eChapters

Introduction

In this computer age software plays a vital role in speeding up the research activity. Software and databases help in storage, processing and accessing large volumes of information. Software helps to retrieve right information at the right time at the right place for the right purpose. The time of researchers is very precious. Instead of spending it in monotonous and tedious tasks, it could be used more effectively for new findings. With the advent of computer and its softwares, this problem could be overcome to a considerable extent.

Software is a set of instructions given to the computer to perform certain tasks. In this era of information technology, its essential to apply different softwares to speed up the research activity. It is therefore, utmost importance to have information about the different software already developed in the area of fisheries/aquaculture worldwide. Almost all the routine tasks which the scientists or the farmers are doing, could be automated in the areas like financial & economic analysis, development planning and project appraisal, facility design, management planning and production forecasting, facility construction, management decision support and record keeping, disease diagnosis and treatment, environmental regulation and aquaculture databases. FAO, World Fish Centre and other International Research Organisations have contributed software and database development in the area of aquaculture (Anon, 1999; ICLARM, 1998; FAO, 1999; Erist, 1998). In India also initiative to develop software and database has been taken up. Preliminary report on the availability of fishery related software and databases are available (Roy, 2000). In this communication, an attempt has been made to list softwares and databases that may be used in fisheries and aquaculture research and development/activities.

8.1 Moisture extraction pattern

The moisture extraction pattern reveals about how the moisture is extracted and how much quantity is extracted at different depth level in the root zone. The moisture extraction patter shows the relative amount of moisture extracted from different depths within the crop root zone. The moisture extraction pattern of plant growing in a uniform soil without a restrictive layer and with adequate supply of available soil moisture throughout the zone is shown in Figure. 8.1.

Soil pH

Danish scientist Sorensen (1909) first used the term pH. The H+ concentration is usually small and is expressed in terms of pH, defined as the logarithm of the reciprocal of the H+ concentration, in moles per litre. The pH scale ranges from 0 to 14, with 7 being neutral. Soil acidity is the concentration of H+ in the soil solution. This is active acidity. Besides, there is a potential acidity, that includes the H+ adsorbed on the colloidal fraction of soil. The pH scale is derived from the dissociation constant of water, Kw:

The soil acidity and alkalinity are major driving forces in regard to the mobility of plant nutrients from soil to plants. The extreme acidity or alkalinity cause damage to the crops and thus yield is affected. Correction of soil acidity or alkalinity depend upon the pH of the soil and its previous management options. Application of fertilizer in soil may be one of the factors affecting soil conditions. Exchangeable and soluble iron and aluminium ions and their hydroxy ion species may contribute hydrolysis to release H+ ions to the soil solution. The soluble salts of carbonate and bicarbonates also develop salinity in soils.

7.0 Soil reactions

Soil reaction is an indication of the acidity or alkalinity of soil and is measured in pH . The pH scale ranges from 0 to 14 with pH 7 as the neutral point. When the amount of active hydrogen ions in the soil solution increases the soil pH decreases and thus becoming more acidic in reaction. One of the outstanding physiological characteristics of the soil solution is its reaction. Soil reaction can influence the physico-chemical properties of soil which can regulate the growth and activity of plant and soil organisms associated with it.

Soil acidity is most conveniently measured by pH of soil suspension with water. Pure water undergoes dissociation into hydrogen and hydroxyl ions and are in equilibrium with undissiociated water molecules Thus, H2 O ??? ??? H+ + OH- (1) and in presence of another H2 O molecule, H+ converts to H3 O+ H+ + H2 O ??? ??? H3 O+ (2) Since water is a weak electrolyte and dissociates as per Eqn. 1, the ionic product of water can be written as – KW = aH+ x aOH- = (CH+ x COH– ) x ( fH+ x fOH-) (3) where, a, C, and f represents the activities, concentrations and activity coefficients of respective ions. In pure water and in dilute solutions the activity coefficients are approximately unity thus the product of concentrations of H+ and OH-1 is the ionic product of water and at ordinary temperature (250 C) this has a constant value of 10-14 gm ions per litre so, Kw =(CH+ x COH–1) = 10-14 gm ion per litre (4) such that, CH+ = COH–1 = 107 gm ion per litre Therefore, if hydrogen ion concentration of an aqueous solution exceeds this value, (10-7gm ion per litre), the solution is said to be acidic then there will be a proportionate decrease of OH- concentration to maintain the constant value of ionic product.

Aggregation is a direct indicator of soil structure. Ahealthy soil is considered to have well aggregated structure. Though not routinely followed during soil testing and chemical analysis, aggregation is one of the major indicators of soil physical health. Wet sieve method (Yoder, 1936) is usually followed for soil aggregate analysis. This involves gently raising and lowering a nest of sieves in water to assess the stability of aggregates to rapid wetting. However, the Yoder’s wet sieving method has been modified to make it simpler and currently, the method of Kemper and Rosenau, 1986 is being commonly used in research laboratories. One of the pre-requisites in these methods is the availability of wet sieving apparatus and further, these methods are laborious and time consuming. On the other hand, the method described by Cambardella and Elliott (1993) is considered very ideal because of its simplicity and is being widely used for aggregate bound soil carbon fraction study. The soil sample is wet sieved with a series of three sieves (2000, 250 and 53 micron size).

Aggregation is one of the basic physical characteristics of soil. Under natural conditions, primary soil particles, particularly clays, tend to join together to form secondary units called aggregates. Size distribution of soil aggregates is important because the size of the aggregates determines their susceptibility to water and wind erosion. Also, their size is important in determining the pore size distribution and regulating pore space in cultivated soils.

There are a variety of procedures being in use to test the stability of aggregates and aggregate size distribution. However, choice of the method for analysis of aggregate size distribution is determined by the purpose of analysis. The developed measures are relative and purpose specific. This chapter discusses dry aggregate analysis.

