eChapters

Introduction

Phosphate solubilising microorganisms include different groups of microorganisms such as bacteria, fungi and actinomycetes, which convert insoluble phosphatic compounds into soluble form. The species of Pseudomonas, Micrococcus, Bacillus, Flavobacterium, Penicillium, Fusarium, Sclerotium, Aspergillus and others have been reported to be active in bioconversion. Such bacteria and fungi can grow in media where Ca₃(PO₄) ₂, FePO₄, AlPO₄, apatite, bone meal, rock phosphate or similar insoluble phosphate compounds are the sole source of phosphate. Such microorganisms not only assimilate phosphorus but they also cause a large portion of soluble phosphate to be released in quantities in excess of their own requirements. The solubilisation is not restricted to calcium salts but iron

Introduction

Biological nitrification is a two-phase process, which consists of the oxidation of ammonia-nitrogen to nitrite-nitrogen by species of genera Nitrosomonas, Nitrosospira and Nitrosogloea, and the subsequent oxidation of nitrite-nitrogen to nitrate-nitrogen by species of the genera Nitrobacter and Nitrocystis. The following equations explain the reaction.The importance of nitrifying organisms in soil is based on their capacity to produce nitrate, the major source of nitrogen assimilated by higher plants. The rate of nitrification is dependent on such factors as concentration of NH₄+, temperature, moisture, aeration and pH. Bacteria have their optimal activity at an alkaline reaction. Below pH 7.0 the process declines.

Introduction

As Rhizobia are slow growers so their enumeration by plating techniques is less recommended. Rhizobia can be enumerated in the presence of a large number of other organisms by most probable number (MPN) method. Soil containing Rhizobia is diluted in liquid and dilutions are used to inoculate roots of legumes. The presence of Rhizobia in a given experimental unit, inoculated by a given dilution, is indicated by the formation of at least one nodule on a root. Thus, the method involves the growth of legumes under conditions such that a single rhizobia cell can multiply and forms at least one nodule on the root.

Most Probable Number Method: This method permits estimation

Introduction

Rhizobia are Gram-negative soil bacteria , aerobic nitrogen fixers and adhere to the roots of leguminous plants. Fixed nitrogen is assimilated to proteins and is transported along the plants. A part of proteins is also released in rhizosphere region.

Requirements

1. Yeast Extract Mannitol Agar (YEMA)
2. Sterile saline
3. HgCl₂ solution (1%)
4. Ethanol (70%)
5. Root nodules of Mung bean
6. Water blanks
7. Pipettes
8. Petri plates
9. BOD Incubator

Introduction

Photosynthetic bacteria are autotrophs and anaerobes. These bacteria produce Hydrogen sulphide. These are predominant in the bottom of stagnant water enriched with mud.

Requirements

1. Mud sample
2. Enrichment medium of Photosynthetic bacteria or salt solution (1.0g/lt. of (NH⁴)₂SO⁴ 1 g; K²HPO⁴, 1 g; MgSO⁴,0.2g; NaCl, 5g; pH 7.2)
3. Sterilized bottle with plug
4. Fluorescent tube

Introduction

A microscope is an optical instrument consisting of a lens or a combination of lenses for making magnified images of minute objects. A simple microscope consists of a single lens of magnified glass held in a frame, usually adjustable and has a stand for holding the object and a mirror for reflecting the light. But a compound microscope consists of two lenses i.e., objective and eye piece respectively. A compound microscope gives much greater magnification than simple microscope. The compound microscope will be extensively used in this course in studying various morphological and staining characters of soil microorganisms.

Introduction

A haemocytometer is a single piece of glass with an H-shaped trough forming two counting areas. Hemocytometers are used to determine the total cell count and viability of many different cell types The full grid on a hemocytometer contains nine squares, each of which is 1 mm¹. Each counting area is defined by a grid system. It has supports that hold the cover glass at the proper distance (0.1 mm) above these areas for the calculation of the concentration per volume of liquid.

Requirements

1. Inoculum
2. Inoculation needle
3. Test tubes

Introduction

The motile bacteria show movements with the help of flagella. The motility of bacteria can be observed by hanging drop method under microscope.

Requirements

1. Bacterial culture
2. Cavity slide
3. Vaseline
4. Coverslip

Procedure

1. Place a very small drop of 24 hours old bacterial culture in the center of a coverslip.
2. Put a small amount of Vaseline at each cover of the depression side of the cavity.
3. Invert the cavity slide over the coverslip. The coverslip adheres to glass slide. When the coverslip is inverted, the hanging drop is suspended in the well.

Introduction

Bacteria are very minute and colourless in their natural environment and are difficult to be seen under compound microscope. To view their exact morphology, various kinds of stains are used. Stains are of three main types.

Acidic stains: These are those stains in which charge on dye ion is negative. e.g. India Ink, Eosin etc.

Basic stains: These are those stains in which charge on dye ion is positive. e.g. Methylene blue, Crystal violet etc,

Neutral stains: These are the salts of dye acid in dye base. e.g. Eosinate of Methylene blue.

Introduction

The actinomycetes are gram positive, non-motile, non-sporulating and nonacid fast bacteria. Sometimes these are called ray fungi and are connecting link between the bacteria and the true fungi. They possess a very fine vegetative mycelium that does not fragment into bacillary or coccoid forms and therefore their colonies on agar are commonly cohesive or tough in consistency. In many soils, the actinomycetes accounts from 10 to 25% of the total count on agar plates. Their number is higher in soils of low moisture content than in wet soils. They are responsible for degrading more resistant carbon material in soil like humus. They are also important flora of manure heaps. Most of these, particularly Streptomyces, produce antibiotics and so are of a great value

Introduction

Fungi constitute an important part of microflora of normal soil. In soils, fungal propagules vary from 2 x 10⁴ to 1 x 10⁶ per gram soil. The propagule being considered as fungal hyphae, spore, and hyphal fragments which is capable of giving colony on the plate. Most soil forms have a filamentous organisation capable of reproduction by means of spores. Their development is especially favoured by soils having acidic reactions. Soil fungi has significant role in organic matter decomposition, as a plant pathogens and in the interaction with other soil microorganisms. Agar plate count method is commonly used as a measure of fungal population in soil.

