eChapters

6.1 general description

Between 13,000 and 3,000 BC, Neolithic period, mountain people in Asia, Africa, and Latin America have practiced shifting cultivation (Mazoyer and Roudart 2006). A cultivation phase, consisting of removing forest and crop production for 1 to 3 years, is followed by a fallow phase, in which agriculture is discontinued to allow soil nutrients to recoup (Conklin 1961). Conklin (1961) distinguished between total and partial shifting cultivation. Pioneer shifting cultivation, in which primary or apex forest is cleared annually, and replaced by shifting cultivation, which entails clearing mostly secondary forests, are both essential forms of cultivation that are primarily practised for farmers' subsistence. Partial shifting cultivation, on the other hand, is done as a supplemental or temporary activity (Conklin 1961). Throughout history, indigenous peoples have used fire to manage their land and natural resources. Pastoralists and hunters-gatherers in Africa's savannas, for example, have used fire to preserve the ecosystem's productivity for livestock and game for millennia (McClanahan and Young 1996). In pre-colonial times, indigenous peoples in North America also significantly altered the landscape, establishing and preserving pastures and open forest savannas through regulated burning (Pyne 1982, cited in: Schneider 2000).

Herbicides degrade over time. The persists of herbicides is dependent on several factors including light, temperature, and substrate moisture. Several processes are responsible for herbicide degradation and include the following:

    1.    Photodegradation: The decomposition of herbicides caused by duration or intensity of sunlight is called as Photodegradation. Photodegradation occurs when ultraviolet (UV) light breaks chemical bonds of the herbicide active ingredient. Secondary molecules resulting from the cleavage of the parent molecule are generally less effective in providing weed control. Herbicides such as Monuron, Trifluralin, PCP, Chloramben etc are prone to photodegradation. So these herbicides should be applied in evening or incorporated in to the soil just after application in order of avoiding photodegradation.

Biological activity or index of a soil is the function of number of organisms present in soil and their physiological efficiency. The rate of respiration can be used as an index of the biological activity of soil as it reflects the physiological efficiency of the organisms. Monitoring of dehydrogenase, which are respiratory enzymes and integral part of all soil organisms, will give a measure of biological activity of soil at a given time.

During respiration biological oxidation of reduced compounds occur which is catalyzed by dehydrogenase. In the process TTC gets reduced to a pink coloured compound Triphenyl formazan (TPF) which can be quantitatively extracted by methanol and measured colorimeterically. The soil dehydrogenase activity in the current experiment was measured as per the methods of Cassida, (1977).

13.1. Introduction

The Delphi technique is a systematic, interactive forecasting method that involves gathering expert opinions to make informed decisions, predict future trends, or address complex problems. The core idea behind this technique is to use the knowledge and insights of experts in a structured manner to produce well-informed and reliable outcomes. By combining expert judgment with iterative feedback, the Delphi method allows for deeper analysis, greater accuracy, and a better understanding of complex issues that cannot be easily solved through traditional data analysis or quantitative methods (Ismail and Taliep, 2023).

Originally designed for defence-related forecasting, the Delphi technique has since evolved into a versatile tool used across a wide range of fields, such as business, healthcare, education, public policy, environmental science, and social research. Its versatility stems from its ability to gather expert opinions in a manner that allows for rigorous analysis of complex issues, without the constraints of traditional group meetings or face-to-face discussions.

Introduction

Food security problem has multiple dimensions that range from ensuring the food supply at global, country and local levels to create its effective demand round the year. The ultimate goal of an effective food security policy is to provide individuals with adequate dietary requirements through availability and accessibility of food, which are necessary conditions for nutritional well being. The level of food security existing in a country, however is a complex interactions, operating at different levels from the macro to the micro level. The components of the system would include international trade and macro policies, the agricultural sector, the market economy, consumption pattern, the micro economy or household income, urban-rural differentiation and gender issues, etc.

Food insecurity is a complex issue having several dimensions such as, poverty, unemployment, famine, gender discrimination, inequity, starvation, food and nutritional practices, for human growth, natural calamities and so on. Poverty has been recognized globally both as a cause and consequence of food insecurity. In the mid 1980s, 72 per cent of the world’s poor and 66 per cent of the world’s extremely poor lived in the Asia-Pacific region. In this region, 272 million people would suffer from chronic malnutrition during the next decade i.e. in the year 2010. In Asia-Pacific region, India alone has 204 million undernourished people, which is quite alarming when compared with neighbouring countries like China, which has only 164 million undernourished people despite being much populous than India. World Health Organization (WHO) report (1998) points out that health expectancy is more important than life expectancy. The impact of poverty and malnutrition on health has widened the gap between the rich and the poor.

