eChapters

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.

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- 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

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 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
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 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