eChapters

Oasis effect : Vertical energy transfer from the air to the crop. It is the exchange of heat between a growing crop and hot air whereby air over the crop is cooled.
 
Observation : In meteorology, the evaluation of one or more meteorological elements, such as temperature, pressure, or wind, that describe the state of the atmosphere, either at the earth’s surface or aloft. An observer is one who records the evaluations of the meteorological elements.
 
Occluded Front : Also known as an occlusion, it is a complex front formed when a cold front overtakes a warm front. It develops when three thermally different air masses conflict. The type of frontal boundary they create depends on the manner in which they meet.

Ultraviolet Radiation : Ultraviolet radiation (UV) is one form of radiant energy coming from the sun. The sun emits a range of energy known as the electromagnetic spectrum. The various forms of energy, or radiation, are classified according to wavelength (measured in nanometers (nm) where one nm is a millionth of a millimeter). The shorter the wavelength, the more energetic is the radiation. In order of decreasing energy, the principal forms of radiation are gamma rays, X-rays, UV (ultraviolet radiation), visible light, infrared radiation, microwaves, and radio waves. Ultraviolet, which is invisible, is so named because it occurs next to violet in the visible light spectrum. Ultraviolet radiation contains the wavelengths between 30 and 400 nm. The UV band is divided into three sub-bands in regard to its biological impacts :

Vacuum : A space in which there is no air or gas. This is more an imaginary situation. This term indicate the air or any other gases at the minimum possible pressure in a space.
 
Validation : Model validation in its simplest form is a comparison between simulated and observed values. Validation is determining whether the model works with totally independent data sets or not and whether it accurately predicts growth, yield and processes by comparing the values predicted by the model with those obtained from the real experiment.

pH is defined as the negative logarithm of hydrogen ion concentration. The amount of the acidic gas CO2 significantly affects the pH of natural water body. Fish have usually blood pH levels of 7.4, but little deviation has been observed, perhaps 7.0 to 8.5pH range is more suitable for the growth and reproduction of the fish. However, pH range 4.0 to 6.5 and 9.0 to 11.0 cause fish death in water pH less than 4.0known as acidic death point or even more than 11.0 known as alkaline death point. The pH of fresh water more fluctuating as compare to sea water due to release and consumption of CO2 and O2 respectively by bacterial oxidation and respiration. However, the pH of marine water often constant at 7.8-8.3 due to presence of buffer like HCO3-, CO2 -, CO3-2 etc.
Principle
The estimation of hydrogen (H+) ion activity through sensing electrode. Electrode composed of a narrow glass bulb with fixed concentration of HCI solution inside it. A wire made of an Ag-AgCI placed in to the bulb which work as electrode to fix voltage. Potential difference forms between the solution in the glass bulb and the sample solution when the electrode immersed into solution.

Dissolved oxygen (DO) refers to oxygen gas that is dissolved in water. Fish are able to absorb oxygen directly from the water into their bloodstream using gills. There are three main sources of oxygen in the aquatic environment: 1) direct diffusion from the atmosphere; 2) wind and wave action; and 3) photosynthesis. Oxygen depletion refers to low levels of DO and may result in fish mortality. A concentration of 5 mg/L DO is recommended for optimum fish health. Sensitivity to low levels of dissolved oxygen is species specific, however, most species of fish are distressed when DO falls to 2-4 mg/L. Mortality usually occurs at concentrations less than 2 mg/L. If fishes gulfing on the water surface and also show the low swimming in the water it indicates deficiency of dissolved oxygen in pond.

The biochemical oxygen demand is a chemical procedure for determining the amount of dissolved oxygen needed by aerobic organisms in a water body to break the organic materials present in the given water sample at certain temperature over a specific period of time. BOD of water or polluted water is the amount of oxygen required for the biological decomposition of dissolved organic matter to occur under standard condition at a standardized time and temperature. Usually, the time is taken as 5 days and the temperature is 20°C. microbes
C6H12O6 + 6O2 ¾¾¾¾®CO2 + H2O
Principle
The test measures the molecular oxygen utilized during a specified incubation period for the biochemical degradation of organic material (carbonaceous demand) and the oxygen used to oxidize inorganic material such as sulfides and ferrous ion. It also may measure the amount of oxygen used to oxidize reduced forms of nitrogen (nitrogenous demand).
Procedure
Fill two BOD bottles with sample (or diluted sample); the bottles should be completely filled.

