eChapters

Mycorrhizae denote the symbiotic associations between plant roots and fungal mycelia. Literally it means fungal root. In 1840, Vittandini proposed that ‘tree rootlets are nourished by certain fungal mycelia which mantle them’. The first illustrations of mycorrhiza were published in the same year by Robert Hartig. However, in 1885 A.B. Frank coined the term “mykorrhizen” to the mutualistic symbiotic fungal association of roots (‘mykos’ fungus ‘rhizen’ roots). He characterized the sheath-forming fungi on tree as ‘ectotropisch’ (ectotrophic) and those without such compact sheath as ‘endotropisch’ (endotrophic). Fossil records reveal that mycorrhizae are as old as terrestrial plants.

In plants, mineral uptake is the process in which minerals enter the cellular material, typically following the same pathway as water. The most normal entrance portal for mineral uptake is through plant roots. Some mineral ions diffuse in-between the cells. In contrast to water, some minerals are actively taken up by plant cells. Mineral nutrient concentration in roots may be 10,000 times more than in surrounding soil. During transport throughout a plant, minerals can exit xylem and enter cells that require them. Mineral ions cross plasma membranes by a chemiosmotic mechanism. Plants absorb minerals in ionic form: nitrate (NO₃^-), phosphate (HPO₄^-) and potassium ions (K+); all have difficulty crossing a charged plasma membrane. It has long been known plants expend energy to actively take up and concentrate mineral ions. Proton pump hydrolyzes ATP to transport H⁺ ions out of cell; this sets up an electrochemical gradient that causes positive ions to flow into cells. Negative ions are carried across the plasma membrane in conjunction with H⁺ ions as H⁺ ions diffuse down their concentration gradient.

Introduction

By enhancing microbial populations, enzyme activity, soil respiration, and microbial biomass, nano-black carbon is a novel method for the enhancement of soil biological characteristics. By reducing soil acidity and boosting soil fertility, nano-black carbon is believed to improve plant development. The application of nano-black carbon to agricultural soils can have a significant positive impact on plant productivity. In addition to potentially boosting soil resilience to climate change, nano-black carbon greatly boosted enzyme activity, microbial activity, and soil organic carbon retention.Due to a liming action, nano-black carbon has been proposed as a potential biotechnology to boost agricultural yields in acidic soils.

Nanotechnology is a field of study which deals with materials at nano-scale like nanometer which is one billionth of a meter (1 nm = 10-9 meter). At nano-scale, physics, chemistry and biology converge towards the same principles and tools. Nanotechnology is domain in science and technology, which is multidisciplinary in nature and any scientist, engineer, medical doctor can do research on nanotechnology. Presently, it is more of a science and less of a technology because of a lack of proper tools for studying the properties of nano-material. Nano-particles (NPs) are materials that are small enough to fall within the nanometric range, with at least one of their dimensions being less than a hundred nanometres. This reduction in size brings about significant changes in their physical properties with respect to those observed in bulk materials. The presence of naturally occurring NPs is implicated in interplanetary and interstellar space (Hochella Jr, 2002) as well as our earth in which life from the beginning has evolved in their presence (Becker and Reitmeijer, 2006). Currently it is observed that NPs can be synthesized from many biological organisms including plants.

Introduction

Since the dawn of the civilization when mankind started agriculture, soil erosion has been the single largest environmental problem and has remained so till date (Sullivan, 2004). This is so because removal of the topsoil by any means has, through research and historical evidence, been severally shown to have many deleterious effects on the productive capacity of the soil as well as on ecological wellbeing. Doran and Parkin (1994) captioned the impact of soil erosion in their popular maxim that “the thin layer of soil covering the earth’s surface represents the difference between survival and extinction for most terrestrial life”. Soil degradation implies decline in its capacity to provide ecosystem services (ESs) of interest to humans and useful to nature’s functions. Principal processes of soil degradation are erosion, salinization, nutrient and carbon (C) depletion, drought, decline in soil structure, and tilth. Examples of ESs provided by soil include ecological/supporting (biomass production, nutrient cycling), regulating (water purification and flow, C sequestration, temperature fluctuations), provisional (food, fiber, fuel, and forages), and cultural (aesthetical, spiritual, and cultural). Erosion-induced degradation diminishes soil’s capacity to provide ESs, and support ecosystem functions.

