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OPP!i A 0, jlll^

2. REVIEW OF LITERATURE

The principle of ecologically sustainable development ensures that

resource extraction does not degrade the environment (Kelvin, 1990).

Organic agriculture, as an alternative to conventional farming is gaining

importance in recent days. Biodynamic, transitional and conventional

systems are being practised to explore ecologically more acceptable

alternatives to existing farming practices (Penford, 1990).

In recent years, there has been a spurt of interest in agricultural

practices, which are tree of chemical fertilizers and pesticides. This trend

is directed towards two factors. Firstly the need to increase the quality of

food and secondly the need to protect out environment.

2. 1. Historical perspective

From the vedic period onwards, there are evidences of the use of

some kind of manure to increase the productivity of the land, The Artha

- sastra gives specific details about the properties of the soil that suit

18

certain crops (Kosambi, 1985). According to Lallanji Gopal (1980), the

Sanskrit text Krishiparashara, which was probably composed during

1050 AD is the only available independent text on agriculture prepared

in ancient India. It mentions about systematic and regular use of cow

dung as manure (Majumdar and Banerji, 1960 and Lallanji Gopal,

1980). Gangopadhyaya (1932) analysed various methods of preparing

dung manure and concluded that the loss of nitrogen, which is the chief

fertilizing element is minimized when dung heap is left undisturbed;

drying dung into balls results in reducing active ammonia, which is

injurious to plants; and placing dung balls in pits increases humus which

contributes to the fertility of the soil.

The first clear reference to the actual use of cow dung as field

manure is found in the Harsha Charita of Bana written in the 7" century

(Lallanji Gopal, 1980). Second source material of the early 12th century

is "Vrikshayurveda" written by Surapala, who was a physician to king

Bhimapala of Bengal and belonged to the early part of the 12th century

(Lallanji Gopal, 1980). This text prescribes specific manures for various

crops, trees and plants. It also recommends carcass water (Kunapa) and

ankola soil for general use and gives directions for preparation and

application (Sadhale, 1996). Third text "Sarngadhara paddhati" written

by Sarngadhara, a courtier of King Hammira of Sakambhari (1283 -

4 19

1301 AD) prescribes manure both for general and specific use (Peterson,

1888 and Lallanji Gopal, 1980).

Irfan Habib (1969a) reported that cow dung was used as manure

and the usefulness of organic materials as fertilizers was certainly known,

since fish manure was used in sugarcane cultivation in Gujarat during

the 1 7th century. According to Husaini the peasants were aware of the

usefulness of certain crops too in making land suitable for cultivation

(Irfan Habib and Raychaudhuri, 1982).

In India the technological developments of the 17' century prove

that agriculture was not static and these developments contributed to the

extension and reinforcement of peasant agriculture (Irfan Habib, 1969b,

1980). According to Kosambi (1985), the peasants in ancient India too

used legume crops as green manure and thus reduced their dependence

on animal meat or fish as manure.

One of the earliest references to compost use in agriculture appears

on a set of clay tablets from the Akkadiam Empire in the Mesapotamian

valley 11,000 yrs before Moses. The Romans knew about compost, the

Greeks and the tribes of Israel both had a world for it. There are

references to it in the Bible and Talmud. Aristotle has referred to

earthworms as 'the intestine of the earth'. Darwin remarks, the plough is

one of the ancient and most valuable of man's inventions, but long before

PA

it existed, the land was in fact regularly ploughed and still continues to be

thus ploughed by earthworms. Earthworm, soil's intimate friend and

benefactor, has since long been helping soil in respiration, nutrition,

excretion and various other vital activities. Through its characteristic

actions of breaking, grinding, churning, assimilation and tunnelling, the

earthworm has proved to be soil's mouth, stomach and intestine.

