eChapters

The variable amount of moisture contained in a unit mass or volume of soil and is the key factor affecting the growth of plants. Numerous other soil properties depend very strongly upon moisture content. Gravimetric (direct) and sensor based (indirect) methods are generally employed for soil moisture determination.

9.1 Gravimetric Method (Direct)

Principle

The gravimetric method is based on the principle that the water in the porous material is lost by evaporation on heating and the porous material undergoes an equivalent loss in its weight. However, the water loss may be limited by the internal operation within the complex porous material such as soil. This method is simple, routine, reliable, inexpensive, and easy to use. The major limitations of this method are that it is destructive, laborious and time consuming.

Breaking of soil aggregates and dispersion followed by a rapid drying leads to rearrangement and coherence of soil solids in the form of surface crust. The cohesion exhibited by soil upon drying is directly related to surface crusting and clod formation. The formation of soil crusts and hard clods is a major structural feature of soils. Seedling emergence of cereal crops is generally controlled by point resistance around the shoot tip (Richards, 1953). Penetrometer, which measures the resistance to vertical penetration in soil, is an effective instrument to evaluate the crust strength. A relationship between penetration resistance and seedling emergence would serve as a guide to ensure optimum soil condition for a desired plant density.

Apparatus and Accessories

Penetrometer, moisture box, trowel, electronic balance and oven.

Soil aggregates refer to a group of two or more primary particles which cohere to each other more strongly than to surrounding particles. Under field conditions, these units also cohere to some degree with neighboring aggregates and form larger aggregates. The aggregates form and break easily into smaller aggregates during tillage and by disruptive action of water and air. The aggregates maintaining their identity are those in which the cohesive forces among particles are greater than the disruptive forces. A quantitative characterization of aggregates is being done by determining aggregate stability and size distribution of aggregates. The aggregate stability refers to the resistance of soil aggregates to breakdown by water, air, and mechanical manipulations. Numerous methods have been proposed to determine size distribution and stability of soil aggregates (Kemper and Rosenau, 1986). The size distribution of wet and dry aggregates determines overall tilth, size of pores and susceptibility of aggregates to movement by water and wind.

Proportion of solid, liquid (water), and gas (air) components in a soil mass indicates physical conditions such as soil structure, porosity and water content. A well Structured soil may have a high pore volume whereas a compacted soil may have little pore-space for other phases to occupy. In general, soil solids may occupy 50 % of the soil volume in a well-aggregated fertile loam and the remaining volume may be occupied by liquid and gases interchangeably.

Bulk density to which a soil can be compacted is dependent on water content and force of compaction. Adsorbed water on soil particles acts as lubricant and every addition of water increases ease of compaction to progressively a greater density. However, this increase in density will occur only to a certain value of water content beyond that it decreases with further addition of water in soil. The moisture content at which maximum dry density is obtained for a limited and fixed effort is called as proctor moisture and the density at that point is known as maximum or proctor density”.

Principle

A soil at varying water contents, compacted with a specific amount of compaction energy, would result in a bulk density-water content relationship. The maximum bulk density obtained at the proctor water content represents 100 % compaction. The test can be performed in laboratory on various soils using Abbot’s compactor

Particle density of soil is the ratio of mass and volume of soil solids. Particle density of soil is an important physical characteristic because the interrelationships of porosity, bulk density and air space, and rates of sedimentation of particles in fluids depend on particle density.

Principle

The determination of particle density (ρ_p) requires the measurement of mass of the solid and its volume. The mass is obtained by weighing the oven- dry soil sample and volume by calculating from the mass and density of water displaced by the sample in a pycnometer. The pycnometer is a glass flask with a ground glass stopper having a capillary opening. The particle density can be calculated using the following equation:

Bulk density is the ratio of oven-dry mass of soil to its total volume before drying. Knowledge of bulk density is useful in calculating moisture content by volume, porosity using particle density, volume of a known weight of soil, and weight of a furrow-slice. Bulk density is a direct measure of soil compaction. Bulk density is highly dependent on any kind of physical manipulation, degree of wetness, and kind and arrangement of soil particles. For this reason, preservation of original structure in the sample is most essential aspect of the methodology for determination of bulk density. Common methods of determining soil bulk density use soil cores or clods in their natural state.

