Materials

Metfiods

Figure 1a: Extraction Assembly (Tullgren Funnel)

/

m /

^ /

Figure 1b: Soil Thermometer

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Figure 1c: Corers

Figure 1d: Boring Tool (For the purpose of removing soil)

5©;

Figure 1e: Quadrant Sampler (1.5 m x 1.5 m)

Matwials and kMhods

MATERIALS AND METHODS

Methods of Sampling

The most commonly adopted method, especially among the more recent workers,

involves the use of some kind of Iwring tool for the purpose of removing soil. Glasgow (1939)

used a tx)rer consisting of a galvanized iron pipe (34.29 cm long and 8.13 cm internal diameter)

with its lower edge sharpened. The banrel was pushed down the soil by means of attached handle

and foot rest; and when with drawn it removed the sample of 51.53 cm sq in area. A vertnal slit

1.27 cm wide at the lower end of the barrel, Militated the removal of the sample, but it would

probably be diffkxilt to remove the soil from such an implement in undisturbed conditnn. Salt and

Hollick (1944), Salt et al (1948) and Salt (1952) used a standard "^re worni barer", which is made

up of a metal cylinder 10.16 cm in diameter and about 20.32 cm deep with three large pistons

used to eject the sample, cause considerable compression of the sample. Macfadyen (1953) took

undisturbed soil samples by pressing small stainless tubes directly into the soil. Each tube was 5

cm long and 3.75 cm in external diameter and was driven into the soil by means of a detachable

handle. The tube together with the enctosed soil was placed in the extraction apparatus so that

the soil structure remains undisturbed.

A modified instrument originally described by Dhilton (1964). The apparatus consisted of

a steel tube 60 cm long with an internal diameter of 5 cm. The upper end of tube was fitted with a

circular handle of 30 cm diameter, resembling the stiering of a car, while the lower end of the tube

was provided with a circular steel cutter 1 cm deep. The inner face of the cutter was vertical while

the outer one was oblique to form a sharp cutting edge.

In the present investigation, a circular corer sampler based on the principle of O'Coner

(1957) was used to avoid the casualty of delk)ate soil ^una but a slight nrKxlifrcation was made in

the corer that it was not split throughout its length; instead the corer was single tube of 7 cm

internal diameter. The tube at its rear end bore a cutting edge. To Militate its rotational

movement, the upper end of the tube was fitted with a handle. In the sampler ten iron rings were

inserted to get an idea of the depth from which the sample was to be taken. An iron pusher was

inserted throughout the length of the handle of the sampler. After each operation, the cutting edge

was detached and the rings were pushed down through ttie pusher (Figure 1c, Id).

65

Materials and Methods

In the present study the author has collected the samples from mineral soil and litter.

1. Litter Four samples of litter in a month were collected from each sampling site.

(Mango Orchards and Teak Plantation). The amount of litter from the sampling sites

was measured by quadrates (Figure 1c) of one-fourth of a square meter and the total

area t)eing 250 square meters.

2. Mineral soil: The soil samples were taken from a depth of 10 cm with the help of a

corer as modified by Averbach and Crossely (1960). For vertical distribution studies,

each sample obtained from 10 cm depth was divided into two sub-samples i.e. upper

0-5 cm and lower 5-10 cm.

Extraction of soil fauna

The extraction of microarthropods by Berlese funnel method has been used in the past

by many investigators. One important early change in the funnel method was modification in

which he substituted a heated water bath placed over and around the sample container, for the

hot water jacket of the original apparatus.

Tullgren (1918) first used an electric bulb suspended above the tray so as to add the

stimulus of light in order to drive the animals downwards in the funnel. Since then the Tullgren

funnel have been improved and improvised by a number of authors Ford (1937), Haariov

(1947), Balogh (1958), Kevan (1962), and Murphy (1962).