Although fertile top soils could be lost when scraped by heavy machineries (Ngwu et al., 2005), the key avenues of topsoil loss include water erosion and wind erosion. Sometimes erosion can be such gradual for so long a time as to elude detection in one’s lifetime, thus making its adverse effects hard to detect. Eswaran et al., (2001) propose an annual loss of 75 billion tons of soil on a global basis which costs the world about US $400 billion per year. A review of the global agronomic impact of soil erosion identifies two severity groups of continents and reveals that Africa belongs to the more vulnerable group (Biggelaar et al., 2004). Soil erosion by water seems to be the greatest factor limiting soil productivity and impeding agricultural enterprise in the entire humid tropical region. This is evident in many regions of Africa (Dregne, 1990), mainly in the humid and subhumid zones of Sub-Saharan Africa (SSA) where population pressure and deforestation exacerbate the situation and the rains come as torrential downpours, with the annual soil loss put at over 50 t ha⁻¹ (FAO, 1995).

Abstract

Satellite imagery interpretation has shown the existence of a major Palaeochannel system in the Great Indian desert. These palaeochannels belong to the mythological Sarasvati river, which seems to have flowed southwesterly close to the Aravalli hill ranges and joined the sea in the Great Rann of Kutch. Subsequently it seems to have shifted northwesterly, and more precisely in an anti-clockwise direction and got buried in the desert in Anupgarh plains. While its oldest course is the now misfit Luni river, its final trace is now represented by Ghaggar river. Whereas its overall northwesterly migration is attributed to NE-SW trending cymatogenic arching along the Great Rann of Kutch in the southwest to the Siwalik hills in the northeast, its multivariate palaeodrainage is attributed to block faulting and land subsidence in the Bikaner sector.

The most oxidizable form of nitrogen is nitrate nitrogen (NO3 -N), which is found in minimal amounts in surface waters but can reach considerable concentrations in some aquifers. An essential plant nutrient, nitrate also contributes to eutrophication in receiving water bodies.
Principle
Nitrate reacts with phenol disulphonic acid and produces a nitro-derivative which in alkaline solution develops yellow colour due to rearrangement of its structure. The yellow colour follows Beer’s law and is proportional to the concentration of nitrate present in the sample. Ultraviolet (UV) technique measures the absorbance of nitrate at 220 nm, which is suitable for screening uncontaminated water (low in organic matter). A second measurement made at 275 nm, may be used to correct the nitrate value (because 275 nm is not absorbed by nitrate, but absorbed by other matter). The nitrate calibration curve follows Beer’s law up to 11mg NO3 -N /L.
Reagents
1. Stock nitrate solution (1ml=100 µg NO3 -N): Dry potassium nitrate (KNO3) in an oven at 105 oC for 24 h. Take 360.9 mg potassium nitrate and dissolve in distilled water and dilute to 500 ml. Preserve it with adding 1 ml of chloroform in per 500 ml stock nitrate solution. This solution will stable for at least 6 months.
2. Intermediate nitrate solution (1 ml = 10µg NO3 -N): Take 100 ml of stock nitrate solution and dilute it to 1000 ml of distilled water. This solution can be preserve by adding 2 ml of chloroform per 1000 ml. This Intermediate nitrate solution will stable for at least 6 months.
3. Hydrochloric acid (HCL) solution, 1N: Take 83 ml of hydrochloric acid and dilute it to 1000 ml of distilled water

Nitrite (NO2-) is formed in waters by oxidation of ammonia compounds (by aerobic nitrifying bacteria, e.g. Nitrosomonas) or by reduction of nitrate (by facultative anaerobic denitrifying bacteria, e.g. Pseudomonas). Such oxidation and reduction may occur in wastewater treatment plants, water distribution system, and natural waters. As an intermediate stage in nitrogen cycle, it is unstable. Very high nitrite levels are usually associated with waters having unsatisfactory microbiological activity.
Principle (Colorimetric method)
When nitrite (NO2 -) as nitrous acid (HNO2) mixes with sulfanilamide in an acidic environment (pH 2-2.5), a diazonium salt is created. This salt then combines with N-(1-naphthyl)-ethylenediamine dihydrochloride (NED dihydrochloride) to make a vivid pinkish red azo-dye. The amount of nitrite in the sample directly correlates with the colour that is created. At 543 nm, the colour follows Beer’s law up to 180 µg/L with a 1 cm light path. By diluting a sample, a higher nitrite concentration can be determined. Sulfanilamide + HNO2 + HCl ? Diazonium salt + H2O.
Diazonium salt + NED-dihydrochloride ? Red colouredazo dye

12.1 Introduction-Nitrogen

Nitrogen is a chemical element which has the symbol N and atomic number 7. Elemental nitrogen is a colourless, odourless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78.1% by volume of Earth’s atmosphere. Nitrogen is a constituent element of all living tissues and amino acids. Many industrial important compounds, such as ammonia, nitric acid, and cyanides are made up of nitrogen.

