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“SOIL” the term is derived from Latin word “solum” which means, “floor”. Soil has been a defining component of humanity since the beginning of civilization. It holds the clues of past cultures, it supports the web of life connecting all ecosystems, provides materials to build houses, and provides the base for our food, feed, fiber and even some biofuels.

Soils are complex mixtures of minerals, water, air, organic matter, and countless organisms that are the decaying remains of once-living things. It forms at the surface of land and is the “skin of the earth.” Soil is capable of supporting plant life and is vital to life on earth. There are several general roles that soils play:

Mineral

A mineral is defined as “a natural substance, usually inorganic, having a definite chemical composition and commonly a definite molecular arrangement which is usually expressed in geometric form”.

There are over 100,000 different types of soil in the world, each with its own set of characteristics. If any soil is dug deep, one can see that it is made of layers, or horizons. The horizons together form a soil profile. Each profile tells a story about the life of a soil.

The development of soil profile is a constructive process where in disintegrated materials resulting from weathering of rocks and minerals get converted into a soil body. Soil Individual or Polypedon is a natural unit of soil that differs from its adjoining unit on the landscape in one or more properties. In modern soil taxonomy, polypedon is the unit of soil mapping. Apedon is the smallest volume recognizable in nature that can be called “a soil”.

The phenomena related to the retention and movement of water in soils, its uptake and translocation in plants and its loss to the atmosphere are all energy related. The more strongly water is held in the soil, the greater is its energy. It means that if water is to be removed from a moist soil, work has to be done against the adsorptive forces. The water movement is always from a zone where the free energy of water is high (standing water table) to one where the free energy is low (a dry soil). This is called soil water energy concept.

17.1. Soil Water Potential

The free energy of soil solids for water is influenced by:

i) Matric force: the attraction of the soil solids for water (adsorption) which markedly reduces the free energy (movement) of the adsorbed water molecules.

Soil Reaction

Soil reaction is an indication of the acidity or basicity of the soil and is measured in pH units. The pH scale ranges from 0 to 14, with 7.0 as neutral point. From pH 7 to 0, soil is increasingly acidic. From pH 7 to 14, soil is increasingly alkaline.

Pure H₂O ionizes to a very small degree, though to a measurable extent, so that it has the following equilibrium: both H+ and OH^- are in concentrations of 10^-7 moles L^-1.

Soil organic matter (SOM) is one of the most complex materials existing in nature. Besides the organic constituents in undecayed plant and animal tissues, SOM contains both living and dead microbial cells, microbially synthesized compounds and an unending array of derivatives of these materials produced as the result of microbial activity. Soil organic matter contains most of the naturally occurring organic compounds. Some components of SOM are undoubtedly unique to the soil environment, particularly those involving inorganic-organic complexes.

The Carbon Cycle

The element that serves as a corner stone for cell structure is carbon. Plant tissues and microbial cells contain approximately 40 to 50% of C on dry weight basis. Yet, the ultimate source is the CO₂ of the atmosphere. The CO₂ is converted into organic C by the action of photoautotrophic organisms (higher plants and green algae). It has been estimated that the vegetation on earth’s surface consume some 1.3 x 10¹⁴ kg of CO₂ per annum which is about V₂₀ of the total CO₂ supply of the atmosphere or ¹/₁₀₀₀ of that in the ocean. Soil carbon constitutes the largest terrestrial pool of carbon.

The synthesis of humic substances is the least understood and the most intriguing aspect of humus chemistry. Studies on this subject are of enduring and continued research. Several pathways have been identified for the formation of humic substances during the decay of plant and animal remains in soil, the main ones being shown in Fig. 26.1.

Soil pollution indicates the presence in the soil of any chemical or substance out of place and/or present at an abnormally higher concentration so as to adversely affect any non-targeted organism. Soil pollution often cannot be visually perceived or directly assessed, thus rendering it a latent danger. The Status of the World’s Soil Resources Report identified soil pollution as one of the main soil threats affecting global soils and the ecosystems services provided by them. Concerns about soil pollution are growing in every region. Recently, the United Nations Environmental Assembly (UNEA-3) adopted a resolution calling for accelerated actions and collaboration to address and manage soil pollution. This consensus, achieved by more than 170 countries, is a clear sign of the global relevance of soil pollution and of the willingness of these countries to develop concrete solutions to address the causes and impacts of this major threat.