In natural condition primary soil particles cohere to each other to form a cluster or an aggregate through the cementing action of various agents like organic matter, carbonates, oxides of iron and aluminium, etc. Aggregate analysis tells one about the structural status, pore geometry which in turn influences the movement of air and water in soil, amount of water stable secondary particles (aggregate) as well as the extent of finer particles aggregated to the coarser particles and the erodibility status of surface soil against wind and water.

In natural condition primary soil particles cohere to each other to form a cluster or an aggregate through the cementing action of various agents like organic matter, oxides of iron and aluminium, carbonates, etc. Aggregate analysis tells one about the structural status, pore geometry which in turn influences the movement of air and water in soil, amount of water stable secondary particles (aggregate) as well as the extent of finer particles aggregated to the coarser particles and the erodibility status of surface soil against wind and water.

Methods of Analysis

Among the several methods of aggregate analysis the commonly used methods practiced in agriculture and related fields are wet sieving and dry sieving method of aggregate analysis.

9.1 Determination of Oxygen Diffusion rate (ODR) of Soil

The rate of movement of oxygen from atmosphere to respiring plant root cells is important for root respiration and thereby the growth and development of plant. While diffusion through the air-filled pores maintains the exchange of gases between the atmosphere and soil, diffusion through water films maintain the supply of oxygen and disposal of carbon dioxide from active root tissues which are typically hydrated.

Principle

Lemon and Erickson (1952) introduced a method for measuring oxygen diffusion in soil with the help of platinum electrode. The process measures the extent of chemical reduction of oxygen by the platinum electrode maintaining a constant potential of 0.65V with a reference electrode.

Soil amendments and organic matter play critical roles in enhancing soil fertility, improving crop productivity, and promoting sustainable agriculture. This abstract provides an overview of the importance of soil amendments and organic matter in soil management practices, highlighting their impacts on soil structure, nutrient availability, and microbial activity. By incorporating organic amendments such as compost, manure, and green manures into soil, farmers can replenish essential nutrients, improve soil structure, and enhance water retention capacity. Additionally, soil amendments can mitigate soil degradation, erosion, and nutrient runoff, contributing to long term soil health and ecosystem resilience. Understanding the benefits of soil amendments and organic matter is essential for promoting sustainable soil management practices and ensuring food security in a changing climate.

A. Soil Sampling

Soil is a store house of several nutrients. These are present in available and reserve forms and a dynamic equilibrium always exists between these forms of nutrients in soil. If the available form of a given nutrient element is depleted by crop uptake or by any other means, there will be immediate replenishment from the reserve source. In this context, it is also appropriate to note that soil is not an eternal source of plant nutrients. In a bid to produce more, soils are exploited very badly and they are gradually becoming deficient in several nutrients. There are several soil related constraints coming in the way of achieving sustainability in crop production.

3.1 Concepts of Soil Sampling

Samplinginvolvesthe selection fromthe total populationof a subset ofindividuals upon which measurements will be made. The measurements made on this subset (or sample) will then be used to estimate the properties (or parameters) of the total population.Samplingisinherent toanyfield research programinsoilscience because the measurement of the total population is impossible for any realistic study.

Samplingdesign involves theselection of the mostefficient method forchoosing the samples thatwill be used to estimatethe properties of the population. The definition of the population to be sampled is central to the initial formulation of the research study. The sampling design defines how specificelementswill be selected from the population, and these sampled elements form the sample population.

Pedogenetic and soilgeomorphic studies focus on determining the processes thatformed the soilproperties or landscapes under study and the environments that controlled the rates of these processes. Pedonscale studies are closely associated with thedevelopmentof soil taxonomic systems andfocus onvertical, intrapedon processes. Soil geomorphic studies are the interface between quaternary geologyand soil science and soil geomorphologistsfocus on lateral transferprocesses and the historical landscape evolution. Hence sampling is difficult for a particular population and is differentfor differentstudy.

3.1 Important Soil Physical Properties

3.1.1 Analysis of Soil Texture

Soil texture refers to the relative proportions of sand, silt, and clay on weight basis. Soil texture was recognized from very early times by experienced farmers from the feel of moist soil placed between the thumb and forefinger. The size groups arbitrarily classified by the International Society of Soil Science (ISSS) into clay (< 0.002 mm), silt (0.002 0.02 mm), fine sand (0.02-0.2 mm), and coarse sand (0.2 2.0 mm). Each soil textural name specifies the weight percent of each fraction falls within certain defined limits. The determination of the percentage of the soil separate present in a sample is called particle-size analysis.

Each type of particle present makes its contribution to the nature of the soil as a whole. Sandy soils are usually quite permeable to air, water, and roots, but they have two important limitations. One is their relatively low water-holding capacity; the second is that they are poor storehouses for plant nutrients. These limitations of sandy soils can, of course, be overcome if both fertilizer and irrigation water are available, but the costs are large.

Clay not only have a large surface area per gram, it also has electrically charged particles. These charges give clay the capacity to attract plant nutrient ions to its surface in forms available to plants, but sand lacks this capacity. Clay holds much more water than sands because they have a large surface area to be coated with water. One important problem with clay soils is their stickiness. When wet, they stick to ploughs, boots, or whatever they contact. Loam and silt loam soils are highly desirable for most uses. They have enough clay to store adequate amount of water and plant nutrients for optimum plant growth but not so much clay as to cause poor aeration or to make working with them difficult.

Soil sampling is the first step of soil analysis. As very small fraction of the huge soil mass is used for analysis, it becomes extremely important to get a true representative soil sample of the field.

6.1 INTRODUCTION

The Climate and soil play important role in growth and development of the plant. Growers in general and fruit growers in particular should have adequate knowledge of the effect of various soil and climatic conditions on raising horticultural crops. Horticultural crops cannot be grown in all types of soil and climate. Hence zone- wise cultivation is made. Climate includes a number of parameters like temperature, rainfall, atmospheric humidity, wind, hail and light whereas soil covers factors like moisture content, texture, soil reaction, nutrient content, chemical composition and soil temperature.