Abstract

Population of Rajasthan as per Census 2011 is 68,621,012 persons which is much higher than census 2001 that records 56,507,188. It includes 12 districts of Rajasthan. Western Rajasthan covers about 61% area of the total geographical area and 39.51% population of the total population of the Rajasthan. The growth rate of population is much higher than that of the Rajasthan State. In the census 1981 Western Rajasthan had registered a phenomenal increase of 35.48 per cent over 1971 population. Regional pattern of growth rate in western Rajasthan shows that extreme hot arid region district (Barmer) is on top having 32.55 per cent growth rate whereas Indira Gandhi Canal Region (Ganganagar) district has least population growth of 10.06 per cent only. In 1981, the average urban growth rate had been 54.52 per cent. In 2001, the rural density of population was 83 persons per sq. km.

Introduction

The various reactions of nitrogen (N₂) cycle, transform one form of the element to another. Mineralization liberates nitrogen in inorganic form, immobilization converts its back to an unavailable state, while nitrification changes the nitrogen from a reduced to oxidized state. Certain transformations of nitrogen lead to a net loss of element from the soil through volatilization. For the purpose of crop production, nitrogen volatilization has a deleterious influence because it depletes part of soils reserve of an essential nutrient. The sequence of steps that results in gaseous loss is called denitrification. So denitrification refers to the reduction of nitrates and nitrites to gaseous nitrogen products, principally di-nitrogen and nitrous oxide, coupled to energy production through oxidative phosphorylation.

10.1 Introduction

Biomass fuels are a potential source of renewable energy. One of the major barriers to their widespread use is that biomass has a lower energy content than traditional fossils fuels, which means that more fuel is required to get the same amount of energy. When combined — low energy content with low density -the volume of biomass handled increases enormously. Compaction or densification is one way to increase the energy density and overcome handling difficulties.

Densification means compaction of loose material or to increase density of loose biomass so that its volumetric efficiency can be increased. Densification essentially involves two parts; the compaction under pressure of loose material to reduce its volume and to agglomerate the material so that the product remains in the compressed state. The resulting solid may be a briquette, a pellet and a cube. It will be briquettes if roughly, it has a diameter greater than 30 mm. Smaller sizes are normally termed pellets though the distinction is arbitrary. The process of producing pellets is also different from the typical briquetting processes. The densified product can be developed in the cubical shapes as well.

If the material is compacted with low to moderate pressure (0.2-5 MPa), then the space between particles is reduced. Further, increasing the pressure will, at a certain stage particular to each material, collapse the cell walls of the cellulose constituent, thus approaching the physical, or dry mass and more, density of the material. The pressure required to achieve such high densities are typically 100 MPa plus. This process of compaction is entirely depending on to the pressure exerted on the material and its physical characteristics including its moisture content.

3.1 Determination of Bulk Density of Soil

3.1.1 Determination of Bulk Density of an undisturbed Soil

Bulk density of soil is expressed as the ratio of the mass (weight) of soil particle to their total volume including the pore space between the soil particles. Alternately, it is the weight of unit volume of dry soil. It is usually expressed in the unit of gram per cubic centimeter (g/cc) or mega gram per cubic meter (Mg/m³). In fine textured soil bulk density varies from 1.00 to 1.60 g/cc, whereas in coarse textured soil from 1.20 to 1.80 g/cc.

3.1. Determination of Bulk Density of Soil

3.1.1. Determination of Bulk Density of an Undisturbed Soil

Bulk density of soil is expressed as the ratio of the mass (weight) of soil particle to their total volume including the pore space between the soil particles. Alternately, it is the weight of unit volume of dry soil. It is usually expressed in the unit of gram per cubic centimeter (g/cc) or mega gram per cubic meter (Mg/m³). In fine textured soil bulk density varies from 1.00 to 1.60 g/cc, whereas in coarse textured soil from 1.20 to 1.80 g/cc.

This chapter contains the description of the Indigenous Traditional Knowledge practices as subject wise manner viz, Traditional varieties, Crop management, Crop protection measures, Post harvest methods, Storage structures, Farm tools, Medicinal plants, Ethnoveterinary practices, Fisheries and others related to agriculture.

Introduction

Desert soils are the soils of arid regions that remain dry for most part of the year and support sparse xerophytes. The amount of water received by precipitation is far less than what is lost by evapotranspiration. Most deserts receive an average precipitation of less than 400 mm. Because of extreme imbalance between evapotranspiration and precipitation, many desert soils contain salts.

Distribution

Deserts occupy about one-third of the areas of Africa and Australia, 11% of Asia and about 8% of the Americas (Boul et al. 1997). Desert soils include both cold and hot desert. In India, desert soils occur in three agro-ecological regions (AER). The cold arid desert of extreme north (Leh, Ladakh region of Jammu & Kashmir ), the hot arid desert of north western India (Rajasthan, southern parts of Haryana and Punjab and northern parts of Gujarat) and the tropical arid desert of the Deccan plateau in South India represents AER 1, 2 and 3, respectively. The three different desert regions in India have characteristic climatic and soil conditions.

