Review Article Journal of PlanWJ~on Crops, 2002, 30 ( 1) : 1-17

Biological conversion of coir pith into a value-added organic resource and its application in Agri-Horticulture:

Current status, prospect~ and. perspective

S.R. Prabhu* and George V. Thomas** Microbiology S~ction

Ce11tral Plantalum Crops Kes~arch Institute ( lmliun Cmuu:il <if Agricrtltnrall?eseatch)

Kasa1Y1god, Kerala, India.

Introduction India currently produces over 15,000 million

coconuts per year. In addition to the utilization of endosperm for edible purposes and extraction of oil, the outer non-edible fibrous portion of the nuts (coconut husk) is used for extracting coconut. fibre or coir, which is commerciality utilized for making value-added products such as mats, geotextiles etc. In the husk. coconut fibres are seen tightly packed along with non­fibrous, fluffy and light weight croaky material known as coir pith or coir dust, which constitutes about 50-70 percent of the husk. The composition and properties of coir pith vary (Moorthy and Rao, 1998) depending on maturity of coconut, method of extraction and disposal, peliod between ex:ttaction and use and environmental factors. Wide variations in C:N ratio of coir pith from 58:1 to ll2: 1 has been reported (Savithri and Khan, 1994). Retted husks yield coir pith with less nutrients Lhan that obt.a ined by mechanical processing of unretted husk. Coir pith obtained from fully mature nuts has bigher amounts of lignin and cellulose and Jesser amount of watet soluble salts compared to younger nuts. When busks of 10,000 coconutS are utilized for coir extraction, one tonne of cqir pith is obtained as a by-product. If all the coconut husks available in lndia are processed, it is. estimated that about 1.5 million tonnes of coir pith conld be obtained a.onually. But in reality, aU the available coconut husks are not diverted for coir extraction and it has been reported that only 5 lakh tonnes of coir pith is produced in India annually (Joseph, 1995).

•e-mail : •prabhueo<:hin@yalwo.com, ••georgevthomas@yahoo.com

Because of high fertilizer prices andenvirom11ental concerns associated with its use and with the enhanced emphasis on commercial horticulture and organic farming, recent years have witnessed growing interest in utilizing coir pith in a more productive way in agri­horticulture (Pmbhu and Thomas, 2001). Coir pith has got many enviable characteristics. making it a highly potential resource if used after proper composting. Coir pith has very high moisture retention capacity of 500-600 per cent and can be as high as 1100% of dry weight (Evans er al., 1996). In a comparative study with coir pith and three types of saw dust, coir pith retained the maximum moisture after 90 days of composting (MlY.lh and Pdili, 1998). It has high potassium content and low bulk density and particle density. The low particle density is due to high specific surface and high specitic surface gives it high cation exchange capacity (CEC) (Mapa.and Kumara, 1995). High CEC, which varies from 38.9-60 meq/lOOg (Evans e.t aL, 1996) enables it to retain large amounts of nutrients and the adsorption complex. bas high contents of exchangeable K. Na, Ca and Mg (Verhagen and Papadopoulos, 1.997). All these characteristics make· it ideal for use as a mulch and soil amendment, especially for dry and sandy areas with low water retention. The stabilized, compostcd co.ir pith resemb1es peat and has got many chardcteristics as that of sphagnum peat, !he most common potting media used in horticulture and hence it is commercially koown as coco peat. With the development of commercial horticulture and reduction in the availability of sphagnum peat, coco peat has

become internationally recognised as an ideal soil amendment and component of soil-less container- media for horticulture plants. Coco peat find.<; use in gemrination of seeds, nursery raising, rooting of cutting and other vegetative plant propagation methods, hardening of tissue and embryo cultured plants, hydroponic systems of plant cultivation, cultivation of glass house plants, soil conditioning, lawn making etc. (Bavappa and Gurusinghe, 1978, Ani.tha Karon et al., 1999, Rao, 1999).

Despite many advmttages and availability in large quantities, coir pith is not fully utilized for productive purposes and every year large amounts of coir pith accumulate nearby coir processing units, causing severe disposal problems, fire hazards and ground water cont11mination due to the release of phenolic compounds. Because of its high C:N ratio(about 100:1), high content of lignin and cellulose (about 40% eacb) and high polyphenol content (about 1 OOmg/1 OOg coir pith), under natural conditions its degradation and mineralization rates are very slow, preventing its direct use as an organic manure. The application ofraw coir pith with wide C;N ratio can result in immobm1..ation of plant nutrients. In addition; polyphenols and phenolic acids can be phytotoxic and inhibit plaut growth (Wang et al., 1967}. Bioassay using Lepidium sativum as indicator plant showed that root growth was inhibited by raw coir pith extracts (Yau and Murphy, 1998). Many farmers who apply fresh coir pith. often complain that plants develop toxic yellowing symptoms. The inhibitory effect can be eliminated by using biodegraded coir pith (Yau and Murphy, 1998). Coirpith can. be made suitable for use in agri-horticolture after stabilization by proper composting process of employing Sllitable organisms capable of degrading lignin and polyphenols and bringing down C:N ratio. According to Nagarajan et al., ( l985) coir pith having a C:N ratio of 24: 1 or less could be used as a good source of organic matter for agricultural use.

Sri L'\nka is the leading processor and exporter of coir pith into a form suitable for horticultural applications. But,.lndia with a capacity to produce over 2.9lakh tonnes of coco peat. (Joseph, 1995) has the potential to become the major source of this valuable organic resource for internal use and for exports. With the increased emphasis on organic farming and horticulture, coir pith is gaining more i.mporta:nce and relevance.

· The intention of this paper is to review tbe recent developments in various aspects of processing of coir pith ~or agri-ho:rticultural use such as, composting and enrichment technologies, and the utilization of the stabilized product for use as a soil amendment, plant propagation and growth medium for economically

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S.R. Prabhu and Gco.rge V. Thomai

important plants. Possibilities of improving composting techniques, quality of compost and utili1.ation of coco peat based on the recent developments in science and technology have also been discussed.

Composting of coir pith

Problems associated with coir pitb eomposling

Plants use different nutrient cycling strategies to their own advantage. It hus been hypothesized that through an evolutionary selection process, some species of plants developed characteristics that enhance the fitness of their envirorunent for themselves at the expense of other plant species (van Breemen. 1993; 1995). For example. fast growing species tend to have residues rhat decompose and mrn over nutrients rapidly. On the other hand, slow growing species often have residues that are high in lignin and secondary metabolities that slow microbial decomposition and thus reduce competition from fast growing species that require bigh levels of available nutrietns in short time (Magdoff e1 a/., 1997). Coir pith with high C : N ratio, lignin and polyphenol contents is highly resistant to easy decomposition and can be stabilized by .suitable composting techniques. Composting of coir pith results in increased content of N, P, K and micronutrients and reduction in lignin and C:N ratio (Nagarajau et al., 1985).

Composting is the biological process of decomposition of organic constituents of bio-waste materials under controlled conditions (Golueke, 1972; Hoitink and Keener, 1993). During this process, carbon from organic molecules gets converted to carbon dioxide, resulting in the reduction of bulkiness of the organic forms, which can be absorbed directly by plants. Rates of decomposition and mineralization of organic residues differ among species having different plant chemistry (Palm and Sanchez, 1991 ). Composting rate depends to a great extent on C:N ratio, lignin and polyphenol contents, presence or absence of suitable microbial agents of decomposition etc. Lignin prevents the easy decomposition and mineraliz:ation of coir pith and any effective compostiug method devised should ensure delignification to the maximum extent possible. Lignin is a three dimensional aromatic amorphous heteropolymer containing stable C-C, ether-ester linkages between monomeric singly or doubly-rnethoxylated phenylpropyl phenolic units making it a recalcitrant biopolymer (Janshek:ar and Fiechter, 1983). In nattlre, lignin is convetted to humic and fulv.ic ac.ids by many microorganisms, but the process is very slow (Kawakami, 1980, Martin an'd Haider, 1980, Crawford, 1981; Stevenson, 1982). The uri.ique structure of lignin

Biological conversion of coir pith into a value·added resource

requiring depolymerization by extracellular oxidative mechanisms accounts for the recalcitrance of lignin toward degradation by most mi<.:roorganisms (Kirk, 1980; Gold and Alic, 1993). Laccase, manganese peroxidase and lignin peroxidase are the main enzymes involved in lignin degradation during secondary (ldiophasic) metabolism, whose onset is triggered by depletion of nitrogen, carbon or sulphur (Gold and Alic. 1993). Lignin degradation also depends on the presence of a readily metabolisable co~substrate such as glucose. In addition, increasing the oxygen levels in culture has strong activating effect ou the rate of lignjn degradation (Gold and Alic. 1993).

Ma.ny microbes can metabolise lignins (Kirk, 1971, Crawford and Crawford, 1976, Crawford and Crawford, 1980; Ulmer et aL, 1983). Basidiomycetous fungi are well known for lignin degradation and most of the studies on the biochemistry oflignin degradation were focused on Phanerochaete chryso!>porium {Janshekar and Fiechter, 1983). Bacteria are also capable of solubilizing, transforming and mineralising a variety of lignin preparations and lignin-like polymers and monomers (Zimmermann, 1990). Actinomycetes such as SttepJomyces sp. also have the capacity to attack and degrade lignins (Crawford, 1978, Phelan et al., 1979).

Coir pith's yet another ch.emical nature which adversely affects its decomposition rate is its poly phenol content, as it contains phenolic compounds to the extent of LO~g/ LOOg. It has been suggested that poly phenolic content may affect N release pauerns from organic residues by'fonning complexes with proteins, which are resistant to decomposition (Basaraba and Starkey, 1966, Vallis and Jones, 1973; Sivapalan el al., 1985; Palm and Sanchez, 1991 ). The problems associated with polyphenols are not that se1ious and there are reports on humification of polyphe110l-rich plant residues (Sivapalau, 1982). As many microorganh,,ns can utilize and degrade polyphenols (Chan, 1986) and as many polyphenols are water soluble, coir pith exposed to rain for many years contain Jess polyphenols and can be used directly whenever composted coir pith is not available.

Low C:N ratio of coir pith is also responsible for low decomposition rate. As nitrogen is required for the reproduction and activity of micro-organisms responsible for degrading organic matter, only that. quantity of organic matter as decided by the quantity of nitrogen available wilt be degraded. As coir pith has high C:N ratio of about 100: l, most micro~organisms do not prefer to act on it.

Techniques for enhancing the decomposition of coir pith

Coir pith can be made more amenable for microbial attack and subsequent decomposition by various chemical and biol.ogicallreatment methods. The C:N ratio can be reduced by adding nitrogen fertilizers or nitrogen - rich organic materials such as legume biomass, oil cakes etc. Lignin can be degraded by favouring the build u·p of native lignin degrading microorganisms or by artificial introduction of starter cultures of eftlcient lignin degrading microorganisms. · Treatment w:ith lime is yet another approach to enhance the process of decomposition of coir pith. This is based on the fact that liming can enhance humification process in plant residues by enhancing microbial population and activity and by weakening lignin structure. It call also improve hum\IS quality by changing the ratio of humic to fulvic acids. Liming has also been shown to decrease the amount of bitumens and humins, thus enhandng the humification process (Nowak and Nowak, 1990). Lime treatment has been shown to make coir pith more su.itable for the growth of ligninolytlc fungi (Eyini et al., 1995), which subsequently ensures faster degradation of lignin and humification of coir pith (Anand et al., 1998; 1999). Pretreatment with .lime @ 5kg/tonne of coir pith is sufficient to enhance the degradation of lignin.

