Chapter 15

Boosting Our Soil With Green Technology: Conversion of Organic Waste Into “Black Gold”

Kuben Naidoo^*

Harry Swatson^**

Kwasi S. Yobo^†

Georgina D. Arthur^*
*    Mangosuthu University of Technology, Durban, KwaZulu-Natal, South Africa
^**    Cedara College of Agriculture, Cedara, KwaZulu-Natal, South Africa
^†    University of KwaZulu-Natal, Pietermaritzburg, KwaZulu-Natal, South Africa

Abstract

Composting is nature’s way of recycling nutrients to sustain soil fertility. Human population growth and enhanced industrialization have resulted in the production of high quantities of degradable waste that need proper disposal. Inappropriate monitoring of waste biomass has contributed to the emission of greenhouse gases and contaminated water and soil. Composted wastes include agricultural residue, animal manure, cafeteria waste, and paper. Agents involved in composting are detritivores that break the substrate to speed up biological processes. Earthworms are great biodegraders and together with their microbial counterparts break renewable into ecologically safe vermicompost and vermileachate. In situ and ex situ recycling of waste can be practically undertaken in an environmentally acceptable and economically feasible manner to reduce the cost of waste disposal. This can improve the socioeconomic status of both small scale and commercial farmers. Earthworms hasten the mineralization of organic matter and breakdown of structural polysaccharides and increase humification rates and leachate production. The world’s best worm composter of biomass Eisenia fetida (red wriggler) offer favorable and commercially acceptable products. Soil amendment by worms improves soil health, plant growth, and suppresses pathogens. Vermicomposting provides a means of handling high volumes of accessible organic wastes from livestock for raising crop organically. Managing excess manure in a sustainable way that prevents ecosystem pollution. This chapter discusses efficient production and use of a complex living system—“black gold” (vermicompost)—as a renewable source of plant nutrients.

Keywords

waste biomass

earthworms

detritivores

biodegraders

humification

vermicomposting

1. Introduction

Environmental degradation has become a major hazard facing the world today, caused by high human population rates resulting in an increase of waste production. There are clear indications that soil fertility is dropping, and that farmers try to compensate by increasing fertilizer applications. This serves to aggravate the problem, as one of the reasons for the decline in fertility is the lack of proper management of soil organic matter. Records have shown that large quantities of waste are produced by human beings through excretion, manufacturing materials, from farming systems and agricultural production; this includes animal manure, food and restaurant wastes, and industrial organic waste (Bajsa et al., 2003; Edwards and Arancon, 2010). Hoornweg et al. (2013) stated that presently, waste is generated faster than other environmental pollutants, including greenhouse gases. According to Edwards and Arancon (2010), the rate of waste production has the potential to become a global threat through soil and water pollution, as they are currently disposed by land-spreading, incineration, or into landfills.

There is an increased recognition that the adoption of earthworm farming (vermiculture) can be a solution for reversing the world’s crisis by recycling waste as natural bioreactors for cost-effective and environmentally sound waste management (Aalok et al., 2008). According to Bajsa et al. (2003) sustainability can be reached by vermicomposting organic matter, which involves an accelerated cycling of nutrients whereby waste products are put to productive end use. Sinha et al. (2009) noted the negative impact of agrochemical usage by farmers on soil, flora, fauna, and water bodies in farms. This in turn affects humans who consume chemically grown agricultural products. According to the United Nation Environment Program (UNEP) and the World Health Organization (WHO), “acute pesticide poisoning” has resulted in the deaths of millions of people worldwide (UNEP/GEMS, 1992). The immense potential of synergistic benefits of organic farming and the benefits and the limitations of organic agriculture were spelt out by Rundgren (2006), as follows. It must be noted that the impact of a conversion to organic practices will greatly depend on knowledge of the farmer and farming community, their skills, and the resources available to them through the following identified relevant keys.

• Organic agriculture can increase productivity, especially in situations where farmers are vulnerable to food shortages.

• Organic agriculture can increase income and/or returns to labor. This can be achieved through higher yields, higher (premium) prices, lower costs (for inputs), or combinations of these three.

• The diversification of production inherent in organic agriculture reduces the risk of crop failure and attendant economic and food security problems. This accords strongly with the risk aversion strategies adopted by low income farming households.

• Organic agriculture produces safe food and a more varied and nutritious diet.

• Organic agriculture eliminates the very real risks associated with exposure to pesticides and other toxic chemicals.

• Organic agriculture has a major role to play in assisting with resource management, such as reducing water demand and run-off, soil erosion, and in maintaining and enhancing biodiversity.

• Organic agriculture makes farmers and consumers more aware of the need for sustainable production and consumption, of the importance of clean and safe food and of the need to protect the environment.

• Organic agriculture brings clear benefits to women in agricultural communities, to other marginalized groups, as well as offering new employment opportunities for the landless poor.