Introduction

Low and erratic precipitation, diurnal fluctuations in temperature and low humidity are the typical characteristics of deserts and their margins. Further, strong winds, sunny and very bright days and unpredictable periods of drought and famines are regular features. These lands are poor in fertility. Uninterrupted increase in human and animal pressures is violating carrying capacity of the natural resources, thus resultant is desertification.

Arid zones are described as a part of the drylands, and have the most severe edapho-climatic conditions. The major distinguishing feature for defining and for planning for the arid zone is the low rainfall (below 500 mm or Aridity Index <0.20) with more than 50% inter-annual variability. This makes a great difference in terms of the nature of the ecosystem, the socio-economic environment and the challenges for sustainability. High wind and solar regimes further increase the effect of rainfall variability and the whole complex makes a fragile ecosystem in which small disturbances may cause great loss to the sustainability, which are sometimes irreversible (Hou’erou, 1996). The hot arid zones of the world are economically and environmentally disadvantaged, with unique problems. The ecosystems of these zones are highly fragile with large risks that cause severe impediments to development programs. Of the total land area in the world, arid zones cover 18.8% and the hyper-arid zones account for 22.3% of the total arid zones (FAO, 1989).

Abstract

Burkina Faso is a landlocked country in West Africa with a dry tropical climate characterised by a short rainy season and a long dry season. The annual rainfall varied between 300mm in the northern part of the country to 1200mm in the meridian part. Since many years, the degradation of climatic conditions is observed. Therefore, the annual rainfalls of the 1971-1981 period were inferior to those of the precedent periods, and also the deterioration of the climatic conditions led the limits of some ishoteques “isohyète” to move southward, more than 50km farther. Furthermore, the decennial rainfalls since 1920 were subjected to a latitudinal displacement to the south. For example the ishoteque “isohyète” 500mm which were located at the North of the 15°N outside Burkina Faso during the years 1950-1960 moved gradually year by year and reached the 14°N during the years 1970-1980 inside Burkina Faso.

Abstract

Conversion of an already arid land into a desert through indiscriminate human actions magnified by droughts. Such actions include overgrazing, repeated burning, intensive farming, and stripping of vegetation for firewood. One quarter of the earth’s surface is threatened by desertification - an area of over 3.6 billion hectares. Since 1990, Six million hectares of productive land are lost every year due to land degradation. Desertification threatens the liveihoods of more than one billion people and has already made over 135 million people homeless. Desertification does not occur in linear, easily mappable patterns. Deserts advance erratically, forming patches on their borders. Areas far from natural deserts can degrade quickly to barren soil, rock, or sand through poor land management.

Concept and Definition

Desertification is a major problem in the drylands of India, affecting the way of life for its inhabitants. The problem is more severe in the arid lands in the northwestern part of the country. There have been a few numbers of definitions of the word “Desertification”. However for simplicity of its origin and meaning we would refer to two of the frequently used ones; (1) proposed in 1991 by UNEP: “Land degradation in arid, semi-arid and dry sub-humid areas resulting mainly from adverse human impact and (2) prepared for the Earth Summit at Rio, held in June 1992, for inclusion in Agenda 21, as “Land degradation in arid, semi-arid and dry sub-humid areas resulting from climatic variations and human activities. (Anonymous 1992).

Comparing two of these initial definitions, it would show that first one indicated desertification as a state of natural resources like soil and vegetation, mainly resulting from human activity while the second one included climate as a major cause. However, it reduced the emphasis of human activities as being the primary responsible factor and tried to link the possible impact of climate change on desertification. But the simplicity of the 1992 definition of desertification helped researchers to bring in sharp focus on the special environmental and socio-economic problems of the drylands.

So over the years, the key words that explains the term “desertification” has been changing or are being amended for specific purposes. This would at least mean that the problem of desertification is still debated world-wide, and its impact is not limited to some nations/regions as was presumed and discussed in first of UNCCD platforms. Therefore, as a precaution and combating this process, few catchy words like non-sustainable management, productivity, over-exploitation of natural resources, dryland livelihood, droughts are found to surround the word desertification. Earlier, some, people equated desertification with advancing boundaries of the existing desert and in India, examples of expansion / contraction of geographical boundary of Thar desert was a public debate among various researchers and planners. In the same time, some of the definitions tried to broaden its geographical scope so that greater populations suffering from adverse effects of land degradation would benefit out of various remedial measures.

