eChapters

Now-a-days, a watershed management or watershed development has been fully recognized as a unit for over all development of rainfed areas (Gupta, 2006a and b). Hydrological problems such as excessive runoff, large scale soil erosion, inadequate or faulty drainage and occurrence of droughts are the most significant problems in almost all the rainfed areas. These problems, however, can be alleviated through running watershed based development programmes that recognize the natural topography and water movement patterns of the land.

Water is precious, but it is a finite natural resource. Although it accounts for about three-fourth of the earthís surface yet very small fraction of it i.e., only 2.7 per cent of the global water is available as fresh water. Around 2.8 billion people live in areas of high water scarcity (Anonymous, 2014d). Out of the total amount of the fresh available water merely 30 per cent is withdrawn to meet the water requirements of the human and livestock population while the remaining 70 per cent is required to produce food crops that fuel human activities.

In modern times, soil tillage has emerged as an integral part of a crop system. Soil tillage or soil surface management has been found important in alleviating soil related constraints encountered in crop production. An important effect of soil tillage on crop productivity is through its influence on soil processes, soil Soil Tillage 39 properties and crop growth. At the same time, soil tillage has its impact on the environment e.g. soil degradation, water quality, emission of green house gases from soil related processes etc.

Agricultural production has made rapid strides in the past four to five decades and has enabled India to achieve self-sufficiency in food grain production. This was only through ìGreen Revolutionî which ushered during 1967-68 onwards, when use of old agricultural practices were mostly done away with. Neglect of old or indigenous agricultural practices such as use of organic manures (farm yard manure - FYM, compost, green manure), cultural control methods like sanitation, tillage/removal of weeds, adjusting sowing/harvesting time crop rotation, trap crops, water and fertilizer management and host plant resistance, and use of plant based insecticides like neem or nim (Azadirachta indica), drek (Azadirachta indica), nirgudhi or bana (Vitex negundo) vis-a-vis biological control measures, has resulted in outbreak of ill-effects in human beings and animals through contaminated food stuffs (Gupta, 2006a).

India is an agriculture based country which is one of the few developing countries in the world. It successfully achieved Green Revolution during the late 1960s (1967-68). At present, agriculture is a principal means of livelihood for over 58.4 per cent of Indiaís population directly or indirectly (Anonymous, 2011). It is worthwhile to mention that although agriculture continued to be the mainstay of the Indian economy previously (Anonymous, 2010b) yet now its share in the Indian economy is declining year after year (Anonymous 2013d). After Independence, agricultureís sector contribution to GDP swings between 50-60 per cent. Even in 1950-51, it was 55.1 per cent, but fell to mere 17-18 per cent in 2008-09 (Mahajan and Gupta, 2009).

 1. A mineral that forms an original component of rock is called

a. Primary         b. Secondary

c. Essential         d. Accessory

1. The smallest size soil separate is

a. Sand      b. Silt

c. Clay        d. Loam

1. Central Fertilizer Quality Control & Training Institute (CFQC&TI) is situated at

a. Mysore           b. Karnal

c. Faridabad        d. Coimbatore

1. Amoeba are unicellular organisms that feed on

a. Bacteria and algae     b. Bacteria and fungi

c. Fungi and algae        d. Nematode and fungi

1. White alkali soils also know as

a. Acid soil                  b. Saline soil

c. Saline sodic soil    d. Sodic soil

Historical Development of Soil Science/Agriculture

Francis Bacon (1561-1624 A.D.): Found the water as nutrient of plants.

Van Helmont (1577-1644): Give the ideas about the role of soil as a simple source of water and minerals for the plants.

Soil pollution is defined as presence of xenobiotics (e.g. chemical compounds, radioactive elements) that alters the soil properties viz., both chemical, physical and biological properties of soil. Soil pollution, including heavy metals, may be of natural origin, like volcanic eruptions, atmospheric lightning, animal excrements or ore leaching. Nevertheless, human activity and mostly chemical industry, mining and metallurgy, as well as municipal waste management and traffic emissions are the main source of environmental pollution.

The soils which owe characteristics that they cannot be economically used for the cultivation of crops without adopting proper reclamation measures are known as problematic soils. Different kinds of problematic soils viz., Physical, chemical and biological problematic soils exists and pose problems of crop production.

Water required for irrigation of cropped land is being degraded in terms of quantity and quality due to fast increasing demand for its use. Furthermore, the soil quality and crop productivity is linked to the quality of the water available for irrigation. In general, evaluation of irrigation water quality should focus on salt content, sodium concentration, the occurrence of nutrients and trace elements, alkalinity, acidity, and hardness of the water.

