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CHAPTER 3

FEATURES OF ORGANIC MANURES

3.1 Manure

Plants need a well balanced diet, for better growth and yield.

Manures are the substances which provide nutrients for proper growth of

plants. Manure is anything that has been added to the soil to increase its

fertility and enhancing for plant growth (Boller and Hani, 2004). The word

manure came from Middle English "manuren" meaning "to cultivate land,"

and initially from French "main-oeuvre" = "hand work" alluding to the work

which involved manuring land. Manure is not just the urine and faeces from

livestock, but also the bedding, runoff, spilled feed, parlor wash, and anything

else mixed with it.

Manure contributes to soil fertility and tilth. In addition to nutrients,

manure provides carbon and other constituents that affect soil humus content,

biological activity, and soil physical structure (Wagner and George, 2004).

Manures contribute to the fertility of the soil due to addition of organic matter

and nutrients, such as nitrogen that is trapped by bacteria in the soil (Haynes,

2003).

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3.2 Classification of manure

Manures can be divided into two classes: Organic or Inorganic.

Organic manures are derived from decaying material of plant or animal

origin. Inorganic manures, also known as fertilizer, are derived from

chemical processes, that are most often man-made. Organic manures often

provide more than one of the many substances needed by plants for their

growth. Inorganic manures usually provide only one of the many substances

needed by plants for their growth (Boller and Hani, 2004).

3.2.1 Organic manures

Almost any kind of organic matter may be used as manure, but some

kinds are better than others. Organic manures vary widely in the amount of

plant nutrients that they contain. Some are more concentrated than others.

Compost is one of the less concentrated organic manures, but it is extremely

valuable in adding extra body to soils especially the sandy soils. Organic

manures which break down or decay quickly are available to the plant faster

than those which decay slowly (Boller and Hani, 2004). In these study four

types of manures namely Seaweed, Cow dung, VermiCompost and Coir waste

were used (Fig 3.1).

57

SEAWEED COW DUNG

VERMI COMPOST COIR WASTE

Figure 3.1 Types of Organic Manure

3.2.2 Inorganic or Artificial manures

These manures, or fertilizers, are either of mineral origin or man-

made through chemical processes. Because these fertilizers are relatively

simple in structure, they break down and are available to plants rather

quickly. Fertilizers are available as 'Complete Fertilizers' with varying

degrees of chemical compositions or as individual chemicals such as

Nitrogen, Phosphorous or Potash. In either case the fertilizers are also

available as timed release or quick acting. Artificial manures are often more

58

expensive than organic fertilizers, but tend to be easier to use, less

odorous and may be stored longer without deteriorating (Boller and Hani,

2004).

Green manure

Soil productivity is an important concern for farmers. Green

manuring is gaining popularity as a method that successfully improves soil

productivity (Haynes, 2004). The addition of peat moss material improves

soil tilth. At the same time, the nutrients used in plant growth are conserved

and returned to the soil to enhance its fertility (Boller and Hani, 2004).

Leguminous crops, such as clover, when used as green manure also fix

nitrogen through rhizobium harboured in their root nodules (Whitmore,

2000). Green manure approaches to crop production may improve economic

viability, while reducing the environmental impacts of agriculture (Cherry

et al., 2006).

Animal manure

Most animal manure is faeces — excrement (variously called

"droppings" or "crap" etc) of herbivores and poultry — or plant material

(often straw) which has been used as bedding for animals and thus is heavily

contaminated with their faeces and urine (Whitmore, 2000). The

Vermicompost manures may be used by mixing earthworm with soil or by

adding them to compost. Cow dung is a good source of nitrogen and

phosphorus. Seaweed with amino acids is an excellent source of calcium and

potash (Boller and Hani, 2004).

59

Fertilizers

Fertilizers quickly break down to provide specific nutritional needs

to plants. Urea is another good source of Nitrogen, but once again, must be

used carefully as it will promote an excess of green growth and make plants

weak, spindly and susceptible to disease. Potassium is an essential element

deficient in sandy soils. Calcium is another essential element for most plants.

Also known as lime, it helps to neutralize the acidity of acidic soils and

allows the release of plant nutrients that would otherwise be bound in the soil

and unavailable to plants. Lime should be applied carefully as it may cause a

deficiency of other elements in plants if used in large quantities.

Superphosphate, Nitro-chalk, Rock phosphate, Calcium cyanamide,

Ammonium sulfate, Ammonium nitrate and Magnesium phosphate are the

different examples of fertilizers (Boller and Hani, 2004).