Earthworms from time immemorial are regarded as friends of

farmers and quite a few poems have been composed in praise of them for

their contribution to soil fertility, by nature lovers such as the renowned

Tamil Scholar Manonmaniam Sundaranar during the Nineteenth Century

(Balasubramanian, 1970). Earthworms are reported to have appeared

during the cretaceous period when dicotyledenous plants are known to

have come into existence (Stephenson, 1930). Arldt (1908) though

estimated their origin much earlier during the upper Jurassic and Triassic

periods, Bouche (19 77) has traced their origin from Paleozoic.

2. 2. Organic wastes availability

Even though the use of mineral fertilizers is the quickest way of

boosting crop production, their cost and other constraints frequently

prevent the farmers from using them in recommended quantities and in

balanced proportion. As a consequence of this, there seems to be no

option but to fully exploit the potential alternative sources of plant

nutrients. Misra and Hesse (1982) reported that the organic wastes

21

available in India are estimated to supply about 7.1, 3.0, 7.6 million

tonnes of N, P 205 and K20, respectively. The crop residues alone can

contribute about 1,13, 1.41 and 3.54 million tonnes of N, P 205 and K20

respectively.

Tran thi ngoc son (1995) pointed out that the potentiality of

organic resources is not fully tapped. There is a possibility of gathering

750 million tonnes of cattle dung, 250 million tonnes of rural and urban

compost and 100 to 115 million tonnes of crop residues. Coir pith,

sugarcane trash, paddy straw, farm land weeds, aquatic weeds etc. are

available in plenty. These agriculture oriented waste potential can be

properly converted into a nutrient source and utilized for sustainable crop

production.

Anilkumar (2000) concluded that the organic wastes are derived

from biological source like plant, animal and human residues. These are

mostly agro-industrial wastes that can be used in agriculture as organic

source for plant nutrition and may also preserve fertility.

2. 3. Composting techniques C

Fowler (1930); Howard (1935) and Acharya (1939) described the

advantages and disadvantages of the different composting processes

practised in rural India. In India, Howard and Wad (1931) at Indore and

Fowler (1930) at Bangalore have done pioneering work on composting

22

and standardized conditions for degradation of leaves, straw and town-

refuse, utilizing dung and night soil as starters for promoting microbial

activity. Waksman and Starkey (1939) have reported the role of

individual groups of microorganisms as well as mixed cultures as

inoculants on aerobic decomposition compared with pure culture.

Arakari et al. (1962) recommended the Padegaon method for

composting resistant substrates like sugarcane trash and cotton stubbles.

Balasubramanjan et al. (1972) and Gaur et al. (1973) found that organic

manures/composts contain a very large population of bacteria,

actinomycetes and fungi and also stimulate those already present in the

soil.

Gaur (1973) suggested that the organic composts harbour a very

large population of bacteria, actinomycetes and fungi and also stimulate

the enrichment of soil macronutrients. Elliott et al. (1981) suggested that

all the organic wastes can not be applied or ploughed directly as such

into the soil because of their variation in decomposition and wide ON

ratio. They are known to immobilize the available mineral nutrients,

which would affect the nutrients availability to the crops and also known

to produce some phytotoxic substances during their decomposition

(Martin et al., 1978). Gaur et al. (1984) noted that no turnings need be

given to the heaps and the material decomposes more quickly than in pits

and can be quickly used after three to four months.

23

Saddler (1986) observed that in an anaerobic environment, the

plant litter is mainly decomposed by the activity of the saprophytic fungi

through secreting a large amount of eco-enzymes directly into the

environment. Zucconi and De Bertoldi (1987) proposed that a compost

should be considered hygienic II a 100 g sample contains no sairnoncUac,

no infective parasitic ova and no more than 5 x iO fecal coliforms and

5 x 10 5 fecal streptococci. Balamurugan et a! (1999) noted the

enhancement of calcium, magnesium, sodium, iron, copper, manganese

and sulphur during composting.

Venkatraja et a/. (2001) analysed the physicochemical and

microbial properties of vermicomposting, biodung vermi composting and

the chinese method of composting and reported that porosity and water

holding capacity of the compost increased significantly while temperature,

electrical conductivity and bulk density values decreased slightly. Further

they concluded that based on the physicochemical and microbial features

though all three methods are found to be suitable for converting leaf litter

into biocomposts, biodung vermicompost method was adjudged as the

best due to its high nutrient value and its physical structure.