• Organic agriculture recognizes the value of traditional and indigenous knowledge and integrates this in its production methods, thereby increasing social capacity and self-value. According to the records of a former revenue inspector in Karnataka, India, rice farmers using high-yielding varieties and chemical fertilizers saw their crops reduced by more than 50% during the 2001–2002 droughts, whereas the region’s organic farmers lost less than 20%. Similarly sugarcane losses were 58 and 1%, respectively. These developments resulted in greater adoption of organic methods in India.

• Organic agriculture is sustainable in the long term. It enhances environmental resilience against, for example, drought, flooding, or other climatic catastrophes. There are also several examples where it has been used to restore degraded and abandoned land.

• Organic agriculture has a clear role to play in helping to meet a range of global environmental policy objectives, including those relating to combating desertification, to maintaining biodiversity and offsetting the consequences of global warming (through carbon sequestration).

Organic agriculture prevents the vicious cycle of land degradation (Fig. 15.1).

Figure 15.1 The Vicious Cycle of Land Degradation (UNCCD, 2013).

2. Brief History of Vermicomposting

Historical evidence have suggested that the ancient Greece and Egyptians civilizations recognized the vital role played by earthworms in fertilizing the Nile Valley croplands after annual floods. Ancient finds have indicated the usefulness and economic benefits and potential of utilizing various species of earthworms in converting diverse organic waste into valuable agricultural compost. Vermicomposting, also known as vermicasting, is a process of using certain species of earthworms, such as Eisenia foetida, Eudrilus eugeniae, and Perionyx excavates to convert, digest, or breakdown organic wastes (Edwards, 2013; Edwards and Arancon, 2010; Nagavallemma et al., 2004). It is a natural and aerobic process that emits little or no odor, and hence very different from the traditional method of composting. Vermicomposting has therefore been associated with a positive way of reducing large volumes of green wastes, to lessen the negative impacts these wastes have on the environment.

Interest in vermicomposting has increased tremendously over the past two decades. It all began in 1881 when Charles Darwin first drew attention to the significance of earthworms in converting dead organic materials into essential plant nutrients (Edwards, 2013). The full potential of using earthworms to digest organic residues has since been explored using different methods and strategies. During the 1970s, research programs on the conversion of organic and food wastes into vermicompost were initiated by Dr. Roy Hartenstein and Dr. Edward Neuhauser at the State University of New York and Cornell University, respectively. This research program was later extended to include different types of wastes, such as poultry, pig, cattle, and urban organic residues. This expansion of the initial research program was an interdisciplinary one made up of 50 scientists that involved agricultural engineers, biologists, and economists (Edwards, 1995). The extended research program was done at the Rothamstead Experimental Station, United Kingdom, and elsewhere in other research institutes (Edwards, 2013). Vermiculture started spreading in the United States and the United Kingdom from 1950 to the 1980s (Bareja, 2011). The phenomenon was later adopted by the Philippines in 1979 (Guerrero, 2009). Ontario (Canada) is currently processing about 75 tons of refuse per week (Aalok et al., 2008). It has been noted that there is a steady increase in the production of vermicompost worldwide, especially in the Western countries, Asia-Pacific and Southeast Asia, and South Africa (Farthing, 2009; Zafar, 2015). Since then, work done on vermicomposting by various researchers in Europe has greatly complemented the earlier work on vermicomposting (Zafar, 2015).

3. Management of Worms

There are different basic types of vermicomposting methods that can utilized in both small and large scale production. These include bins of beds, windrows, pits, cement rings, heaps, and tanks (Aalok et al., 2008; Nagavallemma et al., 2004; NIIR Board, 2004). The vermicompost can be produced indoors and outdoors. Outdoor vermicomposting thrives under suitable climatic conditions and indoors in buildings or plastic tunnels. For maximum productivity optimal environmental conditions should be maintained (Edwards and Arancon, 2010).

3.1. Bins and Tanks

Bins and tanks are the most convenient method of processing vermicomposting; this is done through the aid of bins and tanks made of plastic or nonaromatic wood (Aalok et al., 2008). Shredded paper or composted animal manure or decaying leaves can be used as bedding to provide the worms with material through which to burrow (Nagavallemma et al., 2004). Tanks can be made from materials, such as bricks, hollow bricks, shabaz stones, and asbestos sheets (Nagavallemma et al., 2004). The bedding must be watered frequently to keep it moist, allowing aeration and making it easy for the worms to breathe. It is advisable to feed the worms organic foods, such as vegetables and fruits. The worms should never be fed with fatty, oily foods as this promotes an unpleasant odor in the bins or tanks (Aalok et al., 2008).

