Keywords

1 Solid Waste: The Preamble

Solid waste is unwanted debris resulted from various residential, industrial and commercial activities. It may be categorized depending on their contents or the hazardous potential of the waste that causes an impact on humans and environment. Rise in large-scale industries, rapid urbanization, increase in population density and also changing lifestyle has challenged the balance between environment and man (Yadav and Garg 2011). Solid waste includes most of organic, domestic refuse, commercial and institutional wastes, municipal solid waste, ashes, sludge sewage, etc. Also agricultural waste from dairy, poultry and farmyard exhibits most of the organic contents. This article also highlights waste management through recycling of an aquatic weed by employing the earthworms, the final product of which is a boon to agriculture and organic farming.

1.1 Impact on Human and Environment

Discharging the waste products in the open land or releasing into the neighboring water bodies would be problematic for both land and water ecosystems. Man is responsible for polluting the major environment including air, water, soil, etc., as a result of illegal waste disposal and failure of definite scientific protocol for waste management. This results in breeding of infectious vectors in the society which may cause contagious diseases (http//:www.unescap.org).

1.2 Indian Context

Per capita waste generated in India is 0.498 kg/day and municipal solid waste generated ton per day (TPD) is 129,593 and 47,301,346 ton per year TPY (Annepu 2012). Reuse techniques of solid wastes: use the energy efficiently, preventing pollution and beneficial to society. Agricultural and animal waste may be converted into manure by composting and producing biofertilizer (i.e. vermicompost) and biofuel (Furedy and Choudhary 1996). It is highly essential and responsibility of one and all to collect, treat and dispose of the waste generated from various sources in a sustainable manner. Dumping of these wastes leads to the emission of various dreadful gases which may pose serious threats to humans and overall environment, therefore the immediate attention has to be diverted to the management of municipal solid waste in a more scientific, sustainable and eco-friendly manner. The application of three concepts reuse, recycle and reduce is contributed towards depleting the environmental pollution which may lead to the healthier environment and cleaner surroundings.

2 Pollution of Aquatic Bodies by Weed

Water bodies are an important source of natural resources, on which almost all the activities (viz. agriculture, human consumption, industrial, etc.) of human are totally dependent. Water bodies like lakes, ponds, pool and wetlands form the major freshwater bodies whose ecosystem is enriched with biotic and abiotic interactions. When these freshwater bodies get overexploited by aquatic vegetation, it is said to be an infestation of aquatic weed. The main root cause of pollution of aquatic bodies from urban areas is mainly due to the release of domestic sewage and effluents directly into these precious resources. The waste enters into the aquatic bodies enriched by the nutrients induce enormous growth of aquatic weeds.

2.1 Water Hyacinth (Eichhornia crassipes)

Eichhornia crassipes is a perennial aquatic plant with long fibrous roots, rounded leaves, leafy stem with showy lilac-coloured flowers. A single plant has an ability to cover an area of 600 m2 in few months. The factors responsible for the rapid proliferation of water hyacinth are their ability to grow on open water, rapid growth by means of stolons, low environmental demands and bladder-like petiole which makes the plant float, dissemination of seeds and reproduction by both sexual and asexual methods (The Wealth of India 1952).

Dense mats of water hyacinth reduce light to submerged plants hence decreasing oxygen levels in aquatic bodies (Ultsch 1976). These weeds make a negative impact on the water bodies, affecting biodiversity, fish production, nutrient loss of water, hindering oxygen interaction, causing insects and vectors, problems for navigation (Lancar and Krake 2002; Becker et al. 1987). Water hyacinth and alligator weed due to their overgrowth and dense mat block the route for boating and even ships (Lancar and Krake 2002). The application of water hyacinth raw material for manufacturing handmade papers and boards reported 1 ha. of infested pond area will yield 0.9–1.8 tons of dry matter basis per day (Thyagarajan 1983). The proliferation of water hyacinth rapidly is due to the availability of nutrients through anthropological activities such as the discharge of wastewater in water bodies, industrial effluents, run off from land, etc. (Ojeifo et al. 2000).