6.2 SOIL

Soil is a thin outer covering of the earth surface. It is the natural resource directly developed by different natural forces acting on natural materials. Soil serves as a base and support for plant growth. It is a basic medium for plant growth and supplies nutrients for growing plants. Soil is the home of the plant root and the reservoir for essential nutrients and water for growth and development of crop plants.

Soil
Cashew is grown on a wide variety of soils in India. It comes up well in all types of soils at an altitude up to 700 m. It cannot stand in water logged or saline soils. It can come up in very sandy soils also. Adoption of cashew has been found in wide variety of soils from coastal sands to degraded laterites. The worst soils, not suited to other crops, are normally allotted for cashew. In Sri Lanka and Philippines, it is grown in alluvial soils. Cashew comes up well even in volcanic soils of Indonesia, Fiji and some part of Philippines. Cashew is not suitable in heavy clays, water logged conditions and ill drained soils. It is grown abundantly in loose sandy soils particularly in South India, East Africa and Brazil. In Karnataka and Kerala, it grows well in poor laterite soils. Cashew prefers well-drained aerated sandy loam soils with adequate moisture. Coastal plains and plateau are very good for cashew cultivation.

In India, cashew is mostly grown on laterite and red soils and coastal sands. The tree has an extensive root system, which helps it to tolerate a wide range of moisture levels and soil types, but commercial production is only advisable in well-drained, sandy loam or red soils with slight acidic pH (4.5-6). The cashew tree can flourish in the sand of open beaches, but it grows poorly in heavy clay or limestone.

Though cashew can be grown on a variety of soils, a well-drained 1-1.5 m deep soil having a water table between 2 and 10 m depth and pH of 5.6 to 7.0 is preferred. Laterites, red and coastal soils rich with organic matter are best for cashew growing. Even the marginal soils can be used for cashew cultivation but the waterlogged condition should be avoided as the cashew is very susceptible to it (Farooki and Sreeramu, 1999).

Soil: Soil is the upper most crust of earth surface which supports plant growth. It is defined as a three phase system in which plants grow. These phases are solid, liquid and gas and are essential. Solid part is frame which provides space for other two. This consists of minerals, clay minerals and organic matter. The soil is also a living system with millions of microbes that breakdown organic matter and builds it again.

Some points are following

•    Microbes are essential and survive only when soil is well aerated and rich in organic matter and avoid of waterlogged conditions.

•    Texture of soil depends on the size of solid particles and classified as gravel, coarse and fine sand, silt and clay.

•    Soils are classified according to relative distribution of these particles and there are 12 textural classes.

•    Likewise, arrangement of these particles is referred as structure, and both texture and structure land soil physical properties like water holding capacity, aeration and bulk density.

Soil

Soil has a pronounceed effect on the plant growth and productivity in kewda. Well drained sandy-loam soil with adequate supply of moisture is best suited for its vigorous growth and flower production. Thickly distributed profitableKewda plantations with normal flowering are found in the lateritic belts with deposits of silty loam soil and adequate moisture supply. In heavy clay soil with inadequate moisture supply, the plants grow vegetatively with poor flowering. At places close to the Bay of Bengal like Rangiagarh, Kujang, Paradeep of Jagatsinghpur district, where a silt-loam soil deposit is found over the clay zone, the dense plantations of kewda with free flowering ability are noticed. But surprisingly, the female plants are more at few places close to the Paradeep port, which may be due to seed propagation by drifting of ripe fruits from the uplands; while in Ganjam district, the farmers are used to plant the selected male plants in their field resulting in high flower production.

The tentative age of the natural plantations is estimated from the rates of leaf production, stem and branch growth (5-50 cm / year) and development of branching pattern (primary and secondary) in conjuction with the interactions made with the local farmers of kewda (Fig. 9). The plants of different age groups (1 to 5 years) are observed for growth characters and flower production at Tulu of Ganjam and Konark of Puri districts under farmers’ field condition and it is observed that the initiation of flowers started at 5 years of age and the rate of flower production was 1.7 to 2.2 per plant (Table 9).

Soil- Soil is the upper most crust of earth surface which supports plant growth. It is defined as a three phase system in which plants grow. These phases are solid, liquid and gas and are essential. Solid part is frame which provides space for other two. This consists of minerals, clay minerals and organic matter. The soil is also a living system with millions of microbes that breakdown organic matter and builds it again.

Some points are following

Microbes are essential and survive only when soil is well aerated and rich in organic matter and devoid of waterlogged conditions.

Texture of soil depends on the size of solid particles and classified as gravel, coarse and fine sand, silt and clay.

Soils are classified according to relative distribution of these particles and there are 12 textural classes.

Likewise, arrangement of these particles is referred as structure, and both texture and structure lend soil physical properties like water holding capacity, aeration and bulk density.

Generally loamy soils and crumb structure are most preferred for fruit crops.

According to level of organic matter, soils are classified as mineral soil or organic soil and soil having more than 20% organic matter is organic soil like peat and muck.

SOIL MANAGEMENT PRACTICES

Good soil management is the basic for deriving greater benefits from the fertilizers used in crop production. Some of the good soil management practices are

Good tilth is the first feature of good soil management. It means a suitable physical condition of the soil and implies in addition a satisfactory regulation of soil moisture and air.

The maintenance of soil organic matter which encourages granulation is an important consideration of good tilth.

Tillage operations and timings should be adjusted as to cause the minimum destruction of soil aggregates. Good tilth minimizes erosion hazards.

The choice and sequence of adaptable crops or crop rotation are other very important considerations. These are related to climate, particularly rainfall and its pattern of distribution and the characteristics of the soil profile, including drainage and extent and duration of available soil moisture. A proper sequence of crop varieties greatly influences soil conditions. It is more realistic to evolve cropping patterns and land management practices according to land capability. Cropping patterns chosen and management practices adopted should aim at soil and moisture conservation for efficient nutrient and moisture utilization.

