Carbon Sequestration in Agricultural Soils
.
Alessandro Piccolo
Editor
Carbon Sequestration
in Agricultural Soils
A Multidisciplinary Approach
to Innovative Methods
Editor
Prof. Dr. Alessandro Piccolo
Universita di Napoli Federico II
Ordinario di Chimica Agraria
Via Universita
`
100
80055 Portici
Italy

ISBN 978-3-642-23384-5 e-ISBN 978-3-642-23385-2
DOI 10.1007/978-3-642-23385-2
Springer Heidelberg Dordrecht London New York
Library of Congress Control Number: 2011943755
# Springer-Verlag Berlin Heidelberg 2012
This work is subject to copyright. All rights are reserved, whether the whole or part of the material is
concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting,
reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication
or parts thereof is permitted only under the provisions of the German Copyright Law of September 9,
1965, in its current version, and permission for use must always be obtained from Springer. Violations
are liable to prosecution under the German Copyright Law.
The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply,

of carbon seque stration in agricultural soil to a scientific audience was hardly
received positively. There is a general skepticism of the use of biomimetic catalysts
in agricultural soils, perhaps because of the possible negative consequences on the
biological soil quality and the reduced nutritional functions of soils, due to a
restricted availability of soil humus for microbial transformation.
v
The criticism was a beneficial stimulus to scale up research amb itions from
laboratory or glasshouse to fully-fledged field agronomic trials, through which not
only the effectiveness of the soil carbon sequestration methods could be verified in
practice, but also the concerns about the eco-toxicological, biological, biotechno-
logical and nutritional effects of the cat alytic soil treatment could be dissipated.
A multifaceted research project was presented to the Italian Ministry of Research
(MIUR) within the strategic FISR programme. The intention was to cover all
possible aspects inherent in soil organic matter transformations in agricultural
soils leading to enhanced soil carbon sequestration, while maintaining soil quality
and the high levels of crop productivity required by the farming market. The project
was titled “Metodi Sostenibili per il sequestro del carbonio organico nei suoli
agrari. Valutazione degli effetti sulla qualita
`
chimica, fisica, biologica ed agrono-
mica dei suoli”, with the MESCOSAGR acronym. The project was approved, under
the coordination of this Editor, and was funded with a total budget of 2.5 Mio Euro
over a 3 years working span.
The MESCOSAGR project relied on the work of six research units belonging to
six different Italian Universities. In particular the Universi ty of Napoli Federico II
comprised: the group of Prof. Alessandro Piccolo, for the determination of
carbon and nitrogen sequestration in all treated soils, as well as the molecular
transformation of soil organic matter upon soil treatments; the group of
Prof. Fabrizio Quaglietta Chiaranda
`

biological potentials of the treated soils.
Readers will find in this book data and results of their own interest, but they will
also have the advantage of being able to cross reference with other interdisciplinary
subjects, thereby receiving a complete picture of the effects of the new soil
management methods and their potential for practical application in farm manage-
ment. I am also sure that the most perceptive soil scientists will find in the book
several hints for new confirmative experiments, further ground for speculating on
more soil–plant-technology interactions and the possibility to develop new methods
or applications.
Finally, I take the chance to thank all the scient ific and administrative collabora-
tors of the MESCOSA GR project who made it possible, despite the many logistic
difficulties often encountered, in reaching the project’s ambitious objectives.
Portici, Italy Alessandro Piccolo
November 2011
Preface vii
.
Contents
1 The Nature of Soil Organic Matter and Innovative
Soil Managements to Fight Global Changes and Maintain
Agricultural Productivity 1
Alessandro Piccolo
2 The Kyoto Protocol and European and Italian Regulations
in Agriculture 21
Davide Savy, Antonio Nebbioso, RocíoDánica Cóndor, and Marina Vitullo
3 Field Plots and Crop Yields Under Inn ovative Methods
of Carbon Sequestration in Soil 39
Carlo Grignani, Francesco Alluvione, Chiara Bertora, Laura Zavattaro,
Massimo Fagnano, Nunzio Fiorentino, Fabrizio Quaglietta Chiaranda
`
,

