eChapters

Injudicious and indiscriminate use of several agrochemicals viz. pesticides, herbicides, insecticides, dyes and medicaments in the field of agriculture and veterinary practices threatens the human and animal population for the toxicity of these environmental deterrents. These agrochemicals have been associated with several episodes of accidental poisoning and mortality among human and animal population. The episode of Mass ethion poisoning in Gujarat is one of the commonest example of inclusion of pesticides or agrochemicals in the environmental pollutants. There are modern tools to evaluate and analyze these chemicals in the environmental pollutants of human and animal use. The sensitivity of these modern highly sophisticated tools has now immensely changed the analytical environmental pollutants industry. Gas chromatography and Mass Spectrophotometry i.e. (GC-MS) technique is employed to detect the volatile residues from environmental pollutants. Whereas, High performance liquid chromatography i.e. HPLC is employed to analyse and detect non volatile drug residues. Gas Chromatography/Mass Spectrometry (GC/MS) instrument separates chemical mixtures (the GC component) and identifies the components at a molecular level (the MS component). It is one of the most accurate tools for analyzing environmental samples.

ABSTRACT

Genetic relationships were estimated among twenty five ashgourd (Benincasa hispida (Thunb.) Cogn.) landraces of different types using PCR-based random amplified polymorphic DNA (RAPD) markers. The molecular survey of the ashgourd germplasm by RAPD using three random primers resulted in twenty scorable bands (average of 6.66 bands per primer) of which two were monomorphic and rest, 18 were polymorphic (90.0%). Pair-wise genetic similarities among the landraces determined using Jaccard’s coefficient ranged from 0.14 to 1.00. The dendrogram based on clustering matrix separated the landraces with morphologically distinct smooth textured fruits from waxy textured fruits and the former group showed less divergence than the latter. With in the group of waxy textured fruits, limited variation was detected among landraces with small and medium sized fruits. Further, morphologically similar landraces with large fruits form distinct clusters with in the major clusters. The study demonstrated the usefulness of the RAPD marker analysis in effectively assessing the genetic relationship present among the ashgourd landraces examined.

ABSTRACT

Genetic variability was assessed among twenty five distinct drumstick (Moringa oleifera Lam.) landraces using PCR based random amplified polymorphic DNA (RAPD) markers. Genomic DNA extracted from tender leaves was used for RAPD analysis. Thirty five primers were screened and based on the number of bands three primers were selected. The primers produced 34 bands, of which 58 % (20 bands) were polymorphic. The data were analysed using NTSYS pc 2.1 software. The similarity matrix constructed using Jaccard’s coefficient method was subjected to cluster analysis using UPGMA (Unweighted Pair Group Method with Arithmetic Mean) and dendrogram was generated. The pair wise coefficient values in the genetic similarity matrix among the landraces varied between 0.28 and 1.00. The dendrogram based on the matrix separated the landraces with distinct morphological characters and it was noted that the cluster formation was not fully in agreement with the geographical location. The study showed the use of RAPD markers in detecting genetic variability present among the drumstick landraces studied.

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.

Introduction

The most common method of bacterial transformation utilizes high levels of calcium chloride to facilitate the entry of plasmid DNA vectors into E.coli in conjunction with structural alteration of the bacterial cell wall. In general, there are three basic steps in the introduction of plasmid DNA unto cells.

1. Preparation of “competent” cells to enable cells to accept DNA.
2. Transformation of these competent cells, and
3. Selection of transformants.

Most E.coli strains exhibit transformation efficiency (measured as transformants per microgram plasmid DNA) in the range of 10⁵ to 10⁸.

The factors influencing this efficiency depends upon the condition that render cells competent.