As compared to total N soil total P is present in much smaller amounts in soil; it is roughly about 10% of total N. Further, while N in soil is in the largest amount in surface 0 to 15 cm layer, soil P may be the same or in larger amounts in the sub-soil. Again, organic P constitutes only a small portion of total P. Thus, the Chemistry of soil P is generally centered on inorganic P. Total and organic P in some Indian soils is given in Table 8.1; hill soils had the highest and the desert soils the least total as well as organic P.

FRACTIONS OF INORGANIC P

All P in soils has originated from apatites [3 (Ca₃ (PO₄)₂.Ca×₂, where ×₂ could be F, Cl, (OH) or CO₃). Large deposits of apatites form phosphate rocks, which are the major materials for making phosphate fertilizers. As the soil weathering proceeds, P in apatite reacts with Al, Fe and other cations and forms compounds of different solubility. A knowledge of these can help in understanding the P-supplying capacity of soils. A number of chemical extractants and resins are used for determining different fractions. In general, 7 fractions of inorganic soil P are mentioned. These are: saloid-P (soluble and loosely bound P extractable by NH₄Cl), labile P (determined by using anion-exchange resins), Al-P (NH₄F extractable), Fe-P (NaOH extractable), Ca-P (H₂SO₄ or HCl extractable), reductant-soluble- P (CDB or sodium citrate-sodium dithionite-sodium bicarbonate extractable) and occluded P (CTB followed by NaOH extractable)

Out of the three primary plant nutrients (NPK), potassium (K) is taken up by crop plants in the largest amount, yet as compared to N and P, only a tiny fraction of it goes in the grain or seed. For example, Shivay et al. (2015) reported from a study on rice that about 20 kg N, 6 kg P (13.7 kg P2O5) and 46 kg K (55.2 kg K2O) was taken up by the crop to produce each Mg or tonne (1,000 kg) of rice kernel; however, only 4.3% of K taken up by the crop was found in the rice kernel as compared to 44% of N and 66% of P taken up by the crop. Some information on N, P and K removed per tonne of grain/ seed for some crops is given in Table 9.1.

Soil is defined as a thin layer of earth’s crust which serves as a natural basic medium for the plant growth. Soil is a dynamic natural body composed of minerals, organic materials and living forms on which plants grow. Soil are formed by the weathering of rocks and minerals in presence of soil forming factors like climate, organisms, relief or topography, parent material and time (cl,o,r,p,t).The weathering of rocks and minerals are associated with physical and chemical phenomenon. The principal agents of physical weathering are temperature, water, wind, plant and animals. Chemical weathering is affected through the process of hydrolysis, hydration, carbonation, oxidation and reduction.

Each soil is characterized by a given sequence of horizons. Combining of this sequence is known as soil profile. Soil profile is a vertical section of the soil through its horizons. The layers or horizons in the soil profile vary in thickness and have different characteristics like colour, texture, structure etc. The horizons are designated by O, A, E, B, C and R.

Horizon: The layers seen in the vertical section of the soil profile are called horizons.

Soil is a living, dynamic ecosystem that nurtures plants. Soil is responsible for Sustaining plant and animal life below and above the surface, Regulation water and fertilizer/pesticide runoff, Storing and cycling nutrients. But, the natural soil balance was disturbed by man due to agricultural activities to get food. The intensification of agriculture leads to soil erosion, which leads to creation of unproductive soils.

In agriculture, soil erosion refers to the wearing away of a field’s topsoil by the natural physical forces of water and wind or through forces associated with farming activities such as tillage. As a result of improper cultivation practices, deforestation and overgrazing aggravates the problem of soil erosion.

Globally soil erosion has reached a level that endangers the sustainable supply of food for the growing global population. It already threatens food production and ecosystem service delivery and therefore, there is a pressing need to address this threat. This is especially true in India where, in a total area of 328 million hectares (m ha), 121 m ha is undergoing soil degradation, 68% of which is attributed to water erosion. Water erosion rates range from 5 t ha^–1 yr^–1 in dense forest regions to rates in excess of 80 t ha^–1 yr^–1 where erosion is most severe, such as in the Shiwalik mountainous region. India’s average soil loss has been estimated to be 15t ha^–1 yr^–1; however, given the limited coverage of measurements, this should be treated with caution. In the light of the serious threat that soil erosion poses in the country, there is a pressing need for a systematic nationwide assessment of land degradation due to erosion using appropriate techniques. The area under ravine soil erosion is highest in UP to a tune of 12.30 lakh hectares and lowest in Maharashtra to a tune of 0.20 lakh hectares

ABSTRACT

Shivaliks, the most impor tant ecosystem of the foothills of the Himalayas, have been identified as one of the eight most degraded rainfed ecosystems of the country. They are characterized by undulating barren hill slopes, undulating agriculture fields and erratic rainfall pattern. Majority of the lands under cultivation and orchards in the hilly terrain of the state are thus subjected to runoff and soil loss of varying degrees. The soils of Shivalik hills in Solan district of Himachal Pradesh were found to be coarse in texture with abundance of gravels (upto 73.20%). According to the erodibility indices i.e erosion ratio (ER) and erosion index (EI), all the soils were found to be erodible; however, grasslands and forestlands recorded lowest values for these indices. Forest soils had higher water stable aggregates (WSA), mean weight diameter (MWD) and lower dispersion ratios than the cultivated and orchard soils. The dispersion ratio was comparatively higher under cultivated lands (17.37-22.54) followed by orchards (14.36-14.99) and lowest under forest soils (12.59-13.70). Areas having barren lands recorded very high soil loss (86.05 t ha^-1 yr^-1) followed by intensively cultivated areas (58.87 t ha^-1 yr^-1) and both of these have fallen in very high category of priority. A medium category of soil loss has been observed under degraded forests, agro-horticultural plantations and scrubs (14.77 – 18.27 t ha^-1 yr^-1). While low to very low soil loss was recorded under moderately dense, mixed and dense forests (3.46 – 9.59 t ha^-1 yr^-1). Weighted soil loss of 10.60, 17.12, 19.20 and 256.73 t ha^-1 yr^-1 was observed under 5-10, 10-15, 15-35 and >35 per cent slope classes. However, dense forests in all the slope classes registered annual soil loss within the tolerance limit (5 t ha^-1 yr^-1). Hence, maximum runoff, soil loss and available NPK losses were recorded from the barren lands and lands under cultivation followed by orchards and minimum under forests. Risk of soil erosion is higher on steeper slopes. Mixed forests in slope class of 15-35% have also reflected very high soil loss. However, dense forests in all the slope classes registered annual soil loss within the tolerance limit (5 t ha^-1 yr^-1). There is an urgent need to adopt suitable soil and water conservation measures to check runoff losses causing loss of soil and nutrients.