29.1. Sources of Soil Pollution

The main anthropogenic sources of soil pollution are the chemicals used in or produced as byproducts of industrial activities, domestic, livestock and municipal wastes (including wastewater), agrochemicals, and petroleum- derived products. These chemicals are released to the environment accidentally, for example from oil spills or leaching from landfills, or intentionally, as is the case with the use of fertilizers and pesticides, irrigation with untreated wastewater, or land application of sewage sludge. Soil pollution also results from atmospheric deposition from smelting, transportation, pesticide applications and combustion of many substances as well as radionuclide fallouts from atmospheric weapons testing and nuclear accidents. New concerns are being raised about emerging pollutants such as pharmaceuticals, endocrine disruptors, hormones and toxins, among others, and biological pollutants, such as micropollutants in soils, which include bacteria and viruses.

Soils play a vital role in the health of ecosystems in the world. Soils connect with air, water, rocks and organisms and are responsible for a multitude of functions in the global ecosystem services. These functions include providing habitat for most living things, air composition and quality, temperature regulation, carbon and nutrient cycling, water cycling and quality, and natural waste recycling. Mankind cannot survive without these soil functions.

30.1. Habitat

Soils are the environment in which plants grow. They provide heat, nutrients and water to nurture plants to maturity. These plants, together with other plants and organisms, create ecosystems. These plants then provide valuable habitat and food sources for animals, bacteria and other things. Ecosystems depend on the soil and soils determine the nature and kind of ecosystems.

Horticulture is an art and science of growing plants. It is the practice of engaging ailing people in various horticultural activities such as gardening and flower arrangements in order to improve their physical, mental and spiritual health. Research confirms that health benefits escalate manifold when people connect with nature and plants by viewing and/or interacting with them. Major benefits of horticultural therapy includes sensory simulation and mood enhancement, mental relaxation, improvement of memory and concentration and an overall feeling of wellness. Horticulture therapy also helps in cultivating positive emotions and provides a meditative mood. It eases both physical and emotional pains and also improves social skills. It is proven that a simple viewing of a garden benefits a person both physically and mentally.

This practice has been used as therapy for centuries. In 1798, Dr. Benjamin Rush, considered as the “Father of American Psychiatry” documented that gardening has positive effects on mentally ill patients. Following World War, II gardening was used as a form of occupational therapy for war veterans. The concept of using nature to improve human health began to gain credibility in 1970’s. Rachel and Stephen Kaplan (1989) found that natural environments had relaxing and restoration benefits for people. The Journal of Therapeutic Horticulture, a peer-reviewed publication of the American Horticultural Therapy Association, has published authentic research papers since 1986. The American Horticultural Therapy Association (AHTA) serves to promote and advance horticultural therapy as a therapeutic intervention and rehabilitative approach. Degrees and certificate programs in horticultural therapy are offered at several colleges and universities and information is available on AHTA website.

Horticultural therapy is a worldwide practice and recognized as an effective treatment for clients of all ages and abilities. It is being used in several diverse settings including hospitals, rehabilitation centres, youth outreach and recovery programs, nursing homes, senior care facilities, prisons, mental health facilities, schools, botanical gardens etc. The client is engaged in horticultural activities facilitated by some trained therapists to achieve specific and documented goals. AHTA believes that horticultural therapy is an active process that occurs in the context of an established treatment plan where the process itself is considered as the therapeutic activity rather than the end product.

Horticulture therapy is a growing profession in rehabilitation and addiction centers, vocational centers, youth mental health programs, hospitals and nursing homes, and old age homes or senior citizen centers, mental health centers, schools and colleges.

To study the characteristics of microorganisms, it is essential to culture and growth them. Growth is the increase in cell number which can be obtained by providing proper physical and chemical conditions. Medium is a substance that provides nutrients for growth and multiplication of microorganisms. Any medium for the cultivation of bacteria and fungi must provide certain basic nutritional requirements which include a carbon, nitrogen, phosphate and various mineral nutrients. The following is the medium composition for the isolation and culturing of different biocontrol agents

The isolation of microbes is commonly done using serial dilution technique.