2.2 Worldwide Prevalence and Eradication of Water Hyacinth

Its prevalence around the world included Africa, Asia, Australia and North America (Téllez et al. 2008). Water hyacinth is introduced in India as an ornamental plant in botanical garden in Bengal (Biswas and Calder 1954). A field study done by (Narayanan et al. 2007) indicates that majority of states from India are infested with water hyacinth. These include in Kerala (from Ashtamudi wetland, Sasthankotta lake, Vembanad-Kol wetland), in West Bengal (from East Kolkata wetlands), in Madhya Pradesh (from Bhoj wetland), in Uttar Pradesh (from Upper Ganga river), in Himachal Pradesh (from Chanderertal wetland), in Punjab (from Harike lake, Kanjli wetland, Ropar wetland), in Andhra Pradesh (from Kolleru lake) and in Manipur (from Loktak lake) are greatly polluted with exorbitant infestation of this dreadful weed (Narayanan et al. 2007). Water hyacinth can also be used as compost and mulch, as it contains higher concentrations of nitrogen, phosphorous, potassium, calcium, magnesium (Mukhopadhyay and Hossain 1990). It is used as raw material in industries for paper, plastics, as a fodder for cattle, etc. (The Wealth of India 1952). Free-floating aquatic weeds are mainly water hyacinth (Eichhornia crassipes), water fern (Salvinia molesta), water lettuce (Pista stratiotes), duckweed (Lemna minor), rooted floating weeds like arrow head (Sagittaria guayanensis), nikalmi (Ipomea hederacea) (Lancar and Krake 2002).

Sambhaji tank is situated at 17° 38′ 52″N latitude and 75° 54′ 14″E longitude, 2 km from the centre of the city. Thousands of migratory birds visit every year and few of them are flamingoes, demoiselle cranes, etc. This tank is a recreational point for boating, bird watching center, also it is used for immersion of idols, other offerings of god like (nirmalya), fishing is done and is a beautiful place that attracts many tourist visitors. But now this tank is invaded by the water hyacinth aquatic weed which is creating problematic situations like blocking the routes for boating, fishing, affecting the biodiversity of tank and influencing the recreation. Various attempts have been made to remove manually from Sambhaji tank and subsequently heaped in huge quantities as dumps on the roadside in piles. This dumping makes the environment an invitation for many disease-causing insects and vectors. Water hyacinth weed interferes with the activities of birds, hinders the use of larvicides and mosquito repellents thus creating a menace (The Wealth of India 1952).Water hyacinth forms a dense mat over a water body surface, thereby obstructing the sunrays to penetrate through surface thus affecting the aquatic plant growth due to which plants decay and pollute the water body (The Wealth of India 1952). The tank is facing the problem of pollution due to domestic wastewater entering the lake from nearby residential and commercial establishments, washing of clothes, animal washing, etc. Due to an infestation of water hyacinth, Sambhaji tank is facing water pollution, which causes health hazards to public and municipal sewage waste management (Figs. 1, 2, 3, 4 and 5).

Fig. 1
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Sambhaji Tank, Solapur (without infestation)

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Fig. 2
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Sambhaji Tank, Solapur overcrowded with water hyacinth

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Fig. 3
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Boating in Sambhaji Tank, Solapur

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Fig. 4
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Obstruction for boating in Sambhaji Tank, Solapur due to overgrowth of water hyacinth

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Fig. 5
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Loading of water hyacinth weed from Sambhaji Tank, Solapur for disposal

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2.3 Bioconversion and Reuse Techniques by Energy Trapping

Non-conventional energy can be generated from different types of organic wastes like domestic, industrial, agricultural and aquatic weeds. Plant or animal waste is the best source of organic material for conversion into usable products or energy sources such as composting, liquid or gaseous fuel by biological processes or agents: such as certain microorganisms, some detritivores or enzymes (Wise et al. 1981). The bioenergy can be utilized for various purposes in the form of biogas, biofuel, biofertiliser, etc. The recent technologies like anaerobic digestion, gasification, incineration, pyrolysis and pelletization are implied in sustainable solid waste management (Zhu et al. 2008). Energy can be trapped, created and reutilized in the form of biogas, biofuel, thermal power, biofertilizers, etc., from various solid wastes.

3 Why Vermicomposting?

Huge amount of waste is generated in India which is sent for dumping and landfilling. Vermibiotechnology can be used to minimize this waste by converting it into nutrient-rich vermicompost. Worm castings also contain plant beneficial microbes and improve soil health. Vermicompost is superior as compared to chemical fertilizers because it not only enriches the soil but also provides organic matter needed for the soil. Vermicompost is superior to chemical fertilizers as it also decreases the use of pesticides for controlling plant pathogens. Decomposing and breakdown of organic wastes are time consuming when it is dumped and left as it is, but earthworms feed voraciously on decomposed waste, fragment the organic waste rapidly, resulting output which is nontoxic, has a potency of economic value. Decomposed organic wastes have a large population of pathogenic microbes which is harmful to humans and environment but vermicomposting reduces pathogenic microbial population (Kumar and Shweta 2011). It plays a leading role in minimizing environmental problems of soil, water and air pollution. Vermicompost technology can be practiced as cottage industry which lifts up the economic graph and provides employment and also supports a supplementary income. Vermicomposting is a low-cost technology and potentially agronomical valuable, could be practiced near wetlands, encouraging farmers to imply and harvest the weed.