Abstract
Infectious diseases pose significant threats to global aquaculture, causing substantial economic losses exacerbated by intensive farming practices. RNA viruses, including birnavirus, nodavirus, rhabdovirus, and others, infect both wild and cultured fish, leading to severe mortalities. This study focused on detecting two RNA viruses, Infectious Hematopoietic Necrosis Virus (IHNV) and Spring Viremia of Carp Virus (SVCV), using the TRIZOL reagent method. Fish samples, including Tilapia, Mrigal, Catla, and Minor carp, were observed for clinical symptoms and dissected to collect organs like kidney and spleen. RNA extraction was performed using TRIZOL, followed by cDNA synthesis and PCR amplification targeting specific viral genes. Gel electrophoresis confirmed the absence of IHNV and SVCV in all samples tested. This comprehensive methodology ensures efficient surveillance and early detection of viral infections in aquaculture, thereby enhancing disease management strategies and economic sustainability. The findings indicate a current absence of IHNV and SVCV in the studied fish populations, emphasizing the importance of ongoing monitoring to safeguard aquatic health.
Keywords: (RNA Viruses, Trizol reagent method, Viral detection)

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

A detention reservoir temporarily stores storm runoff and releases it gradually at a controlled rate, thereby reducing the peak discharge reaching downstream channels and communities. Unlike a conventional conservation reservoir, its principal function is short-term flood moderation rather than permanent water storage. Its performance depends on basin capacity, inlet and outlet arrangements, catchment response, design storm, allowable downstream discharge, and available drawdown time. This chapter explains the concept, purposes, and functioning of detention reservoirs and distinguishes them from ordinary storage reservoirs. It covers their classifications, site requirements, storage estimation, outlet design, routing principles, benefits, limitations, maintenance, and application in rural watersheds, urban drainage systems, and integrated flood-control programmes.

To overcome the limitation of proximate analysis P.J. Van Soest in 1963 developed a method which makes use of the concept that the dry matter of plant origin consists of two principal parts:
    1.    Cell contents 
    2.    Cell wall contents

The method is efficient to take care of the defects in the principle of estimating crude fiber and NFE by proximate analysis. Van Soest has partitioned the carbohydrates into various fractions by a system of analysis using detergents. Cell contents are soluble in neutral detergent includes lipids, sugars, organic acids, starch, soluble proteins, NPN compounds and other water soluble materials, where as cell wall (fiber) is insoluble in neutral detergent but it is soluble in acid detergent includes hemicelluloses, cellulose, lignin, lignified nitrogen compounds, heat damages proteins, keratins and silica. This method of partitioning carbohydrate is essential to be expressed in case of ruminants, due to their capacities for making use of different fractions of crude fibre especially the cellulose and hemicellulose, while the simple stomached animals can rarely do so. 

Water is one of the most important production assets and securing access to and control and management of water is key to enhance livelihood base of any country like India where most people depends on agriculture. India is endowed with rich and vast diversity of natural resources, water being one among them. But water resources in India are unevenly distributed over the country. The more than 50 per cent of the total resources distributed with five states namely Uttar Pradesh, Odisha, Andhra Pradesh, Karnataka and West Bengal (MWR, 2008) and left other states much prone to water scarcity.

I. FILL UPS

1. _____ is the most important source of varietal deterioration during seed production.
2. _____ in oats is caused due to mutation.
3. In peas, _____ is caused due to mutation.
4. _____ is another most important source of varietal deterioration due to introgression to genes from unrelated stocks.
5. _____ is the major source of genetic contamination and varietal deterioration in cross fertilized crop.

Genetic purity (trueness to type) of a variety can deteriorate due to several factors during production cycles. The best means to insure genetic purity therefore, would be to overcome to the greatest possible extent the various factors responsible for genetic deterioration. The important factors of apparent and real deterioration of varieties as listed by Kadam (1942) are as follows:

Developmental variations

Mechanical mixtures

Mutations

Natural crossing

Minor genetic variations

Selective influence of diseases

The technique of the plant breeder

Introduction

Organic farming is an inclusive system of producing high-quality products through such processes which have the least impairment on the environment, humans, plants, or animal health. Thus, the term in its essence concentrates on sustainability in the farm management practices and food production system. Chopra et al. (2013) in their study defined organic farming as a management & ecological production system that not only promotes biodiversity but also benefits biological cycles and soil nutrition activities. It focuses on minimal use of pesticides and encourages those farm practices that restore balance, and increase ecological harmony. 

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.

Wood apple (Feronialimonia) commonly known as Bael in various Indian sub-continent languages is the most under-utilised fruit despite of its aromatic flavor, high nutritional components and important medicinal values. Reason may be due to challenge in harnessing the pulp from the fruit. It is considered under seasonal fruit but it has long duration of shelf-life as compared to other fruits.The physic-chemical characteristics revealed that it has high shell weight of 55.67% as compared to pulp weight of 43.77% (Devi et al. 2018).