3.3 Forms of available nitrogen in manures

As Figure 3.2 indicates about half of the nitrogen in manure is in the

form of ammonium and about half is in the form of organic material.

Microbes that consume the organic compounds excrete ammonium. One of

the four things will happen to the ammonium - regardless of whether it comes

directly from the manure or from microbes consuming the organic

compounds. The ammonium may either be used by plants immediately,

converted to ammonia and lost to the air or converted to nitrate which will be

used by plants or microbes. The "immobilized" nutrients become available to

plants when the microbes are consumed by other organisms that release

ammonium as a waste product. In the warmth of summer, plants and microbes

60

grow more vigorously and use ammonium and nitrate quickly. Losses of

nitrate to leaching are greater in spring and autumn when fewer plants and

microbes can turn it into organic matter (Wagner and Georg 2004).

Figure 3.2 Forms of available nitrogen in manure

3.4 Physical and chemical properties of soil nutrients

Plants need only 16 nutrients for good growth. It must be provided

either by the soil or by animal manure or mineral fertilizer. Some other

mineral nutrient elements, e.g. Na, Si, Co, have a beneficial effect on some

plants but are not essential. About 13 essential mineral nutrients are required

for growth (Mc Lean, 1987)

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Macronutrients

a) Major nutrients present in fertilizers for almost use in all crops

on most soils:

N = nitrogen (taken up as NO3- or NH4+)

P = phosphorus (taken up as H2PO4- etc.)

K = potassium (taken up as K+)

b) Secondary nutrients are added to fertilizers mainly for use in

certain crops on some soils:

S = sulphur (taken up as SO42 -)

Ca = calcium (taken up as Ca2+)

Mg = magnesium (taken up as Mg2+)

c) Micronutrients of which the critical contents in plants are 0.3-

50 mg/kg of dry matter: Heavy metals like iron, manganese,

zinc, molybdenum and copper (Fe, Mn, Zn, Mo, Cu taken up

as divalent cation or chelate) and non metals like chlorine and

boron.

d) Beneficial nutrients like sodium (taken up as Na+; can partly

replace K+ for some crops), silicon (taken up as silicate, etc.,

for strengthening cereal stems to resist lodging), cobalt

(mainly for N-fixation of legumes) and chlorine (useful for

some crops in greater than essential amounts, for osmotic

regulation and improved resistance to some fungi).

62

Components of soil fertility (Lory and Russelle, 2005)

Soil depth (determines the volume of soil accessible to the

root system).

Soil structure (size distribution and aggregation of particles).

Soil reaction (an indicator and regulator of chemical processes

and equilibria).

Content of nutrients in different degrees of availability.

Storage capacity for soluble nutrients from the soil and

fertilizers.

Humus content and quality (including proportion in

mineralizable form).

Quantity and activity of soil organisms as agents of

transformation processes.

Features of high fertile soil

Mobilizes soil nutrients from the reserves.

Stores water soluble nutrients in available forms.

Offers a balanced nutrient supply due to its self regulatory

system.

Maintains good soil aeration for the oxygen requirements of

roots.

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There are alternative ways of making use of soil fertility in farming:

Exploitation i.e. farming without any added fertilizer (e.g. in

shifting cultivation).

Utilization of as many components of soil fertility as possible

without compensation and yet without negative yield effects

(e.g. by applying only moderate amounts of fertilizer N and

P).

Maintenance and improvement of soil fertility to assure

consistent high yields (e.g. by compensating for losses due to

removal and by soil amendments to improve fertility).

Physical parameters of soil

3.4.1 Estimation of soil pH

The pH of the soil suspension was estimated using a pH meter.

3.4.2 Determination of bulk density of the soil sample

The soil sample was dried in a hot-air oven at 105°C and its dry

weight was recorded. The procedure was repeated three times till a constant

weight was achieved. The dried soil sample was transferred into a 100ml

measuring cylinder and the volume was measured. The bulk density was

calculated using the formula.

Bulk density (g/m3) = Weight of the soil (g)/ Volume of the soil (cm3)

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3.4.3 Determination of specific gravity of soil sample

The soil sample was homogenized and dried in a hot air oven at

105°C. This was repeated until a constant weight was achieved. Two wide-

mouthed glass bottles were taken and their initial weight was recorded. The

dried soil sample was transferred to a fixed volume in a bottle and was filled

in bottle distilled water to the same volume. The weight of both the bottles

with soil and distilled water was measured. The specific gravity of soil was

calculated as shown below.