Chemical oxygen demand (COD) is measurement of oxygen demand of waste in terms of the total quantity of oxygen required for oxidation of the waste to carbon dioxide and water. This test is based on the fact that all the organic compounds, with few exceptions, can be oxidized The test is based on the fact that all organic compounds, with a few exceptions, can be oxidized by the action of strong oxidizing agents under acid conditions. Organic matter + Oxidizing agent = CO2 + H2O. The major advantage of COD test is the short time required for evaluation. The determination can be made in about 3 hours rather than the 5-days required for the measurement of BOD
Principle
The oxidizing agents like potassium permanganate and potassium dichromate is usually used to determine COD. Potassium permanganate is selective in the reaction like it reacts with carbonaceous on the other hand it shows nonreactive with nitrogenous matter. Estimating of COD with any method, oxidizing agent must be present to ensure that organic matter is oxidized completely. The organic matter and oxidisable inorganic substances present in water or wastewater get oxidised completely by standard potassium dichromate (K2Cr2O7) in the presence of H2SO4 to produce CO2 + H2O.The excess K2Cr2O7 remaining after the reaction is titrated with ferrous ammonium sulphate [Fe(NH4)2 (SO4)2]. The dichromate consumed gives the 02 required for oxidation of the organic matter.

Fish excrete Ammonia, is a byproduct from protein metabolism and bacteria break down organic waste such as discarded food, faeces, dead planktons, sewage, and so on. When ammonia is unionized form (NH3) is extremely dangerous; yet when ammonia ionized form (NH4 +) it is harmless; both forms are known as total ammonia. Fish suffering from ammonia toxicity often”become lethargic and frequently emerge near the surface gasping for oxygen. common effects of ammonia in the range >0.1mg/l include Gill damage, breakdown of mucous-producing membranes, “sub-lethal” effects like reduced growth, poor (FC) feed conversion, and reduced disease resistance at concentrations lower than lethal concentrations, osmoregulatory imbalance, and kidney failure.
Principle
When Ammonia react with alkaline Nessler reagent (K2HgI4 or 2KI + HgI2) it produces a yellowish-brown coloured compound. Pretreatment with ZnSO4 and NaOH precipitates Ca, Mg, Fe and sulphide, which form turbidity and apparent colour. Addition of ethylene diamine tetraacetic acid, EDTA (before nessler’s reagent) or Rochelle salt solution prevents precipitation of residual Ca and Mg in presence of the alkaline Nesslers’s reagent.

Around the world, nearly one billion people live along the 3,12,000 Km long coastline. The Indian coastline runs around 8,129 Km distributed along nine coastal states, two groups of islands and two union territories. The coastal ecosystem of India forms a very valuable resource community, supporting the livelihood security of several million rural poor and also contributing the national economy in a large measure. The latest estimates by National Bureau of Soil Survey and Land Use Planning (NBSS & LUP), Nagpur, India, using Global Assessment of Soil Degradation (GLASOD) guidelines indicate that the coastal area in the country is spread over an area of 11.8 million hectares (Mishra, 2005). Yadav et al. (1983) have reported about 3.1 M ha and 2.1 lakh ha of coastal salinity in India and Tamilnadu respectively.

Sulfate can have harmful effects on aquatic life in freshwaters, sulfate cause osmotic stress or specific ion toxicity in aquatic organisms, especially in soft waters where Ca2+ and Mg2+ concentrations are low. Egg fertilization and early embryonic development were the most sensitive developmental stages of whitefish to sulfate (Karjalainen et al., 2021).
Sulphate (SO4 2-) may be estimated by either turbidimetric or gravimetric methods (APHA, 1995)
1. Turbidimetric method is more applicable in the range of 1- 40 mg Sulphate (SO4 2-)/ L
2. Gravimetric method is suitable if the concentration of Sulphate (SO4 2-) is above 10 mg/ L
Turbidimetric Method (Range 1 - 40 mg/L of sulphate) Principle
Sulphate ion (SO4 2-) precipitated with barium chloride (BaCl2) in an acetic acid medium in order to form crystals of barium sulphate (BaSO4).
BaCl2 + SO4 2-+ BaSO4 (precipitate)
The formation of these crystals is increased in the presence of an acetic acid solution containing sodium acetate, potassium nitrate, acetic acid and magnesium chloride. The suspended barium sulphate (BaSO4) is measured by spectrophotometer and concentration of sulphate (SO4 2-) is determined by comparison of the reading with a standard curve. Minimum detectable concentration is approximately 1 mg (SO4 2-) / L.

Remote Sensing in Mineral Exploration

Remote sensing is a powerful tool used in mineral exploration to study and identify minerals and mineral deposits from a distance. This technology allows geologists to gather information about the Earth's surface and subsurface without having to physically access the site. Here are some ways remote sensing is used in mineral exploration:

Mapping Geology: Remote sensing can be used to map geology by identifying surface features associated with mineral deposits. Geologists use images collected by remote sensing satellites and aircraft to create detailed maps of the geology and topography of a region. These maps can help identify areas that are likely to contain mineral deposits.