Elliott et al. (1981) reported that all organic wastes cannot be

applied or ploughed directly as such into the soil because of their

variation in decomposition and wide C:N ratio. They are known to

immobilize the available mineral nutrients which would affect the

24

nutrients availability to the crops and also known to produce some phyto-

toxic substances during their decomposition (Martin et al., 1978). To

mitigate such problems, these materials could be precomposted in an

appropriate manner with suitable and scientific microbial inoculants and

then the final product of the well-decomposed materials could be better

utilized as organic resources for crop production.

Nij huan and Kanwar (1952) observed that earthworm soil

contains more organic matter, total nitrogen and total phosphorus

compared to parent soil. Gupta and Sakal (1967) reported that

earthworm soil contains more available phosphorus and nitrogen. Pane

(1963) found that the earthworm casts harboured increased number of

microorganisms. Parthasarathi and Ranganathan (1998) recorded

similar types of bacteria and fungi in the pressmud and pressmud mixed

with sawdust. Watanabe (1975) found that the concentration of

exchangeable calcium, sodium, magnesium, potassium and available

phosphorus and molybdenum were high in earthworm casts than the

surrounding soil.

Holter (1979) reported the increase in the level of macro and micro

nutrient contents in vermicomposted cattle dung. Similar observation

was made in maize and soybean plant residues (Mackay and Kadivko,

1985). Lee (1985) and Edwards and Bohlen (1996) reported that

earthworm casts usually have greater populations of bacteria, fungi and

25

actinomycetes and more enzyme activity, larger concentrations of

available nutrients and greater structural stability than the surrounding

soil aggregates. Shaw and Pawluk (1986) and Lavelle and Martin

(1992) found that earthworm casts are enriched in terms of available

nutrients and microbial numbers and biomass, relative to the

surrounding soil (Sannigrahi and Charkraborthy, 2000).

Several authors studied the role of earthworms in organic matter

decomposition, nutrient cycling, soil structure and plant productivity

(Lavelle, 1988; Scheu and Wolters, 1991; Zhang and Schrader, 1993;

Blair et al., 1994 and Stephens et al., 1995). Tiwari and Mishra (1993)

and Daniel and Karmegam (1999) noted that the increase of

microorganisms is due to the activity of earthworms and their castings,

which has encouraged the growth and proliferation of microorganisms.

Manna et al. (1994) observed significant increase in water soluble

carbohydrates after decomposition of wheat and chickpea straw and city

garbage treated with earthworms. Tomlin et al. (1995) suggested that

the microbial activity is greater in casts than in uningested soil which

contributes greatly to the increased stability of casts.

Ramesh and Gunathilagaraj (1996) studied the degradation of

coirwaste and tapioca peel by earthworms with and without feed under

laboratory condition. They concluded that the rate of degradation was

maximum in treatments with earthworms that received cow dung as

26

feed. Degradation was marked by the decrease in organic carbon content,

the C/N ratio and the subsequent "increase in major and minor nutrient

contents and microbial activity in both coirwaste and tapioca peel.

Edwards and Bohlen (1996) reported that earthworm casts are rich

in ammonia and partially digested organic matter and provide a good

substrate for the growth of microorganisms. Asha Gupta (1997) pointed

out that casts of the worm collected from the experimental pots were

found to have enhanced level of pH, high contents of organic matter and

nutrients than in the parent soil. Ismail (1997) has said that earthworms

promote microbial population by virtue of their own intestinal

mechanism or by their casts, serving as best couture media.

Talashilkar et al. (1999) reported that vermicomposting of all the

residues resulted in significant reduction in the ON ratio and increase in

other parameters like humic acid content, cation exchange capacity and

water soluble carbohydrate content of all the residues after 150 days of

composting over the residues uninoculated with earthworms. Ghosh et

al. (1999) observed higher level of transformation of phosphorus from

organic to inorganic state and thereby into available forms during

vermicomposting compared to ordinary composting.