Introduction

Soil is the natural habitat of a number of microbes viz. bacteria, fungi, actinomycetes, algae and many viruses. Out of these, bacteria are morphologically very simple as made up of just one cell of small size, therefore can multiply rapidly. Each viable bacterium at appropriate dilution can develop into a colony. Hence by counting the number of these colonies which develop on a selective growth medium, the number of viable cells of bacteria present in soil can be ascertained. Since the number of the bacteria present in soil is very high, the soil suspension is to be sufficiently diluted to reduce the number of colonies and to prevent their overlapping. The number of colonies formed from a diluted sample multiplied by the extent of dilution (dilution factor) gives the number of viable cells present

Introduction

Microbes like all other living beings require suitable nutrients as well as favourable environment like pH, osmotic pressure, temperature, humidity etc. for growth. The substrate/food base which fulfills any of these requirements and supports the growth of an organism is called culture medium. Selection of a medium to grow a particular type of microorganism is extremely important, as the microbes vary in their nutritional requirements. Thus, different media are used for different groups of microbes. The following are the main types of media:

a) Natural/Empirical media: These are made up of natural substrates, such as herbaceous or woody stems, seeds, leaves, corn meal, wheat germ, and oatmeal etc.The exact chemical composition of this media is not known. e.g. Nutrient agar

b) Semi-synthetic media: 

1. General Instructions

Instructions to work in the laboratory are given below. Students are advised to read them carefully before they begin their work in the laboratory.

• Apparatus to be used should be neat and clean.
• Graduated pipette should be used for pipetting.
• The small amount of liquid remaining in the pipette should not be blown out while standardizing the pipettes; allowance is always made for this. However, a frosted ring near the top of recently manufactured pipettes indicates that the last drop is to be blown out.

Q.1 Fill in the blanks

1. _______and_______are pulse crops.
2. Rice is a_______pollinated crop.
3. Different breeds of cattle are_______and_______
4. _______and_______are sugar crops.
5. _______Important cereals are_______and_______
6. _______and_______are examples of fibre crops.
7. _______Dapog method is originated from_______
8. The origin of rice is_______region.
9. Best temperature range for germination of wheat is_______oC.
10. Adsali sugarcane is of_______months duration.
11. _______portion is taken in cane for propagation

Farming System Approach (FSA)

Farming systems refers deliberate raising of crops,forest and fruit trees, animals including fisheries, piggery and duck farming, sericulture, mushroom, on a given unit of land to increase the productivity and profitability, to upgrade natural resource base and to achieve overall improvement in the environment

The philosophy behind shifting from cropping system to the farming system mode involves

1. In situ recycling of organic residues including farm wastes generated at the farm to reduce the dependency on chemicals
2. Decrease in cost of cultivation through enhance input use efficiency,
3. Effective use of bye-products/wastes of one component for the benefit of other component/components
4. Upgrading of soil and water quality and bio-diversity,

The women is the backbone of agricultural workforce and are a vital part of Indian economy. Over the years, there is a gradual realization of the key role of women in agricultural development and their contribution in the field of agriculture, food security, horticulture, dairy, nutrition, sericulture, fisheries, and other allied sectors. Women form the backbone of agriculture, in India, Comprising the majority of agricultural laborers, women have been putting labour not only in terms of physical output but also in terms of quality and efficiency. With various targeted efforts, her enlightenment will change the face of rural India.

Women make essential contributions to the agricultural and rural economies in all developing countries. Their roles vary considerably between and within regions and are changing rapidly in many parts of the world

Power transmission through belts, pullies, gears, speed and size

Both stationary and portable types of agricultural machines make use of various types of power transmitting devices for doing useful work.

Some of these power transmitting devices are meant to convert rotary motion into linear motion or oscillating motion.

This transmission of power from generating unit to useful unit is possible through belts, pullies, gears, cams and couplings are also employed to transmit power. eg. The self propelled combine is a machine which employs most of the above power transmitting devices.

In some machines the belt drive is used to transmit power between two parallel shafts placed a short distance apart. In others a sprocket and chain drive is preferred, when the two parallel shafts to be operated

Being an agricultural country with 1/5^th of the world’s population of cattle and half of the world’s buffaloes. The cows and bullocks are the backbone of agriculture and play major role in the rural economy. India stands first in milk production in the world. Corresponding increase in human population, the per capita availability of milk is 145 gm/day which is far lower than the recommended level of 285 gm/day/head.

Importance of Livestock Management

• Provides milk and milk products. Milk is a perfect food as it contains proteins, fat, milk sugar, minerals and vitamins. It is the only source of animal protein in vegetarian diet.
• Livestock gives us meat.
• Provides farmyard manure

Vegetables: Three conditions shoul1d be met to be called a horticultural produce as a ‘vegetable’ viz.

• Vegetables are herbaceous plants
• They mostly serve culinary purpose
• They are also used in small quantity in a raw form.

Scenario

Area

• India is the second largest producer of vegetables in the world, next to China. India’s share of the world vegetable market is around 14%.
• India produces 188.28 m tonns