Mineral Identification: Remote sensing can help identify specific minerals by analyzing the reflectance or absorption patterns of light. Different minerals have unique spectral signatures that can be detected by remote sensing instruments. By analyzing these signatures, geologists can identify the type and abundance of minerals present in an area.

The total plate count (TPC) is also called the Bacterial plate count (BPC), aerobic plate count, standard plate count (SPC), total viable count (TVC) or mesophilic count represents the number of colony forming units (CFU) per g (or per mL) of growing microorganisms such as bacteria, yeast and mold on a nonspecific solid bacteriological growth medium under the specified conditions. Temperature, incubating time, medium type, and any other conditions used in the enumeration varies upon reference standards and laboratory objectives. Laboratories participating in the program choose their own routine conditions.
Principle
Usually direct count of too many bacteria in a sample is difficult but the bacterial colonies may be used as a measure of the bacterial cells in the known serially dilution and plated out on an agar surface in such a way that single isolated bacteria form visible isolated colonies. However, colony-forming unit might actually consist of a chain of bacteria rather than a single bacterium if the organism often develops various cell configurations, such chains. Furthermore, a portion of the bacteria might be grouped together. Thus, typically refer to the process of using the plate count technique as a means of estimating the number of colony forming units (CFUs) in that known solution. Then further this figure use to extrapolate the total amount of CFUs present in the original sample.

Potassium availability in most of the coastal salt affected soils of India is rich except when the soils are low in clay content (Bandyopadhyay et al., 1985). Plants grown under high salinity may show K deficiency due to the antagonistic effect of Na on K absorption and / or disturbed Na / K ratio. Under such conditions application of K is also known to reduce the adverse effect of salinity and sodicity on crop growth (Qadar, 1995). Singh et al. (1980) reported that the addition of FYM increased the K concentration in the soil. Swarup (1987) reported that the incorporation of green manure increased the available N, P and K status of the soil. Available P and K remarkably increased to a tune of 30 and 44 per cent respectively by the application of coir waste (Santhi et al., 1991).

The entire world is now facing a crisis situation. The problems encountered to address the crisis are interactive with each other and there is no easy way to find solution. The world’s population is expected to increase by 70 per cent by the end of year 2050 and there is need to step up agricultural production for a hunger free world. Nearly 70 per cent of the fresh water is used in agriculture sector. The demand for water in agriculture sector can be judged by the fact that several thousands of litres of water is required to produce one kilogram of food grains. Whatever maybe the source from which water is drawn for agriculture, all the sources depend upon the precipitation for replenishment on continuous basis. The precipitation patterns are not consistent and are known for greater variability from season to season, year to year and from region to region. These inconsistencies are further increasing due to recent threat of climate change triggered by the atmospheric pollution. The atmospheric pollution due to increase of greenhouse gases in the atmosphere is responsible for rise in temperatures. The rise in temperature induced changes in global pressure and wind systems. The consequence effect of it is changes in rainfall patterns, frequent occurrence of extreme weather events like floods, droughts, heat waves, intensified cyclonic activity. Rise in temperatures is increasing evaporation of water and water requirement of crops as well. There is considerable increase of the chemicals in the agriculture sector in the form of fertilizers, pesticides, fungicides and weedicides how to increase crop production and protection of crops from biotic and abiotic stresses. Consequently, there is increased pollution of water resources which may adversely affect the availability of fresh water, which is essential and critical input in agriculture for increasing agricultural production. It calls for efficient utilization of water resources in agriculture. More concerted efforts are required immediately to:
• Improve water use efficiency in agriculture
• Reduce pollution of water resources
• Conservation of fresh water resources
• Reduce emissions in agriculture sector and
• Prevent dwindling of fresh water resources

Abstarct

The Photosynthetically Active Radiation (PAR) measure of radiant power is important in evaluating the effect of light on plant growth. The photosynthetic response correlates better with the number of photons than with energy. This is expected because photosynthesis is a photochemical conversion where each molecule is activated by the absorption of one photon in the primary photochemical process. PAR is defined in terms of photon (quantum) flux, specifically, the number of moles of photons in the radiant energy between 400 nm and 700nm. One mole of photons is 6.0222 x 1023 photons ( 6.0222 x 1023 is Avagadro’s Number). The Phtotssynthetic Photon Flux Density (PPFD), i.e. the photon irridiance, is expressed in moles per squre meter and per second (formerly, Einsteins per squre meter and per second). The absorption of PAR by wheat varieties increased from 7.30 h to 11.30 h followed by a decline at 13.30 h at CRI, tillering and milking stages.