While carrying out studies on the decomposition of weeds such as

Boerhaa via Musa, Pavonia odorata, Sida acuta and Trianthema

27

portulacastrum, Karmegam and Daniel (2000a) showed that all the four

common weeds can effectively be used for the production of

vermicompost of high quality based on the NPK values, increased rate of

electrical conductivity, reduction of organic carbon and higher range of

microbial colony forming units (bacteria, fungi and actinomycetes) in

combination with cow dung in 1:1 ratio by dry weight.

Krishnappa et al. (1977) reported that Biogas slurry is well

decomposed and rich in NPK and it also contains trace elements like zinc

and iron. It has a higher fertilizing effect than decomposed dung since it

contains greater amount of water-soluble nitrogen which is easily

available to plant. Asija et a! (1984) noted that cowdung and waste

fodder enriched with fertilizer viz., urea, superphosphate and rock

phosphate were used to improve the quality. Fontenot et al. (1983)

analysed and reported that poultry wastes contain higher concentrations

of nitrogen, calcium and phosphorus than wastes of other animal species

and the potential value of poultry wastes as a source of these nutrients

provides more incentive for the utilization of this resource.

Poincelot (1975) in their report pointed out that the compost,

previously amended with rockphosphate, with culture to Azotobacter

chiorococcum and the phosphate solubilizing strain Aspergilus awamori

increased the total nitrogen and humus content appreciably. Waksman

and Starkey (1939) brought out the role of individual groups of

28

microorganisms as well as mixed cultures as inoculants on aerobic

decomposition compared with pure culture. Gaur et al. (1968) and

Sadasivam et al. (1981) showed an improved manurial value of compost

when inoculated with Azotobacter, Chiorococcum and phosphate

solubilisers. Gaur (1980) has investigated the effect of microbial (bacteria

and fungi) inoculants on the composting of rice straw and karanji leaves

(Pongamia pinnata). Sadasivam et al. (1981) reported that the manurial

value of compost was improved significantly due to the inoculation of

Azotobacter, chiorococcum and phosphobacteria.

Piearce (1983) concluded that the chemical changes and structural

breakdown of the necromass (detritus) are brought about by the catalytic

activities of decomposers especially fungi and bacteria. Fungi play an

important role in the decomposition of cellulose, lignin while bacteria

make significant contribution to the breakdown of proteins. Bharadwaj

and Gaur (1985) have elucidated the use of cellulolytic fungi in the

preparation of plant residue compost for faster decomposition. Due to

microbial inoculation, the period of composting was reduced by one

month as well as the quality of compost could be improved.

The use of Trichoderma harziaaum as an activator for rapid

composting of agricultural wastes was first pointed out by Cuves et at.

(1998) from Philippines. According to Verma and Mathur (1990) and

Thanikachalam and Rangaraj an (1992) had observed increased

29

production of rice straw and biomass yield when treated straw was

inoculated with efficient cellulosic fungi, Aspergi/lus sp. exhibited

maximum percent conversion (80.0 percent) followed by Fusarium (78.0

per cent) and Trichoderma sp. (76.0 per cent).

Thennarasu (1994) studied that enrichment through fortification

of different organic wastes with microbial consortia of Trichoderma sp.

Fusarium sp. and Aspergi/lus sp. along with the required quantity of P, K,

Fe and Zn enhanced the composting and chelation processes and

increased the nutrients.

2. 4. Effect of organic and inorganic manures on cropgrowth and yield

Sen and Bains (1965) recorded that the yields of berseem green

fodder was found to be higher on applying super phosphate and FYM.