55.1. Aim

To determine dietary fibres in given samples.

55.2. Theory

Fibres can be classified into four categories like crude fibre (cellulose); acid detergent fibre (cellulose + lignin); neutral detergent fibre (cellulose + lignin + hemicelluloses) and total dietary fibre.

55.3. Procedure for estimation of dietary fibre

55.3.1. Acid detergent fibre (ADF)

Reagents: Cetyl tri-methyl ammonium bromide (CTAB) reagent and Acetone

Apparatus: Digestion apparatus vacuum pump, oven, desiccator and sintered glass crucible.

Purpose: The organic acids present in fruits and vegetables influence the flavour, colour, keeping quality and maturity. The maturity standards are determined by the acid and sugar ratio. The total acidity (citric acid) is determined by titrating the juice against standard alkali solution.

Equipments and chemicals: 10 ml., pipette, 25ml. Burette, small glass funnel, dropper, juice extractor, distilled water, 100ml. volumetric flask, burette stand, beaker, N/10 sodium hydroxide, filter paper, phenolphthalein indicator (one gram of phenolphthalein in 100ml. of 95% ethyl alcohol)

High-performance liquid chromatography or high-pressure liquid chromato graphy (HPLC) is a chromatographic method that is used to separate a mixture of compounds in analytical chemistry and biochemistry so as to identify, quantify or purify the individual components of the mixture. It involves the injection of a small volume of liquid sample into a tube packed with tiny particles (1.8- to 5-micron (μm) particle size called the stationary phase) where individual components of the sample are moved down the packed tube (column) with a liquid (mobile phase) forced through the column by high pressure delivered by a pump. These components are separated from one another by the column packing that involves various chemical and/or physical interactions between their molecules and the packing particles. These separated components are detected at the exit of this tube (column) by a flow-through device (detector) that measures their amount. An output from this detector is called a “liquid chromatogram”.

Aflatoxins are toxic and carcinogenic compounds produced as metabolites by many Aspergillus species. This fungus invades habitats such as soil, grain, nuts, or decaying vegetation when- ever suitable conditions such as high moisture and temperature are met. B1 is the most toxic of at least 14 different types of naturally occurring aflatoxins. Therefore, many countries and regulatory agencies impose strict limits on B1 as well as other common aflatoxins such as B2, G1, and G2 despite exhibiting lower toxicity. The U.S. FDA set the action level to20 μg/kg (ppb) for human food and to 300 μg/kg (ppb) for animal feed. Aflatoxin B1 is extremely widespread and is present in food and feed products such as cottonseed, corn, and peanuts. It is highly toxic and has been classified as a group 1 carcinogen by the WHO. The aflatoxins B2 , G1 , and G2 are usually found accompanying B1 , in lower concentrations in the contaminated samples. The order of toxicity is AFB1 > AFG1 > AFB2> AFG2.

Aim

To determine the angle of repose of the given biological materials.

Materials required

Angle of repose apparatus
Grains
Scale

Aim

To determine the area of the field by intersection method using a prismatic compass.

To determine the included angle of the closed polygon.

Materials required

Prismatic Compass

Tripod

Measuring tape

Arrows

Ranging Rods

Aim

To determine the area of given field by intersection method of plane table survey.

Materials required

Tripod

Plane table

Plumbing fork

Level tube

Magnetic compass

Alidade

Measuring tape

Ranging rods

Drawing sheet

Pins, pencil and eraser

Aim

Studies on plane table survey instruments

To determine the area of given open field by radiation method of plane table survey.

Plane table survey

Plane table surveying is a simple method of surveying for determination of area of field. The plane table survey is quite suitable for plotting small-scale and medium scale mappings directly in the field where great accuracy is not required. It is also used for plotting the topographical maps in the field. The plane table survey is generally more rapid and less costly than other types of survey.

In this survey, a plane table is used for taking the measurements and for plotting the plan in the field. Plane table surveying is a method in which the field observations and plotting of the plan proceed simultaneously. The plotted map can be compared with the actual features in the field. Errors in measurements and plotting can be easily detected in the field by taking suitable check lines.

Aim

To determine the area of given field by intersection method of plane table survey.