Introduction

Desertification is now accepted as a major environmental issue because of the fact that 69.5 percent area of the world’s dry lands and more than 1.2 billion people in over 110 countries living in this habitat are affected by various land degradation processes. During last 20 years, researchers have focused their discussion either on a condition or a cause or a set of processes to assess different paradigms of desertification. Several studies carried out in arid western part of Rajasthan (Singh et al., 1992, Kar, A. 1993b, Kar, 1995, Dregne, H.E. 2000, Kar et al.2007) show that wind erosion is still a major problem. Though, there are many instances of location specific problems like water erosion, salinity/ alkalinity and water logging, about 75% area in arid western Rajasthan is affected by wind erosion hazard of different intensities (SAC, 2007, Kar et al. 2009). Decreasing rainfall gradient from east to west and increasing wind strength in that direction are responsible for the spatial variability in sand reactivation pattern. Water erosion in the form of sheet, rill and gully erosion is a major problem in areas, where average annual rainfall exceeds 350 mm, the rainfall intensity is high and the topographic and soil characteristics favour high run-off. Destruction of vegetation cover and excessive ploughing of shallow soils, especially on the sloping lands, accelerate the problem.

Introduction

Desertification, which is considered a major threat in the drylands of the world, is not about advancing boundaries of the existing deserts, but about land degradation in the arid, semi-arid and the dry sub-humid regions, which together form the drylands (Anon., 1995). Secular variation in climate that has resulted in periodic expansion and contraction of the desert boundaries and regional-scale changes in vegetation condition (Tucker et al., 1991; Nemani et al., 2003; Hickler et al., 2005) is one of the drivers of desertification. Human activities constitute the other major driver. According to Geist and Lambin (2004) the prominent core variables that drive degradation are climatic, economic, institutional, national policies, population growth and remote influences.

We let you know that the type of people in a given region is closely linked to the kind of resources found in the concerned region; and which are necessary for human beings to survive.

In fact, more than 100 countries possess arid lands, where more than 40% of the global population lives. The soils of these regions present too much fragility and they are too degraded that they can’t allow people to survive.

Let’s emphasize that in Africa, two third of the total area are arid zones. Thus, for Africans, the type of their struggle for adaptation to the context of their land, illustrates their ingenious capacity to model their hostile surroundings and to leave marks of their cultures all over prehistory and history.

Social organizations in those arid areas are closely linked to modes of exploitation and valuation of resources (water and land). However, human productions in those areas are doubly menaced; on one side by the action of humans who exploit resources for their immediate needs, and on the other side, by climate adverse effects during long periods of drought. It means that climate change and violent meteorological phenomenon worsen circumstances. That leads to environmental degradation and biodiversity reduction; alarming deterioration of vital conditions; and intensification of poverty, both in rural and urban areas; particularly among women and young. Consequently, there are non durable (viable) agricultural practices, overexploitation, overgrazing, excessive and illegal forestry exploitation; destruction of forests and bushes by non-controlled fires, pillages and conflicts with weapons; reduction of vegetation, due to the scarcity of rain; of water in general and menaces of heaps of sands.

1.0 General

 The design of canal involves following three major aspects:

 A Irrigation and drainage canal network planning.

 B Determination of discharge / capacities of  canals and drainages.

 C Determination of shape and size i.e. geometrical dimensions of the proposed canal section, generally

 known as design of canal section. More appropriately it can be called as design of internal section

 of canal. It can be further divided in three following parts viz.

 i. Design of unlined canals:

 ii. Design of lined canals: or a canal may be partly lined and partly unlined.

 iii. Choice between the unlined and lined canals. This aspect should be distinguished from the selection of type of lining. However, the scope of choice of lining may include both the aspects.

 The design of canal section remains incomplete without the design of its embankments, either in lined or unlined canal, so the next aspect is

 iv. Design of canal embankments. Still to complete the design of a canal one more aspect is required i.e.

 v. Canal aesthetics and canal arboriculture.

A canal of approximate discharge of less than 80 cumecs (3000 cusecs) discharge may be called a medium or low capacity canal).

3.1 Mehboob Section

A Mehboob Section is only a modification of best trapezoidal section by making its complete bottom circular as shown in figure 3.1. Also see figure 1.6 and para 1.7. That is why these canals are also known as canals of zero bed width, or trapezoidal canals with curved bottom, or cup shaped canals.

But these cannot be called as triangular canals with curves, as often spoken. In fact it is a truncated triangle circumscribing the semi circle. Trapezium is also a truncated triangle circum scribing a circle.

More accurately it can be said as a combination of semi circular and best trapezoidal section so as to take full advantage of their hydraulic efficiency and practicability.

This is such a beautiful section that the designer can never commit a mistake, even if he wants to commit a mistake. The dimensions are so geometrically fixed that no one can play with any dimension.