Geographic location of India is in Northern hemisphers and located between 80 4' & 370 6' N latitude and 640 7' & 970 25' E longitude. Extent of area is 329 M Ha or 329 x 104 Sq.Km or 3.29 MSq.Km. The physiography of India can be broadly grouped into triangular plateau, mountains, Indo-gangetic plains and islands. India is divided into twenty agro ecological regions and sixty five agro ecological sub regions as per NBSS and LUP. Agro ecological regions( AER) is referred to identification and demarcation of land units having comparable landform, soils, bioclimatic conditions and the length of growing period (LGP).

Soil is a dynamic, vital living natural resource. Soil health is the condition of the soil and its potential to sustain biological functions, maintain environmental quality, and promote plant and animal health. It is qualitative trait of soil. Healthy soil is the foundation for profitable, productive, and environment friendly agricultural systems.

The word “Manure” is originated from the French word “Manoeuvrer” which refers to “work with soil”. The word Manure is also originate from Latin word “Manu” (hand) and operate (to work). Manures are the substances which are organic in nature, capable of supplying plant nutrients in available form, bulky in nature having low analytical value and having no definite composition and most of them are obtained from animal and plant waste products. Formerly, the word in use was “Dung ”in English (at present fertilizer).

Soil fertility is defined as the quality that enables the soil to provide proper nutrient compounds in proper amounts and in proper balance for the growth of specified plants. Soil fertility is also defined as the ability of soil to supply adequately the nutrients normally taken from the soil by plants.

Soil degradation is defined as a decrement in the soil health status resulting in a diminished capacity of the ecosystem to provide goods and services for its beneficiaries. Degraded soils have a deteriorated health status such, that they do not provide the normal goods and services of the particular soil in its ecosystem. Soil degradation is the physical, chemical and biological decline in soil quality.

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.

Soil organic matter is any material produced originally by living organisms (plant or animal) that is returned to the soil and goes through the decomposition process. At any given time, it consists of a range of materials from the intact original tissues of plants and animals to the substantially decomposed mixture of materials known as humus. Soil organic matter (SOM) is the organic component of soil, consisting of three primary parts including plant residues and living soil organisms, decomposing (active) organic matter, and stable organic matter (humus). Most soil organic matter originates from plant tissue.

Soil minerals are naturally formed inorganic compounds with definite chemical composition and characteristic geometric (crystalline) form. They are classified as primary and secondary minerals, silicates and non-silicates minerals, and crystalline and non-crystalline minerals. Primary minerals have not been significantly altered chemically since deposition or crystallization from molten magma and are usually found in the sand and coarse silt fractions. Secondary minerals form as a result of the alteration of primary minerals by weathering and are found in the clay and fine silt fractions.

Soil Chemistry is the study of chemical composition of soil in relation to crop needs. It deals with the chemical constitution of the soil, the chemical properties and the chemical reactions in soils. Traditional soil chemistry focuses on chemical and biochemical reactions in soils that influence nutrient availability for plant growth, and potential environmental consequences associated with inorganic and organic fertilization. Soil chemistry has increasingly focused on soil genesis and the environment over the past few decades.

Soil physics is the study of soil’s physical properties and processes. Soil physics deals with the dynamics of physical soil components and their phases as solid, liquids, and gases. Physical properties of soil include texture, structure, density, porosity, consistency, temperature, colour and water content. The physical properties depend on the amount, size, shape and arrangement and mineral composition of its particles , kind and amount of organic matter and the volume and form of its pores and the way they are occupied by water, air at a particular time.

Soil genesis, or pedogenesis, is the combined effect of physical, chemical, biological and anthropogenic processes working on soil parent material (rocks & minerals). Soil is said to be formed when organic matter has accumulated and colloids are washed downward, leaving deposits of clay, humus, iron oxide, carbonate, and gypsum, producing a distinct layers. These constituents are moved from one level to another by water and animal activity.

Soil is the most fundamental resource to fulfill basic requirements of food, fiber and shelter of human race. Although soil is perceived as something of insignificant value and it is considered as dirt but humans cannot survive without soil. Soil forms
basis for all terrestrial life. Soil provides a wide range of ecosystem services (Table 1) that make humankind to survive and progress.

Aim : To determine the Magnesium in plant sample.

Aim : To determine the Calcium in plant sample.

6.25 HNO3 (for 2 ltr) : Take 181 ml of conc HNO3 and diluted to 2 ltr in a volumetric flask.

Take 5 ml/2.5 ml aliquot in a 25 ml volumetric flask.

100 ppm ‘P’ : By dissolving oven dry KH2 PO4 salt. Take 0.4393 gm of KH2 PO4 and volume to 1 ltr that gives 100 ppm ‘P’.

Digestion Mixure : This is a mixture of two salt. That is potassium sulfate and cupper sulfate with 9:1 ratio (90 g Potassium sulfate + 10 g Copper sulphate).

Take 1 g phenolpathalin powder in a 100 ml volumetric flask. Then add volume up to 100 ml by ethanol (Ethyl alcohol).