Soil is made up of minerals, organic matter, gases, liquids and micro-organisms in different proportions. It provides anchorage to plants. It is important for life as it provides the medium for the growth of a plant, habitat for several insects and other organisms. Soil is a store house of nutrients, micro-organisms, air and water. It is the source of four essential ‘living’ factors including food, clothes, shelter, and medicines.

Introduction

Many of the globe’s major food crops viz., wheat, rice and vegetables have reached “yield stagnation” or “yields plateau”. This can be attributed to the land degradation and soil diminishing capacity to supply nutrients at the required rate due to over mining of essential nutrients. Further, imbalance use of fertilizers and lesser use of organic manures over the years have badly affected the soil health. To bring back life to the soil and relieve it from nutrient stress; fertilizers and manures/bio-fertilizers have to be applied in a scientific manner. At the same time, their indiscriminate use can result either in their under utilization and toxicity or leaching to the lower horizons, leading to underground water and create pollution problems. The soil is also the main source of sixteen mineral elements identifies in view of their importance for plant growth. These are N, P, K, S, Ca, Mg, Na, Fe, Mn, Zn, Cu, Mo and Cl (Tisdale et al., 1985). Nitrogen, potassium and phosphorus have been designated as major nutrient elements in order of their removal by the plant; sulphur, calcium and magnesium as secondary nutrients while zinc, copper, iron, manganese and molybdenum are called micro nutrients as these are taken by plant in traces. 
Nutrients need of vegetables depends upon the yield response to applied nutrients from fertilizers, agro-climatic conditions, variety and nutrient availability from the soil pool. The nutrient status of the soil further depends upon the quantity of total and available nutrients present in the soil pool. The soil tests helps in selecting the proper manuring schedule for various crops in a sequence by knowing about the nutrient build up or depletion in the soil profile. The adequacy of soil testing methods to correctly predict the fertilizer needs varies with the soil type, climate/soil moisture and crop species. The rainfall also influences the efficiency of soil testing methods, especially nitrogen and potassium when it becomes imperative to have tissue analysis for modify the fertilizer recommendations. Plant tests also help to identify the nutrient deficiency in standing crop and in the event of deficiency of a particular nutrient helps in taking corrective measures (Sud 
et al., 2008).

3.1 Soil Inhabiting Fungi

There’s a wild and wonderful world that remains hidden for most of us, at least most of the time. It’s an amazing ecosystem filled with fascinating creatures interacting with one another to create an intricate, dynamic web of life. It’s right under our feet: the soil ecosystem! Many organisms make up this ecosystem, and some of the most important ones are the fungi. Healthy soil is alive and teeming with an array of fungus species, each playing a vital role in its environment. Healthy soils are alive with an especially diverse array of fungal species, and many are essential to the health of the plants growing in that soil. In fact, a soil devoid of fungi is a dead soil, and is unlikely to support thriving plants. Some soil fungi are single-celled and visible only through a microscope. Others form large, underground networks of filaments that can cover an area the size of a football field or larger. Most of us are familiar with the above-ground parts of some soil fungi, the mushroom.

Fungi are one of the key microbial groups in terrestrial ecosystems that enabled colonization of land by plants and facilitated development of soil that supports most of the biota on Earth. The kingdom Fungi is one of the most diverse groups of life with an estimated 1.5–6 million species that represent heterotrophic mutualists, pathogens, and saprotrophs (Tedersoo et al., 2017). The 70,000–100,000 currently recognized species are distributed among 156 orders, 46 classes, and 12 phyla. Fungi have traditionally been identified and classified based on morphological characters of fruiting bodies and living cultures. Similar to bacteria and archaea, merely <1% of fungal species have been cultivated with established protocols, which renders large taxonomic groups undescribed and virtually unknown to science. Roughly 80% of all soil-inhabiting fungal taxa cannot be identified at the species level, and 20% cannot be reliably assigned to known orders.

SUMMARY

To meet the food requirement of spirally growing population we need to produce more crops per unit area of land. Soil is the raw material for land and is the outer covering of earth surface. It is a very important resource and gift of nature for the substrate where plant can grow. Agriculture is the backbone of our country, and agriculture mainly dependent on soil quality. The success management of soil quality depends on the mechanistic approach, how soil responds to agricultural use and practices over times. As soil degradation grows day by day there is a big challenge against agriculture to sustain. Now days the main cause for soil degradation is non-planed use of land resources. This is the time when we think about this big challenge and face it for the future generation which we need to manage the soil quality for self sustainability. Because adaptation of appropriate soil management scientific methodologies and land use planning could replenish the degraded soil properties for sustainable agriculture which is need of the hour.