The value of this section was realised for the first time by Er S I Mehboob (1943) in his Punjab Irrigation Branch Paper No.260" Lining of Canals". There after this canal section became well known as Mehboob Section after his name. He also stated that the most economical section i.e. the maximum area for the minimum perimeter is when the centre of the arc is at the full supply line of the section. This is also evident in figure 1.6. This is also the condition for all best hydraulic sections. This section is also useful to a higher silt carrying capacity than a wide shallow one..

Abstract

The paper presents the innovation of solar tunnel dryer; it is a walk in type semi-cylindrical poly house framed structure with UV-stabilized polythene sheet, where products on large scale could be dried under controlled environment. Chilly drying in solar tunnel dryer to reduce the moisture content from 83.4 % (w.b.) to about 9 % (w.b.) and Aonla pulp from moisture content of 81 %(w.b.) to safe moisture content 9.5 %(w.b.) successfully dried. 20-30^ºC of higher temperature was obtained in solar tunnel dryer over the ambient temperature, depends on product. In comparison to open sun drying to obtain the same level of moisture contents resulting in a net saving in drying time of 40-50% for solar tunnel dryer over open sun drying.

A. Rectangular Canals

5.1 Design of Best Rectangular Canals

After the Mehboob and Trapezoidal canals, next best section is rectangle. This section is also generally adopted for small discharges say upto 10 cumecs (350 cusecs). This section ranks at No. 4. Yet, this is the only section most commonly adopted for flumes of discharges upto140 cumecs (5000 cusecs). Typical example is Orsang acqueduct, 1 km. long for 1140 cumecs (40000 cusecs) in ractangular sections on Narmada Canal Project, Gujrat, India, built in the years from 1990 – 2000. Such sections are common in power house canals due to limitation of space and very sharp curves. It is free from the effect of change of side slopes as in the trapezoidal canals (see para 3.3) Still some small side slope (batter) is adopted in thick masonry / concrete lining. It adds to structural stability with economy in thickness of wall and as well as hydraulic efficiency. It may still be called as rectangular section.

Details of its hydraulic efficiency in comparison to semi circle, Mehboob and trapeziodal sections are discussed in chapter 1, para 1.8

The pipe network in a drip system consists of a mainline, sub mains, laterals, and distributors. The layout of the pipes depends on the physical factors like shape and size of the area, topography and any other obstacles in the field. In any field there may be the scope of different layout of the pipes. The most economic one should be selected. In general, contour line is followed in laying the laterals in sloping land, sub main length usually be shorten in uphill and equally spaced laterals on either side of a sub main in a flat land provides good layout.

Hydraulic Formulae /Head Losses in Pipes

There are numerous equations for solving the head loss in pipes. The most commonly used are the Darcy-Weisbach, Hazen-William and Scobey’s.

A canal of more than 80 cumecs (3000 cusecs) approximetly may be called as a high capacity canal.

It has already been pointed out in chapter 1, that for the best section of any shape, R is always equal to d/2 only, and such depth is the most optimum depth. But such channels are not always practical or most economical due to many other practical reasons, (see para 4.1 and 6.3) and many times shallower depth then this depth is adopted. Typical examples are lining of existing earthen channels, given in para 6.3.

All the best sections have fixed ratio of dimensions very near to the semi circle. For large discharges, radius of semi circle increases that, means depth of canal as well as velocity increases. But higher velocity is not permissible with every type of lining (see table 2.1 and para 2.3). Similarly depth also has limitation of construction, maintenance, stability of slopes, etc. see example–4.2.

Because of limiting velocities and depth, deeper canal section are not practically feasible/possible. Therefore for large discharges, say more than 100 cumecs, Mehboob or best trapizodal sections are just not possible/practical, and recourse has to be taken to trapezoidal section with increased bed width then depth. This section is hydraulically inefficient or uneconomical. Larger the B/D ratio, larger is the inefficiency and section is more costly. (For Mehboob Section, B:D ratio is zero and for best trapizodal section it is much less than 1, see para 3.1, table 3.1 para 3.5 and table 3.4).

Kaushik Kumar

Design Thinking

Design thinking has emerged as one of the skill set in the recent competitive environment.Basic science has been mainly involved in development of various models that fulfills the requirements of engineering domain.

However, the engineering graduates being produced did not possess the required industrial skills and hence were perceived by academia and industrialists as ineligible to be employed in various industries.

12.1 Monitoring Strategies: Pre- and Post-Release
12.1.1 Introduction
Monitoring of genetically modified organisms (GMOs) or transgenic crops is a critical component of biosafety governance. It involves the systematic collection of scientific data to assess the presence, behavior, and potential impacts of transgenic organisms in controlled and natural environments. Monitoring strategies are divided into two principal stages:
1. Pre-release monitoring, which takes place during confined field trials, and
2. Post-release monitoring, conducted after commercial or environmental release.
These strategies ensure that transgenic technologies are introduced responsibly, maintaining human safety, ecosystem integrity, and regulatory compliance.
12.1.2 Objectives of Monitoring
• To evaluate the biosafety and efficacy of GMOs in different environments.
• To detect unexpected adverse effects on human health or the environment.
• To monitor gene flow, resistance development, or weediness.
• To ensure compliance with biosafety regulations, stewardship programs, and licensing agreements.
• To maintain public trust and provide transparency in GM deployment.