3.2. Pits

Vermicomposting pits are mainly used by farmers. These farmers dig a large hole that serves the purpose of burying worms and organic waste material. Pits made for vermicomposting are usually 1 m deep and 1.5 ms wide. This method can allow some worms to escape into the soil; hence precaution has to be taken by lining the pit before adding the worms and the bedding into the pit (Nagavallemma et al., 2004). The lined pit should be filled with organic materials, such as straw, grass clippings, and manure, and covered with soil (Garg et al., 2005). The lining must be done to ensure proper water drainage. The vermicomposting procedure usually starts after about a week, when the pit has been lined and filled with manure, grass, straw, and covered with soil (Lynch, 2015).

3.3. Windrows

Windrows are mostly used by commercial farmers; these structures are about 100 feet long, 3 feet high, and 3 feet wide. This method can be done using different ways. The common ways include static pile (batch) windrows, top-fed (continuous) flow windrows, and wedge windrows, which are similar to continuous flow (Munroe, 2007). The static pile windrows are made up of piles of mixed bedding and feed. The piles are made up in an elongated form in a windrow style. The shape can also vary from elongated forms to squares and rectangles. They are usually not more than 1 m in height (Munroe, 2007). They are usually produced outdoors, covered with top roofing using corrugated iron to prevent rain while allowing ventilation on the sides (Biernbaum, 2015). Fresh organic matter feed is added toward the edges of windrows to ensure ongoing movement and production of vermicompost by the worms (Appelhof, 2007). In pits and windrow vermicomposting methods, lining is used to prevent worms from escaping. However, lining can limit the movement of air, thereby resulting in an anaerobic condition in the compost pile (Papadopoulos and Savvides, 2003). Anaerobic conditions can lead to rapid and total loss of the worm-composting population.

The top-fed windrows, which are a continuous flow, are similar to static windrows, except that they are set up in a continuous flow operation. The bedding is placed first and inoculated with the required type and amount of earthworms and then repeatedly covered with thin layers of feed for the earthworms. Usually, layers of new bedding are periodically added to replace the bedding material that is gradually consumed by the earthworms (Usman et al., 2015).

Wedge windrows are also a continuous flow system, but at the same time a variation of the top-fed windrow. An initial stock of earthworms in bedding is placed inside a corral-type structure (usually three-sided) of about 1 m in height. The materials used for the sides of the corral can be wood, concrete, or straw. Fresh materials are added on regularly through the open side. The earthworms follow the fresh feed over time, thereby leaving the processed material behind (Appelhof, 2007).

3.4. Beds or Bins

This is the simplest form of vermicomposting. It involves a bin made from plastic or untreated nonaromatic wood (Lynch, 2015). Shredded paper or composted animal manure can be used as bedding. The bedding requires water to stay moist to allow the worms to breathe.

3.5. Heaping and Cement Rings

This is usually above the ground. In this method, the organic waste material is spread on a polythene sheet on the ground. This is then covered with cattle dung. For the ring method, cement rings that have been made above the ground can also be used (ICRISAT and APRLP, 2003). The size of the cement ring should be about 90 cm in diameter and 30 cm in height. A description of the various systems and methods is shown in Table 15.1 (Usman et al., 2015).

Table 15.1

Brief description of different vermicomposting systems.

Vermicomposting System	Descriptions
Windrow	Long rows on ground up to a depth of 50 cm, organic waste is placed and worms are introduced.
Continuous flow system	Container above the ground with mesh floor.
Stacking system	Several trays on top of one another. Mostly, three trays are used, each 150 mm in depth.
Batching system	Compiled using boxes.
Wedge system	Horizontal feeding method, feed is applied on the bedding at a 45-degree angle.
Pits	Below the ground, 1 m deep and 1.5 m wide pits with varying lengths.
Heaps	Above the ground, heaps are made with placement of polythene sheet on ground.
Tanks	Above the ground, tanks are made with normal bricks.
Cement rings	Cement rings are made with dimensions of 90 cm diameter and 30 cm height.

After Usman, A., Nida, S., Azeem, K., Luqman, R., Muhammad, M.R., Jabir, H.S., Riffat, N.M., 2015. A review on vermicomposting of organic wastes. Environ. Prog. Sustain. Energy 34, 1050–1062.

4. Vermicomposting and Vermicompost Modern Strategy

Through the feeding of organic waste materials, the earthworms release vermicompost in a granular form (Zafar, 2015). This is also known as excrement, which is called casting. It increases the microbial activity in the soil; it improves the water holding capacity, as well as the humus levels in the soil (Masciandaro et al., 2014). The chemical secretions in the earthworm’s digestive tract help break down soil and organic matter, so there are more nutrients in the castings that are immediately available to plants (Zafar, 2015).