Ford (1937) employed an apparatus, which consisted of a battery of 12 Tullgren

funnels, the heat being suspended by electrically heated resistance were placed in cylinder on

the chimney resting on each funnel. Hammer (1944) introduced the practice of placing

undisturbed samples in the funnel in an inverted position rather than breaking the samples

apart. Haariov (1947) modified the funnels so as to prevent the condensation of moisture in

them. Macfadyen (1953) combined these devetopments into a compact set of small funnels in

order to produce a high gradient of temperature and humidity in the samples. With the growth

of interest in Soil Zoology modifications in the method of extractnn have been suggested from

time to time by many workers such as Balogh (1958), Kevan (1962), Murphy (1962), Nef

(1962), discussed the role of desiccation and temperature on the telegram funnel behavior type

66

Materials and Methods

extractor. In the opinion of Macfadyen (1962) the sampling and extraction method to be used in

a research project must be selected in accordance with the nature of the problem. In the

present investigation, the dynamic extraction method was used. This method is based on the

principle of the use of the stimuli which drive the animals out of their medium and the efficiency

of the method largely depends upon animal t)ehavior, changes in climate, moisture etc. The

present worker has used a t)attery of 4 split funnel composed of three parts: (Figure 1 a).

1. A bulb covered with a aluminum shade

2. An aluminum vessel with a sieve at its base

3. An aluminum funnel

The vials containing 70% alcohol and tew drops of glycerol were placed beneath each

funnel. An illumination with electric bulb of 15 watts was provided to each funnel. The litter and

soil in the rings were exposed for 36 - 72 hours. The intensity of illumination was controlled

through a regulator. The intensity of illumination was gradually increased with the time of

exposure. Initially the intensity was low and after every 12 hours, intensity was gradually

increased. A stereoscopic binocular microscope was used for counting of insects and mites

and later on insects were separated from mites and preserved in 70% alcohol. Some of the

insects were mounted in polyvinyl alcohol which was prepared by the followir^ method:

Polyvinyl alcohol 30 gms

DistiHed water 300 cc

Both were boiled in water bath for complete dissolution, to this solution 10 cc of glycerin and 10

cc lactic acid was added.

Mites were macerated in lactic acid with slight heat and were mounted in Meyer's Medium.

Composition of Hover's Medium

Distilled water - 50 cc

Gum Arabic - 30 gm.

Chloral hydrate - 200 gm.

Glycerin - 20 cc

Small and light cover glasses were used for mites in order to save the specimen from crushing.

67

MatBrials and HMhods

Larger insects and insect larvae were simply dehydrated by the usual methods and were

mounted in DPX. Before mounting, the insects of darker colour were treated with cedar wood

oil to impact transparency to these insects. The sides of the cover glasses over the slides were

sealed with ordinary nail polish as to avoid evaporation of the mountant.

Mechanical Analysis

It has t)een done by the Hydrometer method (Piper, 1942) as per the following procedure:

Procedure:

A given quantity of air dry soil equivalent to 100 gm of oven dry soil was transfen^ to

100 ml graduated tall cylinder 200 ml of water and 15 ml of 0.5N sodium oxalate solution were

then added. After thorough shaking the suspension was diluted to 1 liter by distilled water. The

percentage of silt and clay in suspension was determined by nothing the hydrometer reading 5

minutes after the commencement of sedimentation and the percentage of clay from the

hydrometer reading after 5 hours sedimentatbn. To record these readings accurate, the

hydrometer was carefully introduced into the suspension 20-30 seconds before the

predetennined time, when the temperature of the suspension differed markedly from 10-20(>C,

a correction to the scale reading was made by adding 0.3 degree units for every degree about

19.4(>C or substracting the same amount for each degree below 19.4^0. The values so

detennined would correspond directly to the percentage of silt and clay in the oven dry soil

provkJed a 100 gm sample was taken. The data obtained in respect of mechanical analysis

were mentioned in table 2.

Analysis of edaphic fectors

For this purpose, the soil samples were cored from the same pbts from where the soil

samples were collected for population analysis. Various edaphb factors such as temperature,

soil moisture, hydrogen ion concentration, relative humidity, content of organic carbon, organk;

matter, available nitrogen phosphate and potash have been analyzed by standard laboratory

methods as discussed betow:

68

Materials and Methods

Temperature

Temperature of the soil was measured by directly inserting the soil thermometer into the soil

upto 7 cm. the soil thermometer used in present investigation has been shown in photograph.