1. Trichoderma

Trichoderma is one of the important biocontrol agents. The colonies first produce mycelial growth and then turn yellow and finally produce a dark green color mat.

The discovery and use of synthetic chemicals has contributed greatly to the increase of food production industry by controlling pest and diseases. However, the use of synthetic chemicals has raised number of ecological problems apart from increasing the cost of cultivation. In recent years, scientists have directed their attention in exploring the potential of beneficial microbes for plant protection measures. Biocontrol agents exhibit antagonistic activity against plant pathogens and activate resistance mechanisms in the host despite improving plant growth. In agricultural soils the nutritional condition is depleted hence beneficial microbes decrease and increase the pathogenic microbes. To ensure the sustained availability of biocontrol agents mass production technique and formulation development protocols has to be standardized which also increases the shelf life of the formulation. Though these agents have a very good potential in the management of Pest and Diseases it can not be used as cell suspension under field conditions. The cell suspensions of these biocontrol agents should be immobilized in certain carriers and should be prepared as formulations. The organic carriers used for formulation development include peat, turf, talc, lignite, kaolinite, pyrophylite, zeolite, alginate, pressmud, sawdust, vermiculate, etc.

Introduction

Studies on biocontrol agents have revealed the presence of a diverse range of antifungal metabolites derived from amino acid, polyketones and isoprenoid biosynthetic pathways, each of which has distinctive regulatory points and is subjected to different stimuli within organisms. In this experiment, the extraction of secondary metabolites from the culture of T. viride and Chaetomium globosum will be demonstrated.

Entomopathogenic nematode (EPN) viz., Heterorhabditis, Neosteinernema and Steinernema have been recovered from many regions of the world. They selectively infect many insects and a few other arthropods but do not adversely affect mammals or plants. They are actually vectors of pathogenic bacteria, cause relatively rapid death of the host (24 – 48 h) and show considerable potential in biological control of insect pests in the integrated pest management systems.

EPNs are similar to insect parasitoids in that the immature form develops at the expense of one host individual; they are ecologically similar to both parasitoids and arthropod predators because the host individually killed. However, these nematodes differ from predators and parasitoids in two ways: (1) the nematode is mutualistically associated with a bacterial pathogen which actually kills the host, and (2) the pathogenicity of the bacterium has a great influence on the efficacy of the system (Ehler, 1990). The purpose of this chapter is to introduce EPN as biocontrol agents in this refresher course and to provide an overview of some current issues in biological control of insects with particular emphasis on their relevance to the use of EPNs.

Biological control is defined as the action of natural enemies which maintains a host population at levels lower than would occur in the absence of the enemies. Natural enemies will include parasitoids, predators, nematodes, microbial pathogens and their gene products. Entomologists generally divide biological control into two categories: (1) natural biological control which is effected by native or coevolved natural enemies in the native home (origin) of a given insect and (2) applied biological control which due to human intervention. Applied biological control is further divided into classical biological control (introduction of exotic natural enemies) and augmentative biological control (enhancement of natural enemies already in place).

Wood apple is also known as kaith, kavat, curd apple and monkey fruit. It is found almost throughout the country. It is one of the very hardy tree found growing in arid and semi arid regions of the country. Hill region of northern India and Ceylon are supposed to be its native land (Reuther et al., 1967). Chundawat (1990) thought it to be a native of India and Sri Lanka. It is a popular tree of forest, Indoor yard garden and can be exploited for regular cultivation in dry areas. The cricket ball size fruits have sweet and aromatic pulp, eaten fresh or used for drinks, chutneys, jellies etc. In forests of Rajasthan, it is commonly found in Aravalli range and Hadoti Plateau.

Word manure derived from French ‘Manoeuvrer, means to manipulate, to work, to produce crop.

11.1. Sources of organic wastes

Cattle shed wastes, dung, urine and slurry from biogas plants.

Human habitation wastes-night soil, human urine, town refuse, sewage, sludge and sullage.

Poultry jitter, droppings of sheep and goat.

Slaughterhouse wastes-bone meal, meat meal, blood meal, horn and hoof meal, fish wastes.

Byproducts of agro industries-oil cakes, bagasse and press mud, fruit and vegetable processing wastes etc.

