Quantifying the Agronomic Value of Biosolids and Biowastes
Author(s)
Rigby, Hannah
Type
Thesis
Abstract
Predicting N release in agricultural soils amended with organic residuals is
essential to ensure there are sufficient nutrients for crops, and minimal losses to
the environment. Factors such as moisture, temperature, soil type and organic
residuals type may affect the amount of mineralised nutrients. Information is
required to describe microbial N immobilisation in biosolids-amended soil, which
may vary between soil types influencing extent and rate of nutrient release.
Industrial biowastes are increasingly being used as soil amendments as a diversion
from landfill disposal; these materials result from a diverse range of processes and
vary greatly in physical and chemical characteristics. There is little published or
advisory information regarding their agronomic benefit, therefore research is
required to quantify their fertiliser value. The aims of this research were to quantify
mineralisation of N, and investigate other agronomic benefits of biosolids and
biowastes, and to investigate microbial biomass N (MBN) dynamics, with the aim of
improving fertiliser guidelines. A field trial was established at the Imperial College
field station in Wye, Kent, in spring 2005, to investigate N transformations in
contrasting soil types amended with conventional and enhanced treated biosolids.
Analysis of MBN in biosolids-amended soil indicated that there were differences in
N immobilisation processes in soils of differing fertility status, with greater
immobilisation observed in the lower fertility soil in some cases. Despite initial
differences in rate of mineralisation and nitrification, overall extent of N release was
similar in both soils. A programme of field trials was established at Imperial College
Silwood Park campus in 2006-2007 to quantify the agronomic value of a range of
industrial biowastes. Biowastes from the vegetable, meat and dairy industries and
from aerobic and anaerobic digestion plants were investigated. Yield response and
N offtake of perennial ryegrass to biowastes, at five rates of application, in
comparison to mineral N fertiliser, was used to calculate the replacement N fertiliser
value. The results of a laboratory incubation experiment, to investigate MBN and
mineral N in biowastes-amended soil, demonstrated lower recoveries of N in fine
textured soil with low stability waste. Denitrification was suspected as the potential
mechanism for this observation. Interactions between soil type and biowaste type
on N availability, and the implications for gaseous N losses to the environment from
biowastes-amended soils require further research.
essential to ensure there are sufficient nutrients for crops, and minimal losses to
the environment. Factors such as moisture, temperature, soil type and organic
residuals type may affect the amount of mineralised nutrients. Information is
required to describe microbial N immobilisation in biosolids-amended soil, which
may vary between soil types influencing extent and rate of nutrient release.
Industrial biowastes are increasingly being used as soil amendments as a diversion
from landfill disposal; these materials result from a diverse range of processes and
vary greatly in physical and chemical characteristics. There is little published or
advisory information regarding their agronomic benefit, therefore research is
required to quantify their fertiliser value. The aims of this research were to quantify
mineralisation of N, and investigate other agronomic benefits of biosolids and
biowastes, and to investigate microbial biomass N (MBN) dynamics, with the aim of
improving fertiliser guidelines. A field trial was established at the Imperial College
field station in Wye, Kent, in spring 2005, to investigate N transformations in
contrasting soil types amended with conventional and enhanced treated biosolids.
Analysis of MBN in biosolids-amended soil indicated that there were differences in
N immobilisation processes in soils of differing fertility status, with greater
immobilisation observed in the lower fertility soil in some cases. Despite initial
differences in rate of mineralisation and nitrification, overall extent of N release was
similar in both soils. A programme of field trials was established at Imperial College
Silwood Park campus in 2006-2007 to quantify the agronomic value of a range of
industrial biowastes. Biowastes from the vegetable, meat and dairy industries and
from aerobic and anaerobic digestion plants were investigated. Yield response and
N offtake of perennial ryegrass to biowastes, at five rates of application, in
comparison to mineral N fertiliser, was used to calculate the replacement N fertiliser
value. The results of a laboratory incubation experiment, to investigate MBN and
mineral N in biowastes-amended soil, demonstrated lower recoveries of N in fine
textured soil with low stability waste. Denitrification was suspected as the potential
mechanism for this observation. Interactions between soil type and biowaste type
on N availability, and the implications for gaseous N losses to the environment from
biowastes-amended soils require further research.
Date Issued
2008
Date Awarded
2008-10
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Smith, Stephen
Sponsor
Defra, Summerleaze Ltd. and Tanks and Vessels Ltd.
Creator
Rigby, Hannah
Publisher Department
Department of Civil & Environmental Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)