Mariakulandai and Morachan (1966) recorded increased grain and straw

yield in millets by continuous application of FYM. Naik and Ballal (1968)

observed higher yields of both grain and straw when nitrogenous

fertilizers along with FYM were added. Kunzli and Geering (1973) noted

that FYM was as effective as mineral fertilizers in increasing the 'dry

matter production in a natural meadow,

Rangaswamy (1973) reported an increase in the grain yield of

early duration ragi varieties by 9.1 percent due to the application. Sahu

and Ray (1976) reported that combined application of FYM and K

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increased the yield of both rice grain and straw by 1.03 and 1.97 t,

respectively over NPK alone. Sharma et al. (1979) observed an increase

of dry matter yield in wheat crop by the addition of FYM and gypsum in a

calcareous alkali soil. The interaction of FYM and Gypsum showed

increased yield.

Ravikumar and Krishnamoorthy (1980) in their studies reported

that application of poultry manure, FYM and lime sludge significantly

improved the yield of finger millet. They also concluded that organic

amendments were superior to inorganics in improving the chemical

properties of soil and yield of finger millet. Padalia (1980) stated that

compost increased the yield not only during the years of application but

had beneficial residual effect on succeeding rice crops too even upto 5

years.

Kale and Bano (1986) and Karmegam et al. (1997) reported that

the vermicompost application had significantly influenced the growth and

yield of paddy and radish. Reddy (1988) reported increased growth of

Vinca rosea and Oryza sativa after addition of cast material from

Fhretima alexandri.

Anabayan and Palaniappan (1991) observed that application of

enriched FYM resulted in higher leaf index area, dry matter production

and grain yield of rainfed sorghum, Rahman (2001) showed that black

31

polythylene mulch as complete bed cover had significantly reduced weed

growth and resulted in the best growth performances (201 cm plant

height, 67 cm spread, 39 CM2 leaf area index and early flowering in 50%

plants).

Published literature strongly supports the merits of integrated

nutrient management with repeated emphasis since 1980 to date with no

one to doubt its merits. It is our endeavour to blend ecology and

economy in cost-benefit framework. It takes into consideration the

systematic and simulataneous account of the environmental aspects, the

quality of the produce and the profitability of the farm. The Indian

situation presented is more than convincing that to practise integrated

nutrient management is more than impossible as long as the complex

NPK is worshipped in India. That India should abandon blanket

recommendations for crops individually and a systematic approach for the

entire cropping system is repeatedly underlined, but the response was

poor. The current experience of steep drop in use efficiency and yield

fatigue is the result of misuse and abuse of the fertilizer. A holistic

approach in association with nature is necessary, where the intensity- of

all practices lies within the carrying capacity. To revive our time

honoured traditional practices is not an easy task and to blend with

recent advances is neither free nor fair, under patent rights which Third

World farmers (increasing in numbers and decreasing in size) can ill-

32

afford. From the chronology of soil fertility studies, the 2 l S century

represents the seventh milestone-soil productivity through ecosystem

management i.e. the integrated approach to achieve the health of soil-

plant-environment on a sustainable basis. This is not only distinct from

the green revolution, physico-chemical paradigm, but also from organic

agriculture', in that it does not accept petrochemically-d riven inputs but

emphasizes the efficiency of their minimum use. The green revolution

failed as a strategy because high output needs were extended beyond

reasonable limits despite loss in use efficiency, that ended up with loss in

yields and profits. India needs more sustainability for agriculture, not just

more fertilizers, or total organic approaches, but a blend of both (Ayala

and Rao, 2002).

Bawa (1995) and Srinivasa Reddy and Uma Mahesh (1995)

observed a significant increase in dry matter and yield of green gram

upon application of vermicompost and FYM. Tiwari et a! (1997)

observed that biogas slurry and sugar factory pressmud along with 50%

recommended NPK were beneficial for higher growth characters, yield,

quality and nutrient uptake from a sugarcane crop.

Singh et a! (1997) observed that maize yield increased with

increasing nitrogen levels either alone or in combination with organic

manure. Sree Rekha and Narsa Reddy (1999) studied the effect of

phosphours, molybdenum and FYM on nutrient uptake, dry matter and

33

yield of Rabi Groundnut and concluded that application of FYM and

phosphorus individually did not influence the pod yield of groundnut.