1

1

y ySpecificgravityof soilz z

where y = Final weight of bottle with soil

y1 = Initial weight of bottle used for soil

z = Final weight of bottle with distilled water

z1 = Initial weight of bottle used for water

3.4.4 Determination of moisture content of soil sample

The homogenized soil sample was dried in a hot air oven at 105°C

till a constant weight (I) was achieved and cooled in a desiccator to record its

final weight (F). The moisture content of the sample was calculated as

follows.

(I F) 100Moisture content (%) of the soil sampleI

where I = Initial weight of the sample (in g)

F = Final weight of the sample (in g)

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3.4.5 Determination of the water holding capacity (WHC) of soil

sample

For WHC determination, bottom-perforated rounded soil boxes of

about 5.6 cm and 1.6 cm diameter were used. The initial weights of the empty

box were recorded. The soil sample was homogenized by drying it at 105°C.

A filter paper (preferably Whatman No.1) was kept above the perforated

bottom of the soil box. The box was filled with dried soil and its final weight

(F1) was recorded. The soil box was placed in a petri dish containing water

and the whole set-up was left undisturbed for about 12 hrs. This allowed the

water in the petri dish to enter into the oil box and ultimately to saturate it.

The box was dried on the outside before weighing.

The WHC was calculated as follows.

2 1 1

1

(F F ) (F I) 100WHC (%)(F I)

where I = Initial weight of soil box (g)

F1 = Final weight of soil box with soil (g)

F2 = Final weight of the soil box with water-saturated soil (g).

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Chemical parameters of soil

3.4.6 Determination of total nitrogen in soil sample

Reagents

a. Catalyst mixture: 20 g of copper sulphate 3 g of mercuric

oxide and 1 g of selenium powder.

b. Concentrated sulphuric acid.

c. Sodium hydroxide (40%)

d. Zinc granules

e. Boric acid indicator solution (4%)

f. Hydrochloric acid (0.1N)

Methodology

10 g of soil sample was taken into a clean dry kjeldahl flask and

20 g of catalyst mixture was added .The contents were mixed well and left for

20 min. 35 ml of sulphuric acid was added to the flask, mixed well and left it

for another 15 minutes. The content was digested over the Bunsen burner for

about 2 hr and was cooled 100 ml of distilled water was added. Then it was

distilled with 100 ml of sodium hydroxide solution and a few zinc granules in

a distillation flask. 25 ml of boric acid cum indicator solution was pipeted out

in a 500 ml Erlenmeyer flask and keeping its delivery end below the

condenser of the distillation flask. Collection of distillate in the flask was

confirmed by titrating it against 0.1N Hydrochloric acid using an indicator.

Color change from blue to light brown to pink was the end point.

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Calculation

1 2(V V ) N 14Total Nitrogen (mg / g)S

1 2(V V ) N 1.4Percent total nitrogenS

where V1 = Volume of titrant used against sample (ml)

V2 = Volume of titrant used against blank (ml)

N = Normality of titrant (0.1)

S = Weight of soil used (g)

3.4.7 Determination of total phosphorus content of the soil sample

Reagents

a. Ammonium molybdate solution (6%)

b. Stannous chloride solution (0.1N)

c. Concentrated nitric acid

d. Concentrated perchloric acid

e. Sulphuric acid solution

Methodology

The acid-dried soil sample was dried to a fine powder and weighed

0.5 g of it was weighed in round-bottomed flask.2 ml each of concentrated

nitric and perchloric acid were added to the soil sample. The flask in a hot

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plate was heated till the content became dry. Then 2 ml of sulphuric acid was

added and heated for 15 min. The digested content was filtered through

Whatman No.44 filter paper the filtrate was made up to 250 ml with distilled

water. The phosphorus content of the filtrate was determined by adding 4 ml

of ammonium molybdate solution.

Calculation

1P VTotalPhosphorus (ppm)1000 W

where P1 = PO4P in digested content (mg/l)

V = Total volume in solution (ml)

W = Weight of soil sample

3.4.8 Estimation of calcium in soil sample

Reagents

a. Solid ammonium chloride

b. Potassium permanganate (0.1N)

c. Silver nitrate

Methodology

50 ml of the hydrochloric acid extract was taken in a 500 ml beaker

and 2 g of solid ammonium chloride and a piece of red litmus paper was

added to indicate the pH of the beaker content. The content of the flask was

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boiled with 10 ml of saturated ammonium oxalate. After this, the beaker was

undisturbed for another 5 min. An ammonium oxalate can be added until no

more precipitate was formed and then filtered through a filter paper

(Whatman No. 40). The filtrate was collected in the conical flask and added

10 ml of dilute sulphuric acid was added and heated in a hot plate at 70°C for

3 min and the supernatant was titrated against 0.1N potassium permanganate.