Vermicomposting in the 1950s to 1980s was mostly done in pits by farmers, where they dug a large hole which served the purpose of burying worms and organic waste material. The pits made were usually 1 m deep and 1.5 m wide. This method risked the escape of some worms into the soil, and therefore strategies of keeping these worms in place to produce vermicompost, such as the use of bins and tanks made of plastic, were adopted (Aalok et al., 2008) and were suggested to be the most convenient way of processing vermicomposting (Nagavallemma et al., 2004).

The production process involves:

• Collection of wastes, shredding, farm wastes, crop residues, vegetable market waste, fruit market waste, and all other biodegradable waste that is suitable for vermicompost production.

• Predigestion of organic waste for 20 days by heaping the material along with cattle dung (except pig and goat and wet dung which should not be used for vermicompost production).

• Preparation of earthworm beds. Use of bins and tanks made of plastic or nonaromatic wood for vermicompost preparation. Loose soil is also added to allow the movement of worms. Watering enables dissolvable nutrients to leach into the soil along with water.

• Collection of compost by sieving the composted material to separate fully composted material. The partially composted material will be again put into a vermicompost bed. If there is need to keep your worms for another round of composting, separate them from the compost into a new bin with some fresh bedding and feed.

• Store the vermicompost in a proper facility to maintain moisture and allow beneficial microorganisms to grow.

Vermicomposting is a mesophilic process that involves microorganisms and earthworms. These earthworms feed on food waste materials. There are nearly 3600 types of earthworms that can be used for vermicomposting (Manyuchi et al., 2013; Nagavallemma et al., 2004). There are the burrowing types (Pertima elongate, Pertima asiatica) and nonburrowing (Eisenia fetida, Eudrilus eugenae) types. Nonburrowing types are known to convert organic food wastes into vermicompost faster than the burrowing types.

They are also known to eat 10% of soil and 90% of organic and food waste materials that are used as feedstock for vermicomposting. Among the earthworms, E. fetida is the species that is mostly used for conversion of organic wastes (Usman et al., 2015). Some useful species of earthworms in vermicomposting include Dendrobaena veneta, Lumbricus rebella, E. eugeniae, and P. excavates (Edwards, 1998). Organic waste and soil ingested by earthworms passes through their body and mixes with digestive enzymes (Lavelle, 1988). The roles played by these earthworms in the vermicomposting process are performed more efficiently in moist soil and aerated soils with low acidic value (Usman et al., 2015).

There are some important factors that must operate at optimum ranges to have maximum influence on vermicomposting processes. These include feeding the earthworms, pH of the mixture, temperature of the process, moisture content, stocking density, and carbon:nitrogen (C:N) ratio (Usman et al., 2015).

According to Neuhauser et al. (1988), feeding rate is influenced by other factors, such as moisture, particle size of the organic feedstock, and the content of the substrate. The methodology adopted while feeding the substrate to the earthworms is important to avoid the build-up of anaerobic conditions in the process that will lead to the production of foul odor. Moreover, the presence of toxic metals in the organic feed should be avoided, as this is fatal for earthworms (Gupta et al., 2005). A pH between 4.5 and 9.0 has been suggested as a suitable and favorable range for worms during the vermicomposting process (Edwards and Lofty, 1977). Studies have also shown that different types of substrates used as feedstock (Table 15.2) do affect the pH vermicomposting system (Elvira et al., 1998; Yadav and Garg, 2009). The C:N ratio of the vermicomposting system is crucial for the metabolism, growth and cell synthesis of earthworms (Usman et al., 2015). Proper nutrition therefore depends on the amount of carbon and nitrogen present in the feedstock and this should be the correct ratio needed (Ndegwa et al., 2000).

Table 15.2

Advantages and disadvantages of different worm feedstocks.