Complex substrates such as lignins are not usually fully degraded by a single organism. but arc degraded by consortium of organisms or a mixed population, each carrying out different degenerative steps. Co-metabolism and conservative decomposition indicate that fostering both diversity and latge population would be beneticial in decomposition of complex molecules. The biodiversity of microflora and saprophytic fauna and consequently composting rate can be enhanced by blending coir pith with more easily utilizable organic wastes such as leguminous weeds, green manures, cowdung, oil cakes, biogas slurry etc. during ~ompost preparation.

Enrichment of coir pith to enhance degradation and nutrient content

As a nutrient source, coir pith bas not much value. But, it can be enriched by addition of specific nuttients · and cultures ofbeneficial microbes capable of enhancing the availability of nutrients. These enrichment techniques would make coir pith compost better equipped to influence plant growth and soiJ quality more efficiently.

Rockphosphates · and pyrites are gaining importance in composting r.e.chnologies for the production of phosphate-rich phosphocomposts (Manna and Gangu·ly, 2000). Preparation of phosphate - enriched

compost is based on the concept of ~olubiliz:ation of added rock phosphate during: the process of composting (Bangar et aL, 1985, Mishra and Bangar, 1986). These enriched composts not only suppJy more phosphates. but also have the additional advantage that they prevent the loss of nitrogen (Bangar et al., 1988). Partial acidification of appetites of phosphate rock results in the conversion of phosphates into soluble forms (Singh and Si.ngh, 1991). The add produced by biological or chemical ox.idatiou of sulphur from pyrites together with the organic acids produced duting organic matter decomposition may help in the dissolution of phosphate rock. Coir pith can also be composted and enriched with phosphates using rockphosphate (Biddappa et a/., 1998). Anand et al., (1998) reported thatenticlunent of coir pith compost with rockphosphate resulted in more labile fractions of phosphorus in the resultant compost In addition, use of rock phosphate @ 20 kg per toiUle of coir pith during composting resulted in greater percentage of carbon Joss (Anand et al., 1999).

Coir pith composts can also be enriched with superphosphate, biogas slurry and cowdung slurry. This treatment in addition to increasing nutrient content. enhances the composting rate (VijayaJakshmi et al .. 1989). It can also be enriched with nitrogen from organic sources such as green manures, weeds etc and their use @ lOOkg per tonne of coir pith has been found beneficial (Anand et al., 1999). Composting can also be done along with coffee husk (Moorthy et al., 1996). In addition to increasing nitrogen co·ntent of the final compost, ameudmem with organ:ic additives in coir pith during composting results in more labile and aliphatic humic acids (K.adalli et al. , 2001 a). Being less aromatic and labile. these fractions form more labile chelated complexes with tnicron.utrienr.s. Hence, with organic amendments, more availability of mkronutrients in coir pith compost has been observed. Coir pith compost prepared with additives such ns cowdung, garden weeds, green manures such as sunhemp. rock phosphate and micronutrient& along with Pleurotus sa}or-caju recorded the least lignin, lignin/nitrogen ratio, and C/N ratio and was superior with respect to nutrient composition (Kadalli et al .• 2001b).

Coir pith compost can also be fortified with micronutrients (Kadalli et al., 200la). These metals can be added to coir pith at the beginning of the composting process. The trace metals get chelated with natural ligands like humic acids and fulvic acids synthesized duri-ng decomposition of coirdust (Kadalli et al., 2001 a). Zinc can be chela ted by mixing zinc sulphate @ 4kg per 750 kg raw coir pith and allowing the mixture to undergo

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S.R. Prabhn and George \: Thomas

composting (Marimuthu and Nagarajan, 1993). This zinc· enriched coir pith compost has been shown to be effective in enhancing the yield of rice (Devarajan and Krislmaswamy, 1996). Manganese is yet another micronutrient, which can be enriched in coir pith compost In addition to its value as a plant nutrient, manganese is important in lignin degradation, and lignin degradation by several white rot fungi is strollgly dependent on the presence of manganese (Gold and Alic, 1993). This might be because of the involvement of manganese perox.idases in lignin degradation. Hence the addition of manganese 8alts during composLing may additionally help to degrade coir pith better.

Coil.' pith Call also be enriched wil.h cultures of beneficial microorganisms such as Trichoderma. Azotobacter and phosphate solubilizers (Moorthy and Rao, 1997), so that the compost could serve as a biofertilizer and biopesticide.

BioJogicnl treatments for enhancing the rate of composting of coir pith

(a) Use of microbial starter cultures for enhancing the decomposition of coir pith.

The first approach in the use of microbial starter cultures for enhancing composting rate is to isolate and select microorganisms adapted to coir pith. The cultures of efficient: species cau be multiplied in laboratories and can be used for accelerated composting. Or, these naturally occurring microbes in coir pith can be put into action by making conditions favourable for thei.r multlplication and activity. Ramamoorthy et al. (2000) found rhat BaciUus sp., was numerically predominant in raw coir pith. The other organisms encountered were Streptomyces sp., Aspergillus niger, A. flavus, Penicillium sp., Trichodemu.1 sp .• and. Fusarium sp. In e.xperiments using these microorganisms, it was observed that Aspergillus sp. and Trichoderma sp. were effective to a certain extent in degrading coir pith (Theradirnani and Marimutb.u, l993a; Ramamoo.rthy t~t (1/., 2000).

Yet another approach to enhance the decomposition rate of coir pith could be the use of well­known and efficient microbial cultures capab~e of fast degradation of lignin. Phanerochaete chrysosporium is an efficient ligninolytic basidiomycetous fungus employed for commercial delignification of higi1-lignin organic materials, as it has got many advantages. It can multiply rapidly on lignin-rich materials by producing asexual spores and is highly thennotolerant. Uyenco and Ochoa ( 1984) found thnt among sever<~l species of white rot fungi. Phanerochaete cllrysosporium was the most effective organism fo~ degrading Jignocelluloses of coir

Biological conversion of coir pith into a value-added resource

dust; 31.37% of lignin was degraded in 4 weeks. Degradation was done with minimal nitrogen, coconut water supplement and at 85-90% .moisture level.

Many species of Pleurotus can be utilized for coir pith degradation, as the genus is we!J-known for its lignin degradation capacity. The oyster mushroom, Pleumtus sajor-caju wa.<; used for complete degradation of coir pith (Nagurajan er al., 1985). Nallathambi and Marimuthu (1993) evaluated Pleurotus citritwpileatus, P. sajor-c({ju, P. platypus, P. sapidus and P. florida for degrading coir pith and it was found that P. platypus was the most effective. Theradimani and Marimuthu (1992) also found that P. platypus was the most efficient degrader of coir pith. It was found P. sajor caju elaborated more celltJlase and laccase and mediated. a reduction of82.92% of lignin. P. platypus inoculation resulted in 58.6% reduction in cellulose and 78% reduction in lignin after 35 days of inoculation and the C:N ratio was minimum with this (18:1) as against the uncomposted coir pith (104:1).

The efficacy of various biocontrol agents such as Trichoderma and Chaetomimn with cellulolytic activities was tested for degrading coir pith (Ramamoorthy et al., 1999a). Among a number of species tested, Trichodemra harzianum brought about maximum degradation. However, compared to Pleurotus spp .• the efficacy of degradation of coir pith using T. harzianum was tess. Nitrogen fertilization and inoculation with Chaetomium globosum has been shown. to enhance biodegradation of hemicellulose, cel'lulose and lignin of coir pith and the action resembled soft rot (Yau and Murphy, 1998).

Pseucromonas species has been found to degrade lignins of coir pith (Urn a eta(., 1994 ). Streptomyces spp. isolated from coir pith was tested and found to be a poor degrader of coirpith (Ramamoorthy et al., 2000). lVIa:lliga et al. (1996) reported that the blue green alga (BOA) or cyanobacterium Anabaena azollae wh~n inoculated to coir pith exhibited polyphenol oxidase and laccase· activities and degraded lignin. These coir pith degrading cyanobacterial cells we.re seen immobilized in the colr pith matrix.

(b) Use of earthworms for composting coir pith

Even though the actual composting process is carried out by microorganisms, so.il fauna can enha-nce

· the process of decomposition of hard organic materials tlnough their role in mechanical destruction and partial humification of organic matter. There is evidence that they can demethylate and cleave various aromatic compounds of plant origin (Neuhauser et al., 1978). In addit·ion to their ability to enhance microbial activity by

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enhancing the sw'face area of organic matter by feeding and casting activities, the gut microflora of many invertebrates elaborate dioxygenase enzymes capable of cleaving aromatic rings of lignin aud lignin-related compounds (Neuhauser and Hartenstein, 1976). Among the invertebrates, earthworms have attracted lots of attention in recent years for composting a variety of organic residues (Kale, 1998), and they have more relevance in the degradation of hard-to-decompose organic wastes than the easily decomposable ones. Earthwotm castings have hormone-like activity (Tomati el al., 1988) and are valued for their use i.n plant propagation (Grappelll et al., 1985). Considering these advantages and their role in humification process (Bmssaard and J uma. 1996), the services af enrthwonns have been utilized for composting lignin and polyphenol­rich coconut palm. wastes including coir pith, and a local strain of Eudrilus spp. has been found to be highly useful for this purpose (Prabbu et al., 1998, Prabhu et al .. 2001 ). A Technology for large scale vermicomposting of coir pith has been standardised at CPCRI, Kasaragod using this local earthw01m.

Other ep.igeic or compost worms such as Perionyx excm•ates (Ramesb and Gunnthilagaraja, 1996) and Eudrilus eugeniae (Patil et al., 1999) have also been utilized for vermicomposting of coir pith.

Technologies for composting coir pith

A technique for decompos·ing coir pith into useful organic manure using Pleurotul· has been developed (Nagarajan et aL, 1985). For composting one tonne of coir pith, 5 kg urea and 1.5 kg spawn of Pleurotus sajor­caju is required. Select an area of S meters length arid 3 meters width in a shady place and spread 100 kg of coir pith. 300 grams of Pleurotus spawn is spread uniformly over the coir pith 'layer. Cover the layer with ~nother 100 kg of coir pith. On this layer, spread 1 kg urea uniformly. This process of sandwiching spawn and urea alternatively with 100 kg coir pith is repeated until the heap reaches one meter height. The heap is periodically watered to maintain a moisture level of 200 per cent. After 30 days C:N ratio and lignin content reduces and the golden or yellow coloured fresh coir pith turns into black coloured. compost.

Anand et al., (1998) noted that mere addition of nitrogen source and lignin degrnding fungal culture does not encourage faste.r decomposition and optimum humifi.cation. Coir pith <:an be made more responsive to the attack of Pleurotus by using coir pith treated with lime @ 5k:gl tonne and by using amendments such as rock phosphate @20kg/tonne and organic additives such as cow dung. and garden weeds @ 1 OOkgftonne.

The work done at CPCRJ, Kasaragod has resulted in the isolation of an efficient ligninolytic basidi.omycetous fungus,Marasmiellus troyanus capable of degrading coi r pith treated with lime and rockphosphate. A technology based on this fungus has been standardised (Thomas et al., 2001).

The following method can be adopted for large scale vennicomposting of coir pith. Coir pith treated wjth lime and rock phosphate @ 0.5% each and incubated for three weeks has to be mixed with cow dlrng @ 10%, fresh vermicompost@ 10%. This mixture has to be layered with uncut coconut leaves @ 20% to facilitate aeration in the bed. The local earthworm Eudrilus sp·p. has to be introduced at the rate of 1000 numbers/ton of organic .materials and the bed should be mulched and protected from direct sunlight. Sufficient moisture has to be maintained by regular spr.aying of water. Earthwonns from burrows in coir pith bed and vermicastings appear as surface castings. A granular vermicompost with 1.2% nitrogen and a C:N ratio of 16.7:1 can be obtained in two months (Thomas et al., 2001).

