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Extractable lipids as an indicator of compost maturity

Place: Bari, italy, Europe
Sustainable management of natural resources Sustainable management of natural resources
Total Budget: € 0,00 | Period: From January 2009 To December 2011

Summary

Soil amendment with compost, produced by a controlled biological transformation of organic wastes, is a traditional practice favoring sustainable management of productive systems. To ensure a safe agricultural use the quality of composted materials must be guaranteed by an appropriate management of the composting process. It means that a careful control of the progressive changes in physical, chemical and microbiological characteristics with time is needed to establish the optimum composting endpoint and to avoid the numerous harmful effects caused by non-matured compost application.
Maturity is a term used to indicate the level of phytotoxic substances in composts and compost suitability for plant growth. There is currently no universal method for measuring compost maturity. Some of the methods that have been used include carbon-to-nitrogen ratio (C/N), changes in nitrogen content, pH, electrical conductivity, cation exchange capacity, organic chemical constituents, reactive carbon, humification parameters, optical density, temperature, color, odor, structure, specific gravity, plant assays, respiration indexes, germination and root elongation indexes, microbial population changes, and enzyme activity. Current approaches for the estimation of compost stability and degree of maturity are related to the concentration of polyphenols and lipids. This thesis works were proposed to explore the potentiality of extractable lipids for indentifying the compost maturity.
Three turned windrows compost piles were prepared from raw materials of cow dung, chicken and cheese industries residues bulking with vineyard wood at the Mediterranean Agronomic Institute of Bari, Italy. Besides, irrigation water was used for maintaining moisture in case of first pile, while drinking water was used for pile 2 and 3. Samples were collected at 0, 7, 14, 28, 45, 60, 91 and 120 days of composting from 6-8 different points of piles to have a representative composite samples for physio-chemical, biochemical and microbiological analysis.
Pile temperature was recorded daily and moisture was analysed frequently. Pile turning and water adding were done to maintain pile temperature lower than 70°C and moisture between 55 and 65%. analysis of compost sample were done to determine humidity, pH, organic matter, total nitrogen, inorganic nitrogen forms, CO2 evolution rate, microbial biomass C and N, diethyl-ether and chloroform extracted lipids, and germination index.
The temperature profiles of three windrows demonstrate that the management of the piles was done adequately to facilitate optimum composting process, though they differ from pile to pile. From the beginning of composting process, till to the end of the incubation  period, the organic carbon decreases while the total nitrogen increases. The evolution of C/N ratio and NH4+  along the composting time in the 3 composted piles found to be inadequate for determining compost maturity.The daily respiration shows a similar decreasing trend over increasing of composting time.. However,  the values differ consistently from pile to pile making  difficult to use this parameter as indicator of  compost maturity.The values of microbial biomass C and metabolic quotients are also not consistent across the piles. The DEE extractable lipids content decreased sharply while the CHCl3 extractable lipids decreased slowly in all the composting piles along the incubation period. However, it was not possible to identify the compost maturity based on extractable lipids except for  pile P2. The germination index (%) gave differentiate results. Till to the the end of composting process, toxicity problems were found for pile 1 and 2.
It is evident that that none of the single parameter is applicable to identify compost maturity in the case of the organic waste used here. Thus, a careful selection of parameters and a optimum value for each selected parameter are necessary on the basis of the characteristics of the starting waste.. 

Partnership

Parthenope University of Naples - Italy

Lead applicant

Department of Agricultural and Environmental Biology and Chemistry Laboratory - Italy

Initiative partner

Cotton Development Board Ministry of Agriculture - Bangladesh

Initiative partner

To sustain the productivity of agricultual land, maintaining and enhancing the soil organic matter is utmost necessary that can be achieved by recycling of biodegradable organic wastes through appopriate composting procedues and to incorporate the quality compost in soil. Simultaneously, to optimize the benefit from compost application, it is widely recognized at national and international levels, the compost should be mature and stable. Although, concerns of compost maturity and stability has been growing over the last few decades, a standard protocol for assessing compost maturity and stability is till debated. This is mostly due to the wide diversity of organic wastes and as well as various methods developed and proposed by various authors. The proposed physico-chemical and bilological parameters are proved to be inconsistant. While some advanced procedures required costly equipments, skilled manpower and high analytical cost. In this context, determination of compost maturity and stabilty on basis of the dietyl ether and cholorofrm extractable lipids found to be promising.

Composting confers agronomic value to organic wastes and it is in line to the recycling philosophy widely acknowledged as a primary concern of the industrialized societies. The compost quality has to be consistent to the keeping of soil biological functions, to the safeguard of its physico-chemical characteristics and to crop protection. In this regard, maturity is an essential parameter to take into consideration in order to prevent detrimental effect on soil and crops, when compost is used as soil conditioner. The compost maturity  should  assure the suitability of compost for plant growth. Our study revealed that none of the single parameter is applicable to identify compost maturity in the case of the organic waste used here, although the process was managed in the same way for all the windows.. In order to come to an unambiguous maturity index, a careful selection of parameters is necessary on the basis of the characteristics of the starting waste. 

