CRANFIELD UNIVERSITY Maria I. Kokkora Biowaste and vegetable waste compost application to agriculture School of Applied Sciences PhD Thesis CRANFIELD UNIVERSITY SCHOOL OF APPLIED SCIENCES NATIONAL SOIL RESOURCES INSTITUTE PhD Thesis 2004-2007 Maria I. Kokkora Biowaste and vegetable waste compost application to agriculture Supervisor: Dr. Mike Hann March 2008 This thesis is submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy © Cranfield University, 2008. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder. i Abstract The landfilling of biodegradable waste is proven to contribute to environmental degradation. Compost use in agriculture is increasing as both an alternative to landfilling for the management of biodegradable waste, as well as means of increasing or preserving soil organic matter. This research aimed to contribute to the identification of a system for managing the utilization of vegetable waste (agricultural plant-tissue waste) and biowaste (source-separated biodegradable municipal solid waste) composts for sustainable agriculture, with particular regards to nitrogen availability and leaching. The two compost types were analyzed for physical and chemical properties potentially related to soil and crop parameters. Composts were applied to forage maize and annual ryegrass production on light textured soils, using different rates and methods, to determine the effects on crop production, soil properties and N leaching, in lysimeter, pot and field conditions. An incubation trial was carried out to study compost N mineralization potential under controlled conditions. The economic implications of using compost in agriculture were also considered. Biowaste and vegetable waste compost properties varied significantly between compost types and dates of production, thus suggesting that to properly manage compost application, agricultural practise should adjust to the specific characteristics of each material. Both composts were low in nutrients. A quantity of 19-30 Mg biowaste or 50- 63 Mg vegetable waste compost was necessary in order to apply 250 kg total N ha-1. There was higher nitrogen mineralization from vegetable waste compost than from biowaste compost. This was attributed to the lower C: N ratio and/or the lower content of recalcitrant to decomposition carbon sources. Compost with C: N lower than 15 is likely to result in net mineralization of organic N, thus increasing soil available N and excluding negative effects on crop production from N immobilization. N mineralization following the application of biowaste and vegetable waste composts with C: N ratios varying from 9 to 21, ranged from approximately -4% to 10% of the total N applied, depending mainly on the compost C quality, climatic and soil conditions. Compost N mineralization was not influenced by application rate and method. Maria I. Kokkora PhD Thesis, 2008 NSRI ii Applying biowaste or vegetable waste compost based on their total N content, whilst taking into consideration the compost N mineralization potential, the crop N requirements and the soil N is not likely to increase N leaching on light textured soils, in comparison to non-amended soil. Properly managed compost application resulted in less N leaching than mineral fertilizer N, because of the slow release of the compost N mineralized, which allows for more efficient crop N uptake. Forage maize and annual ryegrass dry matter yield significantly increased following biowaste and vegetable waste compost application. Crop N recovery varied from 0% to 12% of the compost total N applied. Higher DM yield and N uptake was achieved with higher rates of onion compost application. The application of biowaste and vegetable waste composts increased soil total C, OM, organic N, and extractable K content and water retention of light textured soils (the higher the application rate, the higher the increase), thus improving soil fertility for better crop production, and water conservation. However, it also increased extractable Na levels hence potentially introducing salinity and/or sodicity problems in Na sensitive soils and crops. Surface applied biowaste or vegetable waste compost resulted in higher soil moisture, under enhanced evaporation conditions, and in lower Na content. Compost application increased P solubility and resulted in transport of soil available P below the root zone of coarse textured sandy soils thus reducing P availability for plant uptake and increasing the risk of water eutrophication. However, the increase of P solubility prevented the fixation of available P, thus suggesting that compost application in calcareous alkaline soils may increase P availability for plant uptake. The cost of using biowaste or vegetable waste compost to agriculture is relatively high; considering a compost application rate of 250 kg total N ha-1 yr-1, the cost ranged from £172 to £ 489 ha-1 yr-1. Key factors influencing the cost were the compost N content in fresh weight basis and the haulage distance. Despite the high costs involved, compost application to agriculture is a sustainable practise because of the increasing mineral fertilizer prices, and the resulting soil quality improvement, organic waste diversion from landfills, decreasing of N leaching, and preserving of non-renewable resources. Maria I. Kokkora PhD Thesis, 2008 NSRI iii Acknowledgements The author is grateful to Korgialenion Athlon Institute in Greece, for the financial support that made this research possible. Sincere gratitude and appreciation is expressed to my supervisor Dr. Mike J. Hann, and my thesis committee Prof. Richard J. Godwin and Dr. Sean F. Tyrrel, for their continuous support, encouragement and valuable feedback during this work. Thanks go to the laboratory technicians Gabriela Lovelace, Maria Biskupska, Mary Cook, Margaret Boom and Richard Andrews for their help and inspiration during the long laboratory analysis. Thanks also go to the field technicians Peter Grundon, Bob Walker and Ian Seymour for their technical help towards the establishment of the experiments. Also, Peter’s help on soil sampling in the field is sincerely acknowledged. The author wishes to thank Dr. Ruben Sakrabani for his comments on the soil chemistry results analysis. Also, the guidance of Charles Marshall and Patricia Bellamy on the statistical analysis is gratefully acknowledged. This thesis is devoted to my parents, Ioannis and Dimitra Kokkora, to whom I am sincerely grateful for all their continuous support, patience and encouragement throughout the project. Maria I. Kokkora PhD Thesis, 2008 NSRI iv List of contents Abstract.......................................................................................................................... i Acknowledgements ..................................................................................................... iii List of contents ............................................................................................................ iv List of figures .............................................................................................................. ix List of Tables............................................................................................................. xix Notation ................................................................................................................... xxiii 1 Introduction .............................................................................................................. 1-1 1.1 Research background........................................................................................... 1-1 1.1.1 The importance of waste recycling to land................................................... 1-1 1.1.2 Compost application to agricultural soil....................................................... 1-2 1.2 Research aim........................................................................................................ 1-4 1.3 Objectives ............................................................................................................ 1-4 1.4 Outline methodology........................................................................................... 1-4 1.5 Thesis structure.................................................................................................... 1-7 2 Literature review ...................................................................................................... 2-1 2.1 Introduction ......................................................................................................... 2-1 2.2 Biodegradable waste processing.......................................................................... 2-1 2.2.1 General principles......................................................................................... 2-1 2.2.2 Biological treatment of biodegradable waste ............................................... 2-2 2.2.2.1 Composting ........................................................................................... 2-3 2.2.2.2 Anaerobic Digestion (AD) .................................................................... 2-5 2.2.2.3 Mechanical Biological Treatment (MBT) ............................................. 2-7 2.3 Composting of bio- and vegetable waste............................................................. 2-8 2.3.1 Definition of biowaste and vegetable waste................................................. 2-8 2.3.2 Composting methods ...................................................................................