Applications of coJr pith iD agri»horticulture

(i) Components of soil media for container­grown plants

Suitability as a medium for growth of plants : Throughout the world, with the development of commercial horticulture, nursery and glasshouse. industries, the emphasis on media for raising plants has changed gradually from the exclusive use of mineral soil mixtures to soil-less and completely artificial substrates for producing an increasing proportion of container­grown plants. The productive field soils are not only heavy. but also often give inferior results because of compaction und inadequate drainage when confined to containers. The components of artificial media may ideally have lhe following characteristics: low cost, high organic matter content, high moisture holding capacity. fast drainage, resistance to easy decomposition, light weight, and capability to support uniform growth of plants. Sphagnum peat, sawdust and ground bark are conunonly used in a variety of mixtures of artificial media for container-grown plants (Maas and Adamson, 1982). Among these, peat was the mainstay of the nursery and glasshouse indnstries until recently. There is growing realization that the availability of peat cannot be sustained, as it is a non-renewable resource. In addition to the declining availability, excavation of peat has been legally banned in many countries thanks to environmental reasons. AU these reasons demanded the quest for a suitable substi.tute for peat with characteristics similar

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S.R. Prabhu and George V. Timmas

to peat. A number of trials in many countries did reveal that decomposed coir pith can be used us a cheap but effective substintte for peat because of its peat-like chamcteristics. Unlike sphagnum peat, it is a renewable resource, as it c.an be sustain ably produced from coconut husks regular~y available from well managed coconut gardens. Decomposed coir pith has very high moisture retention capacity and its wettability is much better than peat (Evans and Stamps, 1996). The decomposition of lignins present in coir pith results itl the fonnation of humic fractions (Kndulli et al., 2001 a). which imparts coco peat high no.trient retention capaci.ty. Additionally. these humic substances in coco peat must have a role in making it suitable for use in plant propagation and culture of plants, as humic substances are known to have hOLmone-like activity and can stimulate plant growth (Lee an.d Bartlett, 1976) and enhance rooting (Schenitzer and Poapst, 1967). It is light in weight, porous and predetermined levels of air space in the potting media could be obtained by mixing appropriate levels of coconut fibre with coco peat (Prasad and Roeber, 1997). The pH of coco peat is closer to the optimum for the growth of most plants than that of sphagnum peat, which is highly acidic. So, replacing sphagnum peat with coco peat can also result in considerable saving, as lot of lime is required for bringing down pH of sphagnum peat (Cresswell, l9f:J7). Coir pith~ based growth medium shows least changes in air porosity and water holding during its use in comparison with sedge peat (Meerow, 1995). As coco peat is a light weight material, it is convenient for use in roof gardens. glass houses etc. Because of its recalcitrant ligno-cellulosic nature, its decomposition rate is slow, thus avoiding the unnecessary burden of replacing potting media regularly. One of the most des.irable qualities of media for container-grown plants and composts in general is their plant disease-suppressing ability. There are indications that coco peat can suppress many fungal diseases (Kumar and Marimuthu, 1994; Ramamoorthy et al., 1999b), and because of this additional benefit, it is likely that it will become a part of integrated disease management systems for horticultural crops. In view of all these positive aspects, coco ·peat is presently used widely by many commercial horticultural companies worldwide and is in high demand. Highly compresse.d. brickettes of coco peat are now commercially available for easy transportation and use hl horticulture. Also, composted coir pith can be pelletted using pelletting equipment (Varadaraju and Gothandapani, 1998).

Despite many positive aspects, one should be vigilant when coir pfth composts are used as potting

Biological conversion of coir pith into a value-added resource

media, as some are deficient in certain nutrients and some contain excess chlorides, which may adversely affect plant growth. Chlorides have to be removed by leaching if coir pith makes t1 high proportion of any media (Handrock. 1993). When coco peat is used as a complete replacement of sphagnum peat. it may have to be amended with magnesh1m, calcium, sulphur, copper and iron. Due to high potassium content of coir pith, K:Mg ratio is unfavourable for magnes;ium uptake and hence coir pith needs to be enriched with magnesium when it is used as a potting medium (Mapa and Kumara, 1995). Also, extra nitrogen may also have to be given regularly to sustain good plant growth (Handreck, 1993).

Porosity and moisture holding capacity of the growth medium intluences root growth, plant health and establishment. Coir pith when added to other media increases aeration, water holding capacity, CEC etc. Eecause of all. these characteristics, coco peat has been found to be better than peat in supporting seed germination, and eady growth of plants (Cresswell, 1997). Enhancement of plant height and root fresh mass in coco peat-grown plants is a frequent observation (Evans and Stamps, 1996~ Evans and Des, 1997; Sreerama eta/., 1999). Time require.d for flowering in plants such as Tagetes grown in coco peat usually gets reduced (Evans and Stamps, 1996). Coir pith has been shown to be an adequate alternative to sphagnum peat i.n soilless container media. (Pill and Ridely, 1998). Growth index and root and shoot growth were more in Ravenea and Anthurium grown in coir pith containing media (Meerow, 1995). Leaf number, plant height and flower nwnber were more in anthurium grown in co.ir pith medium. Zinnia, Celosia and marigold also perfonned 'better in coir pith media (Awang et al., 1997). Bnre-·root viburnum (Viburnumdentatum) and perston lilac grew better with high fresh root and shoot biomass in coco peat when compared to peat-based media (Evans and lies, 1997). Pelargonium. hortorum, Tagetes patula and Petunia hybrida also pe.rfonned better in coir pith medium (Evans and Stamps, !.996). Pemas lanceolata and Jxora coccinia exhibited higher growth index, top and root weight when grown in coir pith medium as compared to sedge peat­based medium (Meerow, 1995). Coco peat. has been found to be au ideal medium for Begonia semperflorms (Saravanan and Nambisan, 1995) and Gerbera jamesonii (PiUai eta/. l999a), Chrysanthemum (Sreerama et al., 1999) and a numbe:r of other ornamental plams (Pillai et al., 1999b). Use of coir pith as a potting medium for the ol'chid Vanda rothschildiaml resulted in higher production of flowers (Rajamani et al., 1999): In additioJJ to the use of coir pith as a pott.ing medium, it has been found to be

7

effective in hydroponic cultivation of economically important plants such as tomato (Caraveo-Lopez et al. , 1996).

(ii) Other applications in horticulture : Because of its high moisture holding capacity and porosity. coco peat has a number of other applications in horticulture. Some of them arc :

Compost : Pots known as compost for rearing orchids such as Dendrobium and other plants and also for propagation of plants can be made from coir dust, using the stalks of banana and water lily as binders (Catibod, 2000).

Rooting of cuttings : The use of coco peat in vegetative propagation is gaining importance, as it is known to give better percentage of rooting of plant cuttings. Higher rooting percentage was observed when coco peat was used as a medium for rooting of cuttings of Acalypha and Bougainvillea. This pronounced effect has been explained as being due to the presence of phenolics (Lokesba et aL, 1988). Vegetative propagation of Eucalyptus using single node cuttings was very effective when coco peat was used as a rooting medium (Wattier et al., 1998).

Air Jayerlng and hardening of air layers : Coco peat is an effective root initiating medium for a nwnber of plants which are propagated by air layering (Krislmamoorthy and Rema, 1994~ Nazcem etal., 1984). Additionally, coco peat can very well be used for hardening air layers before transplanting to main field (Shetty and Melanta, 1990).

Storage of scion : Coi.r p:ith can retain the viability of plant materials used in vegetative propagation and this has advantages, especially when the materials have to be stored and transported. The scion wood of 'Qutmeg used for graftiog, when preserved in polythene bags with coir dust can effectively preserve the viability for more than 10 days (Rema and Krishnamoorthy, 1998).

Storage of horticultural produce : Post-harvest losses in many horticultural crops is an area of major concern in India. Simple and low cost techniques for reducing the rate of moisture loss and retaining the freshness of fruits and vegetables are needed for fanns in villages without any refrigeration facilities. Storage of banana in cartons with. coir dust has been shown to reduce moisture loss, weight loss, shrivelling and skin bla.ckening (Thompson et al., 1974). This simple technique could revolutionize post-harvest storage and transportation of horticulture produce in villages.

{iii} Use as a son amendment: Coir p:ith has gained importance and relevance as a soil amendment

for problem soils with poor moisture retentivity. drainage and aeration and also far soils affected with salinity, a.lkalinity rutd chemical pollutants. For normal soils. it is usually applied. at the rate of 12.5 tonnes/ha. For sandy soils, it is best to apply ttt the rate of2lt/ha for maximum benefits (Arachchi and Somasiri, 1997). Application of coir pith to soil can improve hydraulic conductivity, porosity. water infiltration rate. water holding capacity, and nutrient storage capacity. lt can also suitably reduce the bulk density of heavy soils.

If nutrients such as nitrogen and magnesium co old be supplemented, coir pith compost would be a practical soil amendment for sandy and sandy clay loam soils with low specific surface (Mapa and Kumard, 1995) because of its high spe--eific surface. The microstructural studies on coir pith showed the presence of plenty of open cells with large empty cavities (ldicullaet al.. 1983; Pavithran, 1993), which can act as capiiJaries for absorption and storage of water and nutrit-'llts. It has been reported that water holding capacity of soil increased by 40 percent due to coir pith addition (Brian, 1975). As coir pith decomposes slowly, all the beneficial effects could last for 8-lO years (Liyanage. 1988). AI> the capacity to store moisture increases with age of coir pith, it is best to use old coir pith weathered for 20 years as a soil amendment (Arachchl and Somasiri, 1997). So, if composted coir pith is not available, old coir dust exposed to sunshine and rains for many years can very well be used instead of fresh one as a soil amendment. Because of the conservation of water, improvements in aeration and hormone-like activities of humic substances from coir pith, its application usually results in enhanced rooting . . May be because of this, many workers did observe reduced seedling mortality and enhanced seedling establishment after the application of coir pith. Joshi et al. ( 1982) reported that application of coir pith and other coconut sheddings when mixed with chemic<tl fenilizers for 10 years increased water holding capacity and reduced bulk density of coastal sandy soil as compared to inorganics alone. Nambiar et aL (1983) noted that the application of coirpith blended with fertilizers. enhanced. growth and vigour of seedlings as compared to fertilizers alone. Reduced seedling mortality and early flowering was also noted.

The use of coir pith is also considered to be very useful for rain fed crops. as it serves more as a moisture regulator and conservator rather than nutrient supplier. lnadvertently, the supply of potassium to soil through coir pith might indirectly have its own role in plant water relationship (Savithri and Khan, 1994).

In addition to the practice of incorporalion of coir pith in soil, it cnn also be buried deep into soil for

S .R. Prabhu and George V. Thomas

conservation of moisture. Liyanage ( 1988) recommended layering of coir pitb in alte.rriatc layers of soils in pits taken in coconut gardens for conserving moisture in gardens.

Coir pith has a)so been found effectLve in remediation of soils affected with a variety of pollutants. Crop growth and yields have been shown to increase in agricultural soils polluted with tannery effluents and t1uorine water(Singarwn, 1994; Jnyakumar etal., 1997). The use of coir pith as an amendment was tded in reclaiming saline alkali soi.ls (Clarson, 1986). In these soils, it reduces the encrustation by salts and aids in cation exchange with its rich calcium and magnesium content (Marimuthu. and Nngarajan, 1993).

(iv) Use as a mulch :The or gallic wastes intended for use as soil mulch should have slow decomposition rates and high water holding capacity. High C:N ratio and water holding capacity of co.ir pith makes it the best material for use as a mulching material. Under rainfed conditions and in sandy so.ils. where water retention capacity is minimum, plants perfonn well and yield better with coir pith mulch. If applied in dry areas coir pith mulch helps to maintain high moisture regimes and reduces soil temperature. Its use has been shown to enhance the establishment of tree crops in dry areas

. (Singh et al.,1988). Application of coir pith around cashew trees has been shown to enhance water retention and suppression of weeds {Komar et al., 1989). Spreading of coir pith as mulch up to one meter radius to a thickness of I 0 em around the bole of coconut palms was reponed to conserve moisture for a very long time resulting jn enhanced growth (Uthiah et al., 1993).