12.1.1 History

Nitrogen (Latin nitrogenium, where nitrum (from Greek nitron) means “native soda”and genes means “forming”) is formally considered to have been discovered by Daniel Rutherford in 1772, who called it noxious air or fixed air. That there is a fraction of air that did not support combustion is well known to the late 18th century.

Argon was discovered when it is noticed that nitrogen from air is not identical to nitrogen from chemical reactions. Compounds of nitrogen were known in the Middle Ages. The alchemists knew nitric acid as aqua fortis (strong water). The mixture of nitric and hydrochloric acids is known as aqua regia (royal water), celebrated for its ability to dissolve gold (the king of metals). The earliest industrial and agricultural applications of nitrogen compounds involved uses in the form of saltpeter (sodium- or potassium nitrate), notably in gunpowder, and much later, as fertilizer, and later still, as a chemical feedstock.

Soil microorganisms are the most important agents in the cycling or transformation of various elements (N, P, K, S, Fe etc.) in the biosphere; where the essential elements undergo cyclic alterations between the inorganic state as free elements in nature and the combined state in living organisms. Life on earth is dependent on the cycling of nutrient elements from their elemental states to inorganic compounds to organic compounds and back into their elemental states.

The microbes through the process of biochemical reactions convert / breakdown complex organic compounds into simple inorganic compounds and finally into their constituent elements. This process is known as “Mineralization”.

Mineralization of organic carbon, nitrogen, phosphorus, sulphur, and iron by soil microorganisms makes these elements available for reuse by plants. In the following paragraphs the cycling or transformations of some of the important elements are discussed.

To meet the food needs of the burgeoning population, India will need to produce 300 million tonnes of food grains by 2020. At present more than 75% of the total food grains produced in the country are of rice and wheat. Use of nitrogenous fertilizers has contributed much to the remarkable increase in production of rice and wheat in India that has occurred during the past three decades. During the last half-decade or so while fertilizer N consumption is touching new heights, the production of both rice and wheat is showing a trend of plateauing. In fact, fertilizer N efficiency of food grain production expressed as partial factor productivity of N (PFPN) has been decreasing exponentially since 1965. The PFPN is an aggregate efficiency index that includes contributions to crop yield derived from uptake of indigenous soil N. fertilizer N uptake efficiency, and the efficiency with which N acquired by the plant is converted to grain yield. A decrease in PFPN occurs as farmers move yields higher along a fixed N response function, unless other factors shift the response function up. In other words, an initial decline in PFPN is an expected consequence of the adoption of N fertilizers by farmers and not necessarily bad within a system’s context

14.1. Determination of Total Nitrogen in Soil (Modified Kjeldahl Method)

Nitrogen mostly present in soil in organic form. Relatively small amount of nitrogen usually occur in ammonium and nitrate form, the available form. The Kjeldahl method of total N determination includes both organic and ammonium form and with modification nitrate form of N can also be included.

Greek scientist Theophrastus (300 BC) advocated legume rotation. As early as 1750 AD it was known that plants require Nitre. Louis Pasteure in 1860 AD stated the possibility of atmospheric nitrogen fixation by microorganisms. Hellriegel and Willfarth (1886) strengthened the views of Louis Pasteure by his observations on the irratic behaviour of legumes to nitrate nutrition. Beizerink (1890) isolated the organism involved in nitrogen fixation. The systematic field experiments conducted at Rothemstead experimental station showed that the plants respond to inorganic nitrogen.

ROLES OF NITROGEN IN CROPS

Plants contain 1-5 per cent nitrogen by weight. It is a structural component of chlorophyll, aminoacids and proteins. Plant proteins contain 16 per cent nitrogen (6.25 × %N = protein). Plants are dependent on protein for their propagation. Cereals possess a threshold protein level below which grain will not form.

Nitrogen (N) is an essential element for all forms of life because it is a major component of amino acids, which are the building blocks of proteins, nucleic acids such as deoxyribonucleic acid (DNA) and other cellular constituents. It is a structural component of chlorophyll in plants, which is used in photosynthesis to make their food. Nitrogen ranks first among the essential nutrient elements required for plants. Its careful management is very important for crop production.

Nitrogen exists as two main stable isotopes (isotopes of a given element have the same number of protons but different numbers of neutrons in each atom) namely, ¹⁴₇N (abundance 99.63%) and ¹⁵₇N (abundance 0.37%). These can be separated by chemical exchange or by thermal diffusion. Both ¹⁴₇N and ¹⁵₇N isotopes of N are stable isotope which do not disintegrate as in case of other radioactive isotope like ³² ₁₅P. There are four other isotopes of N viz. ¹²₇N, ¹³₇N, ¹⁶₇N and ¹⁷₇N, mostly are radioactive having very short half-life and not used in agriculture. The ¹³₇N has a half-life of about 10 min, while other three have half-life of only few sec. The ¹⁵₇N (tracer) isotope is used as a tool for determination of pathways of transformation of N in soil or plant or animal.