Worm Feed	Advantages	Disadvantages	Remarks
Cow dung	Good nutrition: natural food, therefore little adaptation required	Weed seeds make precomposting necessary	All manures are partially decomposed and thus ready for consumption by worms
Poultry droppings	High N content results in good nutrition and highly N-rich product	High protein levels can be dangerous to worms, and hence it should be mixed with other organic residues or may be precomposted	Some suggest that poultry manure is not suitable for worms because it is so “hot”; however. Georg has shown that worms can adapt if initial proportion of poultry manure to bedding is 10% or less by volume
Sheep/goat excreta	Good nutrition	Requires precomposting (weed seeds): small particle size can lead to packing, necessitating extra bulking material	With right additives to increase C:N ratio, these manures are also good beddings
Pig waste	Good nutrition; produces excellent vermicompost	Usually in liquid form, therefore must be dewatered or used with large quantities of highly absorbent bedding	Scientists at Ohio State University found that vermicompost made with hog manure outperformed all other vermicomposts, as well as commercial fertilizer.
Agricultural waste	Higher N content makes this good feed, as well as reasonable bedding.	Moisture levels not as high as other feeds, requires more input and monitoring	Probably best to mix this feed with others, such as animal manures
Horse excreta	It can be a very good material for vermiculture.	Nitrogen content lesser than cow dung. C:N ratio is very high	Must be mixed with other organic wastes, such as cow dung before feeding to earthworms
Aquatic weeds	Good nutrition; results in excellent product, high in micronutrients and beneficial microbes	Salt must be rinsed off, as it is detrimental to worms: availability varies by region	Beef farmer in Antigonish, Nova Scotia, Canada, producing certified organic vernicompost from cattle manure, bark, and seaweed. Water hyacinth has been tested as a feedstock for earthworms
Preconsumer vegetable waste	Higher N content, results in excellent product, worms like this material	Moisture levels are high, requires more monitoring	Vermicast Industries Inc. has developed a process to vermicompost preconsumer vegetable waste in 8–10 days (www.csrplusx.com)
Paper waste	Excellent nutrition, worms like this material	Must be shredded and/or soaked (nonwaxed) prior to feeding	Some worm growers claim that corrugated cardboard stimulates worm reproduction
Municipal solid waste	Good nutrition, results in excellent product, high in micronutrients. The waste is stabilized and free from foul odor	Precautions are required to control the harmful microorganisms if sewage sludge is used	The in statute of Natural Organic Agriculture (INORA) has developed techniques for vermicomposting of MSW

The amount of nutrients in the vermicompost leachate is of help especially in improving soil physical, chemical, and biological properties, as well as crop quality and productivity.

A wide range of agricultural residues, such as straw, leaves, stalks, weeds, and husks can be used for the production of vermicompost (Table 15.3). Organic wastes, such as cow, sheep, horse, and goat droppings have been found more favorable as feedstock for the production of vermicompost (Garg et al., 2005). In addition, poultry litter, dairy wastes, food processing wastes, and sugarcane bagasse can also be used as feedstock for vermicompost production. However, this range mostly depends on the sensitivity of the earthworm species or types being used for the production of the vermicompost.

Table 15.3

Common bedding materials (Munroe, 2007).

Bedding Materials	Absorbency	Bulking Potential	C:N Ratio
Horse manure	Medium–good	Good	22–56
Peat moss	Good	Medium	58
Corn silage	Medium–good	Medium	38–43
Straw: general	Poor	Medium–good	48–150
Straw: oat	Poor	Medium	48–98
Straw: wheat	Poor	Medium–good	100–150
Paper from municipal waste stream	Medium–good	Medium	127–178
Newspaper	Good	Medium	170
Bark: hardwoods	Poor	Good	116–436
Bark: softwoods	Poor	Good	131–1285
Corrugated cardboard	Good	Medium	563
Lumber mill waste: chipped	Poor	Good	170
Paper fiber sludge	Medium–good	Medium	250
Paper mill sludge	Good	Medium	54
Sawdust	Poor–medium	Poor–medium	142–750
Shrub trimmings	Poor	Good	53
Hardwood chips, shavings	Poor	Good	451–819
Softwood chips, shavings	Poor	Good	212–1313
Leaves (dry, loose)	Poor–medium	Poor–medium	40–80
Corn stalks	Poor	Good	60–73
Corn cobs	Poor–medium	Good	56–123

According to Usman et al. (2015), earthworms have fairly complex responses to changes in temperature with the optimum ranging from 25 to 37^oC. This range has also been shown to favor activity of the earthworms with respect to their function as organic wastes converters to cocoon, but with a variation. For example, E. eugeniae and P. excavates have been found to show higher hatching percentage at lower temperatures (20 to 24^oC) when compared to higher temperatures of 27–30^oC (Giraddi et al., 2008).

An optimum moisture range between 50% and 80% is efficient for vermicomposting (Camp Dresser and McKee, 1980). Moisture is very important for proper cocoon end product. Rodriguez-Canche et al. (2010) reported that the growth of earthworms used in vermicomposting depends on the moisture level in the system. Low moisture conditions have been found to delay sexual development of earthworms (Rodriguez-Canche et al., 2010). Notwithstanding, some earthworm species, such as Lumbricus terrestris do survive in dry conditions (Albanell et al., 1988).

The initial substrate quality and quantity, moisture, and temperature have been reported to influence the density of earthworms in a vermicomposting system (Lee, 1985; Wever et al., 2001). It has been reported that the frequency of copulation of earthworms in a vermicomposting system is high at low earthworm population densities. There was a decrease in copulation frequency when the population was found to approach the carrying capacity of the substrate used as feedstock (Rodriguez-Canche et al., 2010).