12.1. Problem soils

Chemical constraints: Salinity, sodicity, acidity and nutrient toxicities

Physical constraints : High or low permeability, sub soil hard pan, surface crusting, fluffy paddy soils, sandy soils etc.

13.1. Soil survey and soil mapping

Refers to study and mapping of soils in the fields.

Process of classifying soil types and other soil properties in a given area and geo-encoding such information.

Draws information on geomorphology, theories of soil formation, physical geography, analysis of vegetation and land use patterns.

Primary data for the soil survey are acquired by field sampling and by remote sensing.

Remote sensing principally uses aerial photography (Illuminating the object/ target with pulsed laser light and measuring the reflected pulses with sensor), but LiDAR ( Light Detection and Ranging) and other digital techniques.

Major 2 types of erosion (i) soil erosion and (ii) wind erosion

2.1. Soil erosion

Detachment of soil particles from the surface • Transportation by water, wind, ice or gravity.

1.1. Watershed development

Refers to the conservation, regeneration and judicious utilization of all the resources viz., land, water, vegetation, animal and human within a particular watershed in integrated manner.

Water drainage area on earth’s surface from which runoff, due to precipitation, flows into a single to a larger stream, a river, a lake or the ocean.

1.2. Concept of watershed management

Planning and design of soil and water conservation structures such as bunds, waterways, overflow structures, water harvesting structure.

3.1. Land use classification

3.1.1. Classes

Capability class is the broadest category in the land capability classification system.

Class codes 1, 2, 3, 4, 5, 6, 7, and 8 are used to represent both irrigated and non-irrigated land capability classes.

Class 1: Soils have slight limitations that restrict their use.

Class 2: Soils have moderate limitations that reduce the choice of plants or require moderate conservation practices.

Class 3: Soils have severe limitations that reduce the choice of plants or require special conservation practices or both.

1.1. Status of irrigation in Tamil Nadu

Geographical area of 13 million hectares is ranked eleventh in size among the Indian states.

Net area sown is about 6 million hectares.

3 million hectares or 50% get irrigation facilities.

3.1. Ground water development

3.1.1. Rain water harvesting

Collecting and using precipitation water from a catchments surface.

Extensive rain water harvesting apparatus existed 4000 years ago in the Palestine and Greece.

In ancient Rome, residences were built with individual cisterns and paved courtyards to capture rain water to augment water from city’s aqueducts.

As early as the third millennium BC, farming communities in Baluchistan and Kutch impounded rain water and used it for irrigation dams.

4.1. Water Use Efficiency (WUE)

An efficient irrigation system implies effective transfer of water from the source to the field with minimum possible loss.

To identify the nature of water loss and to decide the type of improvements in the system.

Evaluation of performance in terms of efficiency is prerequisite for proper use of irrigation water.

Term moisture stress is generally applied to the stomata opening and transpiration increases with time until they close due to high temperature.

5.1. Causes of moisture stress in plants

Main reason is extent of transpiration which is affected by leaf size and composition, size and distribution of stomata on leaf, atmospheric humidity, temperature, wind velocity and day length.

High atmospheric temperature due to intense sun and increased transpiration causes closure of stomata and wilting of leaves even, if soil moisture content is not limiting.

This deficit is made up during night due to decreased transpiration.

In plants, moisture content decreases either due to increased transpiration or reduction in absorption or both.

6.1. Quality of irrigation water

Asia per capita water availability has fallen by around 80 per cent during last five decades.

Suitability of waters for a specific purpose depends on the types and amounts of dissolved salts.

Some of the dissolved ions such as NO₃ are useful for crops.

Word manure derived from French word ‘Manoeuvrer, means to manipulate, to work, to produce crop.

2.1. Sources of organic wastes

Cattle shed wastes-dung, urine and slurry from biogas plants.

Human habitation wastes-night soil, human urine, town refuse, sewage, sludge and sullage.

Poultry litter, droppings of sheep and goat.

Slaughter house wastes-bone meal, meat meal, blood meal, horn and hoof meal, fish wastes.

Byproducts of agroindustries-oil cakes, bagasse and press mud, fruit and vegetable processing wastes.

4.1. Physiological disorders in field crops

Identification of physiological disorders in agricultural crops

1.1. Types of energy

1.1.1. Potential energy

Stored energy and the energy of position (gravitational).