Antonio Gelsomino, Maria Rosaria Panuccio, Agostino Sorgona
`
,
Maria Rosa Abenavoli, and Maurizio Badiani
11 New Modeling Approach to Describe and Predict Carbon
Sequestration Dynamics in Agricultural Soils 291
Stefano Mazzoleni, Giuliano Bonanomi, Francesco Giannino, Guido Incerti,
Daniela Piermatteo, Riccardo Spaccini, and Alessandro Piccolo
x Contents
Contributors
Maria Rosa Abenavoli Dipartimento BIOMAA, Universita
`
Mediterranea, Reggio
Calabria, Italy
Francesco Alluvione Dipartimento di Agronomia, Selvicoltura e Gestione del
Territorio, Universita
`
di Torino, Turin, Italy
Mariana Amato Dipartimento di Scienze dei Sistemi Colturali, Forestali e dell’
Ambiente, Universita
`
della Basilicata, Potenza, Ita ly
Maurizio Badiani Dipartimento BIOMAA, Universita
`
Mediterranea, Reggio
Calabria, Italy
Chiara Bertora Dipartimento di Agronomia, Selvicoltura e Gestione del
Territorio, Universita
`
di Torino, Turin, Italy

Universita
`
di Napoli Federico II, Naples, Italy
Massimo Fagnano Dipartimento di Ingegneria Agraria e Agronomia del
Territorio, Universita
`
di Napoli Federico II, Naples, Italy
Angelo Fier ro Dipartimento di Biologia Strutturale e Funzionale, Universita
`
di Naples Federico II, Naples, Italy, fierr
Nunzio Fiorentino Dipartimento di Ingegneria Agraria e Agronomia del
Territorio, Universita
`
di Naples Federico II, Naples, Italy
Annachiara Forte Dipartimento di Biologia Strutturale e Funzionale, Universita
`
di Napoli Federico II, Naples, Italy
Antonio Gelsomino Dipartimento BIOMAA, Universita
`
Mediterranea, Reggio
Calabria, Italy,
Francesco Giannino Dipartimento di Ingegneria Agraria, Agronomia e Territorio,
Universita
`
di Napoli Federico I, Naples, Italy
Carlo Grignani Dipartimento di Agronomia, Selvicoltura e Gestione del
Territorio, Universita
`
di Torino, Turin, Italy,
Guido Incerti Dipartimento di Arboricoltura, Botanica e Patologia Vegetale,

`
di Bari Aldo Moro, Bari, Italy
Olimpia Pepe Dipartimento di Scienza degli Alimenti, sez. Microbiologia
Agraria, Universita
`
di Napoli Federico II, Naples, Italy
Alessandro Piccolo Dipartimento di Scienza del Suolo, della Pianta, dell’
Ambiente e delle Produzioni Animali, Universita
`
di Napoli Federico II, Naples,
Italy,
Daniela Piermatteo Dipartimento di Arboricoltura, Botanica e Patologia
Vegetale, Universita
`
di Napoli Federico II, Naples, Italy
Edoardo Puglisi Istituto di Chimica Agraria ed Ambientale, Universita
`
Cattolica
del Sacro Cuore, Piacenza, Italy,
Pacifico Ruggiero Dipartimento di Biologia e Chimica Agroforestale ed Ambien-
tale, Universita
`
di Bari Aldo Moro, Bari, Italy
Davide Savy Dipartimento di Scienza del Suolo, della Pianta, dell’Ambiente
e delle Produzioni Animali, Universita
`
di Napoli Federico II, Naples, Italy,

Agostino Sorgona
`

Abstract A new era in soil management is emerging on the basis of the novel
understanding of soil organic matter (SOM), as a noncovalent supramolecular
association of small molecules surviving microbial degradation of plant and animal
tissues. The recognition of such molecular nature of humus may have technological
implications in agri cultural soil management that are yet to be developed. Here we
discuss the implications of the supramolecular structure of humus on innovative
methods for carbon sequestration in agricultural soil. One method exploits the
capacity of humified/hydrophobic matter, such as mature compost amended to
soils, to protect from mineralization biolabile hydrophilic molecules rhizodeposited
by crops. Another method is the use of biomimetic catalysts to be spread on soils to
oxidatively photopolymerize SOM in situ. The formation of intermolecular cova-
lent bonds among soil humic molecules increases the chemical energy required by
microbes to mineralize SOM. Both methods were verified in their effectiveness in
soil before the scaling up of their use on real field trials under agricultural crops.
1.1 Current Concepts and Technologies
A sustainable use of soil means its exploitation in a way and at a rate that preserves
at the long term its multitude of functions and protects or improves its quality,
thereby maintaining its potential to meet the likely needs and aspirations of present
and future generations (Van-Ca mp et al. 2004 ).
Soil organic matter (SOM) plays a fundamental role in plant nutrients status;
maintenance of soil functions; and release of CO
2
, methane, and other gases in the
atmosphere. Two factors influence SOM content: natural (climate, soil parent
A. Piccolo (*)
Dipartimento di Scienza del Suolo, della Pianta, dell’Ambiente e delle Produzioni Animali,
Universita
`
di Napoli Federico II, Naples, Italy
e-mail:

base) (EU Soil Thematic Strategy 2004). The role of soil, both as an emitter and a
sink for carb on, is particularly important in this context. At global scale, research
indicates that the soil carbon pool of 2,500 billion ton includes about 1,550 billion
ton of soil organic carbon, which is 3.3 times the size of the atmospheric pool
(760 billion ton) and 4.5 times the size of the biotic pool (560 billion ton) (Lal
2004). Between 1850 and 1998, the emission from terrestrial ecosystems was
136 Æ 55 billion ton. The latter includes 78 Æ 12 billion ton from soil, of which
about one-third is attributed to soil degradation and accelerated erosion and two-
thirds to OM mineralization (IPCC 2000). The European Union endorsed the need
to link soil sustainability and its role in mitigating climate change, by calling for “a
robust approach to address the interaction between soil protection and climate
change from the viewpoints of research, economy and rural development, so that
policies in this areas are mutually supportive” (EC 2006).
Management options available to sequester carbon in cropland include reduced
and zero tillage, set-aside, perennial crops and deep rooting crops, more efficient
use of organic amendments, improved rotations, irrigation, bioenergy crops, inten-
sification of organic farming, and conversion of arable land to grassland or wood-
land (Smith et al. 2000, 2008). Due to advances in weed control methods and farm
machinery which allow many crops to be grown with minimum tillage (reduced
tillage) or without tillage (no till), these practices, which limit soil disturbance and
consequently soil C losses through reduced microbial decomposition, are now
usually believed to increase SOC seque stration in cropland soils. However, there
2 A. Piccolo
are no solid scientific bases to justify this belief (Cerri et al. 2004; Smith and Conen
2004; Gregorich et al. 2005; Plaza-Bonilla et al. 2010; Mancinelli et al. 2010).
Moreover, a long-term application is usually required for reduced tillage practices
to produce a significant and steady improvement of OC content in cultivated soils
(West and Post 2002). Reduced tillage is also advocated to affect N
2
O emissions

10
15
20
25
30
35
40
45
50
55
t C ha
–1
per year
A
g
ronomic Practices
Soil carbon
sequestration potential
(t C ha
–1
per year)
Total soil carbon
sequestration potential for
EU15 (MtC per year)
Fig. 1.1 Carbon sequestration potentials limited only by availability of land, biological resources
and land suitability, and the potentials estimated to be realistically achievable by 2012
1 The Nature of Soil Organic Matter and Innovative Soil Managements 3
1.2 Conceptual Innovations
To meet the described need, it is required to introduce in agriculture more scientifi-
cally reliable, effective, and persistent soil management practices for carbon

A major breakthrough in understanding SOM chemistry in the last decade came with
the recognition that soil humus is a self-assembled supramolecular associations of
small heterogeneous molecules held together mainly by weak hydrophobic linkages,
rather than being composed of large molecular weight macropolymers (Piccolo
2001).
Humus, otherwise referred to as Humic Substances (HS), is the natural organic
matter comprising up to 80% of SOM. Because of the beneficial effects that HS
have on the physical, chemical, and biological properties of soil, their role in the
soil environment is significantly greater than that attributed to their contribution to
sustaining plant growth. The HS are recognized for their controlling both the fate of
environmental pollutants and the chemistry of organic carbon in the global ecosys-
tem (Piccolo 1996).
Despite their prominent importance, a better knowledge of the basic nature and
reactivity of HS has been elusive for a long time because of their large chemical
4 A. Piccolo
heterogeneity and geographical variability. Because it is a mixture that originates
randomly from the decay of plant tissues or microbial metabolism–catabolism or
both, the chemistry of humus is not only of utmost complexity but also a function of
the different general properties of the ecosystem in which it is formed: vegetation,
climate, topography, etc. The tremendous task of advancing the knowledge of
humic chemistry and its consequences to other environmental domains still lies
ahead of us. It should be obvious, to a world that appreciates the potentials of
genetic engineering based on an understanding of DNA structure, that accurate
predictions of reactivities and development of related technologies can only be
made when there is a basic knowledge of the chemical structure of the reacting
molecules.
Piccolo summarized his and other authors’ experiments supporting the supra-
molecular structure of humus in different reviews (Piccolo 2001, 2002; Piccolo
et al. 2003). These experimental results cannot be explained by analytical
interferences or the traditional macropolymeric model of HS. They can rather be

