Table Of ContentLabile organic nitrogen dynamics and indicators of mineralizable nitrogen in manure-amended
soils
Ben William Thomas
Department of Natural Resource Sciences
Faculty of Agricultural and Environmental Sciences
McGill University, Montreal
December 2015
A thesis submitted to McGill University in partial fulfillment of the requirements for the degree
of Doctor of Philosophy
© Ben W. Thomas 2015
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ABSTRACT
Organic-N applied by manure increases soil mineralizable-N pools for current and subsequent
growing seasons, but the magnitude is manure type and soil texture specific, complicating the
prediction of manure fertilizer-N value. The objectives of this thesis were to (1) determine
manure type and soil texture effects on soil mineralizable-N, (2) evaluate labile organic-C and -N
fractions as predictors of mineralizable-N and (3) quantify the temporal labile organic-N
dynamics by using the soil microbial biomass, salt (0.5 M K SO ) extractable organic-N, and
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particulate organic matter N as surrogates for biological, soluble and non-soluble labile organic-
N. In the sandy loam soil, solid poultry litter depleted Pool I (mineralized-N in 2 wk), and in the
silty clay soil, liquid dairy cattle manure increased Pool I. Pool I was a robust indicator of
mineralized-N over 48-wk in sandy loam and silty clay soils. In the liquid dairy cattle manure-
amended sandy loam soil, there was 7% more organic-N mineralization than liquid swine
manure-amended soils (P < 0.05). In the sandy loam soil, increasing mineral N concentrations
coincided with a significant decrease in soluble organic N and narrowing of the particulate
organic matter C/N ratio from 16:1 to 14:1 between 3 and 28 d (P < 0.01). In the silty clay soil,
liquid dairy cattle manure increased soluble organic-N and particulate organic matter C more
than liquid swine manure, but did not result in greater organic-N mineralization. There was
greater depletion of particulate organic matter in the liquid dairy cattle manure -amended sandy
loam than silty clay soil, implying fresh particulate organic matter is more decomposable source
of C and N in coarse- than fine-textured soils. I conclude that Pool I, particulate organic matter
and soluble organic-N hold promise as general indicators of mineralizable-N in manure-amended
soils and thus the fertilizer-N value of manure applied to sandy loam and silty clay soils of the
Saint Lawrence Lowlands of Quebec.
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RÉSUMÉ
La contribution de l’azote organique issue du fumier de ferme au pool de N mineralisable du sol
s’étends sur plusieurs saisons de croissance. Cependant, l’amplitude est fonction du type de
fumure et de la texture du sol, ce qui rend difficile la prédiction de la valeur fertilisante en azote
du fumier. Les objectifs de cette thèse étaient de (1) déterminer l’influence du type de fumier et
de la texture du sol sur le pool de N mineralisable du sol, (2) évaluer la capacité de la fraction
labile de la matière organique à prédire le N mineralisable des sols de textures différentes
recevant du fumier, (3) et de déterminer la dynamique du N organique en utilisant la biomasse
microbienne du sol, le N organique extractible au sulfate de potasse (0.5 M), et l’azote associé à
la matière organique particulaire comme substituts de N biologique, soluble et non-soluble labile.