The major part of N comes from atmosphere (air). On the basis of volume by volume (v/v), air contains about 78-79% N₂, 20-21% oxygen (O₂) and 0.03% carbon dioxide (CO₂). Most living organisms cannot utilize N₂ gas present in the atmosphere directly because it is present as di-nitrogen form or di-atomic form (N≡N). It is called as an inert gas. Therefore, to break this triple bond, huge amount of energy is required. After breaking of triple bond of N₂ molecules, it combines with other element particularly with O₂ or hydrogen (H) to form oxides of N (NO, NO₂, NO₃ and N₂O) or ammonia (NH₃). Thus, breaking of triple bond is must for forming NH₃ which further can be used as the key material for almost all fertilizers. Therefore, the fixation of N₂ is vital for production of all nitrogenous and complex fertilizers like NP/NPK and nitrophosphates.

Introduction

Soil is a vital, complex, and firm layer of the land surface that provides a source of minerals and organic matter interacting with air and water to harbor life forms. (Lobmann et al., 2022). Versatile micro and macro living organisms, i.e., bacteria, fungi, and actinomycetes, inhabit soil and contribute to its quality, health, and inevitable role in serving the environment (Elsakhawy et al., 2022). Soil roots for a variety of crucial functions which involve ecosystem services or socioeconomic activities, e.g., biomass production, climate gas fluxes of CO2 , N2 O, and CH4 , water cleaning, storage and supply, foundation of construction and provision of construction materials, or provision of habitats etc. The responsibility of soil in sustaining life on earth by providing and conserving resources is not negotiable.

7.1. Developing Sector in Scientific and Technological Approach of Waste Management

From the very past, many traditional practices have been put into use for waste management like landfilling, composting, and recycling, which are practiced even today. However, the boundless upsurging waste compels the modern world to modify the traditional methods or to introduce innovative techniques with the grace of technology

The study of soil organic matter is becoming increasingly important by the day as world agriculture attempts to ensure sustainability of soils, while at the same time striving to enhance food production to feed an ever-burgeoning population. The use of green manures and pasture leys, the return of residues and additions of organic amendments to the soil are often resorted to in an attempt to increase soil organic matter which immensely benefit the physical, chemical and biological make-up of the soil.

Abstract

Groundwater flow modeling in hydrological sciences is one of the main tools used to assess the resource potential in terms of quantity and to predict the future impacts under different stresses/scenarios. This case study is prepared to present the  groundwater flow model for the Osian-Mandore pilot area with 12 villages of Mandore Block and 21 village of Osian Block in Jodhpur district of Rajasthan. The spatial model parameters and spatio-temporal fluxes were acquired and processed using remote sensing, GIS and Groundwater flow modeling interfaces. MODFLOW software was used to model the groundwater flow system in three interfaces PMWIN 5.3.0, Groundwater Modeling System and Visual MODFLOW. 

A well-managed nursery is essential for producing healthy, uniform, vigorous, and field-ready planting material. This chapter explains nursery planning, site selection, propagation structures, growing media, containers, trays, irrigation, fertilization, sanitation, pest management, hardening, and transplant quality assessment. Protected raising techniques using shade nets, polyhouses, insect-proof structures, and controlled environments are discussed for improving germination and seedling survival. Particular attention is given to biosecurity, disease prevention, substrate sterilization, water quality, and environmental control. The chapter also introduces quality indicators such as root development, shoot growth, and physiological fitness. Efficient nursery management reduces establishment losses and provides the foundation for productive and profitable horticultural enterprises.

Concept of nutrient availability: The ions in the soil solution are available to plant provided they can reach an active root or it can reach them. The concentration of ions in the soil solution at any given moment is however; usually low, except immediately after the application of water soluble fertilizers.

Most of the nutrients are taken up by the plant in the form of cations which are positively charged. Available cations either in the soil solution or held against leaching by negatively charged clay or humus particles are easily taken up by the plants. Other plant nutrients notably phosphorus, boron and molybdenum are taken up by the plant as anions which are negatively charged. The concentration of anions in the soil solution is usually low because they become converted to new less soluble forms e.g., soluble phosphate ions forms less soluble iron or aluminium phosphates. Minerals upon weathering and organic matter upon mineralization release nutrient ions.

Physical factors

However, much readily available nutrients a soil may contain various physical features of the soil make it impossible for the plant roots to absorb it. It then becomes positionally unavailable. These features include hard pans, undesirable soil structures, presence of hard clods, dry soil horizons and water logged situation.

Low soil cation exchange capacity leads to less retention of calcium, magnesium, potassium, copper and zinc.