8

(v) Use of coir pith to enhance nutrient supply to plants : Coir pith acts in many ways in ensuring good nutrition to plants. It is a good source of potash (about 0.8%). Coir pith can curtail the loss of nitrogen tbrough leaching and other ways by reducing the rate of nitrification thanks to the presence of nitrification inhibitors in it. It can also prevent the loss of nutrients because of its high nutrient stordge capacity by virtue of high cation exchange capacity.

Application of coir pith can enhance the availability of micro and macronutrients and increase yields. As coir pith is rich in potash and being acidic, its application can enhance the release offlxed and mineral potassium in soil and hence the quantity of potash fertilizers can be reduced in agriculture (Savithri et al., 1993). As it decomposes slowly, ·potash will be available slowly for many years. Application of coir pith blended muriate of potash has been shown to enhance potash use efficienc.y in flooded rice soi1s (Arnmal and

Biological conversion of coir pith into a. value-added resource

Durairajamuthiah, 1996).

Due to very low efficiency of nitrogenous fertilizer use in soils, nitrification inhibitors of chemical and plant oligin have gained relevance in agriculture (Prasad et al., 1971 ), which can reduce the rote of nitrification and loss of nitrogen from soils. Many polyphenols and tannins of plant origin can retard. the nitrification process (Basarba, 1964, Baldwin et al., 1983, Sivapalan and Fernando, 1983). There are indications that coir pith can be util.ized for reducing nitrification in soils (Nambiar et a/., 1988). Joshi er al. (1985)found that polyphenol-rich coirpith when blended with urea can make urea available slowly, thus increasing fertilizer use efficiency. Retted coirdust when blended with urea gave lower production of NH4-N. Production of total mineralized N was consistently lowest when urea was blended with retted coir dust (1: l). The results indicated the usefulness of urea + coir dust for controlled and gradual 'release of urea nitrogen. In addition, because of its peculiar porous microstructure, coir pith has the potential use in the slow release for agrochemicals (Pavitlu·an, 1993).

Rao et al .• (2001) reponed that coirpith cam posted along with garden weeds, Glyricidla, rock phosphate and micronutrients can be an effective component of integrated nutrient supply system, and 50% of inorganic fertilizers could be saved without sacrificing yields. Application of coir pith compost prepared along with cowdung. green manures, rockphosphate and micronutrients along with Pleurotu.~ sajor-caju at the rate of IOtlha along with 50% recommended dose of NPK­fertilizers for maize, .resulted in 15 percent increase in the grain yield over control which received recommended dose (100%) of nutrients alone iJ1 the from of chemical fertilizers. The studies showed that coir pith compost application could be an important component of integrated nutrient management with 50 per.cent savings in fertilizer use (Kadalli et al., 200lb). For a number of crops, coir pith application has been found to be highly effective as an organic manure (Devarajan and Krishnaswamy, 1996); Swarupa and Reddy, 1996; R.anganathan and Selvaseelan, l997, Suharban eta/., 1997). Coir pith application also increases yields of a nwnber of cereals, millers, puls_es, oil seeds and fruit crops (Ahmed, 1993; Marimuthu and Nagarajan, 1993).

(iv) Other emerging trends in utilization of coir pi.tb in agriculture

Production and use or biofertilizers : Biotcrtilizers are carrier~based microbial inoculants for seed, root or soil treatment and are meant. for enhancing the availability of nutrients in the root zone of plants.

9

The viability of beneficial microorganisms and hence the sto~age life of biofertilizers depends mainJy on tbe mo~sture conten~ of canier materials. Because of its high mo1sture retention capacity, coir pith can be used as carrier maLerial for the delivery of beneficial micro­organisms, as the product can be stored for several months. The benefits of using coir pith as a carrier material for beneficial micro-organisms was realised as early as 1956 for inoculating legume cover crops of rubber withRhiz:obiumin plantations situated in Malaysia (Rubber Research JJ1Stitute of Malaysia, 1956). This finding was later confirmed by many workers (John. 1966~ Iswaran, 1972, Faizah et al. ; 1980, Van Nieuwenhove, et al., 2000). Research at CPCRI also has shown that coir pith after composting can be used for the preparation of biofertilzers based on Beijerinckia, Azospirilium, Herbaspirillum, Arthrobacter and Bacillus. Malliga et al. (1996) reported that when nitrogen fixing Anabaena azollae was inoculated to coir pith. _it invaded ~nd profusely sporulated in coir. pith matnx and hence 1t can be used as an inexpensive carrier for cyanobacteria for Rpplications in paddy fields.

Under natural conditions, the presence of active nitrogen fixers is a necessary but often not a sufficient condition for significant nitrogen fixation to occur. Lack of appreciable activity in regions of soils where. beneftcial microorganisms are naturally present or deliberately added through biofertilizers is often attributable to abiotic stresses that affect survival, proliferation or metabolism of tb~se .orga.nism.s. Hence, it was opined that nitroge~ fuation m so11s is rarely limited by the absence, of active or efficient nitrogen fix.1ng baceria (Alexander, 1982). By improving physicochemical properties of soil~. beneficial microorganisms can be put int.o action. As th~ application of coir pith in soil enhances aeration and moisture holding capacity, coir pith enhances the survival of biofertilizers applied in soil, and plants can derive more benefits from the association. Better nodulation and

· yield in pulses has been obtained when Rhizobium biofertilzers are used along witb composted coir pith (Prabhakaran and Srinivasan. 1995~ Jayakumur et al .• 1997).

Disease oontrol in crops : Of late, the question of susta.ina"bility of present.day chemical agriculture has heeD: rai.sed and a number of organic amendments with spe.cial qualities to improve soil and crop health are getting recognition in world agriculture (.Thomas and Prabhu, 2001). Composts and water extracts of composts (compost tea) are highly effective in many cases for the control of plant diseases (Hoitink and Fahy, 1 986~ Logsdon, 1993; Zhang et al., 1996), Zhang et al .• 1998)

and because of this property, composts are being sold as pest control products (Segall, 1995). This additional service from composts would be of greater relevance in high value container-grown floriculture und ornamental plants grown commercially under controlled conditions. The use of the.se disease - suppressive composts capable of reducing soil-borne diseases such as root rot and crown rot in tbese crops is gaining more importance (Hoitink er aL, 1997; Hoitink et aL, 1991; Hoitink and Kuter. 1986; Daft et al., 1979. Hoitink et al., 1977). Composted bard wood bark has fungicidal properties and is popular as a disease suppressive compost (Hotink, 1980). Sustainable supply of tree bark for compost production is in question and coir pith compost which is light in weight similar to composted bark could be a suitable substitute. A number of workers did observe the disease suppressing ability of coir pith compost and it is likely that in years to come, it may find practical applications in the management of plant diseases. especially soil-borne diseases of field crops and container-grown plants. Application of coir pith composted using Pleurotus djamor at the rate of lOtlha has been shown to effectively reduce the dry rot disease of black gram caused by Macrophomina phaseolina and was comparable to the appHcation of 0.1% carbendazim (Ramamoorthy et al., 1999b ). Root diseases of capsicum and black gram reduced significantly by the application of decomposed coir pith (Theradimani and Marimuthu, 1993b). When used in pouing mixture for raising eucalyptus seedlings, coir pith reduced damping off caused by Rhizoctonia so/.ani and Fusarium equiseti (Marimuthu and Nagarajan, 1993).

Trichoderma is a potent antagonistic fungus commonly used for the biocontrol of soil-borne plant diseases. It is also valued for its competitive ability to degrade cellulose. This f-ungus can be employed alone or as a component of microbial mixtures for composting coir pith, so that it wil1 not only help in the degradation of cellulose, but also the compost obtained will be enriched with the propagules of the fungus. This would enable the direct use of the composted coir pith as an effective biocontrol product with plant disease suppressing capabilities. Ramamoorthy et al., (1999a) used the biocon.trol agent Trichoderma harzianum for degrading coir pith and the compost as a carrier for the delivery of the fungus. The population of antagonist in the compost after 30 days of composting was 128 x 104

/

gram. As composted coir pith f-avours good growth of Trichodemw. (Kumar and Marimuthu, 1997), it can be used for mass multiplication and distribution of Trichodernw.- based biocontrol products.

10

S.R. Pmbhu and Geo~e V. Thomas

Mushroom cultivation : Recent studies have shown that a number of edible mushroo~ fungi such as Pleurotus and Calocybe capable of degrading lignocellulosic materials can be grown on coir pith for producing protein-rich mushrooms (Quimio, 1978; Eyini et al., 1995. Thomas et al., 1998). In addition to these protein-rich edible mushrooms, the degraded coir pith obtained after mushroom production can be used as a soil amendment or as a component of potting mixtures.

Use in poultry farms : Due to its high moisture absorption capacity, coir pith is an ideal organic material for use as a bedding material in poultry farms (Maheshwarappa et al., 2000).

(vii) Other uses of coir pith : A number of possibilities exist for the exploitation of coir pith for a number of commercial applications (Natarajan, 1995). It can fmd applications in the following areas : generation of biogas (Radhika et al., 1983; Mathew et al .. 2000), energy source for electricity production and production of particle boards (V.swanathan, 1998), production of cellulase eozyme by solid state fermentation using Trichodentul viride (Muniswaran and Charyulu, 1994), preparation of activated carbon with .industrial applications for removing heavy metals from waste water (Namasivayam and Kadirvelu, 1997; Kadirvelu et al. , 2001), component of concentrate feed mixtures for crossbred calves (Ananthasubramaniam et al., 1982), mass rearing of baculovirus infected grubs and adults of rhinoceros beetle for material in verrnicomposting units meant for the production of vennicompost from organic wastes. ·

Conclusion and future line of work

It could be seen from the above discussion that due to environmental and economic reasons, coco peat has great potential to play an important role in agriculture and botticulture h1dustry in future. Coir pith, a renewable resource has solved the environmental problems caused by excavation of peats and has proved to be another source of income to coconut producers (Agbo, 1997). Recognition of the importance of coir pith has already resulted in international market demand for the value­added processed coirpith and numy small a:p.d large scale coir pith processing industries have come up in many. parts of the countty.

As coir pith carinot be used fresh, more effective and fasl composting techniques and methods for nutrient enrichment and other quality improvements will be the main areas of research in coming years. An understanding of the optimal culture requirements of lig.n inolytic fungi may help to exploit these· organisms effectively, but

Biological conversion of coir pith into a value-added resource

usually this aspect is not giveu due priority while developing composting technologies. Major cultural parameters which affect lignin degradation by white rot fWlgi include temperature, pH, presence or absence of organic carbon co-substrate, nitrogen source and concentration etc. (Penn and Kirk, 1979; Keyser et al., 1978; Kirk. et al., 1978; Reid, 1979). Most lignin degrading microbes require easily availabl.e carbon co­substrate such as cellulose-rich organic wastes with coir pith while composting, could be helpful in enhancing the composting rate. Lignin is dcgmded better under nitrogen starvation conditions (Leatham and Kirk, 1983), as the degradation is as a result of the onset of secondary metabolism triggered by nitrogen limitation. Nitrogen, particularly in inorganic fonn strongly inhibits lignin degradation by white rot fimgi Coriolus versicolor and Plumerochaete chryso~poriu.m (Keyser et al .• 1978). Reduced lignin degradation1n coirpith by Phanerochaete chryJosporium was observed with nitrogen supplements (Uyenco and Ochoa, 1984); No work has been done on the effect of nitrogen on decomposition of ligniLl by Pleurotus species. Work in this direction is worth pursuing, as supplementation of 5 kg urea per tonne of coir pith is recommended in the presently followed procedures for compost production. In additiou to the nitrogen regulated lignin degraders, non·nitrogen regulated species also do exist. Streptomyces badius degrades lignins in the presence of high amounts of organic nitrogen (Phelan et al., 1979; Barder and Crawford, .1981) and such species may be helpful in certain circumstances for degradation of coir pith.