Materials required

Tripod

Plane table

Plumbing fork

Level tube

Magnetic compass

Alidade

Measuring tape

Ranging rods

Drawing sheet

Pins, pencil and eraser

Aim

To determine the area of given field by triangulation method of chain survey

Materials required

Metric chain

Measuring tape

Ranging rods

Chain pins

Aim

To find out the area of given field by cross-staff survey method

Materials required

Cross-staff

Metric chain

Measuring tape

Ranging rods

Chain pins

Aim

To determine the area of the given field by radiation method using a prismatic compass.

Materials required

Prismatic Compass

Tripod

Measuring tape

Arrows

Ranging Rods

Materials Required

Sample, reagents, beakers, conical flasks, pestle and mortar, funnels, volumetric flasks, pipettes, weighing balance, spectrophotometer/colorimeter.

Reagents

    1.    2% Metaphosphoric Acid Solution: Weigh 20 g of HPO₃ and dilute to 1 litre in water or 4% oxalic acid.
    2.    Dye Solution: Dissolve 100 mg of 2, 6 Dichlorophenol-indophenol dye (Phenolindo-2,6- dichlorophenol sodium salt, AR, C₁₂H₆Cl₂NNaO₂ 2-3H₂O) and 84 mg of sodium bicarbonate (sodium hydrogen carbonate AR, NaHCO₃) in hot (85-95ºC) distilled water. Cool and make up the vol 100 ml. Filter and dilute 25 ml of the dye to 500 ml with distilled water. 
    3.    Standard Ascorbic Acid: Weigh 50 mg of ascorbic acid (AR) and make up to 50 ml with 2% metaphosphoric acid or 4% Oxalic acid solution (1000 ppm i.e. 1000 µg/ml). Dilute 4 ml of this solution to 100 ml with 2% HPO₃ or 4% oxalic acid. (1ml = 40 µg ascorbic acid).

Principle: Sample extract in oxalic acid is titrated against standard sodium 2, 6 dichlorophenolindophenol dye to a faint pink colour which persists for 5-10 seconds.

(Indophenols Method)

Purpose: The ash content of plants represents the deposition of minerals elements in the plant or in its parts. The value of ash content in the plant tissue indicates the health of the plant. Plant ash is also used both in qualitative and quantitative estimation of mineral elements.

Material and Equipments: Crucible, oven, chemical balance and weight box.

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.

Introduction

In recent years, the boom in industrialization has revolutionised the countries but has also added much of sufferings. There is tremendous increase in the water and air pollution. Large amounts of effluents from industries containing organic substances of different nature are discharged and enter the aquatic systems resulting in water pollution. Biological Oxygen Demand (BOD) is the amount of dissolved oxygen required by the aerobic microflora to oxidise the organic matter of dirty water. Increased organic matter results in more oxygen requirements by microorganisms to oxidise it and it results in enhancement of BOD of water. As the BOD of water rises, due to decrease in dissolved oxygen (DO), there is increase in death of fish due to suffocation. Determination of biological oxygen demand (BOD) only is insufficient to give a clear picture of organic content of water bodies and the presence of toxic chemicals in the sample so the chemical oxygen

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.

Theory

Bulk density of the food material play an important role in many applications such as drying, storing, separation of undesirable material, determining the purity of seeds, grinding, maturity evaluations, design of storage structures, etc. It is an important parameter in packaging requirement and is often 2-20% of true density. Bulk density is the density of material when stacked or packed in bulk. Bulk density of powder can be determined under loose conditions. Loose packing is defined as the state obtained by pouring a powder sample into a vessel without any consolidation.

Bulk density

Bulk density of the food material can be defined as the ratio of weight of an untapped material to its volume including the contribution of the inter-particulate void volume. There are two kinds of voids, voids between particles and void within particles. Weight of the material can be determined by weighing balance. Volume can be determined by measured dimensions or using liquid or gas or solid displacement methods.

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.

Aim : To determine the Calcium in plant sample.

Principle

Carbonate (CO₃) and bicarbonate(HCO₃) ions are species of the same acid, carbonic acid. Their proportionate content is a function of pH. The CO₃ starts to form as pH rises above 8.4. Carbonate and bicarbonate are generally determined in soil saturation extract by titration with 0.01 N H₂SO₄ to pH 8.3 and 4.5, respectively.

Apparatus Required

Burette, pipette, conical flask and mechanical shaker etc