Introduction

Spoilage in agricultural products due to mould growth can occur at various stages of production and storage and is significant in terms of trade economics, food safety and public health (Shephard, 2008). It has been reported that 5–10 % of agricultural products in the world are spoiled by mould contamination to the extent that they cannot be consumed by humans or animals. Mould growth decreases the quality of food and also creates a potential risk for human health because of the production of toxic secondary metabolites known as “mycotoxins”. Foods contaminated by mycotoxins, when consumed by humans and animals causes a disease called “mycotoxicosis”, resulting in death (Wagacha and Muthomi, 2008).

ABSTRACT

A number of secondary metabolites are produced by cyanobacteria involving the non-ribosomal peptide biosynthetic pathway. Some of these compounds have potential biotechnological applications, whereas others (the cyanotoxins) are undesired due to their toxicity to animals. The occurrence of toxic cyanobacterial blooms in freshwater bodies that are used as source for human consumption, recreation and irrigation are frequent nowadays due to increasing artificial eutrophication of these environments. It is important to monitor toxin-producing strains in order to prevent the adverse effects caused by their toxins to human and animal health. Thus, the development of rapid and sensitive methods for the detection of cyanotoxins is important as they could be useful to monitor water supplies and contribute for watershed monitoring strategies. Current methods include cell counting, microscopic identification and toxin analysis by biochemical and analytical techniques. However, in recent years, molecular biology techniques, such as polymerase chain reaction (PCR), have been used to amplify specific regions within biosynthetic genes for rapid and sensitive identification of toxic cyanobacteria. The aim of this chapter is to provide an update of cyanotoxin biosynthesis and discuss the advances and limitations of molecular biology regarding its application as indicative of cyanotoxin production.

Remote sensing has proved its credibility beyond doubt in natural resources survey and environmental monitoring owing to its synoptivity, multispectral photographic capability and repetitive coverage. While its synoptivity gives unbiased information on the regional panorama of the earth surface, its multispectral possibility aids precise interpretation of various objects, as different terrestrial objects exhibit various spectral responses in different bands of the electromagnetic spectrum. Amongst various terrestrial objects, water has a characteristic spectral response of its own, i.e. it permits the blue / red part of EMR (electromagnetic radiation, 0.4-0.8 µm) to penetrate inside. On the contrary, it totally absorbs the infrared part of EMR (0.8-1.5 µm). As such blue/red part of EMR penetrates the water bodies, the impurities and suspended sediments are seen very clearly in various shades of gray as and when the water bodies are shallow. Many workers, therefore, have used blue / red band of the satellite data in such water-quality studies^l-3. Hardy⁴ has observed that the infrared light in the spectral regions of 0.6-1.4 µm has the potential to map the turbidity in the ocean water, whereas Kritakos et al ⁵ have used the rationed data of visible and near infrared bands (0.4-1.1 µm) and obtained better results for water quality monitoring. Keeping such facts in mind, the blue/red band (band 2) of the IRS 1A satellite data was used to configurate the bathymetry along Madras coast in Bay of Bengal (Figure 1 a).

In the present study, the IRS lA band 2 data (0.52-0.59 µm) of March 1991 was used and subjected to edge enhancement studies for the coastal zone of Madras (Figure 1 a). Such edge enhancement normally sharpens the edges of two contrasting objects or sharpens the edges of objects of contrasting relief. In such edge enhanced data, few

Abstract

Training is essential but expensive. Hence, training impact is a crucial measure. National Agricultural Research System (NARS), India employs about 30000 scientists. To effectively manage such huge scientific-capital, Indian Council of Agricultural Research (ICAR) establishedCentres for Advanced Faculty Training (CAFT) and National Academy of Agricultural Research Management (NAARM). CAFT train faculty of State Agricultural Universities (SAUs), while NAARM trains scientists of ICAR institutes and SAUs. Assessing impact of these training programmes becomes essential. Application of knowledge, skills and attitude (KSA) acquired during training back at job environment is training-transfer that addresses learning, behaviour and results levels of training impact. This chapter critically analyses training-transfer of NAARM and CAFT programmes, suggests empirical framework to enhance impact of NAARM and CAFT programmes and thus contributes to literature. Policy strategies suggested in this paper hold wider applicability.