(Figure 1b)

Relative Humidity

Relative humidity of the sur^ice of the soil has been detemiined with the help of a Dial

hydrometer.

Hydrogen ion concentration (pH)

To 100 ml of double glass distilled water taken in a glass bottle 20 gm of fine earth

was added. The bottle was stoppered and shaken in a mechank^al shaker for an hour; after

which the solution was transferred to a glass beaker and its pH value was examined with the

pH meter.

Before taking the reading of pH of soil solutk}n the instrument was standardized each time with

a standard Backmen Buffer Solution to avokj the instrumental en'or.

Water Content

The absolute content of water whrch has an impact on the activities and distribution of

the animals generally exists in variable quantity rising to a maximum after heavy rain and

falling rapidly during the hot months. For this reason, sample for the determination of water

content were never collected immediately after heavy rains.

Content of water has been determined here by a method described by Dowdeswell (1959).

Procedure

Soil samples after collection were kept in a tray for 24 hours for preliminary air drying.

It was then crushed in mortar and pastle and passed through fine sieve no. 80 to obtain fine

powder of earth. Ten grams of this air dried fine earth was taken in an evaporating dish and

kept in a hot air oven at about 105°C for an hour. It was then cooled in desiccators and again

weighed. This was repeated at regular intervals until the weight become constant. The loss in

weight expressed in percentage represented the moisture derived from both hygroscopc water

some of the capillary water.

69

Materials and Metfiods

Potassium

Principle

Water soluble Potassium in the soil can be detemiined by precipitation in water

solution as cobaltinitrite. The amount of potassium in the precipitate is deterniined

colorimetrically. The method requires removal of ammonium ions present in the sample.

Reagents used

1. Sodium hydroxide (10%)

2. Hydrochloric acid (1 N)

3. Nessler reagent

4. Phenolphthalein indicator

5. Potassium hydroxide (6 N)

6. Hydrogen peroxide (3%)

7. Potassium bicarbonate (saturated)

Procedure:

Precipitating Reagent

20% sodium cobaltinitrite solution was dissolved in 20 g of sodium cobaltinitrite Na3Co(NC)2)6 in

distilled water (80ml) and made the volume to 100 ml. After stending for 4-5 hours it was

filtered through a retentive paper to remove traces of insoluble matter. The solution was kept in

stopper bottle, at 5°C.

Solvent for Potassium

Acetic acid was used as a solvent for potassium. 4% fbnnaldehyde was also added to remove

traces of ammonia fiiom interfering through co-precipitation with potessium.

Standard potassium Chloride Solution

0.1907 g dried KCI was dissolved in water and transferred it to the volumetric flask to make the

total volume to 500ml. Each ml contains 0.2 mg of K.

70

Matwials and Methods

Removal of Ammonium

Two to three drops of phenolphthalein indicator was added to the beaker containing potassium

solution. Then 10% NaOH solution was added drop wise until the colour of phenolphthalein

turns red. The solution was evaporated to dryness to remove last traces of ammonia. When

the evaporation is complete, 2 ml of 1 N HCI was added and also a drop of this HCI solution to

a spot plate and test for ammonium ion with Nessler reagent.

Preparation of Solution

The t)eaker was cooled and atx)ut 15 ml of the solvent for potassium (i.e., acetic acid

containing 4% fonnaldehyde) was added. The solution was filter through a dry filter paper into

a 50ml conbal flask whk:h is then stoppered. The amount of potassium in the precipitate is

detennined colorimetrically.