Le N mineralisable du sol a été influencé par le type de fumier et la texture du sol. Dans le loam
sableux, le N facilement mineralisable (Pool I) a diminuée avec l’apport de litière de volaille
solide et dans le limon argileux, le Pool I a diminué avec l’apport de lisier de bovin laitier. De
plus, le Pool N a été un indicateur robuste du N total minéralisé après 48 semaines dans le loam
sableux et le limon argileux. Dans le loam sableux, la minéralisation apparente nette de N dans le
lisier de bovin laitier a été supérieure de 7% par rapport au lisier de porc (P < 0.05). En outre,
l’augmentation de la concentration du N minéral a coïncidée avec une diminution significative
du N organique soluble et du rapport C/N de la matière organique particulaire (de 15.9 à 14.4
entre 3 et 28 jours). Dans le limon argileux, le N organique soluble et la matière organique
particulaire ont été plus élevés avec l’apport de lisier de bovin laitier qu’avec le lisier de porc. La
diminution de la matière organique particulaire avec l’apport de lisier de bovin laitier a été plus
grande dans le loam sableux que dans le limon argileux, indiquant que la matière organique
particulaire fraîche est source importante de C et N dans les sols à textures grossières que ceux à
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textures fines. En conclusion, le Pool I, la matière organique particulaire, et le N organique
soluble sont de potentiels indicateurs de la minéralisation de N dans les sols recevant du fumier
et en conséquence de la valeur fertilisante du fumier en N dans les loam sableux et limon
argileux de la Région du Saint Laurent à Québec.
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DEDICATION
In memory of, Dr. Roland Jung, for his mentorship, friendship and humour that I dearly miss and
will never forget, and Chris Boudreau, for the countless hours we spent roaming the Acadian
forests of Nova Scotia, fishing, hunting and exploring - the foundation of my interest in the
natural world.
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PREFACE AND CONTRIBUTIONS OF AUTHORS
This thesis is composed of five chapters. The first chapter is a literature review that summarizes
previous research on N mineralization in manure-amended soils and how manure application
affects labile organic matter and their potential for use as indicators of N mineralization in
manure-amended soils. Experimental results are presented in chapter two to five, which are
written as scientific manuscripts, with connecting paragraphs between each chapter linking each
experiment, according to guidelines of the Graduate and Postdoctoral Studies Office, McGill
University.
The candidate was the senior author on all manuscripts. Co-authors included Dr. Joann K.
Whalen, Dr. Mehdi Sharifi, Dr. Martin H. Chantigny, and Dr. Bernie J. Zebarth. The candidate
conducted the research with financial support from Natural Sciences and Engineering Research
Council of Canada (NSERC) Discovery Grants awarded to M. Sharifi and J.K. Whalen. The
candidate received Graduate Excellence Awards from the Department of Natural Resource
Sciences of McGill University, a Western Ag. Innovations Inc. Student Research Award, and a
Canadian Society of Soil Science Student Travel Award.
The candidate undertook the literature review in chapter one and was solely responsible
for designing the experiments in chapters two to five, all day-to-day activities in performing all
experiments, data collection, analysis and interpretation, and writing the manuscripts. The
candidate solely conducted every soil fractionation and extraction procedure. Technical
assistance was provided by Hicham Benslim, Hélène Lalande, Susan Robinson, Jessica Stöckli
and Scott Baker to measure the C and N concentrations in the extractions. The soils for chapters
two, three and five were collected from a field site at the Laval University Experimental Farm in
Saint-Augustin-de-Desmaures, Quebec, Canada. These sites were maintained by Les Moulins de
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Soulanges, Universite Laval, and Agriculture and Agri-Food Canada. Physical and chemical
characterization of the manure applied to the field site and soil texture analysis was conducted by
Dr. Chantigny’s staff at Agriculture and Agri-Food Canada. Dr. Whalen and Dr. Sharifi provided
financial support, advisory guidance about the experiments, and editorial assistance with the
manuscripts. Dr. Chantigny provided advice and editorial assistance on manuscripts in chapters
two, three and five and provided the liquid dairy cattle and liquid swine manures for the chapter
five experiment. Dr. Zebarth and Dr. Burton provided advice and editorial assistance for the
chapter two manuscript.
The manuscript-based chapters are presented in the following order:
Chapter 1. Thomas, B.W., Whalen, J.K., Sharifi, M. Predicting nitrogen mineralization in
manure-amended soils to sustain crop production in humid temperate regions. Invited review:
Adv. Agron.
Chapter 2. Thomas, B.W., J.K. Whalen, M. Sharifi, M.H. Chantigny, and B.J. Zebarth. 2016.
Labile organic matter C:N ratios as indicators of soil N supply. J. Plant Nutri. Soil Sci. (in press).