Boron occurs as anion in soils and isrequired by plants in very small quantity. Water soluble B makes the estimate of its availability to plants. Total boron in soils varies from 20 to 200 mg kg^-1 and available (water soluble) boron in soils ranges from 0.03 to 12 mg kg^-1 respectively. The threshold value ranging from 0.1 to 0.5 mg kg^-1 (water soluble B) depends upon the soil type, crops, and other factors, below which the response to applied boron may be expected. Its availability is affected by soil pH as under:

Soluble chloride (Cl) concentration in the extract is determined by silver nitrate titration. This method quantifies the concentration of Cl (meq/L) in the saturation paste extract. Chloride may be determined using anion selective electrode (potentiometric). Plant tolerance to Cl can be related to its concentration in the soil saturation paste extract. The method detection limit is approximately 0.1 meq/L, dependent on the method of analysis, and is generally reproducible within ± 10 %.

Apparatus Required

Burette, pipette, conical flask and mechanical shaker etc

Diethylene tetramine penta acetic acid (DTPA) being a chelating agent is used in the determination of available Fe, Mn, Cu and Zn. When the soil is shaken with a solution of DTPA, it combines with metal ions in the solution and form soluble complexes of Fe++, Mn++, Cu++ and Zn++. The CaCl2 and triethanolamine (TEA) solution slightly raise and buffer the soil pH and mitigates the effect of Ca++ and Mg++.

[Alkaline Permanganate / Subbiah and Asija (1956) Method]

Introduction

Nitrogen (N) is found in the arable horizon of the soil, mostly in organic material. In the soil solution, organic N is gradually transformed into ammoniacal (NH₄ ⁺), nitrite (NO₂ ^–) and nitrate (NO₃ ^–) nitrogen by microbial processes. Organic-N is, in itself, of very little use to plants, as it can not be absorbed as such. It is, therefore, necessary to estimate the different forms of mineralized or available N. The NO₃ ^–_N and NO₂ ^–-N together, hardly, exceed 1 % of the total N in normal soil.

The available N in soil refers to a fraction of the total N which is converted into forms accessible to the plants. This constitutes, on an average, only 0.5-2.5 % (rarely 5 %) of the total N in a soil at any given time. Nitrogen is, generally, absorbed by plants as NO₃ ^–, under oxidized environment (upland condition), and as NH₄ ⁺, under reduced condition. NO₂ ^– is sometimes, detectable, but the amount is, generally, very small vis-a-vis NH₄ ⁺ or NO₃ ^– and, hence does not warrant its determination. The sum total of NH₄ ⁺ and NO₃ ^–- N is smaller than the total N, which becomes available to plants and the difference being attributed to the mineralization of the organic N, during the crop growth cycle.

The Kjeldahl method is mainly divided into three main steps. This method needs to be carried out in proper sequence. 

The major part of soil nitrogen exists in complex combination in the organic compounds. It becomes available to plants after breakdown to simple form followed by mineralization. The chemical methods for determination of soil nitrogen availability involve either direct or indirect of total nitrogen or measurement of a fraction of easily hydrosable nitrogen by employing solution of dilute acid or alkali. Distillation of alkaline potassium permanganate solution has often been adopted for estimating the ox disable and reactive form of soil nitrogen. The available nitrogen in soil is determined by alkaline permanganate method as per procedure suggested by Subbiah and Asija (1956).

Principle

A known weight of the soil is mixed with alkaline potassium permanganate (KMnO₄) solution and distilled. The organic matter present in soil is oxidized by the nascent oxygen, liberated by potassium permanganate, in the presence of sodium hydroxide and the released ammonia is condensed and absorbed in known volume of a boric acid with mix indicator to form ammonium borate, the excess of which is titrated with a standard sulphuric acid.

In Bray’s method a mixture of ammonium fluoride and hydrochloric acid (NH4F + HCl) act as the extracting agent. It works in two ways, firstly, the hydrogen ions from HCl have a solubilising effect, especially on Ca-P, which makes phosphate get extracted. Secondly, the fluoride ions (from ammonium fluoride) complex with the Al3+ and Fe3+ ions, thereby releasing the Al and Fe bound phosphorous into the extract.

Olsen P were found to bear a quadratic relationship, with Olsen’s extractant underestimating the content in phytoavailable P of soils with high Olsen P contents relatively to soils with low contents. The ‘‘change point’’ at which phytoavailable P began to increase rapidly per unit change in Olsen P was 53 mg Olsen P kg–1 soil. For the acid soils, a significant quadratic relationship was found between the amount of P desorbed to water and Olsen P at the three soil:solution ratios studied.

The term available phosphorus (P) refers to the inorganic form, occurring in soil solution, which is almost exclusively ‘orthophosphate’. The available P is considered to be a fairly good indicator/measure of the P supplying capacity of a soil. A knowledge of available P content of soils is important for determining its critical limit , based on soil-test-crop response calibration study.