Uyenco and Ochoa (1984) found that coconut water supplement enhanced lignin degradation in coir pith by Phanerochaete chrysosporum, opening up the possibility of enhancing the rate of composting of coir pith using coconut water available in plenty from coconut processing industries, which is otherwise unutilized. Lignin degradation can be enhanced at high oxygen supply rates (Kirk et al., 1978) and the development of simple techniques for enhancing aeration in compost pile could be helpful in getti-ng better quality compost. The research work at CPCRI, Kasaragod did reveal thatcoir pith becomes a hard mass after some days of watering, preventing th~ free movement of air in the compost pile. Inclusion of full coconut leaves along with petiole in different layers in compost pile has been successful in enhancing ae~ation and activity of organisms including earthwonns responsible for composting.

In organic farming, the use of inorganic nutrient sources such ·as urea is not permitted. So. the present technique of coir pith composting, which require$

11

supplementation of urea has limitations. In addition, application of higher amounts of nitrogenous fertilizers for composting can result in the release of excess ammonia, which can kill microbes responsible for decomposition. Any composting technique using nitrogen-rich organic amendments instead of urea would be welcomed by al.l and research in this direction has yielded promising results. Good coir pith compost can be obtained by using organic additives such as cowd ung, garden weeds and sunhemp instead of urea (Anand et al., 1999; Kadalli and Nair, 2000).

Enrichment of coir pith with nitrogen fixing bacteria capable of utilizing Ilgnin and Hgnin-related aromatic compounds could be another approach to reduce the use of inorganic fertilizers during composting. It is a well known fact that many nitrogen fixing bacteria in mixed cultures can fix nitrogen utilizing the energy from tbe organic matter decomposition products (Gibson et al., 1988), Awspirillum (Alexander and Bally, 1999; Diamantidis et al., 2000) andArthrobacter (Sroyk, 1970) possess the capacity to degrade Iignins/polyphenols/other aromatic compounds. Use of cultures of these bacteria along with other organic wastes and green manures during coir pith composting process may help to reduce lignin content and avoid the necessity for addition of inorgauic nitrogen. Additionally, the compost obtained will have beUer nitrogen content and higher counts of plant-beneficial bacteria and can be as effective as biofertilizers.

Enhancement of specific nitrogenase activity of many nitrogen fixing bacteria by aromatic compounds such as phenols has been demonstrated beyond doubt (Werner et aL, 1982; Krot.zky et af., 1983; Werner er al.. 1989). In the light of this finding, coco peat with plenty of aromatic degradation produC:ts is likely to gain further importance in agriculture and when applied to soil in sufficient quantities, may help to enhance the capacity of native and introduced nitrogen fixing bacteria to fix atmospheric nitrogen. Encouraging results have been obtained in this line and experiments have clearly shown that amendment with coir pith can enhance nitrogenase activity of acidic coconut soils (Thomas and Prabhu, 1998).

Use of coir pith compost for suppressing plant diseases is gaining more imp~e and relevance. With increasing awareness of the adv:erse effect'i of pesticides on environment and growing use of coco peat for container grown~plants, their influence on the suppression of plant pathogens would be of additional advantage. Specific groups of microbes developing at specific stages of decomposition of organic matter are.

known to be associated with the suppression of plant pathogens (Boehm et al., .1.993). Such studies in coco peat would be of practical implications and would enable us to select coir pith at particular stages of decomposition for use in plant disease management pesticidal propetties in the bulk organic mattel' used for composting (Shaji, 2000), Coir pith compost having insecticidal properties prepared in similar way would be of additional advantage and should find applications in organic farming for the management of soil~borne insect pests. Composts rich in tartuins and polyphenols are known to control plant patasitic nematodes (Mian and Rodriguez-Kahana, 1982) and composted hard wood bark is commonly used fot controlling plant parasitic nematodes in container-grown horticultural crops (Malek and Gartner, 1975). Coir pith comp'ost is likely to find wider applications in this dire~tion due to its unique chemical composition.

Coir pith from different areas differ in physical (Evans et al., 1996) and chemical (Mapa and. Knmara, 1995, Konduru et al .• 1999) properties. Hence proper quality control should be ensured whHe utili;dng coir pith in large. quantities for horticultural and agricultural purposes. Dangerously high salt levels have been recorded in coir pith samples from India (Cresswell, 1997) and this problem has to be addressed seriously before India could become a major supplier of coco peat internationally. The problems with chlorides is more serious and frequently it reaches toxicity levels of above 1000 ppm, which can affect plant growth adversely. Easy techniques for complete leaching of salts may have to be evolved, so that it can be adopted even by small-scale compost producers.

In addition to the age-old use 1n soil enrichment, composts are increasingly getting worldwide recognition for their use in environmental remediation technologies for the removal of anthropogenic chemical pollutants (Garland e.t aL, 1995; US EPA, 1998). In [he light of theSe developments, there are 'indications t.har coir pith compo!!t could find application in bioremediation of soils polluted with toxic aromatic pollutants. This is based on the fact that the presence of phenolic substances of plant origin in soil can promote the multiplication and activity of rriicrobes capable of degradation of anthropogenic toxic aromatic compounds (Donnelly et al., 1994; Fletcher and Hegde, 1995). Since lignin contains a variety of bonds that are commonly present in aromatic pollutants and the lignin--degenerative system of microbes is non­specific and oxidative, enricl:unent of lignin degrading microbes in soils triggered by the presence of lignin and lignin-related compo.un.ds in coir pith will have the additional advantage of degradation of aroma tic

S.R. Prabhu and George V. Thomas

pollutants. C'..oir pith compost which conta.ins aromatic polyphenols and lignin degradation products may fi~d applications in bioremediation of agricultural and non­agricultural soils polluted with ammatic compounds. In agricultural soils, where a number of harmful aromatic agrochemicals are \lsed for pest and weed control, the use of coir pith as a soil amendment may be of help in the detoxification process. It can be concluded from the information accumulated to date that compos ted coir pith with its multi-functional qualities attracted a lot of scientific attention in recent years and bas become popular is various spheres of agricultural operations. It. deserves much more applications in agri-horticulture and in ensuing years, it will become one of the most sought­after organic resources.

References Agbo, 1997. Dust to dust. Coir News 26 {8) : 25-26.

Ahmed, S. R. 1993. hlfluence of composted coconut coirdust (coir pith) on soil physical propertie3. growth and yieldoftomaro. South Indian Hort. 41: 264-269.

AleXIUKier, M. 1982. Research to enhance nitrogen fixation: misplaced emphasis '? In : Priorities in Biotec:ll11ology Research For lnternntional Developmmt. National AcQdemy of Sciences, USA, pp. 208-229.

Alexander. G. and Bally, R. 1999. Emergence of a Jaccasc-positivc variant of Azmpirillum lipoferum occurs via two-step phenotypic switching process. FEMS MU:robio1. Lell. 174: 371 -378.

Ammal, U.B. andDurairajarnu!hiah,N. 1996. Utilizationofcoirpith as manure for rice and its potassium use efficiency./. Jndi.an Soc. Soil Sci. 44: 445-447.

Anand, H.S., Dcvi, L. S .. Kadalli, G.G .• and Tharamani, G. H. l999. Lime pretreatment for faster degradation and hurrritiooion of coir pith. J. Trop. Agr /.c. 37 : 73-74.

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Anand, H.S., Devi, L.S., Srinivasamurthy, C.A. and Tharamani, G. H. 1998. Chemical and bioche1nical properties of coir dust compost as influenced by pre-treaunent and enrichment. My.sore J, agric:. Sci. 32 : 288-293.

Ananthasubramaniam, C. R .• Mal11en, G., and Mercy, A.. D. 1982. Coconut pith in concentrAted mixtures for crossbred calves. Kuala I. Vet. Sci. 13 (1): 14..1-148.

Anitha Karon, Saj.ini, K. K. and Shivashankar, S. 1999, Embry() culture of coconut :the CPCR[ protocol. lndim1 J. Hort. 56: 348-353.

Arachchi, L.P. V. and Somasiri, L.L. W. 1997. Use of coir dust on the productivity of coconut on sandy soils. C.ocos 12 : 54-71.

Awang, Y., Ismail, M.R. and Roeber, R. u. 1997. The growth ami flowering of some annual oruomentals on coconut dust. Acta Holt. 450: 31-38.

Baldwin, lT., Olson, R. K. and Reiners, W.A. 1983. Protein binding phenolics and the inhibition of nitrification in subalpine b3lsam fir soils. Soil Bioi. Biochem.. 15: 419-423.

Bangar. K.C., K:~poor, K.K. 3nd Mish.ra, M.M. 1!>88. Effect of pyrit:e on conservntion of nitrogen during composting. Bioi. Waste3 25: 227-231.

BiologiC111 cooYcrsion of coir pitll into a value-added resource

Bangar, K. C., Yadav, K. S. and Mishra, A. A. 1985. Transformations of rock phosphate during composting and the effecl of humic acid. Pltmt Sci/85 : 259-266·.

Barder. M. J., and Crawford, D. L. 1981. Effects of carbon and nitrogen supplementation on lignin and cellulose decomposition by a StropiOIIl)!CCJ. Caruulian J. Microblol. 27 : 859-863.

Basmba. J. 1964-.Jntluence of vegetable tannins oo nitrification in soil. Plant Soil21 :8-16. ·

Basaraba. J. and Starkey, R. L 1966. Effect of plant tannins on decomposition of organic substances. S()i/ Sci. 101 : 17-2.3.

Bnvappa, K. V.A. and Gurusinghe, P.de.S. 1978. Rnpid multiplication ofblack pepper for commercial plnnting. J. Pla11m. Crops 6: 92·95.

Biddappa, C. C., Palnniswami, C., Upadhyay, A. K., and Ramanujam, B. 1998 Comparison of te~hniques fOT organic manure production from planllltion wastes, .T. Plant. Crops 26: 120. 126.

Boehm, M. J., Mad,den, L. V. , and Hoitink, H.A.J. 1993 Effect of organic matter decomposition level un bacterial species diversity and composition in relllli.onship to Pythium damping· off severity. Appl.. EJwiron. Microbio/. 59:4171-4179.

Brian, E. G. 1975. CoconuJ plant produc~·. Food :u1d Agrkullure Organization of United Nations. Rome.

Brussaard, Land Juma, N.G. 1996. Organisms and humus in soils. Itl : Humic subJ1(UJces in ter~slrial ecosysttm.s. (Pkcolo, A., Ed.) Elsevier Science BV, Oxford. pp. 329-359.

Caraveo-I..opez. F. de.J., Baca-Castillo, G.A., Tirado-Torres, J. L., and Sanchez·del Castillo, F. 1996. Hydropt)nic culture of tomato with coconut coir dust substrata, and its response to ammonium and potassium. Agrociencia .3(): 495-500.

Catibod, N.A. 2000. Compost from coco coir dmt PC'.ARRD Monior. 28(1j: 6.

Chan Y. K. 1986. Utili7.ation of simple phenolics for dinitrogen fixation by soil diazotmphlc bacteria. Planr Soil90: 141 -150.

a orson, D. 1986. Coir dust for economic reclamation of saline-alkali soils and for better profit.Jndiall Cocon. J. 14 (9) : 6-9.