3.1 Role of Earthworms in Solid Waste Management

Earthworms improve soil aeration and porosity, rapidly decomposes the organic matter by process of feeding on it, fragmentation and excretion of nutrient-rich casts (Edwards and Bohlen 1996; Shuster et al. 2000). Various organic wastes such as coir pit, kitchen waste, agro residues, industrial wastes, sludge are being processed by earthworms into valuable bioenergy-rich vermicompost (Ramalingam et al. 2004; Ndegwa and Thompson 2001; Garg et al. 2006; Nair et al. 2006). Solid waste management of filter mud and sawdust by vermitechnology employing two exotic and one local earthworm species Eisenia fetida along with Eudrilus eugeniae and Perionyx excavatus in monoculture and polyculture vermireactor systems proved to be a potential conversion into value-added end product (Khwairakpam and Bhargava 2009).

3.2 Studies on Bioconversion of Water Hyacinth

Vermicomposting proved an alternate promising option for controlling the menace of water hyacinth waste. Studies on water hyacinth vermicompost have been emphasized by Gajalakshmi et al. (2002), employing different earthworm species. The annelid, Eudrilus eugeniae was found to be an effective candidate for composting of different combinations of water hyacinth. Vermicompost of pre-composted grass clipping and water hyacinth amended with cow dung proved to be a successful treatment for solid waste management of water hyacinth with minimum complexity and economic viability (Ansari 2011). Application of water hyacinth to marigold plants improved growth and yield by enhancing nutrient supply in the soil to plant (Paul and Bhattacharya 2012).

4 Experimental Protocol

4.1 Earthworm Culture and Rearing

Earthworm species, Eudrilus eugeniae was procured from Zonal Agricultural Research Station, Solapur. Eudrilus eugeniae is fast growing and converts organic waste rapidly (Dominguez et al. 2001). The stock culture of Eudrilus eugeniae was grown by raised bed method using partially decomposed farm yard manure and cow dung as a food source.

4.2 Fragmented and Decomposed Water Hyacinth and Cow Dung Collection Procedure

Water hyacinth was obtained by deweeding manually and collected and dumped on the edge of road at the site of Sambhaji tank, Solapur, Maharashtra. This weed was cut into small pieces by mechanical shredder and sundried for 1 week. Cow dung was collected locally from livestock Ahimsa Ghoshala, Karamba, Solapur. The main purpose of adding cow dung is that it enhances the speed of vermicomposting (Muthukumaravel 1996).

Composting was done in specially constructed pits. During experimentation, the treatment used was 50% water hyacinth + 50% cow dung. An inoculum of 500 mature earthworms was released in decomposed organic waste. During pre-composting period, to ensure proper circulation of air and to prevent odour, the pit mixture was regularly turned up and down. Vermicompost treatment (T1) was compared against decomposed water hyacinth + soil treatment (DT1). Average moisture was preserved by sprinkling desired amount of water. To prevent moisture loss and from predators, the pit was covered with gunny bags. The average duration of the experiment was 150 days. Initial 60 days for decomposing and 90 days was required for vermicompost production. For the experimentation, two independent pits were used:

  • Pit 1: The contents of pit 1 were decomposed water hyacinth (DT1) and soil (60 days)

  • Pit 2: 50% water hyacinth + 50% cow dung for 90 days after the release of earthworms (T1).

For determination of physico-chemical and microbial parameters, samples were drawn from both the units, i.e. decomposed stage and after 90 days of vermicomposting.

4.3 Estimation of Physico-Chemical Parameters

The worm worked decomposed waste was subjected to nutrient analysis. The samples of decomposed treatment and vermicompost of experimental group were analyzed for chemical analysis: total nitrogen (N) by Kjeldahl method (Black et al. 1965), phosphorous by Olsen method (Olsen et al. 1954), potassium by flame photometry (flame photometer Elico made with C 1361 flame), pH of the samples were estimated by pH metre (Elico) with L1 612 pH analyzer, Electrical conductivity by EC bridge (Elico, CM-183EC-TDS) and moisture was determined by loss on drying method.

4.4 Field Experiment Using Groundnut (Arachis hypogaea)

A field experiment was conducted to study the effect of vermicompost on growth, yield and quality parameters of commercial crop groundnut during rabbi season in a private field at Karamba, which was 15 km from Solapur. The experimental site consisted of black-brown-textured soil and was neutral in reaction.