The end point was the appearance of faint-pink color. The calcium content of

soil sample was determined.

Calculation

Amount of calcium in 100 g of soil on moisture free basis (%)

0.02 (250/50) (500/50) (100/W) (100/(100 – M)

where W = Weight of soil taken

M = Moisture percent of soil.

3.4.9 Determination of sodium and potassium in soil sample

Reagents

a. Ammonium acetate solution (1N)

b. Standard potassium chloride solution (1mg/100ml)

Methodology

5 g of soil was taken in an Erlenmeyer flask containing 5 ml of

ammonium acetate. The flask was placed on a rotatory shaker and rotated for

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5 min. The content of the flask was filtered through Whatman filter paper

No.1 and the filtrate (25ml) was collected. After setting, the potassium filter

initiated the compressor and lighted the burner of the instrument. The air

pressure was set at 5 lbs using gas feeder to produce sharp flame cones. Using

highest potassium standard solution, the instrument was adjusted to show full

reading. Similarly using extract solution, the zero reading was set. The above

procedure was repeated for sodium filter also. A standard curve was drawn by

plotting the reading of standard against their concentration. From the

calibration curve, the concentration of potassium and sodium in the solution

were calculated.

Calculation

a vAmount of available K (Cmol / kg) 2.24W

where a = concentration of K /Na in the unknown sample read

from the calibration curve

V = Volume of extract (25 ml)

W = Weight of soil (g)

3.4.10 Determination of manganese content of the soil sample

Reagents

a. Manganese stock solution (1mg/100ml)

b. Special reagent: Concentrated nitric acid (2:1), 37.5 g of

mercuric sulphate, 85% phosphoric acid and 17.5 mg of silver

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nitrate. The volume was made up to 500 ml using distilled

water after stirring the contents well.

c. Ammonium persulphate crystals.

Methodology

Different aliquots of working solution were taken in a series of

beakers and the volume was made up to 100 ml using distilled water. 100 ml

of distilled water was taken as blank. Similarly 100 ml of sample was pipetted

out in a beaker. To all the beakers, 5 ml of special reagent was added and

heated. 1 g of ammonium persulphate was added to each beaker and boiled

for two min. The color was measured in a spectrophotometer at 545 nm.

3.4.11 Determination of magnesium in soil sample

Reagents

a. Solid ammonium chloride

b. Diluted ammonium hydroxide (1:4, 1:7)

c. Disodium phosphate and silver nitrate

Methodology

1 g of solid ammonium chloride and ammonium hydroxide solution

(1:4) were added in small quantities till red litmus paper turned blue and

added10 ml of disodium phosphate solution was added to it .This was kept for

about 12 hr and the precipitate was filtered through Whatman No.42 filter

paper .The precipitate was washed with diluted ammonia. The precipitate was

72

placed in a silica crucible and dried in a hot-air oven at 105°C. The dried

precipitate was made to a white ash powder by heating the crucible for 30 min

in a red hot flame and the final weight of the crucible was determined.

Calculation

Amount of magnesium in 100 g of soil on a moisture free basis (%)

48 250 500 100 100(b a)222 50 50 W 100 W

where b = Weight of silica crucible + Mg2P2O7 precipitate

a = Weight of silica

W = Weight content of the soil box

3.5 Results and Discussion

The physical and chemical characteristics of soil at the experimental

site using coir waste manure were taken into to analysis. Physical

characteristics such as pH, sand, silt, clay, specific gravity, bulk density,

moisture content and water holding capacity of the soil were measured.

Further chemical characteristics such as nitrogen, phosphorus, potassium,

calcium, sodium, magnesium, manganese and organic carbon content of soil

were measured and analyzed. Soil samples were collected from before

planting and after harvesting of black gram.