Particle-size distribution is one of the stable soil characteristics, being little modified by agricultural management practices. The particle-size distribution expresses the proportion of various size particles in a soil, especially sand, silt and clay that determine soil texture (Hillel, 2004). Soil texture is closely related to soil physical properties such as water retention and release characteristics, surface area, swelling and shrinking, soil strength and tillage properties. There are two common methods being employed for particle-size (<2.0 mm) analysis namely international pipette method and the hydrometer method. Both the methods are based on Stokes’ law which establishes a relationship between particle size and the rate of sedimentation. Thus, particles are assessed by their settling velocities from suspension in a water solution that can be used to quantify particle size. Size range of soil particles (sand, silt and clay) according to two most adopted systems i.e. U.S. Department of Agriculture (USDA) and International Union of Soil Science (IUSS) formerly known as International Society of Soil Science (ISSS) are given below:

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

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

Land is merely an area of the earth’s surface comprising all physical, chemical and biological environments that influence the land use (FAO ,1976). Land refers not only to soil but also to climate, landforms, hydrology, geology, natural vegetation including fauna and flora. The land use simply means management of a land for specific uses to meet the human needs in all rural, urban and industrial context, whereas the land use plan refers to a coherent set of decisions about the ways to achieve the desired level preferably on economic background. Thus, the land use planning is the systematic evaluation and assessment of a land and associated attributes for the purpose of identifying the best land use options beneficial to landowners or users without degrading the land resources or environment. It includes not only the landowner or users, but also the policy or decision makers as well as economic experts for financial measures from planning stage or logistic planning to execution.

Land cover

Relates to the type of feature present on the surface of the earth e.g., Fields, trees, concrete high ways.

Land use

Relates to the human activity associated with a specific piece of land. The same land would have a land cover consisting of roofs, pavements, grass and trees. The land use in an area is really an intervention by the people over the existing natural eco-environment for satisfying their needs.

Land cover is distinct from land use despite the two terms often being used interchangeably. Land use is a description of how people utilize the land and socio-economic activity - urban and agricultural land uses are two of the most commonly recognised high-level classes of use. At any one point or place, there may be multiple and alternate land uses, the specification of which may have a political dimension.

In recent times, the interpretations cover a wide spectrum of soil uses, both for agricultural and non agricultural (sewage and human waste disposal, high way construction, water and gas supply, recreation, wild life, urban and industrial structures) and many specialized uses. Soil survey if correctly carried out according to scientific principles, can provide the data base for various interpretations. This is because the same soil properties determine the behaviour of a soil for a variety of different uses. For instance, the content of clay, silt and sand, the shrink and swell behaviour, the permeability of soil to water and air, content of calcium carbonate, salts, organic matter, gypsum, soil depth, depth of ground water, hard pan formation, co-efficient of linear extensibility, water holding capacity etc. are examples of such properties that are important to plant growth and these properties also strongly influence non farm uses. Some examples in support are

A hard or petrocalcic horizon or other slowly permeable layer (clay-pan) in a soil restricts the movement of air and water, thus adversely affecting the plant root growth. Such a layer limits the soils suitability for septic tanks and other onsite waste disposal. It also makes a poor sub grade for high way construction.

A soil high in soluble salts is a poor medium for plant growth; it is also corrosive to iron and steel structures, such as pipelines and fences, causing high maintenance and repair costs.

High organic matter content is generally favourable to plant growth, but it is a limitation for road construction.

The strongly gypsiferous soils (gypsum content >10%) are considered unsuitable for arable crop cultivation because of its dissolution under irrigated or even moderate rainfall and making the surfaces uneven through the developments of sink holes. Such soils are unsuitable for irrigation and drainage canal networks and also for construction of roads, bridges etc.

The shrink- swell soils of India (vertisols) because of summer monsoon rains are suitable for growing a “kharif” crop but are very dangerous for construction of roads, air strips, buildings, laying gas, water pipelines which get distorted, develop cracks and lead to sunken floors etc.

Soil Classification

Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use.

Soil classification is grouping of objects in orderly and logical manner into classes based on the properties of soils (differentiating characters) for the purpose of studying and identifying them. The soil individuals are grouped into classes of the lower category (soil series) which are grouped into classes of higher categories (soil orders). The lower categories are defined by large number of differentiating characters and higher category by a few differentiating characteristics.

For soil resources, experience has shown that a natural system approach to classification, i.e. grouping soils by their intrinsic property (soil morphology), behaviour, or genesis, results in classes that can be interpreted for many diverse uses. Differing concepts of pedogenesis and differences in the significance of morphological features to various land uses can affect the classification approach. Despite these differences, in a well-constructed system, classification criteria group similar concepts so that interpretations do not vary widely. This is in contrast to a technical system approach to soil classification, where soils are grouped according to their fitness for a specific use and their edaphic characteristics.

Soil survey is essentially a study and mapping of soils in their natural environment. It is the systematic examination, description, classification and mapping of soils of an area.

