eChapters

Today a number of countries have moved away from the inorganic or chemicalised farming to organic farming yet it is not possible for India to depend entirely upon this system of farming due to increase in human population. As total availability of plant nutrients from different organic sources is projected to 7.75 MT by 2025 against the total requirement of 37.50 MT for 1504 million populations, so it means if we depend on organic sources there would be deficiency of about 30 million tonnes of nutrients.

There is no doubt that after independence, particularly during 1966-68, the use of hybrid and composite seeds of various crops, chemical fertilizers and pesticides resulted in an increase in the Indian agricultural output leading to ìGreen Revolutionî. But quite soon, the deleterious effects of farming based on chemical Organic Farming for Sustainable Agriculture 105 methods came to fore.

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 Out of the total amount of the fresh available water merely 30 per cent is withdrawn to meet the water requirements of the human and livestock population while the remaining 70 per cent is required to produce food crops that fuel human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.

Essential oil is a concentrated hydrophobic oily fragrance liquid extracted from plants, containing easily evapourated chemical compounds at room temperature. Essential oils are extracted from the different plant parts including the flowers, leaves, stem, bark, and roots, and they are extracted from different techniques. The most preferable method of extraction is hydro distillation which is easy to use and cheap. Essential oils are used in every field of life, used in aromatherapy, and act as antifungal, antioxidant, anxiety, pain relievers, and depression.

Anthocyanins are members of the flavonoid group of phytochemicals, a group predominant in teas, honey, wines, fruits, vegetables, nuts, olive oil, cocoa and cereals. The primary players in this group include the anthocyanins (eg, cyanidin, pelargonidin, petunidin), flavonols (quercetin, kaempferol), flavones (luteolin, apigenin), flavanones (myricetin, naringin, hesperetin, naringenin), flavan-3-ols (catechin, epicatechin, gallocatechin), and although sometimes classified separately, the isoflavones (genistein, daidzein) (Skibola and Smith, 2000).

Phenolic compounds constitute a major class of plant secondary metabolites that are widely distributed in the Plant Kingdom. Plant phenolics are biosynthesized through the shikimate/phenylpropanoid pathway leading to different compound classes. They may occur in their natural sources in free forms, as glycosylated or acylated derivatives, and as oligomeric and polymerized structures, such as hydrolyzable and condensed tannins, phlorotannins or lignins. They may also be found linked to plant matrix components such as cell walls, carbohydrates or proteins. It should be indicated that although the terms “plant phenolics” and “polyphenols” are indistinguishably used by some authors, they are not synonymous.

Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. Alkaloids showed quite diverse medicinal properties (Rates, 2001). Many of them possess local anesthetic properties, but their practical use is limited for clinical purposes (Hesse, 2002). Morphine is one of the most known alkaloids isolated from Papaver somniferum (opium poppy), which had been used and still is for medical purposes. This alkaloid is a powerful narcotic which is used for the relief of pain, but its usefulness is limited because of its addictive properties.

The following plants have been worked out in the laboratory of Prof. N. Raaman: Cynodon dactylon, Artemisia pallens, Leptadenia reticulata, Clausena dentata, Tylophora indica, Aristolochia bracteolata, A. indica, Cissus quadrangularis, Hypericum mysorense. and Solanum trilobatum. Out of some of the data of these plants have been included in the previous chapters. In this chapter, compound isolation (CD1) from Clausena dentata (worked by Dr. R. Kamaraj) and characterization of the compound are given in detail.

Phytochemicals are the individual chemicals from which the plants are made. Phytochemical is simply a word that means plant chemicals. Plants have the ability to synthesize mixtures of structurally diverse bioactive compounds with multiple and mutually potential therapeutic effects. The plants have the capacity of manufacturing the secondary products. Phytochemicals with antioxidant properties tend to be brightly colored because they contain chromophores, ie, a series of alternating single-bonded and double-bonded carbons. Isoprene is often the building block of such units. The darkest green vegetables contain the most chlorophyll, and vegetables with the most chlorophyll require the most antioxidants.

After isolation and purification of the compound, it has to be identified. It is necessary to find out the class of the compound first and then to find out the specific compound within the class. The class of compound is usually determined from the colour tests, solubility, Rf properties and UV spectral characteristics of the compound. Further identification within the class depends on measuring physical properties and spectral measurements and then comparing these data with those in the literature.