Hossain and Mohanty (11999) observed that an increase in the levels of

nitrogen and potassium significantly increased the plant growth, yield

and other yield attributing characters in tomato.

Karmegam et al. (1997) recorded maximum shoot length, root

length, number of root nodules and fresh weight and dry weight in

vermicompost applied pots. Rajkhowa et al. (2000) showed significant

positive effect on the yield and dry matter production in green gram by

the application of vermicompost. Karmegam and Daniel (2000b)

observed that biodigested slurry gave more yield in crop plants like

cowpea at field level by supplying with all essential nutrients which

enhanced the activity of microbes in the soil which inturn maintained the

soil health.

Tiwari et al. (2000) observed that the wheat grain yield increased

significantly due to crop residues and biogas slurry application.

2. 5. Organic manures on soil physical properties2. S. 1. pH

Bopiah (1970); Palaniappan (1975) and Chaudhary et al. (1981)

observed that the pH of the soil was slightly affected due to the

application of FYM. They also suggested that slight but non-significant

decrease in the pH due to addition of organic residues might be attributed

34

to the production of organic acids during the process of decomposition of

organic matter. Sarkar and Singh (1997) observed that sole application

of Farm Yard manure decreased the soil pH to 6.6 compared with the

initial status (6.7) of the soil.

2. S. 2. EC

Sarkar et al. (1989) noted that electrical conductivity depends on

the concentration of different bases in the soil solution. Incorporation of

organic sources helps addition of cations like K, Na Ca 2' and Mg2.

Daniel and Karmegam (1999) and Joshi and Kelkar (1952) observed that

cations were found to be increased mainly due to the presence of soluble

minerals available in the vermi compost.

2, S. 3. Porosity

Prasad et al. (1983); Chawla (1987) and Meng Xun et a! (1991)

observed that the decomposition products of organic materials helped in

the granulation of soil particles that increased the porosity leading to

lower BD.

Among the fertilizer application practices the long-term application

of FYM alone was observed to increase the porosity as pointed out by

Prasad and Singh, (1980); Anderson and Gantzer (1989) who obtained

significant result of this long-term fertilizer application on the pore spaces

and over the years the non-capillary porosity also increased.

35

2. 5. 4. Bulk density

Sharma et al. (1956) reported reduced bulk density at higher

altitudes principally due to higher organic matter content. Lowering of

bulk density owing to the continuous application of FYM was reported by

Havanagi and Mann (1970); Anderson and Gantzer (1989) and

Anderson et a! (1990). Rao et al. (1978) and Sands et al. (1979)

observed that application of organic matter to soil decreased the bulk

density.

Korschens and Greilich (1981) noticed an inverse relationship

between bulk density and organic matter content only in the sandy soil

where the bulk density was low and a significant inverse relationship

between the organic matter content and the particle densities of all the

other soils. Durai (1982) and Ramaswami and Sree Ramulu (1983)

observed that application of coirpith decreased the in-situ bulk density of

the soils compared to pressmud and FYM which may be ascribed to

increase in porosity, friability and promotion of better aggregation by the

carbonaceous matter in them. Mahimairaja et al. (1986) observed that

combined application of inorganic fertilizer with organic manures

improved the physical condition of soil by reducing the bulk density of

soils.

Asmus et a! (1987) reported that organic manuring decreased the

bulk density, increased the pore volume and water holding capacity.

36

Pawar et al. (1991) reported that 10 f ha' of biogas slurry application

significantly decreased the bulk density of maize raised soil. Ekwue

(1992) studied the effect of organic and fertilizer treatments on soil

physical properties and erodability and found that FYM treatment

produced the best physical condition having the lowest bulk density and

highest porosity in the soil.