2.1. History of Soil Survey in India

The original investigations on Indian soils were carried out by Voelcker dates back to 1893 and by Leather to 1898.They classified the soils of the country into four major groups, namely the Indo-Gangetic alluvium, the black cotton soil or regur, red soil and laterite soil. Schokalskaya (1932) has published a soil map of India based on the Russian concept which describes 16 soil groups such as climate,vegetation, soil-forming materials, salinity, alkalinity, swamps and peats (Bhattacharyya et al. 2013). In 1935,Wadia and his co-workers collected a soil map of India with significance on geological formations and classified the soils as red, black (regur), laterite and lateritic soils of Peninsular India and also Indo-Gangetic Plains (IGP) which includes delta, desert, bhabar, terai and alkali soils. Vishwanath and Ukil (1943) published a soil map of India by placing the soils in different climatic zones for the first time. This was prepared by Imperial Agricultural Research Institute, New Delhi, and published in the year 1943. There were 17 kinds of soils identified, viz., deep black soils, black clay soils, black loamy soils, black sandy soils, red sandy soils, brown sandy soils, red and yellow soils, dark reddish brown soils, mixed soils (white and yellow), alluvium (Indus, Gangetic, Brahmaputra), coarse alluvium, soils of swamp lands, calcareous soils, usar soils, kallar soils, coastal alluvium soils and soils of Great Himalayan Ranges.

Soil survey works were started in 1954, in most of the states as a part of their agricultural development programme, and Bihar (Soil Survey and Land use Planning Scheme, Sabour) was pioneer. In 1954, the soil survey work was started under the leadership of Dr. P. P. Jha following the conventional procedures in Bihar (including Jharkhand) to delineate the soil associations based on geology, relief, physical and chemical characteristics of soils for the first time in India by the then Soil Survey Scheme at Sabour (Mishra et al. 2001; Mishra 2015, 2016). Meanwhile, the National Atlas Organization, Kolkata, prepared a soil map of India in 1957 classifying Indian soils into six major groups and 11 broad types. Murthy and Pandey (1983) applied the working principles of the USDA 7^th Approximation in classifying the Indian soils with available data on soil classes and thus used the US system for the first time at great soil group level, which was transformed into a soil map of India on 1:6.3 million scale. Mishra et al. (1994) attempted to propose “Fluvisols” as the 13th Order in USDA Soil Taxonomy for active floodplain soils frequently occurring in different parts of India and elsewhere. Mishra (2015, 2016) proposed a framework of Indian system of soil classification mainly based on land use options.

1.1. Soil Resource Evaluation

Soil is the essence of life on the planet Earth. It has sustained humanity and human civilizations through five functions (Karlen et al. 1997) viz., i) sustaining biological activity, diversity and productivity; ii) regulating and partitioning water and solute flow; iii) filtering, buffering, degrading, immobilizing and detoxifying organic and inorganic materials, including industrial and municipal byproducts and atmospheric decomposition; iv) storing and cycling nutrients and other elements within the earth’s biosphere; and v) providing support to socioeconomic structures and protection for archaeological treasures associated with human habitation. Reeling under the pressure of increasing food, fodder, feed, fibre and fuel production, soil has been used as a medium of plant growth with considerable reliance on external supply of major nutrients, irrigation water, plant protection chemicals, etc. Although soil, a product of millions of years of weathering, has supported various forms of terrestrial life, its sustainable management holds the key for meeting the basic requirements of burgeoning population and development commitments. So intense has been the pressure of increasing food, fodder, feed, fibre and fuel production that the soil has been exploited often exceeding its carrying capacity. The soils are increasingly used for agricultural and non-agricultural uses, such as disposal of farm, urban and industrial wastes, ensuring environmental safety etc. This is possible by the judicious use of this resource.

A clear and intimate knowledge of the kinds of soils and their extent of distribution are essential prerequisites in developing rational land use plans for agriculture, forestry, irrigation, drainage, etc. soil resource inventory or mapping provides an insight about their potentials and limitations. It is therefore imperative to prepare an inventory of this resource for developing optimum land use plan and conservation plans.