The physico-chemical properties of field soil were EC 0.21 (mS/cm), pH 7.90, Organic Carbon 0.73, Nitrogen 0.60%, Phosphorus 0.44%, Potassium 0.22%, C:N 27:1. The climate was hot and temperature ranged between 40 and 42 °C during experiment and irrigated by supply of bore water. In plot treatment, 10 plants were randomly selected and tagged with labels for reading of various morphological characteristics.

At village Karamba, Tal. North Solapur, medium deep well-drained soil was selected and two harrowing were given to the selected field for groundnut sowing. The well-decomposed farm yard manure (FYM) was well spread in the field at the rate of 250 kg/ha. as per recommendation. The gypsum application (250 kg/ha.) was also given in the selected field. Regarding chemical fertilizers, the dose was 25 kg nitrogen and 50 kg phosphorous/hectare was applied. The variety TG.26 was selected for the trial. The field layout as per the treatments was done and it was replicated by five times. The seeds were treated by Trichoderma at the rate of 5 g/kg of seed before sowing for better germination and healthy seedlings. The rhizobium seed treatment at the rate of 25 g/kg was also given to the seed before sowing. The seeds were sown by hand at the distance of 30 cm in between rows and 10 cm in between plants.

The plot size was of dimension 2.0 × 1.5 m and was of Randomised Block Design (RBD) method. Groundnut seeds applied were 100 kg/ha. The doses of vermicompost and chemical fertilizers were given to the plot at the time of sowing as per the treatments. One hawing and one weeding were given to the groundnut fields and plots were kept free from weeds. The protective irrigations were given to the plot as and when required at 15–20 days interval. The pest and disease incidence was recorded at 15 days interval till the harvest of the crop. An experimental plant was studied for morphological counts such as plant growth, height, number of leaves, branches and pods/tagged plants. Wet and dry pod along with fodder yield was recorded in kilogram/hectare and ton/hectare. The pest incidence of aphid, jassid, thrips and leaf minor was recorded on the crop. These were controlled by one spraying of dimethoate 30 EC at the rate of 500 ml in 500 L of water/hectare. The leaf minor pest was controlled by spraying quinalphos 25EC at the rate of 1000 ml in 500 L of water/hectare. There was no incidence of tikka or rust disease on the crop and hence no any fungicide sprays were given to the crop. The data obtained during experimentation was subjected to statistical analysis which included paired sample t-test and ANNOVA. p value significance was also calculated of decomposed treatment against vermicompost and comparing field output (Bailey 1965).

  • Randomized Block Design method layout for field experiment of Groundnut ( Arachis hypogaea L.)

 

R I

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4.5 Selection of Groundnut for Field Experiments

Groundnut contributes 35% of world production by India. It is adaptable to all soil types and textures. The yield under irrigated conditions is double as those grown as dry crops. The yield in India is greater as compared to Africa and the USA. India cultivates groundnut in an average area of 6.41 million hectares. Groundnut is an important source of edible proteins and oil in India. India is on lead after China in groundnut production, contributing around 19% of the world production. Groundnut yield in India is 1.13 ton/ha. The major states in India involved in the production of groundnut are Andhra Pradesh, Tamil Nadu, Gujarat and Maharashtra contributing towards 90% of production (Mehrotra 2011).

Around 80% of groundnut in the country is cultivated during kharif season. Grown in tropical and subtropical areas between 25 and 28 °C and under 500 mm rainfall in the loamy and black soil. Botanical name of groundnut is Arachis hypogaea of leguminous family, measures 1–5 ft. in height, the plant is a hairy, tap-rooted which has many nodules. In Khandesh, Vidharba, Sangli and Satara in Maharashtra, groundnut harvest is done during the month of January–May, whereas in Ahmednagar, Pune and Solapur district, the crop is cultivated between March and August. In Marathwada crop rotation of groundnut and wheat is practiced. Solapur, Latur, Amravati and Jalna are four major districts in Maharashtra producing 0.7 million tons of edible oil (Mehrotra 2011). At present there are 98 oil mills including 170 expellers, 152 big and 18 small expellers in Solapur city. Groundnut production in Solapur district during the year 2007–2008 with an average yield was 4.80 ton/ha. (http://www.coin.fao.org/cms/world/india/en/Home.html). Groundnut has 25–33% protein, carbohydrate 10.2%, fat 40.5% and calorie value 500–600. Groundnuts are rich in vitamin, B-complex which includes thiamin, riboflavin and nicotinic acid. Groundnuts are good source of vitamin E (Wrenshall 1949). Oil extracted from groundnut seeds is an important food source. Groundnut cake used as cattle feed in India which has good amounts of protein. Groundnut stems with shoots and branches are fed to cattle in green and dry form. Groundnut shells can be bioconverted into manure to improve soil health as well can be used as a biofuel (Talwar 2004). Due to high fat and protein content, groundnut is a valuable energy-giving food. It is used for oil, seeds, flour and butter, while the plants as fodder and husk for agricultural purpose. Groundnut cake is used for feeding farm animals.