The application of organic residues as a source of organic matter is a common practice aimed at improving soil physical, chemical and biochemical properties.Organic residues mineral nutrients for crops, but they may also contain highly polluting materials. These polluting materials can be leached through the soil profile, transported in drainage waters, and may pollute groundwater, or they can accumulate in the upper soil layer and can be toxic to plants and soil microbial biomass. Thus, sanitation of organic waste before application to soil is widely recommended. A common sanitization option for handling of organic waste is composting during which micro-organisms stabilize the material. The quality of composted materials must be guaranteed to ensure safe agricultural use by appropriate management of the composting process. It is needed to establish the optimum composting endpoint for avoiding the numerous harmful effects caused by non-matured compost application. This book enumerated the potentiality of extractable lipids in comparison with the physico-chemical and microbiological parameters for identifying the compost maturity and stability

The temperature profiles of three windrows demonstrate that the management of the piles was done adequately to facilitate optimum composting process, though they differ from pile to pile. From the beginning of composting process, till to the end of the incubation  period, the organic carbon decreases while the total nitrogen increases. The evolution of C/N ratio and NH4+  along the composting time in the 3 composted piles found to be inadequate for determining compost maturity.The daily respiration shows a similar decreasing trend over increasing of composting time.. However,  the values differ consistently from pile to pile making  difficult to use this parameter as indicator of  compost maturity.The values of microbial biomass C and metabolic quotients are also not consistent across the piles. The DEE extractable lipids content decreased sharply while the CHCl3 extractable lipids decreased slowly in all the composting piles along the incubation period. However, it was not possible to identify the compost maturity based on extractable lipids except for  pile P2. The germination index (%) gave differentiate results. Till to the the end of composting process, toxicity problems were found for pile 1 and 2.
It is evident that that none of the single parameter is applicable to identify compost maturity in the case of the organic waste used here. Thus, a careful selection of parameters and a optimum value for each selected parameter are necessary on the basis of the characteristics of the starting waste. 

Because of the high diversity in the organic residues, many test methods are proposed by various authors to determine compost maturity and stability. These test methods could be classified as 1. physical methods, 2. chemical methods, 3. biological methods, 4. microbiological methods, 5. degree of humification, 6. spectroscopic methods, and 7. chromatographic methods. Physical test methods of compost maturity include 1. temperature, 2. odour, and 3. color. These methods are relatively easy in use but give only rough information of the state of compost maturity. Chemical methods are widely used to determine compost maturity, including measurement of the C/N ratio, water soluble organic-C, the degree of OM humification etc. Biological methods for estimating the degree of maturity are included germination tests and growth tests. The microbial activities, numbers and biomass are key parameters that can also be used to elucidate the composting process. Fluorescence excitation–emission matrix (EEM) spectroscopy is used by some authors. Although, numerous tests  have been proposed to determine compost maturity, many of these have not been proven rigorous, reliable or consistent enough to be used in standard protocols. Some of  that required a substantial investment in laboratory equipment and staff training that their use in regular composting laboratories is not feasible. Thus, the search for a reliable method for assessing compost maturity is continued.

The work was conducted at the store house of the Mediterranean Agronomic Institute of Bari (MAIB) located in Apulia region (Southern Italy), 72 m above the sea level, latitude 41°03’16’’ North and longitude 16° 52’ 45’’ East Greenwich. Three turned windrow of compost piles were prepared at the Mediterranean Agronomic Institute of Bari,Italy, by mixing vineyard pruning with  cowdung ( Pile1), chicken slaughter house (Pile2) and cheese (Pile3) industries residues. Samples were collected at 0, 7, 15, 30, 45, 60, 90 and 120 days of composting. Each representative sample was obtaiined by mixing single samples from 6-8 different points of the pile. All the physio-chemical, biochemical and microbiological analysis were performed in triplicate. Physico-Chemical parameters were determined to know: pH, moisture, organic matter, total nitrogen, inorganic nitrogen forms, diethyl-ether and chloroform extractable lipids. While among microbiological parameters CO2 evolution rate, microbial biomass C and N were determined. Besides, seed germination and root elongation test was used to determine phytotoxicity. The work was done at MAIB laboratory.

I did not face any difficulty to work at MAIB.

With the increase in global population, the rate of waste generation and the amount of waste generated are increasing day by day. Waste management techniques take place in many ways viz., landfill, incineration, composting and anaerobic digestion.  It is reported that in the EU28, 492 kg of municipal waste was generated per person in 2012, while 480 kg of municipal waste was treated per person. This municipal waste was treated in different ways: 34% was landfilled, 24% incinerated, 27% recycled and 15% composted. For the EU there has been a significant increase in the share of municipal waste recycled or composted, from 18% in 1995 to 42% in 2012. Although landfilling is the most common method for waste disposal, concept of landfills for waste disposal has changed its dimension due to large quantities of waste generation, and reduced availability of dumping sites and environmental hazards because of greenhouse gases emission. The problems of waste incineration cannot be overemphasized in the light of the following: construction and start up costs of facilities, which could be too expensive for developing countries Composting of organic waste has a long history and is commonly employed to recycle organic matter back into the soil to maintain soil fertility. However, interest in composting has arisen because of the need for environmentally sound waste treatment technologies. Composting is seen as an environmentally acceptable method of waste treatment .

Presently, I am working on integrated nutrient management of cotton.

The basic concept underlying the integrated nutrient management system, nevertheless, remains the maintenance and possible improvement of soil fertility for sustained crop productivity on long term-basis and also to reduce inorganic (fertilizer) input cost. The three main components of INMS as defined by FAO, 1998 are: 1. Maintain or enhance soil productivity through a balanced use of fertilizers combined with organic sources of plant nutrients 2. Improve the stock of plant nutrients in the soils 3. Improve the efficiency of plant nutrients, thus, limiting losses to the environment.
Thus, integrated nutrient management aims at maintenance or adjustment of soil fertility and of plant nutrient supply to an optimum level for sustaining the desired crop productivity through optimization of benefit from all possible sources of plant nutrients in an integrated manner.

Based on the work a book was published as follows:

Book title:

Extractable lipids as an indicator of compost maturity.

Publisher:

LAP LAMBERT Academic Publishing
OmniScriptum GmbH & Co. KG
Heinrich-Böcking-Str. 6-8,
66121, Saarbrücken, Germany

Publication year: 2014