Abstract

In order to estimate the irrigation need of the crop, stress degree day index computers from canopy and air temperature could be used. During rabi manon, two varieties (Seeta, Brassica Juncea) and (Benoy, Brassica Camperteris) were grown. The canopy temperature of the crop was measured on 45th, 60th  and 75th  days after sowing and stress degree day (SDDI) was also measured. About 67, 70 and 51 per cent activation between SDDI and dry matter production could be explained at 45, 60 and 75 DAS of the crop growth period. Reflectance by mustard canopy was 940 measured. Late sown crop reflected less radiation with the advancement of growth. Extinction coefficient was also measured and the increase in the value of extinction coefficient upon irrigation showed canopy development and better utilization of increasing radiation by the crop. 

Agriculture sector alone uses nearly seventy per cent of fresh water in the world. Therefore, water use economy in the agriculture sector is becoming a necessity. Increasing flood production is possible reducing water used for irrigation if we can adopt precision irrigation (Fig.11.1).
The precision irrigation has to be practiced by providing water to the crop plants in its root zone to meet the water requirements. The precise irrigation can result in-
• Water saving
• Avoid weed control
• Preventing loss of water due to infiltration
• Preventing loss of water due to surface evaporation from the soil
• Minimise salinity problems
• Improving water use efficiency of crops
Traditionally farmers were practicing flood irrigation. It is a method of watering crops delivering to a field and allowing it to flow over the ground among the crops. It is a simple and inexpensive technique followed in less developed areas. Flood irrigation is not very efficient way as nearly 50 per cent of the water applied in the field will be lost through run-off, soil evaporation and other factors. Flood irrigation is only suitable in wet climates and not effective in sandy soils. It leads to water logging in clay soils. There are several types of flood irrigation such as basin, border, furrow and contour irrigation. Although flood irrigation is not very efficient, the water wastage can be avoided to some extent using some techniques

Climate change is a complex and dynamic phenomenon that has significant impacts on agriculture, especially in terms of uncertainty and variability. Agricultural dynamics refer to the various factors that affect agricultural production, including climate, soil, water availability, pests, and diseases, as well as market forces and government policies. Climate change has significant impacts on agricultural dynamics. Variations in temperature, patterns of rainfall, and occurrences of extreme weather can influence crop yields and livestock production in both beneficial and detrimental ways (UCAR, 2021). The effects of climate change on farming can differ based on the geographical location and the specific agricultural practices employed (Wikipedia Contributors, 2019). For example, in some areas, increased rainfall may lead to increased crop yields, while in other areas, droughts may lead to crop failures and loss of income for farmers. Additionally, rising temperatures can cause reduced crop yields and decreased quality of some crops.

Uncertainty is a term used to describe a situation where there is a lack of information, knowledge, or predictability about a particular outcome or event. In agricultural dynamics, uncertainty can refer to a range of factors that can affect the production, distribution, and consumption of agricultural products. One of the most significant sources of uncertainty in agriculture is the weather. The productivity of crops can be significantly influenced by weather conditions, including rainfall and temperature and farmers need to effectively adjust their agricultural practices to adapt to these changing weather patterns (Guntukulaand Goyari, 2020). For example, droughts or floods can reduce crop yields, while frost or hail can damage crops(Lamaoui et al., 2018).

Precise collection and processing of soil sample is the first and foremost step for carrying out any soil study, therefore it is essential to collect the coil sample very accurately keeping in view the variations in slope, colour and texture of the soil management aspects. Soil sampling should be avoided from non-representative sites like recently fertilized plots, bunds, channels, marshy tracts and spots near trees, wells, compost piles etc. It should be kept in mind that erroneous samples will never yield accurate result in spite of very improved method of analysis. The depth of sampling may vary according to the need of soil study and extent of rhizosphere. However, in general the sampling depth for field crops is the plough layer (0 - 15 cm) but it could be up to one meter or as per the purpose of the study. Soil samples in dry farming areas should be taken depth wise as the roots of the crops in this conditions reaches to deeper layers in search of water and nutrients.

Mainly two types of soil samples (disturbed and undisturbed) are used for determining the physical properties of soil. The disturbed soil samples are used for determination of particle size distribution, particle density, aggregation, column studies for diffusion-dispersion coefficients and soil-water diffusivity. Whereas, undisturbed (core) soil samples are used for the estimation of bulk density, porosity, retention and transmission characteristics of air and water.

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.