4.6 Studies on Field Experiments

Organic farming has taken a rapid speed to meet the essential nutrient inputs to soil, because use of chemical fertilizers lead to deterioration of both soil and agricultural products and as well environmental pollution (Liu et al. 2009; Padel et al. 2009). Vermicompost is a stabilized, fine porous material loaded with plant beneficial microbes and nutrients readily to take, has increased water holding capacity (Dominguez 2004).

Growth and yield parameters influenced by vermicompost application were studied on crops like tomato (Lycopersicum esculentum), garlic (Allium stivum L), sweet corn hybrids (Zea mays), rice, cicer, pisum, etc. (Joshi and Vig 2010; Suthar 2009; Lazcano et al. 2011; Sudhakar et al. 2002; Sinha et al. 2010). Increased germination rate reported in crops like groundnut, cucumber, red amaranth, pak choi, Chinese mustard green (Hidalgo 1999; Lee et al. 2012). Favourable effects of vermicompost application on various crops in terms of yield, growth, etc., have been reported. Vermicompost besides having nutrients also shows the increased source of nitrogen useful for growth of plant beneficial microbes (Ravindran et al. 2008). Vermicompost affect positively on plant growth by better aeration to the plant roots, enhancing readily available water, triggering nitrogen, phosphorous and potassium exchange for better plant growth (Manivannan et al. 2009).

5 Aftereffect of Vermicompost Application on Field Experiment

5.1 Physico-Chemical Parameters

Moisture was increased in vermicompost by 59.05 ± 2.94% compared to decomposed treatment (49.48 ± 0.79%), with percent variation of 19.34% significant at p < 0.01 (Figs. 6, 7 and 8). Electrical conductivity increased in T1 by 1.69 ± 0.17 mS/cm as compared to decomposed treatment 0.64 ± 0.35 mS/cm). The vermicompost result was significant at p < 0.001 with percent variation of 164%. pH content was 8.34 ± 0.85 in decomposed treatment and seen reduced in vermicompost by 6.00 ± 0.20 significant at p < 0.05 with a significant difference of 28.05%. Nitrogen percentage in T1 was enhanced by 1.50 ± 0.06% while it was 1.01 ± 0.01% in decomposed water hyacinth with significant difference of 50.00% at p < 0.001, Phosphorus content in vermicompost was 1.89 ± 0.03 compared to decomposed treatment (0.89 ± 0.02) significant at p < 0.001 with percent variation of 112%. Potassium level was increased in vermicompost treatments after 90 days, in T1 the value was 1.15 ± 0.48 compared with control (0.23 ± 0.03) significant at p < 0.001 with percent variation of 400%. C:N ratio in decomposed water hyacinth was 19.63 ± 0.06, which was decreased after the release of earthworms in vermicompost treatment (11.00 ± 0.03) with percent variation of 43.00% significant at p < 0.001.

Fig. 6
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Analysis of physico-chemical characteristics of decomposed water hyacinth and vermicompost water hyacinth (Eichhornia crassipes) (Mean ± SD, n = 3)

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Fig. 7
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Effect of vermicompost processed by Eudrilus eugeniae on groundnut (Arachis hypogaea) dry pod yield compared with control

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Fig. 8
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Effect of vermicompost processed by Eudrilus eugeniae on Groundnut (Arachis hypogaea) dry fodder yield compared with control

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5.2 Pod Yield

The total yield of groundnut pods on a dry basis in control group was 0.546 tons/ha. It was increased in T1 group vermicompost applied field was 1.178 ton/ha. (115%) as compared to control. The results were subjected to ANOVA and F value was 78.96 significant at p < 0.001 (Figs. 9 and 10).

Fig. 9
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Result of vermicompost effect on plant and pods compared with control

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Fig. 10
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Result of vermicompost effect on groundnut plant and pods compared with control

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5.3 Dry Fodder Yield

Dry fodder yield of groundnut crop Arachis hypogaea after harvesting was more from vermicompost applied field as compared to the soil as control applied field. The dry fodder yield in T1 treated plot was 1.519 ton/ha. (102%) compared to control treated plot (0.750 ton/ha.). The vermicompost result was significant at F value of 151.9 at the value of p < 0.001 (Figs. 11, 12, 13 and 14).