Procedure

• Take 1 g soil in a 50 ml beaker

• Add 25 ml 1M KCL solution 

Diethylene tetramine penta acetic acid (DTPA) being a chelating agent is used in the determination of available Fe, Mn, Cu and Zn. When the soil is shaken with a solution of DTPA, it combines with metal ions in the solution and form soluble complexes of Fe++, Mn++, Cu++ and Zn++. The CaCl2 and triethanolamine (TEA) solution slightly raise and buffer the soil pH and mitigates the effect of Ca++ and Mg++.

Soil is shaken with 0.15 % CaCl2 solution. Chloride ions displace adsorbed sulphate during extraction. Calcium ions suppress the extraction of soil organic matter and hence eliminate the contamination caused by extractable organic S.

Soil is shaken with 0.15 % CaCl2 solution. Chloride ions displace adsorbed sulphate during extraction. Calcium ions suppress the extraction of soil organic matter and hence eliminate the contamination caused by extractable organic S.

Reagents

• Buffer solution : Dissolve 67.5 g of Ammo. Chloride in 200 ml distilled water. Add 570 ml Ammonium solution. The volume make up to 1 ltr.

• EBT : 0.2 g in 25 ml methanol.

Potassium is extracted from the soil with the help of suitable extractant CH3COONH4 by shacking followed by filtration or centrifugation & is determined in the extract using flame photometer. The analysis photometer is based on the measurement of the intensity of characteristic lime emission given by the element to be determined .

Olsen P were found to bear a quadratic relationship, with Olsen’s extractant underestimating the content in phytoavailable P of soils with high Olsen P contents relatively to soils with low contents. The ‘‘change point’’ at which phytoavailable P began to increase rapidly per unit change in Olsen P was 53 mg Olsen P kg–1 soil. For the acid soils, a significant quadratic relationship was found between the amount of P desorbed to water and Olsen P at the three soil:solution ratios studied.

In Bray’s method a mixture of ammonium fluoride and hydrochloric acid (NH4F + HCl) act as the extracting agent. It works in two ways, firstly, the hydrogen ions from HCl have a solubilising effect, especially on Ca-P, which makes phosphate get extracted. Secondly, the fluoride ions (from ammonium fluoride) complex with the Al3+ and Fe3+ ions, thereby releasing the Al and Fe bound phosphorous into the extract.

The Kjeldahl method is mainly divided into three main steps. This method needs to be carried out in proper sequence. 

The statement is still valid as long as it is understood that in an aqueous solution the substances involved are subject to dissociation, which changes the ionization state of the substances. 

The lime requirement (LR) of an acid soil is the amount of lime needed to neutralize the acidity from an initial condition to some target soil pH, like 7.0. Different methods are used to calculate a LR for specific soils. Lime requirement tests will always recommend adding enough lime to neutralize all the acidity associated with soil pH, much of the salt-replaceable acidity, and some of the residual acidity.

In the detection of soil organic carbon a known weight of soil is heated with an excess volume of standard K2 Cr2 O7 in the presence of Con. H2 SO4 . The soil is slowly digested at the low temperature by the heat of dilution of H2 SO4 and the organic carbon in the soil is thus oxidized to CO2 . The highest temperature attained by the heat of dilution reaction produced with the addition of Con. H2 SO4 is approximately 12o C which is sufficient to oxidize the active forms of the soil organic carbon but not the more inert forms of carbon that may be present.

Electrical conductivity of the soil is the quantity of electricity in coulombs that passes per second per cm3 of the soil solution under an applied potential difference of 1 volt. It is written as EC in abbreviated form and is expressed in millimohs cm-1 or dS m-1 (deciSiemen m-1). Current flows in the soil solution due to presence of soluble salts like Cl- , SO2- 4 and NO3 - of Na+, K+ Ca++ and Mg++. These salts fully dissociate in water to their constituent cations and anions and the current is carried by those cations anions in the soil solution.

Atomic weight of an element is defined as the relative average weight of its atom as compared to the weight of an atom of C12 (stable isotope) taken as 12 on the a.m.u. (atomic mass unit) scale.

Determination of soil texture mainly depends on the complete dispersion of soil aggregates into their individual primary particles without triturating the particles themselves, accurate fractionation of the sample into various separates, sedimentation of different particles in the viscous medium as well as measurement of individual particle by the hydrometer.

The maximum water holding capacity is the amount of water, expressed as percentage on oven dry basis held by a soil when it is completely saturated with water. At this moisture content, all the pore spaces are completely filled with water.

Infiltration is the entry of a fluid from one medium into another. Soil water plays an important role in nature. The entry of rain or irrigation water into soil is called infiltration. Infiltration rate is defined as the amount of water entering into a soil per unit area per unit time under one atmospheric pressure. The infiltration rate depends upon initial moisture content of soil, condition of soil surface and permeability of various layers.