5. Benefits of Vermicompost

The products of vermaculture (or “Vermiwash,” the liquid filtered through the body of worms) and the “vermicompost tea” (solution of vermicompost) can influence plant growth and development, as well as crop quality significantly when present at very low concentrations (Sinha et al., 2010). Vermicompost stimulated seed germination in pine trees (Lazcano et al., 2011), increased plant growth and productivity; vermicompost may also increase the nutritional quality of some vegetable crops, such as tomatoes (Gutiérrez-Miceli et al., 2007), Chinese cabbage (Wang et al., 2010), and sweet corn (Lazcano et al., 2011).

Sinha et al. (2010) indicated that vermicompost is a very “powerful biopesticide,” eliminating the use of toxic chemical pesticides. The most beneficial aspect of vermicompost is the fact that it is 100% organic. There are no harmful chemicals and it does not need to be mixed with other chemicals (Jesikha, 2013). Vermicompost, compared to garden compost, has a higher percentage of vital macro and micronutrients, such as N, P, K, and micronutrients like Fe, Zn, Mn, and Cu (Castillo et al., 2005; Zafar, 2015) that stimulate cell division to promote growth and build plant biomass (Rani and Srivastava, 1997). Vermicompost plays a major role in improving growth and yield of different field crops, vegetables, flowers, and fruit crops. Current findings suggested that the use of vermicompost leachate could easily serve as a substitute for P and K for the growth of tomatoes (Arthur et al., 2012). The positive effect of soil drenching with vermicompost leachate on the growth of greenhouse-grown “Williams” bananas was also demonstrated in South Africa (Aremu et al., 2012). The application of vermicompost gave higher germination (93%) of mung bean (Vigna radiata) compared to the control (84%). Furthermore, the growth and yield of mung bean was also significantly higher with 80% vermicompost application. Likewise, in a pot experiment, the fresh and dry matter yields of cowpea (Vigna unguiculata) were higher when soil was amended (Jesikha, 2013). Higher yields may be due to plant-growth-promoting hormones that are present in vermicompost (Jesikha, 2013; Zafar, 2015). Earthworms may possibly promote the production of plant hormones auxins, gibberellins, and cytokinins from organic waste. Auxins are responsible for cell elongation, cytokinins for promoting cell division, and gibberellins for stem elongation. These hormones are dose-significant and play a fundamental role in plant metabolism. They can influence plant growth and development, as well as crop quality significantly when present in very low concentrations (Atiyeh et al., 2001).

The use of earthworms and vermicompost in farm production provides dual benefits to crops. While promoting growth, vermicompost protects crops from pests and diseases and thus significantly reduces the use of chemical pesticides (Sinha, 2008). This protects high-risk groups, which include production workers, formulators, sprayers, mixers, loaders, and agricultural farmworkers, from pesticide exposure (Aktar et al., 2009).

Traditional methods of composting results in losses of 55% of organic matter (OM) and from 30% to 50% of N (Ketkar, 1993). Vermicompost has great commercial potential in the horticultural industry and its effectiveness is affected by the soil and water regime. A 60-day vermicomposting experiment (with E. eugenia) resulted in a significant increase in pH (1.12- to 1.13-fold), electrical conductivity (1.30- to 2.45-fold), nitrate (4.28- to 5.77-fold), phosphate (4.37- to 9.21-fold), and potassium (3.01- to 14.00-fold) content, with a significant decrease in total organic carbon (TOC) (6.33- to 9.37-fold) content (Yang et al., 2015). Furthermore, compared to earthworm devoided composting (i.e., simple composting) pH, conductivity, nitrate, phosphate, and potassium content increased by 1.13-, 4.19-, 6.92-, 2.08-, and 2.31-fold, respectively, and TOC decreased by 9.37-fold in vermicomposting, indicating that E. eugeniae accelerated the rate of composting along with nutrient quality in the compost (Yang et al., 2015). The increased level of nutrients in final products in different treatments demonstrated that the vermicompost of poultry litter might be a valuable biofertilizer for sustainable land restoration practices (Nayak and Sahu, 2013).

Organic farming by vermicompost “sequesters” large amount of atmospheric carbon into the soil as soil organic carbon (SOC), improving soil fertility and mitigating global warming (Sinha et al., 2010). Sustainable agriculture is a process of learning new and innovative methods developed by both farmers and the farm scientist and also learning from the traditional knowledge and practices of the farmers and implementing what is good and relevant in present times. Vermiculture was practiced by traditional and ancient farmers with enormous benefits accruing to them and their farmlands. There is a need to revive this ‘“traditional concept” through modern scientific knowledge (Sinha et al., 2010). These two well-established processes have been adopted for solid organic waste reclamation and the final products, composts, and vermicompost can be used as sources of organic matter for soil amendment, as sources of nutrients for soil fertilization or as growing media constituents for soilless cultivation (González et al., 2010). The application causes mineralization of plant nutrients, and therefore produces an increase in soil fertility and quality (Arancon et al., 2006; Ferreras et al., 2006).