Crawford, D. L. !978. Lignocellulose decomposition by selected Srreptomyce.s strains. Appi. Environ. MicrobiaL 35: 1041-1045.

Crawford. D. L. and Crawford, R. L. 1976. Micmbial degntdation of ligno-cellulose : the lignin component. Appl. Environ.. Microbio/. 31: 714· 717.

Crawford. D. L. and Crawford. R.. L. 1980. Micmbial degradation of lignin. Em:_yme Microbial. Technof. 2 : 11-22.

Cr.lwford, R. 0. 1981. LiBnindegradali.on and rran.sfornu::tum. Wiley­lntersciem:e, New York, USA.

Cresswell, G. C. 1997. Coir dust- a viable altcmativ~. to peal. Coir News 26 (8): 31-34.

Daft. G. C., Polle, H.A. and Holtink, H.A.J . 1979. Composred hardwood bark : a substitute for steam sterilization and fungicide drenches for control of poinsettia crown and root rot. Hort Sci. 1.4 : 185-187.

Derylo, M., Glowacka, M., Skorupska, A. and Lorl..iew.icz., Z. 1981 nifplasmid from Ugnobacter. ·An:h. Microhiol. 130 : 322-324.

13

Devamjan, R.. and Krishnaswamy, R. 1996. Effuct of zincemiched organic manures ou rice yleld. Madros agric. J. 33: 280-283.

Diamantidis, G., Effossee, A., Potier, P. and Bally, R. 2000. Purification and chnracterization of the fi.rst bacteriallaccase in !.he rhizospheric bacterium Atospirilfum lipoferJiln. Soil Bioi. BiocMm. 32:919-927.

Donnelly, P. K.. Hegde, R. S. und Fletcher, J. S. 1994. Growth of PCB degrading bacteria on compounds from pholosynthetic plants. Chemosphert 28: 981-988.

Evans, M. R. and lies, J. K. 1997. Growth of l--ibumum dentatum and . Syringa X pmtoniae 'Donald Wyman' ln SphagnUm pest and coir dust-based substrates. J. f:.nviron, Hort. 15 : 156-159.

Evnns. M. R. and Stamps, R. H. 1996. Growth of bedding plants in sphagnum peat and coir dust-based substr.ues. J. Environ. Ron. 14: 187·190.

Evans, M.R., Konduru, S., Stamps, RH. 1996. Source variation in physical and chemical properties <rl' coconut coir dust. Horr Sci. 31 : 965-967.

Eyini. M., Prema, P. and Jayakumar, M. 1995. Cultivation trials of Pleurotus ·ostreatlls Kummer, on lime water pretreated coir waste and paddy straw. MrlShroom Res. 4: 77-80.

Fnizah, A. W., Broughton, W.J. and John, C. K. 1980. Rhizobia in tropical legumes. X. Growth in coir dust-soil compost Soil Biol. Bioclwm. 1Z: 211·218.

Fenn. P., and Kirk, T. K.1979. Ligniuolytic system of Plumeror:luuu clrrysosporium : inhibition by Q-phthalate,.Arch. MicrobioJ. 123 : 307-309.

.Fletcher, J .S. and Hegde, R. S. 1995. Release of phenals by perennial plant roots and their importance in bioremedi~tion. C!Jemosphero 31: 3009-3016.

Garland, G.A., Grist, T. A. and Green, R.E. J995. The compost story : from soil enriclunent ro pollution reruediadon. Bior.ycle 36 :35-56.

Gibson, A. H., Halsall. D. M. and Roper, M. M. 1988. Nitrogen fi;ution assQ<;iated with residue: breakdown. In : Nitrogm Fixation: Hundmi Years After (Bothe, H., De Bruijn, FJ and Newton. WE., ·.Eds.) G. Fischer Verlag, Stuttgart, New York, pp. 753-758.

Gibson, D.T., Roberts, RL., Wells, MC tmd Cobnl, C.M. 1973. Oxidation of biphenyl by a Beijerrn:kia species. Biochtm. Bivphys. Res.ConlltWn. SO: 211-2!9.

Gold, M: H. and Alic, M. 1993. Molecular biology of the lignin· degrading basidiomycete PhanerocFwele chrysosporiwn. Microbial. Rev. 51 : 605-622.

Goluej(e, C. G. 1972. Composling; a study of the process and its principles. R.odal" Press. Emmaus, Pennsylvannia.

Gopal. M. and Gupta. A. 2000. Coir waste f-or a scientific cause. lndiarz CoconuT J. 31 (12): 13-15.

G:rappelli, A., Tomati, U., and Galli, E. 1985. Earthwonn castings in plant propagation. Hort. Sci. 26 : 874-876.

Handreck. K.A. 1993. Properties of coir dust, and its usc in the formulation of soilless potting media. C ownun. Soil Sc~ Plant AnaL 24; 349-363.

Hoitink, H.A.J. Stone, A. G., and Han, D. Y. 1997. Suppression of ·, plant diseases by composts. Hon. Sci. 32:184-187.

Hoitink, H.A. J. and Fahy, P.C. 1986. Basis for the control of soil­borne plant pathogens with composts. Annu. R~11. Phytopathtll. 24; 93-114.

Hoitink, H.A.J. 1980. Composted.bark, a light weight growth medium with fungicidal properties. Plnfll, Di:r. 64~ 142-147.

Hoitinlc, H.A.J. and Keener, H.M. 1993. ScieTICt and Eng inuring of Compo.sting. Renaissance Pub .• Worthington, Ohio.

Hoimik, H.A.J. and Kuter, G.A. 1986. Effects of composts in growth media on soilborne plant P"<lthogens. Tu: 71le RoiL ofOrgalliC Matter in Modern Agriculture (Chen, Y. and Avinmelech, Y., eds.) M:utinus Nijhoff, Dordrecht, The Netherlands.

Hoitink. H.A.J., Iubar, Y. and Boehm. M. J. 1991. Status of compost· amended potting mixes naturally suppressive to soilborne diseases of floricultural crops. Plant Dis. 75 : 869-873.

Hoitiuk, H.A.l., VanDoren, D. M.Jr. and Schmitthenner, A. F. 1977. Suppression of Phytophthora cinnamomi in a cornposted hardwood bru-k potting medium. Phytopatlwl. 61: 56!-565.

Idiculla, R., Radhika. L. G., Seshadri, S. K. and Satyannrayan, K. G. 1983. Microstructure and water sorption mechanism of coconut pith. J: Cht!m. 1ech:nol. Biotecllnol. 33A (8): 439-445.

r.swaran. V. 1972. Growth and survival of Rhlowium rt'l'joil in coir dust and soybean meal compost. Madras agric. J, 59; 52-53.

Janshekar, H., and Fiechter, A. 1983. Ugnin :biosynthesis, application and biodegradation. Adv. Biochem. ~ngg.!Bioreclmol. 27 : 120-178.

Jayakumar, M., Eyini, M. and Velmurognn. R. l997. Effect of seed Rhizobium pelleting treatment' and addition of coir-plth compost to soil on growth and nodulation of fluoride water irrigated blackgram (Phaseolus mungo). Indian J. agric. Sci. 67: 610-603.

lohn, K. P. 1966. A coir dust -soil c<nnpost for Rhiwbium. J. Rubber Res. ln.st. (Malaya) 19: 173-175.

Joseph, G. 199:5. Coir pith, a money spinner. Indian Coconut J. 26 (1&2): 2-3.

Joshi, 0. P. Nambiar, C.K. B. and Khan, H. H. 1982. Effect of organic manuring on some physical properties and wnter. retention of coastal sand. Philippine J. CoconuJ Stud. 7 (1&2) : 42-45.

Joshi, 0. P., Khan, H. H., Biddappa. C.C. Manikandan, P. 1985. Effect · of coir dust on mineralisation of urea nitrogen in coconut

growing red sandy loam soil,.. (Arenuc Pa/e.ustu/ts) J. P/anm. Crops 13 : &8-95.

Kadalli, G.G. and Nair. S. 2000. Manurial value and efficiency of coirdu~t based enriched super compost Tndian Coconut J. 31 {3) : 49-50.

Kadalli, G.G., Suseela Devi, L., Siddararn;q)pa. R., and John. E. 200la. Characterizat:lon of humic fl"dctions extracted from coirdust­based composts. J. lndum Soc. Soil Sci.· 48: 51-55.

Kadalli, G.G., Snseela Devi, L .. Siddaramappa, R., and Patil, C. R. · 200Ib. Quality and efficiency ofvnlue-added coirdust based

compost. J. Indian Soc. SoiJ Sci. 48 : 141·144.

Kadirve1u, K., Tharnaraiselvi, K., Namasivayam, C. 2001. Removal of h.eavy metal!\ from industrial wastewaters by adsorption onto activated ciU'bon prepared from an agricultural solid waste. Bioresource Techrw/. 76 : 63-65.

Kale. R. D. 1998. Earthworm: CfndrellaofOtganicFarmins. Prism Books, Bangalore.

14

S.R. Prabhu and George V. Thomas ;

Kawakami, H. 1980. Lignin biodegrdaJion: microbiology. chemistry l and poten.titJf applications. Vol. ·1. CRC Press, Florida. pp . .

1

103-125.

Keyser. R.. Kirk. T. K. and Zeik:us, J.G. 1978 . . Ligninolytic enzyme . system of PII/Jnerochatte chtysosporium synthesized in the . 11bsence of lignin in response to nitrogen starvation. J. Bacterio/. 135 : 790-797.

Kirk, 1: K. 1971. Effects of micro-organisms ori lignin. Arm. Rev. Phytopathol. 9: 185-210.

Kirk, T. K. 1980. Studies in the physiology oflignin metabolism by white·.rot .fungi. In : Lignin biodegradation : microbiology. : chemistry and applicatkms. Vol IL (Kirk, T.K, Higuchi. T., : andOumg, H.M. Eds. CRC Press, Boca Raton, Flll., 'PP· 51·1 ~ ll

Kirk, T. K., Connors, W. J. nnd Zcikus, J. G. 1976. Requirement of i growth substrata during lignin degradation by two wood rotting fungi. Appl. Envirol'l. Microbiol. 3Z: 192-194.

Kirk, T. K., Schultz, B., ConnorS. W. J., Lorenz, LP., and 7..eikus, · 1

J.G. 1978. Influence of cutlute parameters on lignin metabolism by Phanerochaeu chrysoJportum. Arch. ! ! MicrobiaL 117:285.

Konduru, S., Evans, M.R., ttnd Stamps, R.H., 1999. Coconut husk i ~ and proces5ing effects on chemical and physical properties : . of coconut coir dust. Hort Sd. 34 : 88-90.

Krisbnnmoorthy, B. and ·Rcma, J. 1994. Air lnyering in cassia . . ( Cinnamomum aromatic urn Nees.) J. Spices Aromatic Crops 3:48-49.

.b Krotzky, A. , Berggold, R., Jaeger, D .• Dart. P J., and Werner. '0.1983. ~ •

Enhancement of aerobic nitrogenase activity (acetylene l • reduction assay) py phenol in soils and the rhizosphere of l ~ cereals. Z.Pfanunt:mahr. 1Jode11k. 146 : 634·642.

Kumar, A. and Marimutho, T .. 1994. Biological control of damping-off of Eucalyptus camafdlllensis caused by Rhizoctonia solani ~ with TricfJoduma viridt. and decomposed coconut t:oir pith. · Plaru Dis. Res. 9: 116-121.

Kumar, A. andMarimuUtu, T.1997. Decomp<>sedcocanutcoirpith­A conducive medium for coloni~ation of Trk:hoderma vi ride. · Acta Phytopathol. Hung. 3Z: 51-58.