1.1.2. Kinetic energy

Energy in motion - the motion of waves, electrons, atoms, molecules and substances. It exists in various forms.

4.1. Tractor

Self propelled power unit having wheels or tracks for operating agricultural implements and machines including trailers.

Tractor engine is used as a prime mover for active tools and stationary farm machinery through power-take off (pto) or belt pulley.

1.1. Plant breeding

An art and science, deals with ways and means to change the genetic architecture of plants so as to attain a particular objective.

For ensuring food security, it is important to breed and develop new varieties that are high-yielding, pests diseases and drought resistant or regionally adapted to different environments and growing conditions.

4.1. Synthetic varieties

Produced by crossing in all combinations, a number of lines that combine well with each other.

The Internet of things connects the devices over Internet. The devices can communicate with each other and can be monitored and controlled remotely. The IoT is a system with interrelated computing devices, digital and mechanical machines, objects, animals or people each with an unique identifiers (UIDs ). It has the ability to transfer data over a network without human intervention. The Internet of Things is simply a network with Internet connecting the objects to collect and exchange the data. This chapter covers the basics of Internet of Things and its components.

2.1 Characteristics of IoT

Internet of Things can be used to design products for businesses. The added value to the businesses over IoT is created by the information which is collected by connected devices. The process has five phases of lifecycle, first phase is ‘create phase’, where sensors collects the data from environment. This data can generate the information. Second is ‘communicate phase’ where data generated in first phase is communicated to the required destination. Third is ‘aggregate phase’ where collected data over network is aggregated by device itself. Fourth is ‘analyse phase’ where aggregated data is used to generate patterns and use it to control and optimize the process. Fifth is ‘act phase’ where actions are taken on the basis of information extracted from the aggregated data.

The characteristics of IoT may vary from one domain to other. Few characteristics are listed as follows-

Floriculture has flourished with a considerable growth and a useful crop diversification option, particularly for small farmers over the past three decades. The commercial production of the cut greens has started in India in recent years and has huge demand in the market. They are suited for year round production with low investment and less care and maintenance. Cut greens or fillers are an important component of the floricultural industry and their commercial value depends on vegetative characters, such as stem length, leaf colour, density and side branching. Cut foliages (leaves and stems), which are attractive in form, colour and freshness, are lasting and in great demand. They have various other uses in making attractive fresh floral designs and floral arrangements, such as bouquets, wreaths, decoration of house interiors, etc. Evergreen plants with green, silver or variegated leaves are usually used and species with berries are now also becoming popular. Fillers are critical components in most arrangements as the flowers themselves,used to increase the volume and size of the bunch and provide colour contrast. These floral produce have various other uses in making attractive fresh floral designs and floral arrangements, such as bouquets, wreaths, decoration of house interiors, etc. Colour, freshness, stem length, freedom from pests, fragrance and vase life are important quality aspects of fillers. In the International market, fillers accounts for about 16 percent of the total trade by volume with an annual turnover of more than Rs 800 crores including selling of ornamental leaves, filler flowers, dry and dyed flowers along with berries and capsules. On the contrary, fillers representvery less quantum with poor quality in the domestic market and are unsuitable for cut flower bouquets. Their share in the market is very low and fetches nominal rates.

Volumetric Analysis

Measurement of volume of reagents required for the completion of reactions

Also called titrimetry – most widely used techniques of chemical analysis

Rapid, accurate, convenient and inexpensive

Secondary standard solution

Solution of chemicals which lack one (or) all the properties for a primary standard

A solution standardised by titrating a primary standard

Less accurate than a primary standard

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.

Aim

To determine the tapped bulk density and flowability of the food powder.

Materials required

Raw material (powder)

Measuring cylinder

Electronic weighing balance

Tapped bulk density of the powder

Tapped bulk density is measured for powdery samples. The volume is measured after tapping the powdery material so that the product is adjusted to inter-granular spaces, but it cannot eliminate all the inter-granular spaces. The tapped density is an increased bulk density attained after mechanically tapping a container containing the powder sample.

Theory

Porosity is a physical property characterizing the texture and the quality of dry and intermediate moisture foods. Porosity means inter-granular space. It is the measure of void space between the materials. Porosity may be defined as the percentage of volume of inter-grain space to the total volume of grain bulk. Porosity depends on size, shape, dimension, and roughness of grain surface.