However, there are challenges involved in the production of vermicompost, such as extreme temperature that poses a serious threat to the livelihood of the worms, thereby affecting the productivity of the vermicompost system (Tripathi and Bharrdwaj, 2004). It is often difficult to maintain a temperature that is conducive for the worms, particularly if the vermicomposting system is not well managed (Biernbaum, 2015).

Conditions of excess moisture or dryness can lead to a prompt and total loss of the worm population. Excess water contents limit the porosity of the compost and results in less oxygen, which may cause worm suffocation (Tripathi and Bharrdwaj, 2004). Conversely, dry conditions will limit the movement of worms, thereby reducing the rate of nutrient conversion. This can result in a negative compost production, as well as financial implications. When compared to thermophilic composting, vermicomposting can be produced at a very slow rate due to the low bacterial and fungal populations available for the breaking down of organic material. This process can take weeks or months in vermicomposting as opposed to hours or days when using thermophilic composting (Ndegwa and Thompson, 2011). Useable compost can be ready in as little as 2 to 3 months (60 to 90 days) under favorable conditions, but 4 to 6 months is a better estimate with minimal management of the worm beds (Biernbaum, 2015). Vermicomposting can thus be defined as an eco-biotechnological process that transforms complex organic substances into stabilized humus like product (Benítez et al., 2000).

A revolution is unfolding in vermiculture studies for vermicomposting of diverse organic wastes into a nutritive organic fertilizer for the production of chemical-free safe food, both in quantity and quality. Heavy use of agro-chemicals boosted food productivity, but affect the environment and society. Earthworms help in a number of tasks to support many ecosystem services that favor agrosystem sustainability. However, earthworms can be degraded by exhaustive anthropogenic practices mainly in the use of pesticides (Datta et al., 2016).

A study was initiated to find out the effects of humic acids (HA) from vermicompost on in situ development of the early growth stages of the nodal tissue of the medicinal plant, Bacopa monnieri (Kashyap et al., 2013). It was found that the different fractions of vermicompost could bring about growth promotion in different somatic tissues. Plant growth increased with increasing concentrations of vermicompost media (Kashyap et al., 2013)

Other studies used the vermicompost produced by E. eugenia, which was applied at different concentrations to the medicinal plants V. radiata and Centella asiatica. The results showed that there was higher plant growth, yield, and chlorophyll content in both medicinal plants that received vermicompost at a 20% concentration to the soil than other concentrations and the control (Chiluvuru et al., 2009). The potential therefore exits of using vermicompost to promote plant growth, as well as inducing antimicrobial mechanisms systemically in the host plants facilitated by the organic amendment in the form of vermicompost (Singhai et al., 2011).

6. Use of Vermicompost in Fisheries

The use of vermicompost in fisheries is particularly significant in developing nations where fish farmers are unable to buy costly fish feed and chemical fertilizer vermicompost forms an abundant alternative natural resource for less expensive manure and fish feed. The high fish yield in vats applied with vermicompost is attributed to its highest manorial value (Chakrabarty et al., 2009). Vermicompost might be cost-effective manure in carp culture, replacing the expensive chemical fertilizer diammonium phosphate (Chakrabarty et al., 2009). Application of vermicompost as an organic manure in fishponds is not only better but also safer than raw cow dung. This is excellent manure for nurseries and rearing ponds as it has the potential to produce good rotifers population (Chakrabarty et al., 2009).

7. Marketing Channel

Vermicompost production and marketing have indicated that it is profitable enterprise with better net profits and benefit cost ratio (Devkota et al., 2014). Direct marketing of vermicompost from producer to consumer was found to be the strongest marketing channel; however, marketing through cooperatives and trader was also found in few instances (Fig. 15.2). A financial viability study concluded that vermicompost production is a feasible enterprise (Devkota et al., 2014). An appropriate supply chain of organic waste and cow dung can attract people to produce vermicompost on a large scale. In the present context, demand for vermicompost is increasing and governments, especially in Africa, are now offering subsidies to small-scale farmers. Furthermore, cooperative marketing should be promoted; there should be provision for better market information and organized marketing channels should be established.

Figure 15.2 Marketing Channels and Marketed Volume of Vermicompost (Devkota et al., 2014).