2. S. S. Water holding capacity

Adhikari and Ganguly (1971) reported that the physical properties

like WHC and water stable aggregates were lowered when the soil was

completely free of organic matter. Larson and Clapp (1984) concluded

that organic matter has greater influence on water retention through soil

structural changes i.e., through changes in pore size both within and

between aggregation. Bhriguvanshi (1988) and Singh et al. (1980)

reported that long-term application of FYM for five years enhanced the

soil properties of sandy loam and clay loam with significant increases in

the WHC.

Suresh Lal and Mathur (1989) noticed significantly higher WI-IC in

soils receiving organics than inorganics. Bhattacharya et al. (1990)

observed that application of organic manure to the soil improved the

WHC and resistance to soil microflora. Rose (1990) found that

application of FYM increased gravimetric wetness and WHC. Pawar et a!,

(1991) observed that the application of biogas slurry at different levels

37

increased the maximum WHC of soil as compared to control and

decreased the bulk density of maize raised soil. Bharadwaj and Omanwar

(1992) reported that the application of FYM on long-term basis increased

the WHC when compared to the control and inorganic fertilizer treated

plots.

Pawar et al. (1991) and Rayar (1984) observed that the

application of biogas slurry at different levels increased the maximum

water holding capacity of soil as compared to control. Ekwue (1992)

reported that the addition of organic matter increased the water retention

capacity of the soil. Ekwue (1992) studied the effect of organic and

fertilizers treatments on soil physical properties and erodability and found

that FYM treatment produced the best physical condition having the

lowest bulk density and highest porosity in the soil and increased the

water retention capacity of the soil.

Bharadwaj and Omanwar (1992) reported that the FYM treated

plots showed higher water content than those of the fertilized plots. The

organic matter contents in these plots were responsible for increased

water retention capacity of the soil. Rayar (1984) and Pawar et a!

(1991) observed that the application of biogas slurry at different levels

Increased the maximum WHC of soil when compared to control, Senthil

Kumar et al. (2000) found that vermicomposting increased WHC of the

soils which inturn reduced irrigation water requirement of crops.

38

2. 5. 6. Moisture contentIncrease in the soil moisture through incorporation of organic

matter has been reported by several workers (Salter and Haworth, 1961;

Biswas and Au, 1969 and Sundaramurthy, 1973). Krishnamurthy and

Ravlkumar (1973) found that application of cattle manure improved the

moisture content of the soil as well as increased the water holding

capacity of the soil.

2. 6. Organic manures on soil chemical properties

2. 6. 1. NitrogenOlsen et al. (1970) stated that addition of manure tended to

increase the contents of nitrogen in the soil. Singh and Srivastava (1971)

observed that organic manuring immobilized the available N followed by

a steady mineralization. The soil with mineral fertilizers was found to

contain the same amount of available N after about four months but soil

with organic manures was found to release N slowly in excess of that

added as fertilizers.

Somani and Saxena (1975) noticed considerable increase in

available N status of soil due to the application of slowly decomposing

FYM. Singh and Lal (1976) observed that the nature and quantity of

applied organic material has great control on the available nitrogen

content of soil.

39

2. 6. 2. Phosphorus

Singh and Tiwari (1968) reported that available P was relatively

higher when FYM was applied than poultry manure or goat manure.

Havanagi and Mann (1970); Singh et al. (1983) Yaduvanshi et al.

(1985) and Bhat et al. (1991) reported that the continuous addition of

organic manures and recycling of crop residues increase the available P

content of soil.

Singh and Srivastava (1971) and Prasad et al. (1971) observed

that available P was significantly increased in soil with poultry manure

and FYM treatment. Mc Intosh and Varney (1973) and Mukherjee et al.

(1979) observed that application of organic manure increased the

available P content of the soil.

2. 6. 3. Potassium

Kanwar and Prihar (1962) noticed that the supply of available K

in the soil was derived from the weathering of K containing minerals, a

process encouraged by acidity and consequently by the presence of

decomposing organic matter. FYM registered the highest available K

when compared to different types of organic manures (Sahu and Naybk,

1971; Singh et al., 1980 and Kumaresan et al., 1984). Sharma and

Arora (1987) and concluded that the combined application of FYM plus

NPK increased the available N, P and K and organic carbon contents of

the soil,

40

Sharma et al. (1988) made a comparative study of the effect of

FYM and green manure, and concluded that there was a gradual build up

of organic carbon N, P and K in soil which was maximum with the use of

FYM than green manure. Meng Xun et al. (1991) reported that repeated

applications of biogas fertilizer improved the levels of nitrogen,

phosphorus and potassium contents in the soil.

