should be kept at about 50 percent. Temperature and humidity often affect soil and fertilizer samples. Temperature also affects some chemical operations. Hence, maintaining the temperature and humidity as specified is critical.

3.1 Introduction
Since the dawn of humanity, the expansion of invention and technological innovation has made it possible to make a variety of goods to meet its needs. To get a competitive edge in the market, the manufacture of a product has three main goals, viz. efficient product planning, efficient manufacturing, and effective cost control.
These can be achieved through a random thinking, if the designer is fortunate to have the best design of a product of interest, which satisfies the needs of its customers. But it will rarely happen. Design thinking maximizes the possibility of happening of the best design in the journey of design a product in shorter possible time.
Design thinking, an emerging field in this direction, tries to create a product by utilizing the following steps.
i. Empathize
ii. Define
iii. Ideate
iv. Prototype
v. Test
3.2 Definition of Design Thinking
A design methodology called “Design Thinking” offers a problem-based approach to problem solving. By understanding the human needs which changes quickly, re-framing the issue in human-centric ways, generating a lot of ideas during brainstorming sessions, and taking a hands-on approach during prototyping and testing, design thinking is incredibly helpful in handling complicated challenges that are ill-defined or unknown. Anyone can use the Design Thinking approach to tackle complex problems that arise in our society, such as those in our businesses, governments, and other spheres of influence, if they have an understanding of these five steps of the process.

8.1. Law of Mass Action

Gulberg and Waage, the two Norwegian chemists in the year 1864 stated the law of mass action in this form: ‘The velocity of any chemical reaction at any instant at a given temperature is proportional to the active mass of each of the reactants at that instant present in the system, the active mass in a homogeneous system is defined as the number of gram molecule of the substance present per unit volume i.e., the molar volume’.

Mathematical Formulation of the Law of Mass Action

Let us take a simple case of a reversible reaction at constant temperature represented by the equation:

Soil sampling is an integral and essential component of soil fertility evaluation and nutrient management research. The effectiveness of soil sampling is a prerequisite for soil testing to achieve its goals for efficient nutrient management and plant nutrition for improved yield and quality. The underlying basis for soil sampling is that a soil sample taken represents the “population” which may be a plot, field or a watershed. It further implies that nutrient status of the representative soil sample(s) determined in a laboratory would reflect nutrient status of a plot, field or watershed and is of interest for correcting nutrient disorders in the field or watershed.

The most important factor that influences the effectiveness of soil sampling is soil heterogeneity. However, in a relatively homogenous group of fields or plots, a small number of samples may be sufficient to represent the population to a more heterogenous group of fields that would require more number of samples to represent the soil population. Whenever, soil samples to be taken in field following points needs to be kept in mind.

Bio Control Agents explains how natural enemies can suppress agricultural pests and diseases through predators, parasitoids, and pathogens. It traces the historical development of biological control from traditional practices to major scientific successes and institutional development in India. The chapter describes introduction, augmentation, and conservation strategies, followed by detailed accounts of predators, parasitoids, and pathogenic microorganisms. Important bioagents, their characteristics, mechanisms, field applications, and mass-production methods are discussed, including Trichogramma, Chrysoperla, Cryptolaemus, Beauveria, Metarhizium, Trichoderma, Bacillus, and viral agents. The chapter provides a practical foundation for integrating biological control into environmentally responsible crop protection programs. across diverse farming environments and practical field implementation practically.

All organisms require the six elements CHNOPS in sizable quantities, and that these minerals may occur in different forms. Depending on whether the local environment is aerobic or anaerobic, the exact chemical form of any of these elements may change quickly and drastically. Example: : If the soil becomes waterlogged and anaerobic, sulfate will be converted into hydrogen sulfide and nitrate into nitrogen gas or ammonia (via anaerobic respiration). As the water recedes and the soil becomes aerobic again, the ammonia is oxidized back to nitrate in stages. All of this (and many other processes) occur largely because of the activities of soil microbes. Without these microbes, life as we know it would not occur because necessary elements would remain tied up in unusable chemical forms and gradually be removed by sedimentation. To maintain the level of these components it is essential that they undergo a regular process of recycling. Different microorganisms bring about this process of recycling through various transformations.

