Vermicomposting in Silver Oak Plantation Areas for Sustainable Waste Management and Enhanced Livelihood: A Case Study of Kolli Hills, Tamil Nadu, India

: Silver Oak plantation on farmlands growing coffee and black pepper has gained importance in recent times in the areas surrounding the Kolli hills in the Namakkal district of Tamil Nadu, India. The Silver Oak trees shed significant quantities of dry leaves during the summer season which the local Malayali tribal community burns and/or leaves on ground. The current case study is based on an experiment of vermicomposting using local Silver Oak leaf litter, cow dung and earthworms. The results show that joint production of manure from agroforestry practices is an option in self-sufficiency for the rural communities and has the potential for a business model. Moreover, this ensures environmental sustainability by avoiding green-house gas emissions that are caused by the practice of burning leaves and/or leaving the mulch to rot. The present paper attempts to develop a sustainable model of vermicomposting in the Kolli hills region that can offer triple solutions encompassing organic manure production, environmental quality improvement and livelihood opportunity enhancement. Based on field surveys and physiochemical experiments in the Perungiraipatti village of the Kolli hills, the study presents a sustainable model of vermicomposting with specifications on nutritional quality, environmental sustainability and economic development. This paper is a case study of such an enhanced livelihood model for the farmers in small rural habitats in the hilly terrains of Southern India where Silver Oak plantation is rampant in the coffee and black pepper farmlands. The existing practice of burning and/or leaving the leaf litter on land is proposed to be replaced by simple techniques of vermicomposting. The model aims to have the triple benefits of sustainable waste management, environmental quality and enhanced livelihood for farmers arising out of the vermicomposting activity. The aims of the study are


INTRODUCTION
Agroforestry offers an effective tool for sustainable natural resource management by combining trees into agricultural farms, thereby enhancing social, economic and environmental benefits for local communities, who depend on agricultural farms as well as on the storable renewable forests. It is recognized as a land use option where trees provide marketable products and ecological services while cultivation activities produce agricultural outputs simultaneously. Agroforestry practices provide a practical opportunity to apply a variety of expertise and skills, based on technical knowledge as well as traditional practices that can develop sustainable rural production systems encompassing cultivation and forestry (Alao and Shuaibu, 2013). This two pronged production system helps in rehabilitating the degraded land and also in increasing the farm productivity (Dhyaniet al., 2017). Improvement in the existing practices and designing more efficient expansion paths for future may help the farmers to tapthe complete benefits of agroforestry. While it promotes the diversity of land use management, it can offer sustainable ecological and socio-economic solutions in the face of population growth, limited land and natural resource availability and other developmental problems. Unsustainable management of large amounts of waste generated in the agricultural and forest sectors has been identified as a global environmental challenge in the present world. Biomass from fallen leaves and other woody residues is one major form of the lignocellulosic waste produced in mountain towns and rural villages in India. It is a daunting challenge for the village farmers, community workers and urban resource managers to manage the large amounts of such waste that has significant adverse impacts on the environment, if not disposed properly (Suthar and Gairola, 2014). Many of the dead leaf debris are either burnt in the open or disposed of at farms and/or landfills simply to rot. Such traditions not only lead to air pollution in the local region but can also be responsible for other greenhouse gases emission. Therefore, proper management and safe disposal of agroforestry waste is necessary to address such environmental problems (Singh et al., 2021). Sustainable management of farm and forest waste may also help in reducing pressure on land by maintaining the right balance of moisture and fertility into the soil. Eco-friendly conversion of waste into useful products is a solution to this multitude of problems associated with these unsustainable waste disposal practices. Such projects are becoming increasingly more attractive worldwide, depending on the associated costs and the respective environmental requirements (Ntuli and Hapazari, 2012). Sustainable natural resource management is central to sustainable development. Local community participation is vital for natural resource use and conservation because their livelihoods may be majorly based on forests. Agroforestry combines forest-based livelihoods, such as, timber plantation, growing medicinal plants, spices, bamboo etc., collecting honey, developing forest tourism and allied activities, with farm-based activities, such as, crop farming, horticulture, livestock, poultry and so on. Both may involve practices that are harmful for the environment and thus require interventions in additional and/or alternative livelihood projects with an aim to replace such activities with those having at least the same benefit and lower impact (Wright et al., 2015). However, forestbased livelihood interventions are more beneficial for sustainable rural livelihood development and simultaneous forest conservation. This paper is a case study of such an enhanced livelihood model for the farmers in small rural habitats in the hilly terrains of Southern India where Silver Oak plantation is rampant in the coffee and black pepper farmlands. The existing practice of burning and/or leaving the leaf litter on land is proposed to be replaced by simple techniques of vermicomposting. The model aims to have the triple benefits of sustainable waste management, environmental quality and enhanced livelihood for farmers arising out of the vermicomposting activity. The aims of the study are a) to develop aphysio-chemical model of vermicomposting using Silver Oak leaf litter; b) to compute the nutrient quality of Silver Oak compost and compare it with an alternative compost made of mixed leaves from traditional trees like jackfruit, guava, mango, coffee; c) to estimate the environmental benefit of vermicomposting over the old practice of burning the residue; d) to create a farmer-friendly enhanced livelihood option based on compost made of leaf litter and other local inputs, leading to a viable economic model.