Colorimetric Method for determination of amount of potassium in the precipitate

20% solution of sodium cobaltinitrite was added to the t)eaker containing solution of

potassium salt at a constant temperature. The precipitate fonned was washed several times

with 70% ethanol. The precipitate was then dried for 5 min at 100 to IIO^C. The precipitate

was dissolved in 6 N HCI and the solution was transfened to a tube bearing calibratfon marit

and cotorimetrically standardized. After this 1.5 ml. of 6 N KOH solutfon was added. Then 0.5

ml of 3% H2O2 was added in the tube. The contents mixed thoroughly. In case the brown

precipitates begin to form 6 N HCI was added drop wise to clear the solutfon. Finally 15 ml of

KHCO3 was added and made the volume upto the standard marie on the tube with water and

the cotour was measured in the colorimeter or at 620 nm with spectrophotometer. Also blank

solution was employed for 100% transmission for setting of the colorimeter. The colorimetric

readings was referred to the calibration curve (drawn by taking standard solutfons of KCI) to

find K in the test sample.

Organic Carbon estimation by Walklay - Blacic method

Principle

The soil is digested with potassium dichromate (K2Cr207) and cone. H2SO4 making

use of dilution of heat of cone. H2SO4. Excess dkihromate is not reduced by the organrc matter

of soil in back titration with femjus ammonium sulphate (FeSO^) (NH ja SO4.

71

Materials and HIMhods

K2Cr207+4H2S04 = K2S04+Cr2(S04)3 +4H20+30

This nascent oxygen oxidizes carbon of the soil to carison dioxide.

Procedure

Soil sample weighing 0.5 gm were placed in a 500 ml conical flask after passing

through 0.2 mm (80 meshes/inch) non ferrous sieve 10ml of 1N K2Cr207 solution was pipetted

on to the soil, the two were mixed by swirling the flask, then 20ml of cone. H2SO4 were added

and mixed by gentle rotation for 1 minute to ensure complete contact of the reagent with soil.

The mixture was allowed to stand for 20-30 minutes. A standardization blank (without soil) was

run in the same way.

Back Titration

The solutbn was diluted to 200 ml with water 10ml of 85 % orthophosphoric acid

(H3PO4), 0.2 gm of NaF and 30 drops of diphenylamine indteator was added. The solution was

back titrated with 0.5N ferrous ammonium sulphate solution delivered from a burette. The

solution in flask which turned turbid blue after the addition of the indicator, gradually assumed

green colour and at the end point the colour became brilliant green after adding a drop of

ammonium sulphate. The results were cateulated by the equation given betow:

% 0 M = 10(1-T/S)x1.34

S = Standardizatbn blank titratbn, ml Ferrous soiutbn

T = Sample titratton, ml ferrous solution

a. The standard 1N K2Cr207 was prepared by dissolving 49.04 gm in water and the solution

was diluted to one litre.

b. 0.5N solution of ferrous was prepared dissolution of 19.61gm of Fe (NH4)2 SO4.6H2O in 8

ml of water. To this solution 20 cc of cone. H2SO4 was added. The solution was diluted to

one litre.

Phosphate

Phosphate normally occurs in small quantities but none the less, their detenninatk)n

may be important in the study of a rapidly changing environment. In the present investigation

molybdenum blue test as described by Dowdeswell (1959) was employed to estimate the

72

Materials and Metfiocfs

phosphate content of the soil. The molylxJenum blue test provided as ready nrieans of

cotorimetric estimation involving minimum of time and apparatus.

Principle:

Orthophosphate and molybdate ions condensed in acidic solution to give

molytxiophosphoric acid which upon selected reduction produces a b\\ie colour due to

molylxJenum blue of uncertain composition. The intensity of blue colour is proportional to the

amount of phosphate initially incorporated in heteropoly complex which is thought to be fbmned

by coordination of molybdate ions within phosphorous as the central coordinating atom, the

oxygen of the molybdate radicals being substituted for PO4.

H3P04+12H2Mo04H3P(Mo30io)4+12H20

Procedure

To 100 ml of soil extract taken in a conical flask, 1ml of molybdate sulphuric ackl

reagent and 5 drops of 2.5% stannous chk)ride solution were added. It was mixed well and on

being allowed to stand for 10 minutes. It resulted to blue colour. Similar treatment was followed

with 100 ml of standard phosphate solutbn (with Ippm phosphorus).

