CHAPTER ONE
INTRODUCTION
1.1 Background of Study
Kitchen waste is defined as left-over organic matter from restaurants, hotels and households (Li et al., 2009). Kitchen waste forms a significant part of domestic waste. Food waste is an unwanted raw or cooked food discarded during or after food preparation that is no longer fit for consumption or desirable. Toxic Links at New Delhi conducted a survey in May 2002 and prepared a fact file on solid waste which stated that about 0.1 million ton of municipal solid waste is generated in India every day. So, annual production of solid waste reaches approximately 36.5 million tones (Kaur and Arora, 2012).
Composting is a natural process of rotting or decomposition of organic matter by microorganisms under controlled conditions. Composting helps to reduce the amount of waste that is being directed into landfills. This means a reduction of concentrated, toxic leachates and methane gas that is being released into the atmosphere, which equates to a decrease in overall pollution. Composting also cuts down on the usage of chemical fertilizers, which are harmful to water supply. Compost used to improve soil physical and biological properties i.e., water retention capacity, drainage, pH, better availability of soil micro-organism and reducing the negative impact of chemical based pesticides and fertilizers in the ecosystems. Organic matter is rich in compost, which plays a crucial role in improving physical, chemical and biological properties of the soils. Soil structure can be improved by binding the soil organic matter and clay particles via cat ion bridges and through stimulation of microbial activity and root growth. (Gao et al., 2010). As a result of these improvements, soil: (i) becomes more resistant to stresses such as drought, diseases and toxicity, (ii) helps the crop in uptake of plant nutrients and (iii) possesses an active nutrient cycling capacity because of vigorous microbial activity. There is a large variety of microorganisms present in waste such as bacteria, fungi, protozoa etc. Many fungi are capable of degrading cellulose by synthesizing large quantities of extracellular celluloses that are more efficient in deploymerizing the cellulose substrate. Many celluloses produced by bacteria appear to be bound to the cell wall and are unable to hydrolyze native lignocellulose preparations to any significant extent.
Most commonly studied cellulolytic fungi include Trichoderma, Humicola, Penicillium, and Aspergillus (Gautam et al., 2009) and some bacteria include Clostridium thermocellum, Streptomyces spp., Ruminococcus spp.,Pseudomonas spp., Cellulomonas spp., Bacillus spp (Gautam et al., 2010). Fungi have the ability to degrade organic materials and its potential as decomposer is now used in the production of organic fertilizer to hasten decomposition and improve quality of the product there of (Lou et al. 2014). Trichoderma from other sources is one of the most commonly used compost activator and is now commercialized in the market. Among the different organisms used for cellulolytic decomposition, Trichoderma harzianum, Trichoderma viride and one bacterial strain have been studied for our work. Steiner who introduced the concept of biodynamic farming to include composted materials applied in solid form as soil amendments and in liquid form as compost extracts. Compost extracts are fermented watery extracts of composted materials that are used for their beneficial effect on plants (Litterick et al., 2004).Compost extracts produce plant hormones, mineralize plant available nutrients, fixes nitrogen and providing useful microorganisms that colonize leaf surfaces (Zheljazkov and Warman, 2004). According to many authors, compost applied to soil increases total pore volume, facilitates the penetration of water and increases soil water holding capacity. Mechanisms involved in the antagonistic activity of beneficial microbes from compost including competition for nutrients, site exclusion, production of inhibitory metabolites, and parasitism (Elmer and Reglinski, 2006).
The effect of compost application either as extracts to the foliage or as soil amendments on plant disease control may be due to direct antifungal or resistance inducing/plant strengthening effects. The effects of compost derived from decomposed kitchen waste by different microbial decomposers were also studied for biotic stress management in our present study under different crops. Thus, the present investigation mainly focused on selecting a potential strain for the kitchen waste composting and showing better effect on soil microbial community.
1.2 Statement of the Problem
The soil holds a variety of activities from accumulation of waste. The activities of the soil dare accomplished not without its microbial community. This microbial community makes it possible for a process such as composting. This microbial community ranges from bacteria to fungi to algae. However, properties of kitchen waste such as acidity, loss of nutrients especially nitrogen emission of odor, high lipids content could pose challenges during composting. In Nigeria, streams of waste materials are being generally by its teaching population and its becoming a major problem. Recently, Environmental protection agency (EPA) Nigeria has come up with the notion of the use of composting as it is less harmful to the environment. Nevertheless what kitchen waste compositing does to the microbial community in the soil is worthwhile to be noted or is of great concern and the reason for this research.
1.3 Justification of Study
The fact that compositing provides cheap ecologically friendly and safe methods of disposing kitchen wastes as kitchen waste are substrate as they possesses high organic matter, readily decomposability and how amount of heavy metals and pathogens. and boosting the fertility of agricultural soils makes it a plausible prospect, yet, how the microbial community of the soil on which the compositing takes place/occur responds or get affected is worthy of study quite interesting to study.
1.4 Objectives of Study
The main objective of the work is to assess the effects of kitchen wastes on soil microbial communities.
The specific objectives includes
To isolate, characterize and indentify the microorganisms associated with kitchen wastes/soil sample.
To evaluate the total heterotrophic count in the study samples
To assess the different microbial groups in kitchen waste.
To compare the microbial communities both the kitchen wastes and soil samples.
EFFECT OF KITCHEN WASTE COMPOST ON SOIL MICROBIAL COMMUNITY