2. 6. 4. Secondary nutrients

Bose and Mukherjee (1993) noticed that application of organic

manures in general, improved the availability of micronutrients, like zinc,

iron, manganese and copper. Organic manures not only serve as sources

of N, P and K but these are a potential source of micronutrient too.

Kanwar and Randhawa (1969); Follett and Lindsay (1971);

Balasundaram et al. (1973) and Vittal and Gangwar (1974) observed

that there was a positive correlation between availability of Zn and

organic matter. Takkar (1969) reported that low level of organic matter

showed striking decrease of Fe in all soils.

Olsen et al. (1970) reported that the addition of organic manures

increased the soil pH, organic carbon, available P and exchangeable K, 'Ca

and Mg particularly at higher rates of their population. Balasubramanian

and Ramaswami (1983) reported that organic matter addition influenced

the available Cu, but it varied with soil type. Rajagopal et a! (1974)

reported a negative correlation between available Cu and organic matter

41

while Saba et al. (1982) reported a positive relation of Cu to organic

matter and clay of the soil. Krishnaswamy and Raj (1974) reported that

organic manure with fertilizer increased the available Fe gradually from

tillering to post harvest stage of rice.

Shetty (1975) and Gupta et al. (1988) reported that when ZnSO4

was mixed with FYM and applied the release of Zn was observed in soil.

Singh ci at. (1980) observed the continuous application of FYM in the

semi and region of Haryana resulted in an increase of exchangeable Ca

and Mg. Poonia et al. (1984) concluded that soils enriched with natural

or applied organic matter had higher preference for Ca" as compared

with those low in organic matter. Anand (1991) reported that

application of green manure and FYM in conjunction with gypsum

reduced pH and ESP of soil and increased the yield of rice and availability.

Deepa Devi (1992) reported that the soil available iron was

enhanced significantly due to the application of enriched FYM and

composted sugarcane trash. Saha et al. (1992) reported that the

extractable Cu contents of the soils showed significant positive

correlations with organic carbon and clay of the soil. Kumar et al.

(1993) observed that the availability of Fe, Mn, Zn and Cu were highest

in plots which received balanced NPK fertilization with FYM.

42

2. 6. 5. Organic carbon

Kanwar and Prihar (1962) reported that the combination of

organic manures and fertilizers maintained the organic carbon and total

N at a higher level than control. According to Prasad et al. (1971) the

build up of soil organic carbon was due to organic farming through

application of FYM. Singh (1978) and Sharma et a. (1988) observed

that FYM registered the highest organic carbon and available P content

in the soil when compared to other types of organic manures.

Swarup and Ghosh (1979) reported that continued application of

FYM with 100 percent NPK resulted in a build up of soil organic carbon

content compared to application of 100 percent NPK alone in alluvial,

sandy, clay and loamy soils. Generiri ci al. (1991) showed that

application of organic manure and compost increased the percentage of

organic carbon in the soil. Meng Xun et al. (1991) found that the

addition of biogas slurry led to steady improvement in the soil organic

carbon. More (1994) also reported that the biogas slurry increased

organic carbon content in the soil.

A review of the available literature thus reveals that although

South India is fortunate in having numerous aquatic plants, only a few

plants were subjected to decomposting. Moreover, composting

technologies were carried out only in lesser number of taxa. Some of the

investigations have dealt with only meagre data on one or two aspects.

43

To bridge this gap, the present investigation was carried out to convert

the aquatic weeds into value added organic manures by employing ten

different composting technologies as well as to study the impact of

various composts on the growth of Abe/moschus esculentus,

44