form a supramolecular association. The structures represented molecules such as
saturated and unsaturated fatty acids, carbohydrates, peptides, lignin derivatives,
etc., with molecular weights varying from 116 Da for a dihydroxybenzene to
504 Da for a triglucose. The molecular weight sum of the 11 molecules was
3,065 Da.
The geometry of the association was automatically adjusted and its conforma-
tional energy was minimized in the vacuum (Fig. 1.2a). Ten molecules of acetic
acid were added first to surround the hypothetical supramolecular association
(Fig. 1.2b) and then placed within the conformation of the association (Fig. 1.2c).
The resulting association energies were calculated by the software to be 114, 91.2,
and 84.0 Kcal mol
À1
, respectively.
The association of the different molecules also varied its physical appearance
with the approach of acetic acid molecules which caused a loosening of intermo-
lecular attractions until some spaces among the molecules were formed.
Fig. 1.2 Computer
simulation of the optimum
conformational energy (in
vacuo) for an association of
11 different humic precursors
with a total molecular weight
of 3,065 Da. (a) Upper
picture: molecular
association with an energy of
114 Kcal mol
À1
;(b) middle
picture: molecular
association surrounded by ten

Thus, it would be hardly possible, using this hypothetical polymeric model, that the
simple addition of acetic acid molecules to such a high molecular weight polymer
would provide a rearrangement of molecular associations leading to conformational
disruptions as that described by the experiments funding the supramolecular struc-
ture of SOM (Piccolo 2001, 2002).
1.3 Implications in Soil of the Supramolecular Structure
of Humus
A clarification of the aggregate structures of HS has represented a major innovation
in humus chemistry. A model of soil humus as a supramolecular association of
small molecules, originated from extended microbial degradation of different plant
Fig. 1.3 Computer
simulation of the optimum
conformational energy (in
vacuo) of a hypothetical
covalently linked humic
polymer (MW ¼ 6,326 Da)
as hypothesized by Stevenson
(1994). (a) Upper picture:
humic polymer having an
energy of 627.40 Kcal mol
À1
;
(b) lower picture: humic
polymer containing ten
molecules of acetic acid and
having an energy of
617.26 Kcal mol
À1
1 The Nature of Soil Organic Matter and Innovative Soil Managements 7
and animal biomolecules and assembled together by mainly hydrophobic forces

1.3.2 The Mechanism of Hydrophobic Protection of SOM
to Sequester Carbon in Soil
The recognized importance of hydrophobicity in stable SOM has a relevant implica-
tion in soil carbon sequestration. In fact, the hydrophobic character of OM represents
a biochemical hindrance to microbial decomposition (Piccolo et al. 1999;
8 A. Piccolo
Spaccini et al. 2000), the basis for a persistent soil aggregate stability (Piccolo and
Mbagwu 1999), and an overall SOM stabilization (Rumpel et al. 2004; Winkler
et al. 2005; Zhou et al. 2010). The recalcitrant hydrophobic molecules are the
constituents of the stable and humified SOM fraction (Piccolo 1996; Grasset et al.
2002; Deport et al. 2006), that enters in intimate association with fine soil particles,
such as clay minerals and Fe and Al hydroxides, thus contributing to highly
stabilize soil organo-mineral complexes (Mikutta et al. 2006; Sch
€
oning and
K
€
ogel-Knabner 2006; von L
€
utzow et al. 2006).
Furthermore, the porous architecture of hydrophobic domains of soil humus
exerts a dynamic mechanism of hydrophobic protection toward the biolabile
organic compounds released in soil solution by plant roots exudates and microbial
degradation of crop biomolecules. It was experimentally verified by measuring the
reduced degradation of
13
C-labeled compounds in soils amended with humified
matter at different degree of hydrophobicity (Spaccini et al. 2002). These authors
synthesized a
13

preferentially occurs within organo-mineral association of finer soil particles.
Nevertheless, hydrophobic sequestration of carbon in soil may also take place
within larger size fractions, provided that humified matter of large hydrophobic
character is applied. In fact, the highly hydrophobic HA from lignite was able to
reduce OC decomposition, with respect to treatments with HA from compost and
13
C-2-decanol alone, even in the coarser fractions which are commonly associated
with rapid cycling of SOM pools.
Exogenous organic matter (EOM), such as mature compost added to soils, may
also be capable of reducing the biological mineralization of labile polysaccharides
due to progressive incapsulation into hydrophobic domains of compost. In a long-
term (1 year) experiment, Piccolo et al. (2004) treated both a sandy and a silty-loamy
1 The Nature of Soil Organic Matter and Innovative Soil Managements 9
120
90
60
30
120
90
60
160
120
13
C-OC, % of initial content
80
40
0
240
180
120

of HA from compost previously added with
13
C-labeled 2-decanol;
13
C-HAL, treatment of HA
from lignite previously added with
13
C-labeled 2-decanol). Bars in graph indicate standard deviation
(n ¼ 3)
10 A. Piccolo