Introduction

The hot arid zones in India are spread over nearly 31.7 million hectare area of which 41.5 per cent is arable and 19 per cent is cultural wasteland. These zones are perpetuated mainly in North –West and Southern part of the country. The major parts of the country under hot arid climatic conditions are Western Rajasthan (19.62 Million ha), North-western Gujarat (6.2 M. ha), South-western Punjab (1.45 M. ha), South-western Haryana (1.28 M. ha), Andhra Pradesh (2.16 M. ha), Karnataka (0.86 M. ha), and Maharashtra ( 0.13 M. ha). These areas/ zones are characterized by hostile agro-climate and fragile eco-system, an annual rainfall between 100 – 500 mm with a coefficient of variation (CV) varying from 40 – 70 per cent, low and erratic rainfall combined with extremes of temperature (450-500 cal/cm²/day); low relative humidity; high potential evapo-transpiration value ranging from 1600 mm in eastern part and 1800 mm in western part of the hot arid zones. Other important characteristics of the hot arid regions are hot winds with high velocity, poor soil condition, poor ground water with brackish and saline in reaction, poor vegetation, frequent occurrence of drought and frost, difficult to execute agro-techniques, difficulty in post harvest handling and marketing owning to limited and inefficient transportation and marketing facilities, etc (Yadav and Soni, 2008).

Introduction

The hot arid regions of India are spread over 32 million ha (0.32 million Sq.Km.) in the state of Rajasthan (61%), Gujarat (20%), Andhra Pradesh (7%), Punjab (5%), Haryana (4%), Karanataka (3%), and Maharashtra(0.4%) which are characterized by hostile agro-climatic conditions and fragile eco-system. Out of total hot arid area of the country (India), more than 60% area falls under the state of Rajasthan which covers 12 districts viz., Jaisalmer, Barmer, Bikaner, Churu, Sikar, Jhunhjunu, Naguar, Jodhpur, Pali, Jalor, Sriganganagar, and Hanumangarh of the state. In general, the hot arid region of Rajasthan receives very low rainfall, varies from 100 mm annun^-1in north-western district of Jaisalmer to 450 mm per annum in the eastern boundaries of arid district of Rajasthan. The potential evapo-transpiration varies from 2063 mm in Jaisalmer to 1503 mm in Sikar districts of Rajasthan. The rainfall is very erratic and often experienced prolong drought. The ground water table is very deep and often brackish in nature. The extremes of temperature having severe winter during December-January with temperature as low as -4 °C and very hot summer during May-June with temperature as high as 48-50 °C is another important characteristic of the hot arid regions. The solar radiation is very high. Atmospheric vapour pressure deficit reaches as high as 30 mb during summer (May-June). The wind velocity in June is very high which leads to heavy wind erosion and formation of sand dunes. Some time strong sand storms of very high speed (60-0 km h^-1) with huge amount of sand particles also occurs. The soils are coarse textured with low silt, clay and humus content and water holding capacity is very low and infiltration rate is very high. The soil fertility is very poor having low organic carbon (0.02-0.06%).

Introduction

Some historians of agriculture believe that it was women who first domesticated crop plants and there by initiated the art and science of farming. While men went out hunting in search of food, women started collecting seeds from the native flora and began cultivating those of interest from the point of view of food, feed, fodder, fiber and fuel. This view is strengthened by the fact that women have been traditionally seed selectors. Even today this tradition has continued in many parts of the developing world. Women have played and continue to play a pivotal role in the conservation of basic life support system such as land, water, flora and fauna. They have protected the health of the soil through organic recycling and promoted crop security through the maintenance of varietal diversity and genetic resistance. In many remote areas agriculture is largely in hands of women. Men tend use to go to towns and cities in search of salaried jobs for fulfillment of family income. Therefore, without total intellectual and physical participation of women, it will not be possible to popularize alternative systems of land management for shifting cultivation, arrest gene and soil erosion, and promote the care of the soil and the health of economic plants and farm animals. Women also tend to look at problems in their totality from the sowing of the crop to its ultimate utilization either as food, feed or raw material for industry. Since they are usually incharge of marketing, they generally possess a clear understanding of market preferences and prejudices. Therefore, for an economically and ecologically sustainable agriculture the involvement of women farmers and farm women (agriculture farmers with and without assets) in the process of modernization of farming practices and village industries is absolutely essential. Horticulture is a major part of Indian agriculture, natural foods of man, fruits and vegetables provide protective nutrients like vitamins and minerals besides, some high quality sugars, proteins, oils and fats. Although belated, their importance has now been recognized in India not only to provide the much needed balanced nutrition and gainful occupation to our populace but also to develop viable internal and export trade. Fruits like banana, mango and minors fruit like mahuva, chironji, rayan etc. vegetables like potato being energy rich are considered prominent food crops e.g. banana can produce as high as 37 million calories per hectare. Unfortunately the component of fruits and vegetables in Indian diet is hardly six percent which should be raised at least five times so that the per capita per day consumption becomes 85 g. fruits, 75 – 125 g. leafy vegetables 85 g. other vegetable and 85 g. roots and tubers. To achieve this present production of fruits and vegetables would need to be pushed up considerably by increasing production levels and the area under fruits and vegetables would need to be pushed up considerably by increasing production levels and the area under fruits and vegetables (Lata and Singh, 2010).