Standard curve was pbtted by measuring the optical densities of the series of gradual

concentration derived from the original standard at a wave length 660 nm in a spectro

photometer (Bausch and Lamb). The optical density of the unknown material was compared

against the standard curve and its concentration, phosphate was thus obtained being

expressed as parts of phosphorous per million or as available phosphate as commonly used in

agricultural practices.

Available Nitrogen

Available nitrogen occurs in small quantities whbh ultimately change into nitrate, their

detennination may be important in the study of a rapkjly changing environment In tiie present

investigation Alkaline permanganate method was emptoyed to estimate the available nitrogen

in ttie soil.

73

Materials and MoUiods

Principle

A known weight of the soil is mixed with excess of alkaline KMNO4 solution and

distilled. Ammonia gas formed is at)sorbed in a known volume of standard acid excess of

which is titrated with standard alkali using methyl red as the indrcator.

Alkaline permanganate has been used as an extracting reagent for the characterisation of the

nature of nitrogen in organic manures and this fornis the standard AOAC procedure for the

estimation of active nitrogen.

This method, however, is the quk:kest of all other methods for the ^ m a t k m of available

nitrogen and has been found to work well even in Indian soils.

Procedure

Take 20gm of the given soils sample in distillation flask and add 20ml of water. Now

add 100ml of 0.32% KMNO4 solution and 100 ml of 2.5% sodium hydroxide solution and

immediately fit it up in the distillation apparatus. Pipette out 20 ml of 0.02N sulphuric ackJ in a

conk^al flask and dip the end of the delivery tube in it. Distil ammonia gas from the distillation

flask and collect about 30ml of the filtrate. Now add 5 drops of methyl red indk^ator and titrate

with 0.05 N sodium hydroxide.

Procedure for Isolation of Soil Fungi

One gm soil sample from each site was suspended in 99 ml of sterilized distilled water.

It was thoroughly shaken and further dilution was made so as to give finally a dilutbn 1; 104.

One ml portbn from the final dilution were transfeaed aseptically to sterilize glass Petri dishes,

and one tube of Czapeks Agar medium was added separately to each Petri dish. Each sample

to whk;h Czapek's agar medium was added v/as replk^ated three times. Petri dishes were

rotated with the object of mixing uniformally the sample and media. These were labeled and

kept in inverted position in the incubator at 3&K^. The colonies of fungi, whrch appeared after 4

days of incubation, were counted and studied for their morphologk^al characteristrcs.

74

Mataials and Methods

Identification of fungi isolates

On the basis of colony characteristics and direct examination of mycelia and fmiting

txxlies the fungal isolates were identified up to the generic level with the help of "A manual of

fungi".

Method of preparation of Czaoek's Agar Medium

K2 H PO4 = 1 gm

NaNOa = 2gm

M0SO4.7H2O = 0.5 gm

K61 = 0.5 gm

Malt Agar = 20 gm

Distilled water = 1000 ml

The medium was adjusted to pH = 7. Aliquots measuring 10 ml were transferred to the culture

tubes, which were plugged with cotton and sterilized at 15 l bs pressure per square inch for

half an hour.

STATISTICAL ANALYSIS

Mean, standard deviation, SEM, correlation (r), Regression (y) and Analysis of variance

(ANOVA) were calculated according to the fbmiula described by S. Prasad (2003). Species

diversity (H) and Evenness (J) were calculated by Shanon and Wiener diversity index (1949)

and Evenness (Pielou, 1966) based on the following formula:

Shannon and Wiener diversity index (1949):

H^=-±P^og,P, 1=1

Where,

H' = species diversity

Pi = ni/N is the probability of an individual to belong to a species.

Ni = no of individual in 'fi^ species

N = Total number of individuals in samples.

S = Number of species.

75

Materials and kMiods

Evenness (Pielou, 1966):-

Where,

J = Eveness

H' = Diversity index descriliecl by Shannon wiener equation.

Hmax = 10928

S = Numt)er of Species.

76