INTRODUCTION

Potatois theworld’s most importantnon-grain foodcommoditythatranks fourth as main food crop in the world after rice,wheat and maize. The crop is grown inmorethan 100 countries, mainly in Asia (195.67 million tons)and Europe (121.76 million tons)(yieldin 2017 as per FAOSTAT, 2019). Because of its efficiency in producing high dry matter, energyand edibleprotein per unit area per unit time, it holds promise for food security in the scenario of ever growing world population. The full potential of this crop however, can onlybe realized if diseases and pests are kept under control, especially in asubtropical country like India, wherethe weather is highly conducive for a number of pathogens.

A number of soiland tuber borne diseases are known to affectthe potato crop causing heavy yield losses. These diseases not only reduce quality and market value of the producebut also spread to new un-infested fields through infected seed potato tubers. Diseasessuch as black scurf, common scab and powdery scab disfigure potato tubers and reduce their market value whereas dry rot, charcoal rot and softrot spoilthe harvested produce during transitand storage. Potatowart is a serious disease which once established is difficult to eradicate and thus require quarantine measures. Bacterial wilt or brown rot of potato is another serious disease which is likely to threaten potato cultivation with the rise in globaltemperature and requires immediate attention.

Potato is becoming a more and more important foodstuff in the world and therefore, its cultivation is expanding fast especially in developing countries. This intensivecultivation, in fact, has led to the emergence of diseases in certain areas where they were of less importance in the past. For instance common scab, known to be a minor disease about2-3 decades ago, is now emerging as serious problem in many potato growing areasof the country including Indo Gangetic plains. Similarly brown rot/bacterial wilt which was endemic in mid hills and plateau region, has now become a limiting factor for potato cultivation in many areasin Madhya Pradesh, West Bengal, north eastern region and in Kumoan hills of Uttrakhand. Sclerotium wilt on the other hand has shown upward trend in plateau region especially in Karnataka. This is because the dynamics of pathogens keeps on changing over time and space and also with the changing farming practicesof a region. Many such new diseases are likely to emerge in a big way in future also, hence warrants regular and careful monitoring. In the following pages, the majorsoiland tuberbornediseases are discussed with special reference to India.

The topic deals with methods to increase the amount of water stored in the soil profile by trapping or holding rain water where it falls, or where there is some small movement as surface run – off. Principles: Choice of method. There is no simple way of classifying methods of water conservation. One suggestion is to do it by comparing rainfall with crop requirements, giving 3 conditions: (a) Where precipitation is less than crop requirements; here the strategy includes land treatments to increase run – off onto cropped areas, following for water conservation, and the use of drought – tolerant crops with suitable management practices. (b) Where precipitation is to crop requirements, here the strategy is local conservation of precipitation maximizing storage within the soil profile, and storage of excess run – off for subsequent use. (c) Where precipitation is in excess of crop requirements; in this case the strategies are to reduce rainfall erosion, to drain surplus run – off and store it for subsequent use.
Some design principles: The effect of scale, methods for crop land: Broad bed and furrow system (BBF), Ridging and tied ridging, Conservation bench terraces (CBT; also known as Zingg terrace, and flat channel terrace); Contour furrows (also known as contour bunds and desert strip farming); Water spreading (the use of run–off areas): Natural run – off; Collected and diverted run – off; Inundation methods, Flood diversion; Surface drainage; Other sources of water: Snow, dew, mist . [Figure 4].

Introduction

The natural resources of arid regions particularly soil and water are limited and is often in a delicate environmental balance. Desert encroachment due to lack of conservation planning, and the dangers of destroying or depleting beyond recovery these productive resources, are evident at present time and may be disastrous if development is based on short term expediency rather than long term stability.

The arid zone of India is spread over 38.7 million ha area, out of which 31.7 m ha in under hot arid region and 7 m ha under cold region. The hot arid region occupies major part of north-western India (28.57 m ha) and occurs in small pockets (3.13 m ha) in south India. The north-western arid region occurs between 22o30' and 32o05' N latitudes and from 68o05' to 75o45' E longitudes, covering western part of Rajasthan (19.6 m ha, 69%), north-western Gujarat (6.22 m ha, 21%) and 2.75 m ha (10%) in south-western part of Haryana and Punjab (Faroda et al. 1999). Rainfall distribution is highly uneven over space and time (CV>60%). The region receives low rainfall (<100 mm to 500 mm), has high evapotranspiration and high temperature regime (Rao and Singh 1998). Groundwater is deep and often brackish. The western-central area is devoid of drainage system and surface water resources are meager (Fig. 20.1). Due to low and erratic rainfall, replenishment of water resources is also very poor. The entire Rajasthan state is being categorized as the driest state and water scarce (having per capita water availability below 1000 m3 year-1) since 1991 in the country. Increasing pollution by industrial units, big and small, unregulated mining and even over-extraction of water from deep wells also add to the water quality problem in number of districts. Rapid urbanization and industrialization make such existing differences even more

Out of 329 m ha geographical area in the country, 187.8 m ha or 53% is affected by various forms of degradation process which include 148.9 m ha affected by water erosion, 13.5 m ha by wind erosion, 13.8 m ha by chemical deterioration and 11.6 m ha by physical deterioration. The annual loss of topsoil is nearly 16.0 t/ha/year resulted in to 8.4 m t/year total nutrient loss. 

Soil and water are the basic resources in drylands. Soil supports plant life by providing a medium for their growth and development. It is a non-renewable natural resource and susceptible to rapid degradation through various forms of erosion processes. Worldwide, around 52% of total productive land has been degraded by various kinds of degradation processes and almost 80% of the terrestrial land is affected by water erosion .Further, annually ~10 million hectares (Mha) of cropland becomes an unproductive at the global level due to soil erosion with an average rate of 30 t ha−1 year−1 soil erosion .In India, out of 328 million hectares of geographical area, 68 million hectares are critically degraded while 107 million hectares are severely eroded. Soil degradation in India is estimated to be occurring on 147 million hectares (Mha) of land, including 94 Mha from water erosion, 16 Mha from acidification, 14 Mha from flooding, 9 Mha from wind erosion, 6 Mha from salinity, and 7 Mha from a combination of factors (Battacharya et al., 2015).