Fig. 11
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Moisture content and C:N ratio in vermicompost treatment compared with decomposed water hyacinth

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Fig. 12
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Electrical conductivity, pH, nitrogen, phosphorous and potassium content in vermicompost treatment compared with decomposed water hyacinth

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Fig. 13
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Effect of vermicompost processed by Eudrilus eugeniae on groundnut (Arachis hypogaea) dry pod yield compared with control

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Fig. 14
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Effect of vermicompost processed by Eudrilus eugeniae on groundnut (Arachis hypogaea) dry fodder yield compared with control

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6 Discussion

Vermicompost is organic manure produced by the activity of earthworms in collaboration with gut microflora. It contains rich macro and micronutrients (organic carbon, nitrogen, phosphorous, potassium, calcium, magnesium, sulphur, copper, iron, manganese zinc, boron, sodium, chlorine). Besides these nutrients, physical parameters (moisture, electrical conductivity, pH, ash) have a greater role to play in soil structure. In the present investigation the experiments carried out for converting water hyacinth, an aquatic weed into useful vermicompost with the association of earthworm species, Eudrilus eugeniae using pit method resulted in significant variations in micro, macro and physical parameters of the vermicompost produced from pit method. In the present investigation, the pit method noticed enhancement of the moisture in T1 treatment (Fig. 6). During the conversion of press mud sugarcane waste to vermicompost, it was observed that moisture level of vermicompost between 65 and 75% enhanced microbial population, biomass and cocoon production of earthworm (Parthasarathi 2007). From our results, it is clear that from all the pit method of vermicompost cow dung along with water hyacinth enhanced the moisture contents. In the present study, the electrical conductivity in millisiemens per cm (mS/cm) from vermicompost produced with the help of pit method observed increased values when compared with control decomposed water hyacinth. A significant increase in electrical conductivity levels from compost without worms to worm worked vermicompost was seen during the vermicomposting process, which may be boosted by earthworm activity, the soluble salt level increases in combined action of microorganisms present in the organic raw matter and in the digestive tract of earthworms (Karmegam and Daniel 2008). The variations in pH alter many macro- and micronutrients mobility in the plants. In the present study, pH content from vermicompost, produced with the help of pit method noticed a decrease in the values. While recycling the organic wastes of cow manure, poultry and food industry waste to produce vermicompost with the help of Eisenia fetida a decrease in pH at the end of the experiment was noticed, when compared to initial values (Yadav and Garg 2011). pH variations from different sources of waste may be credited to physic–chemical attributions of wastes used in experimentation. pH change may be due to the formation of organic acids from feeding substrates or due to the type of substrate used as raw organic matter (Suthar and Singh 2008). Earthworm casts contain twofold of both macro and micronutrients, reduced C:N ratio compared to that of garden compost (Saranraj and Stella 2012). While converting milk processing industrial sludge along with plant waste into vermicompost with the help of Eisenia fetida there was significant drop in C:N ratio as that of initial substrate waste which may be due to the loss of carbon during respiratory activities and microflora associated with a decrease in carbon: nitrogen ratio of the substrate (Suthar et al. 2012). According to (Gupta et al. 2005), the lowering of C:N ratio from final product vermicompost is an indication of the maturity of composting. While studying the conversion of organic material into composted final product there was a reduction in C:N to 8.13 for the vermicompost and 1.05 for the compost (Castillo et al. 2010).

Nitrogen is important for plant growth and overall to the food and fibre production of the livestock. In the present study, the nitrogen content from vermicompost produced by pit method with the help of Eudrilus eugeniae after using organic raw material resulted in an increase in nitrogen content. During bioconversion of domestic waste into vermicomposting worked by two epigeic earthworm species Perionyx excavates and Perionyx sansibaricus, there was enhanced nitrogen content from the vermicompost which may be due to inoculation of earthworms in the waste material that significantly enhanced the amount of nitrogen due to earthworm-mediated nitrogen mineralisation of the waste (Suthar and Singh 2008). Earthworm contributes through mineralization of nitrogen, secreting its mucus and excreta providing the sites for chemical reactions, encourages the proliferation of nitrogen fixers (Singh and Suthar 2012; Dominguez 2004). Phosphorous is required in large quantity for routine growth in living organisms. The energy is derived from phosphorous-containing compounds ATP and ADP hence continuous phosphorous supply is highly essential for energy inputs. Rise in level of available phosphorus worked with earthworms from press mud might be due to break down and release of phosphorus by co-ordinated action of faecal phosphatases of these annelid worms and microbial activity in the casts (Vinotha et al. 2000) and due to microbial activities producing organic acids, solubilizing inorganic phosphorous, mineralization of organic phosphorous by phosphatase activity of earthworms (Scervino et al. 2010; Eivazi and Tatabai 1977). Potassium is required for plants attaining optimal growth. In the present study, the potassium content from the vermicompost produced through pit method enhanced the potassium content. Macronutrient Potassium level was reported to be increased in worm worked compost which may be initiated by the action of both Perionyx sansibaricus and microbes that boosted the rate of mineralization (Suthar 2007).