The porosity of an unconsolidated agricultural material can either be determined experimentally using the porosity tank method or theoretically from bulk and true densities of the material. Porosity can be determined from the difference between bulk volume of a porous material and its volume after destruction of all voids by compression. Porosity determination requires the knowledge of the total or apparent volume, and the void volume included in the material matrix; their difference is also known as the particle volume.

Theory

The specific gravity is defined as the unit weight of the product mass divided by the unit weight of distilled water at 4°C. The unit density is obtained by measuring the volume and weight of a unit product. Sometimes it is required to compare the density of the product to the density of water. This comparison is in the form of ratio and is termed as the specific gravity.

Specific gravity also known as relative density is the ratio of density of a substance to the density of a standard substance at the same temperature and pressure. For solids and liquids the standard substance is water while for gasses it is air. The specific gravity of food material play an important role in design of storage bins, conveying equipments, separation equipments, etc. The specific gravity is frequently used to solve the various phase relationships, including void ratio, porosity and degree of saturation together with the moisture content and unit weight. It is also used in calculations associated with the grain size analysis, consolidation and compaction. Pycnometer method, which is a standardized vessel for determining specific gravity. It involves a standard container of accurately defined volume used to determine the specific gravity of solids and liquids.

Aim

To determine the thermal conductivity of the agricultural materials probe method.

Materials required

Thermal conductivity probe

Stainless-steel sample container

Grain or powder sample

Graph sheet

Power source

Theory

Specific heat is defined as the amount of heat needed to raise the temperature of one kg of the material by one degree at constant pressure without a change in state. With food materials, specific heat is a function of different components of a food, moisture content, temperature, and pressure. Specific heat is an important parameter in thermal analysis of food processing and equipment used in heating or cooling of foods. The numerical values of specific heat of the food materials are used in designing food processes and processing equipment. It can be used to calculate the heat load imposed on the refrigeration equipment by the freezing of foods. An apparent specific heat is used in freezing or thawing and in most food processing applications.

The specific heat of a food increases as the product moisture content increases. In unfrozen foods, specific heat capacity is relatively constant with respect to temperature. However, for frozen foods, there is a large decrease in specific heat capacity as the temperature decreases. The specific heat of a material can be determined experimentally by static (adiabatic) calorimetry or differential scanning calorimetry. It can be also predicted quite accurately with the help of a number of empirical equations. The equations are empirical expressions, obtained by fitting experimental data into mathematical models. The mathematical models are based on one or more constituents of the food. Since water is a major component of many foods, a number of models are expressed as a function of water content.

Theory

The energy available in food is expressed in unit is called joules or calories. One kilocalorie is equal to 4.184 kilojoules. The kilocalorie is defined as the amount of heat required to raise the temperature of 1 kg of water by 1°C. The calorific/ energy value of foods is usually determined using the instrument called bomb calorimeter. It is working based on the principles of calorimetry. Basically, this device burns a food sample and transfers the heat into a known mass of water. It measures the heat produced when the food sample is ignited by an electric spark in the presence of oxygen and platinum which acts as a catalyst. The quantity of food sample to be tested is placed inner part and known volume of water is taken in outer part of the bomb calorimeter. When the food sample is electrically ignited, the surrounding water absorbs the heat produced. The energy value of the food is calculated by measuring the rise in temperature of water.

Theory

The amount of moisture in a product is given on the basis of the weight of water present in the product and is usually expressed in percent. Moisture content is designated by (i) wet basis (wb) and (ii) Dry basis (db). The moisture content on dry basis is more simple to use in calculation as the quantity of moisture present at any time is directly proportional to the moisture content on dry basis.

Theory

Indirect methods are based on the measurement of electrical properties of the grain that depends upon moisture content. There are two indirect methods namely (i) electrical resistance and (ii) dielectric methods are used. The electrical conductivity or resistance of a product measures its moisture content at a given compaction and temperature. The electrical resistance is depends on its moisture content, degree of compaction, grain temperature and impurities present in the sample. The universal digital moisture meter measures the electrical resistance of the grain at a given compaction. Universal moisture meter gives fairly accurate readings of moisture content on wet basis. In dielectric method, grain moisture content can be measured with the help of dielectric properties of the grains.