Soil pollution is any physical or chemical change in soil that adversely affects the health of plants and other organisms living in and on it.

Soil pollution is important not only in its own right but because so many soil pollutants tend to move into surface water, groundwater, or air.

The chief soil pollutants are salts, petroleum products, heavy metals, and agricultural chemicals. Point source releases of industrial solvents (both LNAPLs and DNAPLs) and feedstock chemicals (e.g., for making plastics) often occur as the result of LUSTs (leaking underground storage tanks).

Salinization, a common problem in irrigated arid and semiarid regions, makes soil unfit for growing most crops. It is extremely difficult to remove excess salts from salinized soils.

A variety of techniques are used for soil remediation, which is cleaning up contaminated soil.

1. These include physical techniques such as
   1. Soil vapor extraction (SVE), moving air through the soil.
   2. Thermal conduction heating, heating the soil before SVE.
2. Bioremediation methods include
   1. Landfarming, fertilizing, liming, and repeatedly plowing contaminated soil to stimulate bacterial decomposition of high molecular weight hydrocarbons like those in diesel oil.
   2. Bioventing, pumping air at low rates through soil to provided O₂.
   3. Biosparging, pumping air into aquifers to provided O₂.
   4. Phytoremediation, particularly useful for removing heavy metals.

Dry areas specially arid and semiarid regions are characterized by harsh climatic condition with limited natural resources like fresh water and vegetation. Soil which is most important component for agricultural production is also problematic in this region due to high salt content. Further, these regions face dual water problems: very low rainfall and poor quality of available water. Most of the available groundwater in these areas has high salt content, which further enhance salt content in soil after irrigation with this water. Salinity of soil is one of the most severe abiotic factors limiting agricultural production in arid and semiarid regions of the world. Term ‘salt-affected soil’ refer to soils in which salts interfere with normal plant growth, and is broadly divided into saline, saline- sodic and sodic soil, depending on amounts of salt, type of salts, amount of sodium present and soil alkalinity. Excessive soluble salts in the saline soil limit the ability of plant roots to absorb soil water even under wet soil conditions, while high sodium content in sodic soil reduce the availability of Ca, Mg, other micronutrients and finally deteriorate physical condition of soil. Poor physical structure of soil results in difficult to till, poor seed germination due to soil crusting and restricted plant root growth. Due to the poor physical structure, sodic soils are also susceptible to wind and water erosion compared to saline soils. All these negative impact of salt accumulation on the soil finally affect growth and yield of the crops. As per estimates of ICAR-Central Soil Salinity Research Institute (CSSRI), Karnal, crop production loss to country due to sodicity is around 11.18 million tonnes while due to salinity is around 5.66 million tonnes. Furthermore, the area under this category is rising due to secondary salinization caused by faulty management of irrigation water, seepage loss, impeded drainage, rapid rise of water table causing water-logging. Certainly, these soils and saline water threaten the livelihood security of farming community. The area under cultivation is decreasing due to diversion of agricultural land in to other uses to meet needs of rising population and as such, agriculture has to make best use of poor quality land and water resources to meet the food demand. Therefore, management of salt affected soil become necessary for ameliorating negative impact and enhancing agricultural production in these regions. Each type of salt-affected soil has different characteristics and thus required different strategies for management.

The term soil refers to the outer, loose material of the earth’s surface, a layer distinctly different from the underlying parent rock. A number of features characterize this region of the earth’s crust. It is the natural medium, which supports plant growth. It provides the physical support needed for the root system and also supplies nutrients needed for plant growth. It is a perennial source of organic matter. It supports a vast population of microorganisms.

Soil is a strange full of wisdom particularly in terms of biodiversity. Soil biota consists of the microbes (bacteria, fungi, archaea and algae), soil animals (protozoa, nematodes, mites, springtails, spiders, insects and earthworms) and plants, living all or part of their lives in or on the soil or pedosphere. Millions of species of soil organisms exist but only a fraction of them have been cultured and identified. Micro organisms (MOs) (fungi, archaea, bacteria, algae and cyanobacteria) are members of the soil biota but are not members of the soil fauna (Sachidanand et al., 2019). The soil fauna is the collection of all the microscopic and macroscopic animals in a given soil. The size of a soil organism can restrict its location in the soil habitat. Smaller members of the microfauna like nematodes are basically aquatic organisms that live in the thin water f ilms or capillary pores of aggregates preying or grazing on other aquatic microfauna such as amoebas. Soil has a direct effect on the environmental conditions, habitat and nutrient sources available to the soil biota. The term pedosphere is often used interchangeably with soil and captures the concept that the soil is a habitat where the integration of spheres occurs. These spheres include the lithosphere, atmosphere, hydrosphere and the biosphere. Numerous biogeochemical processes regulated by soil biota occur in the pedosphere.

The physical structure, aeration, water holding capacity and availability of nutrients are determined by the mineral constituents of soil, which are formed by the weathering of rock and the degradative metabolic activities of the soil MOs. Soil microbiology is the study of organisms in soil, their functions, and how they affect soil properties. It is believed that between two and four billion years ago, the first ancient bacteria and MOs came about in earth’s oceans. These bacteria could fix N2 , in time multiplied and as a result released oxygen into the atmosphere. This led to more advanced MOs. Soil biology plays a vital role in determining many soil characteristics. The decomposition of organic matter by soil organisms has an immense influence on soil fertility, plant growth, soil structure, and C storage. As a relatively new science, much remains unknown about soil biology and their effects on soil ecosystems. The soil is home to a large proportion of the world’s biodiversity.

This procedure uses Diethylene Tri-amine Penta Acetic acid (DTPA) as the chelating agent, which combines with free metal ions in soil solution and forms soluble complexes.