6.1 Energy Recovery from Water Hyacinth Biomass Through Vermicomposting

In the present investigation, the total dry yield in the form of pods enhanced to its maximum yield in T1 treatment when compared to control (0.546 ton/ha.) of the groundnut crop (Fig. 7). Similarly, the dry fodder biomass after harvesting the groundnut crop (120 days) vermicompost application produced maximum fodder in T1 treatment 1.519 ton/ha. when compared to control group (0.750 ton/ha.). Effect of 4% vermicompost application produced from municipal garbage on growth and productivity of canola an important oil crop, (Brassica napus) was displayed by increased growth, biomass and yield of canola under normal irrigation. There was 47.19% improved yield after 4% vermicompost application and hence vermicompost can be used for sustainable plant production because it is an efficient plant growth medium (Rashtbari et al. 2012). Vermicompost act as a chelating agent and further regulate the utilization of microminerals to the plant which finally influences the overall development of the plant (Giraddi 1993). A study on field application of vermicompost in combination with nitrogen fertilizer on wheat recorded an increase in dry crop husk (16.2 g/plant) and wheat grain yield (3.6 ton/ha.) (Desai et al. 1999). The combined application of nitrogen, phosphorous and potassium fertilizers and vermicompost increased the yield of cabbage (58.67%) over control which may be attributed to increased availability of native and applied macro and micronutrients (Devi and Singh 2012). The application of vermicompost produced from the organic waste resulted in improved growth and yield of an ornamental plant Amaranthus species. An overall increase in nutrient contents especially nitrogen, phosphorous and potassium was seen which finally enhance the total yield attributed towards higher availability and uptake of plant nutrients and growth promoting substances during the entire duration and crop harvesting (Uma and Malathi 2009). Similar might be a case in the present investigation in which eco-friendly manner of converting aquatic weed into vermicompost was utilized and observed higher yield of the commercial groundnut crop. From our studies, it is clear that water hyacinth aquatic weed after converting it into useful vermicompost with the help of pit method by using Eudrilus eugeniae can be applied on the field trials using groundnut crop. In vermicompost treatment pod and biomass yield (fodder yield) increased significantly compared with control. The total dry matter yield in vermicompost treated plot was 1.519 ton/ha. as compared to control plot which yielded 0.750 ton/ha. (Fig. 8). This might be due to the substantial amount of nutrient supplying to the plant treated with vermicompost which leads to the increase in the number of branches, leaves, height of plant and finally pod number and groundnut yield for sustainable agriculture. Recycled vermicompost could be a boon for the farmers. The fresh fodder (2.62 ton/ha.) makes up 52% of total fresh biomass and dry fodder (1.88 ton/ha.) makes up 46% of total dry biomass (Bassam 2010). The studies also cleared the better impact of various combinations such as vermicompost produced from water hyacinth amended with cow dung on field experiments. The positive impact of vermicast to field soils is it makes it fertile enough to withstand same crop growth and yield in repetitive cultivations which later require smaller concentrations of vermicast, whereas chemical fertilizers have to be applied in increasing doses which have a negative impact on soil properties.

In our studies, the initial biomass we used for vermicomposting process reduced to its half, i.e. 35% of original waste after it was decomposed and ready to introduce earthworms. Thus, a huge amount of biomass can be reduced volumetrically by vermicomposting and can be prevented by dumping this large amount of solid waste through landfilling. The reduction of waste occurred during pre-vermicomposting period reduced the time required for vermicomposting and area of worm bed with waste stabilization. A study conducted on effects synthetic nutrients such as iron, manganese, zinc, copper, molybdenum and boron and their influence on earthworm growth during vermicomposting displayed a marked increase in worm growth rate with significant waste volume reduction (Palaniappan and Thiruganasambadam 2012). The volume of municipal solid waste reduced to 35% of total volume in the process of vermicomposting in the Ujjain city (Dalal 2012).