Chapter 3. Thomas, B.W., M. Sharifi, J.K. Whalen, and M.H. Chantigny. 2015. Mineralizable
nitrogen responds differently to manure type in contrasting soil textures. Soil Sci. Soc. Am. J.
79:1396-1405.
Chapter 4. Thomas, B.W., J.K. Whalen, and M. Sharifi. Short-term nitrogen availability
indicators in soil amended with poultry litter containing woodchip bedding. (in review). Can. J.
Soil Sci.
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Chapter 5. Thomas, B.W., J.K. Whalen, M. Sharifi, and M.H. Chantigny. Labile organic
nitrogen dynamics in contrasting soil textures amended with liquid swine or dairy cattle manure.
Target journal: Soil Biol. Biochem.
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CONTRIBUTION TO KNOWLEDGE
The research in this thesis provides the following important contributions to knowledge:
1. This is the first review to describe how labile organic matter fractions contribute to N
mineralization in manure-amended soils of humid temperate regions. I designed a conceptual
model to illustrate the labile organic matter fractions impacted by manure application, and how
the labile organic N undergoes decomposition and mineralization to release mineral N in
manure-amended soils.
2. This was the first experiment to evaluate labile organic matter C/N ratios as an indicator of N
mineralization in manure-amended soils.
3. I showed that the residual mineralizable N in soils with a manure amendment history was not
predictable based on the manure type, due to manure type × soil texture interaction.
4. I showed that Pool I was a sensitive measure of management practice and a robust indicator of
mineralizable N in two soils with contrasting soil texture that were amended with different
manures (3 types) during the past 3-yr.
5. I showed that a short 7-d pre-incubation of poultry litter (PL) amended soils, followed by a
KCl extraction to measure nitrate, was the reliable indicator of wheat N uptake, compared to 14
other N availability indicators. I also showed that ion exchange membranes could replace plant
and soil sampling to monitor N dynamics in PL-amended soils.
6. I showed that the POMC:POMN narrows after LCM and LSM is applied to soil and
decomposes for 28 days, and that this decrease coincides with a decrease in soluble organic N
and increasing mineral N concentrations in sandy loam soils, but not silty clay soils.
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ACKNOWLEDGEMENTS
I am grateful for the support and expertise that Dr. Mehdi Sharifi and Dr. Joann K. Whalen have
provided during my research and manuscript writing. I would like to thank Dr. Sharifi for
offering me the opportunity to conduct doctoral research. I enjoyed our discussions about my
experiments and manuscripts. I would like to acknowledge his tremendous work and effort
guiding the establishment of a Sustainable Agriculture Lab and Experimental Farm at Trent
University.
I would like to particularly offer my heartfelt thanks to Dr. Whalen for welcoming me to
the Soil Ecology Research Group (SERG) at McGill University and for being a great role-model,
teacher and mentor. Dr. Whalen always led by example and pushed me to grow, not only as a
scientist, but as a person. Dr. Whalen took the time to teach me (and other members of SERG)
more than I could have ever imagined about scientific research and writing, and sometimes about
life in general (e.g. if it’s good for you, it does not come easy). In that respect, I have advanced
my knowledge in three plus short years more than I thought possible and I am deeply thankful
for that.
I am also grateful for the opportunity to work with Dr. Martin Chantigny and his team at
AAFC in Quebec City. Thanks to Johanne Tremblay for providing me information and analytical
advice in a timely, friendly manner. The advice of Dr. Bernie Zebarth and Dr. David Burton is
also gratefully acknowledged. I’d like to thank Kyle Gallant, for help with soil sampling back in
2012. I’d like to thank, Joe Crowley of Norwood, ON for allowing Jessica Stoeckli and I to
collect soil and poultry litter from his farm for the experiment reported in chapter four.
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Description:Organic-N applied by manure increases soil mineralizable-N pools for current and subsequent s'étends sur plusieurs saisons de croissance.