Location of the study village
The Kolli hills is a pristine hilly terrainat an altitude ranging from 700 to 1600 meters above sea level, in one part of the Eastern Ghats Mountain rangein the Tamil Nadu state of India (figure 1). It is a block in the Namakkal district, spread overan area of 65,730thousandacres (Census of India, 2011), located between 11 0 10'00''-11 0 30'00" N latitude and 78 0 15'00"-78 0 30'00"E longitude (Vijayakanthet al., 2017).The current study was conducted in a village named Perungiraipatti, situated in the Valavanthinadu Panchayat of the Kolli hills, situated 55 kms away from the Namakkal plains. The total area of Valavanthinadu Panchayat is 4,086.82 thousand acres (Census of India, 2011).  Malayalis practiced shifting cultivation around millets in the past and have shifted to pepper and coffee production in recent years. The primary occupation of this region is agriculture with some farmers tilling own land, some working as marginal farmers on the farms of big landowners and some as daily wage laborers under the Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA) scheme. Migration to the neighbouring state Kerala during agricultural off-season is also a regular annual feature.
Other minor occupations of the region include running grocery shops for daily essentials, low-cost hotels and restaurants as this place is a tourist destination. The overall quality of life in the region is moderate to low and can improve through policy interventions designed for enhanced livelihood and additional occupations.

The Silver Oak plantation
The predominant vegetation of the region is dry deciduous forest with some patches of tropical semi-evergreen and moist deciduous forests. The major cultivation in the Kolli hills is that of black pepper and coffee, done in organic ways. The farmlands overlap Silver Oak estates, with the trees providing support for the creepers (figure 2). Other medicinal plants and traditional fruits, such as, banana, pineapple, guava, and jackfruits are also found in this region. Grevillea robusta, commonly known as Silver Oak, and Savukkumaramin Tamil, is an eastern coastal Australian native species. It was introduced in India by the British particularly for the purpose of tea and coffee plantation. Dry rainforest and subtropical climatic conditions with an average annual rainfall of more than 1,000millimeters are best suited for its growth. Silver oak is a fastgrowing evergreen tree with an average height between 5to 40 meters, with a non-slippery surface androbust structure. These features make Silver Oak suitable for being a supporting tree for growing black pepper and a shade tree for coffee and tea plantation. Almost 75% of sunlight can penetrate intercrops because of their narrow leaves and sparse branches.

Vermicomposting from Silver Oak for sustainable waste management
Silver Oak trees shed dry leaves during the three months of April, May and June of the summer season. The generation of leaf litter is around 30 kilograms per tree during the season for the entire year. Farmers generally leave the large quantities of leaf litter on ground and the natural decomposition rate of silver oak is very slow due to its needle-like structure. Although farmers use some of the fallen leaves as mulch, they treat these leaf litter mostly as waste to decompose naturally. The more dominant practice is to burn the leaves, causing severe environmental pollution. The huge amount of leaf litter may be sustainably managed through vermicomposting, that offers a viable and eco-friendly technology to convert organic wastes into vermicompost through the joint action of earthworms and microorganisms (Domínguez, 2018). The current study examines vermicomposting as a technological model for Silver Oak plantation areas of village Perungiraipatti of the Kolli hills regionfor sustainable waste management. It is further scrutinised as a possible tool for arresting environmental damage andas an economic optionfor generating an additional occupation for the farmers.

The Data
The vermicomposting experiment was done in village Perungiraipattiusing local raw materials, labour from the agricultural family farms and already existing infrastructure, equipment and utilities. The leaf litter was collected after the summer season of 2021 when the trees shed leaves, following which the vermicomposting experiment was carried out during the months of August and September. Local community was involved in the experiments and were interviewed for understanding their practices as well as getting their response towards the vermicomposting activity, both before and after the experiment through focused group discussions.