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Table 3.1 Physical characteristics of soil at the experimental site

Period of sampling Treatments pH Sand(%)

Silt(%)

Clay(%)

Before Planting Soil Sample 4.10 70.2 4.4 25.4Control 4.07 69.8 5.3 24.9Coir waste treatedAnabaenaa azollae

5.40 68.7 6.0 24.5

Coir waste treated Phormidium 4.98 68.0 5.8 24.2

After Harvesting

Coir waste treated Oscillatoria 4.11 70.00 5.2 25.1

Table 3.2 Physical characteristics of soil at the experimental site

Period ofsampling Treatments

SpecificGravity(mg/m3)

BulkDensity(g/cm3)

MoistureContent

(%)

Waterholding

capacity (%)Before

PlantingSoil Sample 2.64 0.4 48.2 52

Control 2.62 0.5 50.4 56Coir waste treatedAnabaena azollae 2.74 0.8 85.3 74

Coir waste treatedPhormidium 2.64 0.6 76.5 71

AfterHarvesting

Coir waste treatedOscillatoria 2.58 0.5 67.3 68

Tables 3.1 indicates an increase in pH content of soil after harvest

of plant using treated coir waste in the order of Anabaena azollae

sp > Phormidium sp > Oscillatoria sp. Application of organic manure

increased the pH of the soil after harvest. This agreed with the findings of

Mulongoy (2003). The maximum reduction of sand and clay in the soil was

observed in coir waste treated Phorimidium sp after harvest of plant. It was

supported with Bill (2001), who observed high reduction of sand and clay

content of soil, after harvesting of black gram using organic manure.

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The silt content of soil was gradually increased in Anabaena azollae

treated coir waste manure when compared with other treatments and untreated

soil. The bulk density of soil was gradually increased in coir waste manures

treated soil (Table 3.2) when compared with control. This is supported by the

work done by Sangakkara (2000), who observed that organic manure

increases the bulk density of soil.

The moisture and specific gravity were found to be higher in soil of

Anabaena azollae treated coir waste manure when compared with other

treatments. The water holding capacity of soil was increased in the

preposition of plant using (coir waste + Anabaena azollae manure) > (Coir

waste + Phormidium) > (Coir waste + Oscillatoria). This result was in

accordance with the findings of Higas (2004), that organic manure enhances

the water holding capacity of soil, plant vigour and soil properties.

Table 3.3 Chemical properties of soil at the experimental site

Period ofsampling Treatments N

(%)P

(ppm)K

(cmol/kg)Ca

(cmol/kg)Before Planting Soil Sample 0.085 6.7 0.07 0.62

Control 0.83 4.4 0.02 0.57Coir waste treatedAnabaena azollae 0.230 6.9 0.05 0.65

Coir waste treatedPhormidium 0.215 6.4 0.04 0.61After Harvesting

Coir waste treatedOscillatoria 0.080 4.6 0.02 0.54

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Table 3.4 Chemical properties of soil at the experimental site

Period ofsampling

TreatmentsNa

(cmol/kg)Mg

(cmol/kg)Mn

(ppm)Organic

carbon (%)

BeforePlanting

Soil Sample 0.30 0.25 4.94 0.79

Control 0.10 0.20 4.30 0.82Coir waste treatedAnabaena azollae 0.30 0.30 3.47 1.02

Coir waste treatedPhormidium 0.27 0.24 4.06 0.91

AfterHarvesting

Coir waste treatedOscillatoria 0.08 0.18 4.14 0.80

Table 3.3 describes the chemical properties of soil before planting

and after harvesting of plant. Coir waste treated with Anabaena azollae and

phormidium showed a significant increase N2 content without any significant

change in the P, K and Ca content. There was no significant change in N, P,

K and Ca content in coir waste treated with Oscillatoria. Artificial /chemical

fertilizers like urea provides N, P, K constituents to the soil. But imbalanced

use of chemical fertilizers on soil is not only harmful to microflora and fauna

but also reduce the progressive productivity potential of land. The

micronutrients such as sodium, magnesium and maganese present in the soil

showed no significant increase in coir waste treated with cyanobacteria

(Table 3.4). This was supported by Maynard (2001) in which cow dung

manure and poultry manures were more effective in amending the soil by

improving the N, P, K levels and micronutrients of the soil.

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The physical and chemical experimental site before planting and

after harvest of a plant using three different cyanobacteria treated coir waste

manures were discussed. Among the three species, Anabaena azollae treated

coir waste manure showed best organic manure activity on the soil (Table 3.1

and 3.4). This was supported by Bill (2001) who observed that organic

manure improves soil tilth, infiltration rate and soil water holding capacity

contributing to increased nutrient uptake by the crop being an important

source of raw or partially decomposed organic matter.

Phormidium sp treated coir waste manure showed 76% of

improvement of soil properties. But Oscillatoria treated coir waste manure

did not interact with soil. The physical and chemical properties of soil were

on par with the control (Untreated) and before planting soil. Thus from the

above results, Anabaena azollae treated manure was selected for the growth

of black gram plants.