Kumar, D. P.. Subbarayappa, A .• Hiremath, I.G., Khan, M.M., and I ~ Sadashiviah 1989. Use of coconut coir-plth: a bio-waste as ' · soil mulch in cnshew plantations. Cas11ew 3 (3) : 23-24.

Leatham, G.F. and Kirk T. K., 1983. Regulation of ligninolytic activity hy nutrient nitrogen in white·rot Basidiomyct'tes. FEMS .b Microbial. Lett. 16: 65-67.

Lee, Y. S. and Bartlett, R.J. 1976. Stimulation of plant growth by . burnie sub.o;tances. Soil Sci. Soc. Amer. J. 40: 876-879. ~

Liyanage, M.de.S. 1988. Use of coir dust far moisture conservation. Coc011ut Bull. S (!): 18-19. . ll

Logsdon, G. 1993. Using composts for plant disense control. Blocyc/~ · 34:33-36.

Lokesha. R.. Mahlshi, D. M. and Sh.ivashank:ar, G. 1988. Studies on use of coconut coir dust as a rooting media. Cun~nt Res. 17 : 15'7-158.

Mans, B. F. and Adamson, R. M. 1982. Artificial muiia i:n horticult11re - their formulation and f~rtillzation. Publication 1726/B. Agriculture Canada, Ot!llwa.

Biological conversion of coir pith into a value-ndded resource

Magdof.f, F., Lanyon, L. and Liebharot, W.C. 1997. Nulritmt cycling, transfer and flows : implications for n more sustainable

. agriculture. Adv. Agron. 60 : 1-73.

Maheshwarappa. H. P., Dhauapal, R., Biddappa, C. C. and Thomas, O.V. 2000. Coir pith· its we in poultry fann.lndian Coccflut J. 31 (9) : 1-2.

Maleic:, R. B. and Gartner, I. B. 1975. Hardwood bark as a soil amendment for snpprcssion of plant parasitic nematodes in container-grown plants. Hort Sd 10: 33-35.

MalligiJ, P., Uma. L. and SUbraiTlllnian, G. 1996. Lignolytic activity of the cyanobacterium Anabaena azallae MI..Z and the value of coir waste as a carrier for BGA biofertilizer. Microbia~ 86: 175-183.

Manna, M.C. and Ganguly, T. K. 2000. Rockphosphate and pyrite in compost technology and their role in improving crop productivity and soil quality. Fert. News45 (7): 41-45 & 47-48.

Map3, R. B. and KLIIlUll'll, G. K. K. P. 1995. Potential of coir dust for agricultural use. Sri Lankan J. asric. Sci. .32: 161-164.

Marimuthu, T. and Nagarajau. R. 1993. Coir pith • a useful crop residue. Biofogy &h.cation, Sept. issue, 161-164.

Martin, J.P. and Haider, K. (1980). Microbial degradation. and sUibilization of ''C-Jahelled lignins, phenols and phenolic polymers in relation to soil humus formulation. In : Lignin bi{)degradation : Microbiology, ChemisTry and Pot~ntial tl.pplicaJin.r. Vol.12. (Kirk, T.K., Higuchi, T. and Chang, H.M, Eds.) CRC Press. West Palm Beach, pp. 78·1 00.

Ma!Mw, A. C., Singh, T. V. and Bosco, SJ.D. 2000. Tecllnology to producebiogas fromcoiTpith. Indian Cocon. J. 31 (3): 46-48.

Mbah, B.N. and Pdili, P.N. 1998. Changes in moisture retention properties of five waste materials during short-term mesophilic composting. Compost Sci. Utili7.tltion 6: (4) : 67-73.

Meerow, A. W. 1995. Growth of twn tropical foliage plants using coir dust as a container medium amendment. Hort. Tech. S :

. 237-239.

Melillo, J. M., Aber, J.D. and Muratore, J. F. 1982. Nitrogen and lignin control of hardwood leaf letter decomposition dynamics. Ecology 63: 621-626.

Minn. I. H. nnd Rodriguez·K.abana, R. 1982. Organic amendments with high lannin and phenolic contents for control of Meloidogyneanmariain infested soiL Nematropica 12:221-234.

Mishro, M. M. nnd Bnngar, K. C. 19S6. Rock phosphatecomposting and transfonnation of phosphorus fonns and mechanisms of solubilization. Bioi. Agric. Hon. 3: 331-340.

Moorthy, V. K. and Rao, K. B. 1997. Recycling of coir pith • a successful VRF experience. Coir News 26 (9): 21-24.

Moorthy, V. K. and Rao, K. B. 1998. Nutritive status of coir pith of varying age and frOm different sources. Coir News 21 (2) : 17-19.

Moonhy, V. K., Moorthy, A. K. and Ra.o, K.B. 1996. Composting coir pith and coffee husk for recycling. Coir News 25 (10): 21 -25.

Muniswaran, P.K.A. and Charyulu, N.C.L.N. 1994. Solid state fermentation <lf coconut coir pith for cellulase production. Enzyme Microb. Ttehno/.16: 436-440.

15

.Nagarajan, R .• Manickam, T. S. Korhand:u'aman, G. V., R&na.swarny, K. and Palaniswaruy, 0. V. 1985. Manurial value of coirpith. Madras Agric. J. 7Z : 533-535.

Nagarajan, R., Manickam, T. S. 811d Kothandaraman, G. V. 1988. Composting coir dust fur better utili7..ation as manure in ngricultural faons. J. P!anJ. Crop: 16 : 59·62.

Nllllathambi, P. and Marimuthu, T. 1993. Pleurotus platyp11s: a potent oyster mushroom for organic recycling of agricult.ural waste. Mushroom Res. 2: 75-77.

Namasivayam, C. and Kadirvelu, K., 1997. Activated carbons prepared from coir pith. by physical and chemica] activation methods. Bioresource TechnoL 62 (3): 123-127.

Nambiar. C.K.B., Biddappa, C.C. and Khan, H. H. 1988. Effect of coir dust blended fertilizers on carbon and nilrogen changes in a coastal slllldy soil. J. Plan111. Cl't{ps 16: 101-104.

Nambiar. C.K.B., Khan, H. H., Joshi, 0. P. and Pillai, N. G. 1983. A rational ~~pproach to the management of coastal sands for establislunent and producli.on of coconuts. J. Planm. Crops lJ: 24-32.

Natarajan, G. 1995. Comrnercitil exploitation of coconut pith· pmblems & prospectS. Coir News Z4 (7) : 23-26.

Nnzeem, P. A., Gopikum.ar, K., and Klunaran, ·K. 1984. Vegetative propagation in jack (Artocarpus heterophylws Lam.) ltgric. Res. J. Kerata 22: 149-154. ·

Neuhauser, E. nnd Hattenstein, R. 1976. On tho pl'esence of Q.

demethylase activity in invertebrates. Comp. Biochem. PhysioL 53:37-39.

Neuhauser, E., Hartenstein, R. and Connors, W. ,1. 1978. Soil invertebrates and the degradation of vanillin, einnamic acid ttnd lignins. Soil Biol. Biochem. 10: 431-435.

Northup, R.R., Yu, Z., Dnhigren, R.A. and Vogt, K.A: 1995. Polyphenol control of nitrogen release from pine litter. NmuT'l! 377: 227-229.

Nowak, a. and Nowak, J. 1990. Prolonged humitication of 14C· labelled oat residues in extensively ferulized. soils. Soil Bioi .. Biochem. 22: 1089-1096.

Palm. C.A. and Sanchez, P.A. 1991. Nitrogen release from leaves of some tropical legumes as affected by their lignin .and polyphenol contems. Soil Bioi. Biochtm. 23 : 83-88.

Pa!il, C.R.., Radhakrishna, D., Mallesb, B. C. and Kale, R.D. 1999. Use of mushroom spent material and earthworms toTecycle coir waste. Coir News 28 (4) : 27-32.

Pavitlmm, C. 1993. Possibility of using coconut pi!h as a matrix for conlrolledlslow release systems in agriculture. Paper presented at the workshop on utilization of coir pith, Pollachi on 13 feb. 1993, Coir Board, Cochin.

Phelan, M.B., Crawford, D. Land Pometto, A. L III 1979. Isolation ofligoocellulose decomposing actinomye¢t,es and degradation of specifically 1'C·Iabelled lignocelluloses by six selected Streptomyces strains. Canadian J. MicrobioL 25: 1270-1276.

Pill, W. 0. and Ridely. K. T. 1998. Growth of tomato and coreopsis in response to coir dust in soilless media. Bnrt. Tech. 8 : 401-406.

Pillai,' P. N., Aswnthl, C., Palaniappan, R. and Choudh:ll')', M. L. 1999a. lnfluence of coir pith and electrical conductivity on growth and development of G~rbera jamesonii. Paper presented at the National Symposium on Emerging Scellario in Ornamental Horticulture, New Delhi, 21-22 July 1999.

Piilai, .P. N .. Stnitha, R., Aswathi, C., Palaniappan, R. and Choudhary. M.L 1999 b. C'Allrpith as a growing medium for ornamentals. Paper presented at the National Symposium on Emergiug Scenario in Ornamental Horticulture, New Delhi, 21-22 July 1999.

Prabakaran, J. and Srinivasan, K.. 1995. Effect of Rhi~obium inoculali.on and coir dust on growth, nodulation and yield of pigeonpea (C-ajamcs cajan).Jndian J. Agron. 40: 518·519.

Prabhu, S. R. und 'l1J.omas, G. V. 2001. cOmposted coir pith as a resource in agri-horticulture. Coir ntws 30 (8) 13-18.

Prabhu, S. R., Subramanian. P., Biddappa, C.C. and Bopalah, B.M. 1998. ProspecL~ of increasing coconut productivity through venniculture technology. Tndian Coconut J. 29 (4): 79·84.

Prabhu, S. R., Thomas, G . V., Subramanian, P., Biddappa, C.C. and Kale "R.D. (200 1). Basic and applied a~pects of vermicompost production IUld use in agri-oorticulture, and some experiences in vennicomposting of coconut plantation wa.~tes. Vatika Spring (Jan-Mar), Issue 1 : 5·16.

Prasad. M. and Roeber. R. U. 1997. Physical, chemical and biological properties of coir dust Acta Hort. 456: 21-29.

Prasad, R .• Rajal.e, G. B. and Lakhdivc, B.A. 1971. Nitrification retardeto and slow release nitrogen fertilizers. Adv. Ag.ron. 23 : 337·383.

Quirnio, T.H. 1978. Introducing: Pleltrofllsjlabellatus for your dinner table. Mushroom J. 69: 282-283.

Rndhika, L. G., Seshadri, s. K., and Moh:mdas, P. N. 1983. A study cJf bioga.~ generution from coc-.onut pith. J. CMm. Technol. Bio~chrwl. 33: 189-194.

Rajnmnni, K., Jawaha.rlal, M .• Muthum:mickam. D. and Bnlakrlsbnamurthy, G. 1999. Studies on standardisntion of potting media for Vanda orchid (Vanda roroschildiana). South Indian Hort. 47 : 348-350.

Ramumoorthy, M., Muthusamy, M. and Meena, B. !999a. Biodegradation of coir pith using fungal biocontrol agents. lndio.n Coconut J. 29 (It) : l· 3.

Roonamoorthy, M., Muthusam.y, M., Meena, B., Sithara.man, K. and Alice, D. l!l99b. Composting of coir pith using ligno­cellulolytic fungi for the management of root rot of black gram. Mcuhroom Rt!s. 8 : 13·17.

Ramamoorth.y, M., Muthusamy, M., Meeua, B., Sitharaman, K.. and Alice, D. 2000. Biodegradation of coir pith using native microflora. J. Planm. Crop$ 28 : 21 8·221.

Ramesh, T. and Gunathilngarajl!, K.. 1996. Degradation of coir waste and tapioca peel by earthworms. Madras ugric. J. 83: 26·28.