This is a distillation method proposed by Subbiah and Asija (1956), where the soil is distilled with alkaline KMnO solution. The ammonia liberated is trapped in boric acid and then determined by titration against a standard acid. This procedure estimates the easily mineralizable nitrogen in soil.

Estimation of plant available phosphorus content in soil has been attempted using several extractants. However, Bray’s reagent and Olsen’s reagent are the two common extractants used in India. Bray’s reagent (0.03 N NH₄F and N HCl) is used for acid soils, where, the fluoride ion complexes with Fe and Al in soil and thus releases the bound P. The Olsen’s reagent (0.5 M NaHCO₃) is used for neutral-alkaline soils.

In soil system, potassium (K) exists as water soluble, exchangeable, non- exchangeable and lattice K. The plant available K refers to the sum of water soluble and exchangeable K. Estimation of available K is usually done using neutral normal ammonium acetate as the extractant.

Introduction

Soil, a dynamic living matrix, is an essential part of the terrestrial ecosystem. It is a critical resource not only to agricultural production and food security but also to the maintenance of most life processes. Soils contain enormous numbers of diverse living organisms assembled in complex and varied communities ranging from the myriad of invisible microbes, bacteria and fungi to the more familiar macro-fauna such as earthworms and termites. The diversity in soils is several times higher than that above ground. Each hectare top soil contains approximately 1,000 kg of different fungi, 500 kg of bacteria, 750 kg actinomycetes and 150 kg of algae and many protozoa (Table 1). These diverse micro-organisms interact with one another and with the plants and animals in the ecosystem forming a complex system of biological activity. Environmental factors, such as temperature, moisture and acidity, as well as anthropogenic actions, in particular, agricultural practices affect soil biological communities and their functions to different extents. Diversity of soil micro-organisms has emerged in the past decade as a key area of concern for sustainable soil health and crop production. Besides, the well-being and prosperity of earth’s ecological balance, the sustainability of agricultural production systems directly depends on the extent and status of microbial diversity of soil.

1. Introduction
Soil is an extremely complex ecosystem and performs many functions, i. e, biomass production; food contingency, fuel and fibre; buffering and transforming actions; breakdown of organic matter; nutrients recycling; carbon sequestration; providing a biological habitat; source of raw materials; and regulation of water quality and supply (Weil and Brady, 2017; Telo da Gama, 2023). However, because of natural as well as anthropogenic reasons, there is a widespread degradation of soils. Soil degradation means deterioration in overall soil functioning which leads to slowdown of distribution of ecosystem services because of the impairment of soil health through anthropogenic perturbations. Therefore, farmers and researchers are very much concerned about soil health and crop productivity. Soil health status and its quality are often used interchangeably and have been defined by research community differently but recently the word soil health is acquiring popularity due to its flexibility in allowing diverse stakeholders, including policymakers to use the term in their own way. Recently, soil health is a topic of much discussion and research (Bünemann et al., 2018). Soil health is described as “the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans” (USDA-NRCS, 2019). A broader, ecologically based approach is “the capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health” (Doran et al., 2000). Soil health refers to the actual capacity of a soil to function, contributing to ecosystem services. Many have defined it as “fitness for use” while the rest regard as “capacity of the soil to function”. Lehmann et al. (2020) stated that the concept of soil health “connects agricultural and soil science to policy, stakeholder needs and sustainable supply-chain management” and compared the soil health concept to soil fertility, soil quality and soil security. Furthermore, they came to a conclusion that soil health is narrower concept than soil security, but more comprehensive than soil quality and even broader than soil fertility, in relation to the current sustainable development goals (SDGs) as proposed by United Nations. From an overall perspective. Soil health comprises of refinement and unification of the chemical, physical, physico-chemical, biophysical, biochemical indicators of soil that supports productivity and environmental quality (Figure 1). Soil can be classified as healthy or unhealthy based on its ability to sustain plant and animal productivity while maintaining air and water quality.

9.1. Introduction

Soil biology is a branch of science that studies the soil inhabiting organisms in relation to their ecology, functions, behaviour and impact on various soil processes and plant growth. Soil fertility is directly dependant on humus content as well as the presence of microorganisms in soil, although surface soil does not contain more than 0.5% by weight of living organisms. However, such a small portion of soil constituent as compared to other organic and inorganic constituents plays a significant and major role in transformation of plant nutrients from their unavailable to available form from organic wastes, soils and fertilizers. They have a direct role in improving soil tilth, providing an appropriate environment for root growth, decomposing organic residues to form humus and in turn releasing nutrients for plants use, releasing many plant growth promoters, fixing inert atmospheric nitrogen in plant usable forms and they promote many other important processes without which plants cannot survive. Absence of living organisms in soil leads to its infertility. An understanding of microbial processes in soil environment, keeping in view of soil nutrient status, carbon sequestration, soil health and quality, overall sustainability in agriculture and also global warming in respect of greenhouse gas emissions (nitrous oxide and methane) through agricultural practices, is very important in regulating nutrient release at different plant growth stages. If we are in a state to understand how various biological processes influence various changes in soil environment or in the opposite way that how different soil conditions alter the soil biota in number as well as in their functions and diversity, it is easier to implement soil management practices that promote to gain more benefits.

Microorganisms are ubiquitous in nature. Possessing a diverse habitat, they are found everywhere in soil, air and water at a varied temperature and pH. One may find the highest genetic diversity of life within the domain of microorganisms. But unfortunately very few are known to us, so far only 1% of the microbial species on the earth are culturable. However, it is believed that soil of one gram may contain hundreds of millions to billions of microbes which may represent several thousand microbial species. In respect of the population, bacteria top the list followed by actinomycetes, fungi, algae and protozoa in accordance with a decreasing numerical order. Out of three important soil fertility components viz. physical, chemical and biological; the biological component is least understood due to its wide complexity.

Study of living organisms in soil is referred to as soil biology (Greek word bios= life, logos = study). The soil is teeming with millions of living organisms which make it a living and a dynamic system.