Introduction

Any project is undertaken and an investment is made with expectation of realizing benefits out of it. This applies to projects both in the private domain as also in the public domain. Hence, it is imperative to assess the benefits derived from the project investment over its entire economically viable. The extent to which project contribute to various aims of development (benefits) and make use of scarce resource (costs) can differ widely. A proper project preparation requires an assessment of the various benefits and costs associated with execution of a project. Methods to determine, analyze and assess the relevant benefits and costs of a project are known as cost-benefit analysis. The cost- benefit analysis ensures that all the relevant factors that contribute to a project’s net benefits are systematically taken into account, whether they relate to an individual, a firm, a social group, the public sector or the country as a whole.

There are many tools or criteria for the financial evaluation of projects. However, the important and commonly used evaluation criteria are simple Rate of Return, Payback Period, Net Present Worth, Benefit- Cost Ratio and Internal Rate of Return.

Economic appraisal and evaluation helps the decision makers who are saddled with the responsibility to prioritize measures in a situation with enormous needs and quite limited resources. Government planners as well as donor agencies are all in need of enough data in order to make rational choice or decision in selection of investment alternatives. Most of the economists believe that economic analysis cannot give the final answers. There will always be lack of data, uncertainty about the future, disagreement on the methods, and similar issues. However, economic analysis, if properly done, can indeed be of much help to decision makers.

Introduction

The Indian arid zone covers nearly 31.8 million ha of the country’s geographical area. It mainly spreads over parts of Andhra Pradesh, Gujarat, Haryana, Karnataka, Maharashtra, Punjab and Rajasthan states of India. Six of the eleven districts in Western Rajasthan i.e. Barmer, Bikaner, Churu, ShriGanganagar, Jaisalmer and Jodhpur lie wholly in the arid zone. High temperature, low precipitation and high velocity winds are some of the main culprits of Arid zone which limit the scope for higher crop productivity in these areas. Under this situation, arid horticulture based farming practices has ample scope to raise the productivity and living standard of peoples of the hot arid and semi-arid regions. Arid horticulture based farming practices greatly favour the development of high quality produce in many fruit and vegetable crops. Horticulture based farming practices are now considered to be the most ideal strategy to provide food,nutrition and income security to the people especially in arid and semi-arid region of the country (Chundawat 1993; Chadha 2002).

Today India is the world largest producer of many fruits and vegetables. Wastes and by-products generated from fruits and vegetables are organic in nature and contribute a major share in soil and water pollution. Also, accumulated fruit and vegetable wastes (FVWs) cause greenhouse gas emission which is a matter of serious environmental concern. Proper disposal and handling of these wastes can help reduce pollution risks, at the same time be a source of several useful and commercially valuable by-products. Organized processing of wastes can help farmers achieve higher incomes.

Introduction

Harvesting and handling are the equally important activities as the entire production system as an individual activity. Therefore, proper harvesting and handling is essential to assure the farm income. There are various factors which directly affect the storage life of fruits and vegetables as below. The natural limits to the post -harvest life of all types of fresh produce are severely affected by other biological and environmental conditions.

Temperature: An increase in temperature causes an increase in the rate of natural respiration of all produce and food reserves and water content become depleted. The cooling of produce will extend shelf-life by slowing the rate of respiration.

Transpiration and water losses: High temperature, low humidity in the store and injuries to produce can greatly increase the loss of water from stored produce beyond that unavoidable lost from natural causes. Maximum storage life can be achieved by storing only undamaged produce at the lowest temperature tolerable by the crop and at the relative humidity appropriate for the produce.

Mechanical damage: Damage caused during harvesting and subsequent handling (i.e. injuries, impact bruising) increase the rate of deterioration of produce and renders it liable to attacks by decay organisms even under refrigerated storage. Mechanical damage to root crops will cause heavy losses owing to bacterial decay and must be remedied by curing the roots or tubers before storage. Curing is a wound –healing process.

Decay in storage: Decay of fresh produce during storage is mostly caused by the infection of mechanical injuries provoked by micro organisms, mostly bacteria and fungi. Furthermore, many fruits and vegetables are attacked by decay organisms which penetrate through natural openings or even through the intact skin. These infections may be established during the growth of the plant in the field but lie dormant until after harvest, often becoming visible only during storage or ripening.