Ranganathan •. D.S. and Selvasee1ao. D.A. 1997. Mushroom spl.'nt rice straw compost and composted coir pith as organic manures for rice. 1. Tndian Soc. Soil Sci. 45: SI0-514.

Rao, K.S. V. !999. Application of coco peat (pith) to horticulture. Coir News 28 (5): 33·35.

R:~o, P. S., Devi,. L. s. und Dattn, A. 2001. Quality of coir dust composts and their effects on the dry matter yield of maize. J. Trop. Agric. 39: 24-27.

Reid. I. D. !979. TI1e influem:e of nutrient bnlnnce on lignin degradation by the white rot fuugus Phanacdwetc chry$osporium. Canadian J. Bot. 57 : 2050-205S.

16

S.R. Prabhu and George V. Thomas

Rcma, J. and Krishnamoorthy, B. 1998. Efft:et of packing rnaierial.s and storage of s~.-ions on graft success in nutmeg (Myrlstica frognms Hotl tL). J. Spices Aromatic Crops 7: 147·148. ·

Rubber Research Institute of Malaya, 1956. Rhizobium compost cultures, Planters' Bulletin, Ruhb. Res. lnst .. Malaya.

Sarav~nan, A. and Nrunbisan, K.M.P. 1995. Utilisarion of coir pith as pot culture medium for Begonia semper:florens. Madras Agtic. J. 82 : 587·589.

Savithri, P. and Khan, H.H. 1994. Ch3racteristics of coconut coir pith and its utilization in ngricullure. J. Plant. Crops. 22 1-18.·

Savithri, P., Murugappan, M. and Nagarajan, R. 1993. Possibility of economising potussin.m fertilization by composted coir pith application. Fen. News 38 : 39-40.

Scbenitzer, M. and Poapst, P. A.. 1967. Effects of a soil humic coTl."lpQUnd on root initialisation. NaJu.n (l..ond.) Zl3 : 598-599.

S<:gall, L. 1995. Marketing compost as a pest control product. Biocycle 36:65-67.

Shaji, A. K. 2000. Pesticidal compost. Plant Horti. ~ch. 29 (2) : 6162.

Shetty, K. K. and Melanta, K. R. 1990. Hardening of cashew (AJUlcardium occidentale L.) air layers in piiUlting media to improve field establishment. Myscre J. agric. Sci. 24 : 375-378.

Singarum, P. 1994. Effect of coir pith as an amendment for tannery polluted soils. Madras agr/c. J. 81 : 548-549.

Singh, B., Gupta, G. N. and Prasad, K 0. 1988. Use of mnlches in establishment Md groiV1h of tree species on dry lands. !n.cUan Foresrtr 114: 307-316.

Singh. T. A. and Singh, G. R. 1991. Evaluation of partially acidulated phosphate rocks and liquid ammonium polyphosphate as phosphoros sources for wheat. J. lndiat~ Soc. Soi/.. Sci. 39 : 191·193.

Sivapalan, K. l9S2. Hurnification ofpolyphenol-rich plant residues. Soil Bioi. Biochem. 14 : 309-310.

Sivapalan, K .. Fernanado, V. and Thenababu. MW 198:5. N­mineralization in polyphenol-rich plant residues and their effect on nitrification of applied ~monium sulphate. Soil Bioi. Bioclum. 17: 547-551.

Slvapalan, K. and Femanado, V. 1983. Humified phenol-rich plant residues and soil urease activity. Platlf Soil70 : l 43-146.

Smyk, B. 1970. Fi:~.ation of atmospheric nitrogen by stnrlns· of Arthrobacter. Lmtralbl. Balaeriol. Parasitenkd. lnfelr.tiortskr. Hyg. Abt. 2. 124:231-237.

Sreerama. R., Reddy, T.V .. oo!d Narayanaswnmy, S. 1999. Effect of cocopeat on root growth of chrysanthemum plants. C11rn'nt Res. 28:53.

Stamps, R. H. and Bvans, M. R. 1999. Growth of Dracaena maf8in.ara and Spathiphyllum 'Petite' in sphagnum peat and. coconut coir dust-based growing media. J. Environ. Hort. 17: 49-52.

Stevenson, F. 1. 1982. Humus ch~mistry : Genesis, composition, ~actions. Wiley, New York.

Suharban. M., Geetha, D. and Nair, M. C. l997. Degrn<latlon ofcoir pith by oyster mushroom (PltunJtus spp.) and its effec. . .-t on yield of bhindi. Mr~hroom Res. 6 : 101-102.

! '.

Biologi~lll conversion of coir pith into a vnlue-added resource

Swarupa. S. <3. and Reddy, A.G.S. 1996. Green value of dry dust ; possibility of recycling colr pith in coff~ cul!l vation. Indian Coffee 60 (5) : 3-5.

1kradimani. M. and Marimuthu. T. 1992. Ulilization of Pleurotus spp. for decomposing coconut coir pith. Mushrvom. Res. 1 : 49-51.

Threadi.mani,M. andMarimuthu, T.1993a. Role of native microfl.or.J in decompsing coil piUt. lndlon CoconuJ J. 24 ( 1) : 5-6.

Theradi.l1lJll.l.i, M. and Marimuthu, T. 1993b. Effect of decomposed coconut coir pith on damping-off of chillies and rout. rot of blackgram. Plant Dis. R~. B: 1-5.

Thomas, G. V. and.Prabbu, S • .R. 1998. Nitrogenase acti. vity in relation 10 organic amendment and Be.ljtrinckia indica. inoculation in acidic SQil from coconut plantation. 39th Annu. Conf. Association ofMicrobiologists of India, College of Fisheries, Mangalore. 5-6 Dec. 1998.

Thomas, G. V. 81J,d Prnbhu, S. R. 2001. Microbial inoculants and organic ainendments for ensuring ClOp health in sustaiuable agriculture: In Biological control of pests (Desluuukh, A.M., ed), Milind Publishers, Karad, Maharn.shtra pp.12J-162.

Thoill3!, G.V., Prabhu, S.R., Reeny, M.Z. :md Bopaiah, B.M. 1998. Evaluation of lignocellulosic biomass from coconut palm as substrata for cultivation of Plcurotus sajor caju (Fr.) Singer. World J. Microbial. Bfotechnol. 14 : 879-882.

Thomas, G. V., Prabhu. S. R.. Subramanian. P. and Iyer. R. 2001 Organic farming technologies in cotonut. ATIC Series Publication No. 4, CenlJ'al Plantation Crops Research Institute, Kasaragod, Kerala. India.

Thompson, A. K., Been, B. 0 . and Perkins, C. 1974. Effects of humidity on ripening of plantain bananas. E.xperienlia 30 : 35-36.

Tiwari. K. N .• Dwiveid, .B. S., Upadhyay, G. P ond Pathak, A. N. 1984. Sedimentary iron pyrites as amendment for sodic soils and carrier of fertilizer sulphur and iron-review. Fert. News 29 (10): 31-41.

ToltUlti, U., Grappelli,l. and Galli, E. 1988. The hormone -like effecc of earthwonn casts on plant growth. Bioi. Fertil. Soils. 5: 288-294.

U.S.EPA. 1998. An analysis of composting a.~ un environmental romodiation technology. EP A530-R-98·008, United States Environme.ntal Protection Agency, Washington, DC.

Ulmer, D.C .. Lci.sola, M.S.A., Schmid!, B.H. and fiechter, A. 1983. Rapid degradation of isolated lignins by Phaneror:haet~ chrysosporum. Appl- Environ. Microbial. 4S: l795-1801.

Uma. L, Kalaiselvi. R. and Subramani:rn, G. 1994. IsolaHon of a lignolytic bacterium for the degradation and possible utilization of colr waste. Biotlclmcl. Leu. Ui : 303-308.

Uthiab, B,C., Jmli'resh. K. M., and Shetty, P.T.K. 1993. Preliminary studies on the effect of mulches and irrigation on growth of young CQ®nut plnnts in coastnl Kn.mataka. fndi(l.ll Coconut. J, 24 (6) :5-9.

Uycnco, F. R. and Ochoa, J.A.K. 1984. Microbial degradution of coconut coir dust for biomass production. Philippine J. Coconu1 Srud. 9 (1-2): 51-54.

17

Vallis, I. and Jones, R. J. 1973. Net mineralization of nitrogen in leaves and leaf litter of Desmodium inrortum and Plraseolu~ atrcpnrpureus mixed "'1Ut soiL Soil Bioi. Bioclltm. 5: 391-398.

Vau BreeiJlJ.,"Jl, N. 1993. Soils a.~·biotic constructs favouring net. primary productivity. Geodmnt1 S1: 183·21.

Van Breemen, N. 1995. Nutrient cycling stl'ategies. Plant Soi/1681 169 : 321-326.

Van Nieuwenhove, C., vnn Holm, L., Kul.asooriya, S. A. and V!assalc, K. 2000. Establishment of Awrhizobium caulilzod<1ns in the rhizosphere of wetland rice (Oryza sativa L.) Bioi. Fertil. Soils 31 : .143-149.

Varndharajn, N. and Gothllndapani, L. 1998. De.sign and development · of equipment for pelleting decomposed coir pilh. Agriculrurol Mechanization in Asia, Africa and Latin America 29 (2) : 33-34,38.

Verhagen, J.B.G.M. an.d Papadopoulos, A.P. 1997. CEC and the ;,aturation of the adsorption complex of coir dust. Acta Horticu/tJirae 481: 151-155.

Vicuna. R., 2000. Ligninolysis. A very peculiar microbial process. Molec. Biorechnol. 14: 173-176.

Vijayalakhmi, J., Murthy, N K and Usha, K. 1989. Biodegrdation of colr pith. Indian J. agric. Sci. 59 : 316-318.

Viswwathan, R. 1998. A process fur thcllfOduction of panicle board from coconut pith. Indimr Coconut J. 29 (7) : 5-7.

Wang, T.S.C., Yang, T -K. and Chuang, T.T. 1967. Soli phenolic acids as plant growth inhibitors. Soil Sci. 103 : 239-246.

Warrier. K.C.S., Kumar, K.G.A. and Venkalaramanau, K. 5.1998. A low cost rooting .medium for m.acropropagation of eucalypts. Sylva Plu.f 6 : 13. ·

Werner, D .• Berggold, R., Jaeger, D., Ko.rt.zky, A., Papen, H., Schenk, S., and Th.ierfelder, H. 1989. Plant, microbial and soil factors determining nitrogen fixat ion in the rh.izophere. Z. Pflanzi!nemahr. Bodeffk. 152: 231-236,

Wemer, D., Krotzky, A., Berggold, R., Thierfelder, H., and Preiss, · M. L982. Enhancement of spWific nitrogenase activity ln Azospirillum brasiltnse and Kl~bsi~lla pne11moniot, inhibition in Rhif.(Jbium japollicum under air by phenoi.An:h. Microbiof. 132 : Sl-56. .

Yau, P. Y. and Murphy, R. J. 1998. Enhancedbiodegmdation of coco peat by soft. rot fungi. Paper presented at the 29lh Annual Meelingofthe IRG, Maastricht, The Netherlands 14-19June. 1998.

Zhang, W., Han, D. Y., Dick, W. A., Davis, .K. R., and Hoitink. H. A.J. 1998. Compost and con\post water ex.rract-induced syslemic acquired resistance: in cucumber and arabidopsls. Plrytopathol. 88: 450-455.

Zhang, W., Dick, W.A. and Hoitink, H.A.J. 1996. Compost-induced systemic acquired resistance in cucumber Ul Py1hiurn root rOl

and anthrocnose. Pllytopathol. 86 : 1066-1070.

Zimmermann, W. 1990. Degradation of lignin by bacteria. J. Diot<>chr10l. 13: 119·130.