Raw Materials
Fallen leaves from the SilverOak tress were the primary raw material for the vermicomposting experiment. Leaves from other trees were also collected from the village farms in order to produce mixed leaf compost. Cow dung available in the farmer households was used for layering over leaves inside the pit. A local Indian variety of earthworms, Lampitomauritii, (family Megascolecidae, genus Lampito (Kinberg), species Lampitomauritii) was used in the process of vermicomposting (figure 3).

Figure3: Leaf litter of Silver Oak and Indian earthworm Lampitomauritii
(picture courtesy: authors)

The vermicomposting process
The experiment was designed to produce vermicompost from Silver Oak leaves and mixed leaves parallelly in order to have a comparison of the quality and quantity of the output. Two cemented pits, already existing in the cow sheds of the households, were used for producing the two types of composts respectively. The pits were 1.5 feet deep, 4.2 feet long and 1.5 feet wide. Leaves were layered for 3 inches in the respective pits and 3 inches of cow dung were put on top for 10 days. The earthworm Lampitomauritiiwas released into both pits inside which the respective materials were mixed. 1 liter of water was sprinkled inside the pits to maintain the moisture level and insect-protection chemicals were put outside the boundaries of both pits to protect them from insects. The mixtures were left for the next 45 days to get the manure ready for harvesting. The manure was made fine through manual straining which also helped in removing the stones and undecomposed matters left after the harvest. The whole process took a total of 55 days for the final output to be ready for nutrient analysis (figure 4).
(picture courtesy: authors) The experimental model used moderate quantities of the three types of raw materials, namely, Silver Oak leaf litter, mixed leaf litter and cow dung. 10 kilograms of the two types of leaf litter were used along with cow dung of 50 kilograms and 30 kilograms quantities respectively. The requirement of cow dung was higher for Silver Oak because of its fern-like leaf structure that makes the litter rough and voluminous. On the other hand, mixed leaves from other plants are softer and less in volume. Moreover, Silver Oak contains more undecomposed matter than the mixed leaves. As a result, decomposition was easier and faster for mixed leaves than Silver Oak. The same amount of leaf litter (10 kilograms of each) required 5 timesmore cow dung for Silver Oak (i.e., 50 kilograms) and 3 times more for mixed leaves(i.e., 30 kilograms). With minor differences, both types of leaf litter produced good amount of biofertilizers. The input-output ratio for Silver Oak turned out to be higher than that of mixed leaves. The resultant outputs were 1.83 times for Silver Oak and 1.75 times for mixed leaves over the total input per weight (table 2). Based on the input-output ratio obtained during the experiment, the annual output of Silver Oak vermicompost was estimated to be around 2196tonnes from the 1200 tonnes of leaf litter inputs. The total time taken was less than two months. Although mixed leaf compost has a comparable input-output ratio and lower requirement of cow dung, Silver Oak compost promises to be the dominant one because of the larger availability of leaf inputs in the region dominated by its plantation.  While the macronutrient variation in vermicompost depends on the raw material, it also depends on the feeding habit of earthworms towards particular organic wastes in the biodegradation process (Crawford,1983); (Gaur and Singh, 1995). This result further seems to indicate that biodiversity is crucial in any region because variations in species impact the nutrient composition of soil. However, more detailed analysis is required for the same, which was beyond the purview of the present study.

Environmental benefits of vermicomposting
A huge amount of dry leaf litter is generated in the villages of the Kolli Hills. In the 100-acre Silver Oak plantation area of the Perungiraipatti village, the average annual generation of leaf litter is around 1200 tonnes. The natural decomposition rate of leaves of Silver Oak is slower than other species and are generally left and/or burnt. In the absence of oxygen at landfills, these dried leaves also hold a considerable amount of greenhouse gasses (GHGs), such as, CO2(~30%), methane (CH4 ~ 60%), and other gasses during their degradation (Polprasert, 2007). The layers of dried and fallen leaves at farms also result in depletion of water table and adversely impacts the moisture and fertility of the soil. Additionally, water and land use raise problems of resource efficiency, while monoculture ofSilver Oak strains bio-diversity. The community practice of leaf burning is a serious environmental concern. Air pollution through emission of CO2, CO, PM2.5,NOx etc. may be detrimental to the environment and cause health concerns of the people who may be ignorant about it. The proposed solution of vermicomposting can avoid such emissions and thereby improve environmental quality (table 4). The annual saving in CO2 emission is to the tune of 1752 tonnes per 1200 tonnes of Silver Oak leaf litter in the study area. The corresponding saving in CO is around 72 tonnes while those of NOx and PM2.5 are minor at 2.4 tonnes and 3.6 tonnes respectively. Although the quantities in the agroforestry sector are lower than potential emissions from agricultural waste like stubble, the figures are significant.