8. Conclusions

Vermicompost has been beneficial for long-term sustainability and crop productivity (Ansari et al., 2016). It is an important tool for waste recycling in the world and it is one of the greatest environmental friendly methods to control and manage organic waste (Sharma et al., 2005). Development of global organic farming and sustainable agriculture can truly bring in “economic prosperity” for farmers, “ecological security” for farms and “food security” for the people (Bhatia et al., 2000; Singh, 2008). Therefore, the most common practices to treat most organic wastes are composting and vermicomposting (Ghosh, 2004). These two well-established processes have been adopted for solid organic waste reclamation and the final products, composts, and vermicomposts can be used as sources of organic matter for soil amendment, as sources of nutrients for soil fertilization, or as growing media constituents for soilless cultivation (González et al., 2010). Apart from all the nutritional benefits, vermicomposting also reduces the use of chemical fertilizers, which may be harmful to soils, and also decreases the amount of waste going to landfills (Sharma et al., 2005). In addition, vermicompost increases plant growth, suppresses pests and diseases, and improves the retention and aeration of water, as well as porosity and microbial activity in soil (Ndegwa et al., 2000). However, natural resources are finite and highly susceptible to degradation by mismanagement by man. The ecosystems of the world offer fertile soil, clean water, food, and other natural resources that need to be sustained. Earthworms accelerate the mineralization rate and convert manures into casts with higher nutritional value and degree of humification than traditional method of composting (Albanell et al., 1988). The increased mineralization of nutrients is due to the activity of earthworms in the decomposition and conservation mechanism (Suthar, 2007). The production of vermicompost is accelerating around the world, as it is recognized as an important organic manure. This compost helps improve and protect topsoil while producing nutrients as well. Vermicomposting system can be designed to meet different requirements, such as single households, group dwellings, and cities. Vermicomposting is now also recognized as agribusiness; it is income-generating for gardeners, farmers, and those who desire a supplementary income source. This process is also beneficial for the environment as it turns waste into value-added organic fertilizer. As waste disposal becomes a global problem, the production of vermicompost offers a solution to this threat. Therefore, if adopted effectively, vermicomposting can become a very effective and environmental friendly method for organic waste management. Waste management involves a large number of different stakeholders, with different fields of interest (Devi et al., 2016). Vermicomposting is self-promoted, self-regulated, self-improved, and self-enhanced, with low or no energy costs, requiring zero-waste technology, and easy to construct, operate, and maintain. Vermitechnology can be a promising technique that has shown its potential in certain challenging areas, such as augmentation of food production, waste recycling, management of solid wastes, and so forth (Kokate and Sasane, 2014). Rundgren (2006) noted that in most cases where the Green Revolution was adopted, the introduction of synthetic chemical fertilizers and pesticides has boosted productivity per hectare and helped increase food production. It has played a major role in meeting the growing demands of a world population that has doubled in the past 40 years. However, these increases in production have slowed down in recent years, and in some cases there are indications that production is declining due to decreasing soil fertility, damage to biodiversity and the environment, degradation or destruction of water resources, and the buildup of pest populations and resistance. Moreover, the success of the industrial agriculture and the Green Revolution in recent decades has often masked significant externalities affecting natural resources and human health, as well as agriculture itself. Environmental and health problems associated with agriculture have been increasingly well documented, but it is only recently that the scale of the costs has come to be appreciated.

The use of sustainable agricultural practices that entail the conservation of resources and the environment remain a viable option to increase agricultural product output (Lazcano et al., 2011). Today, farmers are caught in a “vicious circle” due to higher use of agrochemicals to boost crop productivity at the cost of declining soil fertility (Sinha, 2008). The process of rehabilitation of degraded lands is essentially a long-term development that requires the enactment of appropriate policies and supporting institutions, as well as enabling an environment that ensures participation by all land users. Technology development, acquisition, and adaptation are central for combating land degradation. Various technologies can be employed to benefit and to have a positive influence on the lives of people. New technology innovations in fields, such as land use and soil water conservation are needed most. Equally, research needs to move from research centers and stations to farmer’s lands, who are the target beneficiaries (Hamdy and Aly, 2014). Hart (2009) noted that education, skills development, and technical training are central to agricultural and rural employment. They prepare young people for work in the formal and informal sector in rural areas and thus play an important role in poverty reduction. Better training and skills refinement in terms of human capital, higher income and returns, and the better rural livelihoods are essential to break the cycle of poverty. Hence, establishing organic recycling and the conversion of waste into “black gold” will aid in food security and benefit numerous communities.

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Further Reading

Atiyeh RM, Lee S, Edwards CA, Arancon NQ, Metzger JD. The influence of humic acids derived from earthworm-processed organic wastes on plant growth. Biores. Technol.. 2002;84(1):7–14.

van der Werf HM. Assessing the impact of pesticides on the environment. Agr. Ecosys. Environ.. 1996;60(2):81–96.

Vennila C, Jayanthi C, Sankaran VM. Vermicompost on crop production: a review. Agric. Rev.. 2012;33(3):265–270.

Vig AP, Singh J, Wani SH, Dhaliwal SS. Vermicomposting of tannery sludge mixed with cattle dung into valuable manure using earthworm Eisenia fetida (Savigny). Biores. Technol.. 2011;102(17):7941–7945.

Wilson C, Tisdell C. Why farmers continue to use pesticides despite environmental, health, and sustainability costs. Ecol. Econ.. 2001;39(3):449–462.