Principle

In soil, phosphorus exists in the form of various types of orthophosphates. A very small fraction of these is available to plants at a given time. Available phosphorus content of soil consists mainly of Ca-P, Al-P and Fe-P. In the neutral and alkaline soils particularly, Ca-P is the dominant fraction. Organic –P fraction is also considerable amount, but is usually not include in the determination of available phosphorus. A large number of extractions, buffer solutions, acids and chelating agents have been suggested for available phosphorus from time to time. However, no single extractant appears to be suitable for all types of soils. Two types of extraction methods are more popularly adopted. Under acidic soil conditions, Bray No.1, which involves soil extraction with a solution consisting of 0.003 N NH₄F and 0.025 N HCl is widely followed. The fluoride complexes Al and Fe in soil, thus releasing some bound p besides the easily acid soluble P (largely Ca-P). This extraction is suitable for soils containing less than 2% calcite or dolomite because in calcareous soils, carbonates quickly neutralize the acid, resulting in less extraction of P.

Potassium is extracted from the soil with the help of suitable extractant CH3COONH4 by shacking followed by filtration or centrifugation & is determined in the extract using flame photometer. The analysis photometer is based on the measurement of the intensity of characteristic lime emission given by the element to be determined .

The total potassium content (K) of a soil varies from 0.05 to 2.5%. The total K is distributed in mineral form (90-98%), fixed non-exchangeable (1-10%) and exchangeable plus water soluble K(1-2). Exchangeable K represents an average of 2-15% of the sum of exchangeable bases and 1-3% of the total capacity of cationic exchange.

Principle

It is based on the principle of the equilibrium of the soils with an exchangeable cation mode of the solution of neutral ammonium acetate, in a given soil:solution ratio. During the equilibrium, ammonium ions exchange with the exchangeable K ions of soil.The K content in the equilibrium solution is estimated with a flame photometer.

Soil is shaken with 0.15 % CaCl2 solution. Chloride ions displace adsorbed sulphate during extraction. Calcium ions suppress the extraction of soil organic matter and hence eliminate the contamination caused by extractable organic S.

Soil is shaken with 0.15 % CaCl2 solution. Chloride ions displace adsorbed sulphate during extraction. Calcium ions suppress the extraction of soil organic matter and hence eliminate the contamination caused by extractable organic S.

Sulphur (S) occurs in different forms in soil viz., sulphites, sulphates , sulphides and in organic compounds. Plants absorb S in the form of sulphate(SO₄ ^2-) . The organic forms of S compounds become assimilable, especially following microbiological transformation into SO₄ ^2-. The mineralization of organic sulphur in a soil depends primarily upon the N:S ratio and any SO₄ ^2- formed may be fixed against extraction, particularly if much Fe and Ba is present or if soil is very acidic.

Principle

Beside some amount in the soil solution, available sulphur in mineral soils occurs mainly as adsorbed SO₄ ^2- ions. Both CaCl₂ and phosphate solutions (as monocalcium phosphate) are generally used for replacement of the adsorbed SO₄ ^2- ions. Use of Ca salts have a distinct advantage over those of Na or Na, as Ca prevents deflocculating in heavy textured soils and leads to easy filtration. SO₄ ^2- in the extract can be estimated turbid metrically using a spectrophotometer. Sulphur in the extract can also be measured by colorimetric method using barium chromate but the turbimertic method given below is mainly used in the soil testing laboratories.

Bulk density is the ratio of oven-dry mass of soil to its total volume before drying. Knowledge of bulk density is useful in calculating moisture content by volume, porosity using particle density, volume of a known weight of soil, and weight of a furrow-slice. Bulk density is a direct measure of soil compaction. Bulk density is highly dependent on any kind of physical manipulation, degree of wetness, and kind and arrangement of soil particles. For this reason, preservation of original structure in the sample is most essential aspect of the methodology for determination of bulk density. Common methods of determining soil bulk density use soil cores or clods in their natural state.

Pore space or porosity : Porosity is an index of the relative pore volume in the soil or volume fraction of pores. Its value generally lies in the range of 0.3-0.36 (30-60%). Coarse textured soils tend to be less porus than fine textured soil, though the mean size of individual pores is greater in the former than in the latter. The total porosity, in any case, reveals nothing about the pore size distribution which itself is an important property.

Bulk density is the mass per unit volume of soil including pore space. The normal range of bulk density in most soils is ranging from 1.02 to 1.80 g / cm³. The bulk density of coarse textured soils will be on the higher side while organic soils will have lower bulk density.

Particle density is the mass of soil per unit volume excluding pore space. Pore space is that fraction of soil volume not occupied by solid particles.

Principle

The bulk density and percent pore space are determined from the apparent and true volumes of the soil measures by adding a known quantity of water to a measuring cylinder contain a weighed quantity of soil.