The vermicompost serves as an option for energy generation. Wastes such as sugarcane, spent tea and grated coconut meat turned into vermicompost proved to produce electrical voltage that light up the LED. Thus, it can be an alternative for battery, reducing the negative impact of chemicals in environment (Karim et al. 2011). Rich organic sources such as rice husk, bagasse, groundnut shells and maize cobs are effective sources of electricity generation, heat and cooking fuel due to low concentrations of carbonaceous substances. These also contribute less to total greenhouse gas emissions. Sum total of crop including grain is used as bioenergy feedstock. The remnant to product ratio of groundnut was estimated to be around 0.5–1.2 for pods and 2.2–2.9 for straw; which explains that every ton of nut production yields 500–1200 kg of shells, 2.2–2.9 tons of straw residue are harvested; in total groundnut crop yields between 3.7 and 5.1 tons of biomass per hectare. These residues are an efficient source of solid biofuel, with a relatively high energy content of 16 Mj/kg for shells and 18 Mj/kg for straw—with advanced bioconversion technologies (cellulosic ethanol or pyrolysis) this ‘waste’ biomass can be turned into liquid fuels and bioproducts; alternatively, it could be densified and used in biomass (co-firing) power plants (http://news.mongabay.com/bioenergy/). Groundnut shell has great potential for domestic, industrial energy resource. Groundnut shell residue is a good source of energy for purposes like fuel, cattle feed, making boards, can replace cork, as a mulch, etc. Groundnut shells show woody characteristics with moisture 8.76%, Carbon 15.50%, ash 20.3 and volatile matter 54.96.

Combustible gases like H2, CO, CH4, CO2 and N2 production were successfully produced from groundnut shell (Sivakumar and Krishna 2010). Also, the amount of producer gas, i.e. hydrogen was seen in higher concentration than coconut shell and rice husk. Groundnut crop is termed as an energy crop because it not only yields food as peanuts but also net yield waste, compost from feedlots and dairies are left behind. All of these items can be used for fuel (http//:www.InfinitePower.org). Ethanol was extracted from groundnut shell biomass (Akpan et al. 2005). Agriculture residue such as groundnut shell biomass was used in the production of briquettes which is an alternative source of energy, since briquettes are used as fuel energy (Maninder and Kathuria 2012). Biomass briquettes are substitutes for electricity, heat and cooking fuel. It is found to generate around 61,000 MW energy and briquettes manufacturing industries may turn as employment hubs for around 15.52 million appointments. Farmers too are benefitted and can earn $6/ton by supplying their farm residues to these industries (Tripathi et al. 2000). The end use of briquettes is mainly for replacing coal substitution in industrial process heat applications (steam generation, melting metals, space heating, brick kilns, tea curing, etc.) and power generation through gasification of biomass briquettes (Tripathi et al. 2000). Groundnut shell was used as a biomass which was blended with coal to produce environmental-friendly biofuel briquette in an effective way (Onuegbu et al. 2012). It was also observed that ash contents of groundnut shell were less than that of coal, the lower the ash content, the better and the quality of the fuel. It was found that groundnut shell ash is equivalent to Portland cement concrete and can be used as a substitute for the later (Alabadan et al. 2006). The blending of cement with groundnut husk proved to be effective in soils containing chemical magnesium sulphate and sodium chloride (Adole et al. 2011). In a feeding trial on mature cows, they were fed with peanuts along with shells. The food intake and digestibility data significantly proved that whole peanut along with shells as a source of energetic nutritional valued food (Myer et al. 2009).

7 Concluding Note

From our results, it is evident that vermicompost derived from water hyacinth an aquatic weed has enhanced nutritional value and showed effective outcome on growth and productivity of groundnut crop. Thus, the overall biomass is also increased which contributes towards economic agriculture practices and environmentally eco-friendly method. Our approach of vermicomposting has provided a scope for the solid waste utilization of water hyacinth in Sambhaji tank, Solapur, India in an eco-friendly manner. This could become a source of wealth for Solapur Municipal Corporation if subjected for mass bioconversion of solid waste into a biofertilizer. This will simultaneously control the environmental pollution caused by aquatic weed. Finally, it can be concluded that earthworms are good bioengineers for recycling organic waste produced from the aquatic weed, i.e. water hyacinth. They are the natural bioreactors that can degrade the organic matter biologically, enrich the soil fertility and have a prime role in the total yield of crop. Vermicomposting is the best practice; can be adapted as eco-friendly, economically feasible, pollution-free approach of converting the waste biomass and retrieving the same in the form of useful vermicompost. Excess use of chemical fertilizers can be avoided by using aerobically produced biofertilizers. This is the method of recycling, reuse and reutilizing waste by bioconversion of water hyacinth into a useful product and later such vermicompost effectively used for cultivation of agricultural crops. This technology can be used for sustainable agriculture practices which enrich the soil by addition of nutrients as well as enhancement of microbial population. Vermicompost considered as gold produced from garbage has a greater nutritive value which has combined effects in the overall growth and yield of agricultural crops.