Carbon Cycle

The most important element in the biological realm and substance that serve as the cornerstone of the cell structure is carbon. It constituents about 40-50% of all living organisms, yet the ultimate source is the CO₂ that exists in a perennially short supply, only 0.03% of the earth’s atmosphere, which undergoes a cyclic change from an oxidized to reduced state. The concentration of carbon in living matter (18%) is almost 100 times greater than its concentration in the earth (0.19%). Hence, living things extract carbon from their non-living environment. For life to continue, this carbon must be recycled. Carbon exists in the nonliving environment as carbon dioxide (CO₂) in the atmosphere and dissolved in water (forming HCO₃") carbonate rocks (limestone and coral = CaCO₃) deposits of coal, petroleum, and natural gas derived from once-living things dead organic matter, e.g., humus in the soil. Carbon enters the biotic world through the action of autotrophs: primarily photoautotrophs, like plants and algae, that use the energy of light to convert carbon dioxide to organic matter through photosynthesis and to a small extent, chemoautotrophs - bacteria and Archaeans that do the same but use the energy derived from the oxidation of molecules in their substrate.

Bio-Inputs introduces the concept, scope, and functional diversity of biological inputs used in sustainable agriculture and natural farming. The chapter classifies bio-inputs by core components, including microorganisms, biological extracts, and biomolecules, and then by functions such as bio-fertilizers, bio-stimulants, biomejorators, and biological control agents. It also presents microbial and biological inputs within Integrated Pest Management, emphasizing biopesticides, biofungicides, and plant-defense elicitors. Examples such as Rhizobium, Trichoderma, Bacillus, Pseudomonas, seaweed extracts, vermiwash, neem extracts, and oligosaccharins illustrate how biological resources can improve nutrient availability, plant growth, crop protection, stress tolerance, and ecological sustainability. in contemporary agricultural practice. for sustainable crop production.

Introduction

Soil plays a vital role in fulfilling fundamental human requirements, such as the provision of sustenance and water, while also serving as the primary medium for supporting biodiversity. The sustainability of soil in the 21st century is dependent upon not only the implementation of effective management practices by farmers, foresters, and land-planners, but also on government regulations, policies, marketing strategies, and subsidies (Mishra et al., 2017). The increasing influence of human activities on the Earth’s natural environment has led to significant global challenges concerning the interplay of planetary and public health (J. Huang et al., 2018).

The synthesis of humic substances is the least understood and the most intriguing aspect of humus chemistry. This has been one of the intensely- researched subjects for a long time. Formation of humic substances takes several pathways during the decay of plant and animal remains in soil and the four important ones are shown in Fig. 8.1.

Fig. 8.1: Mechanisms for the formation of soil humic substances

The classical theory by Waksman advocated humic substances as modified lignins (Pathway 1), but a vast majority of current crop of investigators favour a mechanism involving quinones (Pathways 2 and 3). Including sugar-amine condensation pathway (Pathway 4), all the four pathways must be considered as likely mechanisms for the synthesis of humic and fulvic acids in nature. It is absolutely possible that these four pathways may operate in all soils, though not to the same extent or in the same order of importance. 

Bioclimatology examines relationships between climate and living organisms, including crops, livestock and humans. It draws on biology, ecology, meteorology, architecture and physiology to explain how temperature, humidity, radiation and wind influence development, comfort, health and productivity. This chapter introduces bioclimatic indices such as the Temperature-Humidity Index, Humidex, wind chill and thermal-comfort measures. Agricultural applications include crop and livestock suitability, heat-stress assessment, housing design, work planning and development of resilient farming systems. Understanding biological responses to climatic conditions supports appropriate management interventions and helps protect productivity and welfare. Bioclimatic analysis therefore connects atmospheric conditions with practical decisions involving plants, animals and people.

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”.