Results and Discussion

5.7.4.1 Carbon Isotopic Signature in the Sorghum Plants Figure 5.2 shows the average isotopic signature of various parts of the sorghum plant, as evaluated at the end of the vegetative cycle. Generally, data indicated that the roots were more 13C-enriched than the grain and leaves, and in the first 15 cm of roots appeared more 13C-enriched than at deeper soil depths. Our results are consistent with previous studies on isotope ratios in plant biomass which showed that roots are generally more...

Effects of Soil Tillage

Deep soil tillage is the crop management with most impact on soil properties (Fagnano and Quaglietta Chiaranda 2008). Soil tillage may have contrasting agronomic and environmental effects on soil structure and aeration of the tilled layer. The destruction of soil aggregates decreases macroporosity and infiltration rate, with enhanced risk of soil erosion and reduced oxygen diffusion rate. The consequent anaerobic conditions limit root growth and may increase denitrification and methanogenesis...

Effects of the Biomimetic Catalyst

Humic substances comprise the major part of stable organic matter in environmental compartments and their formation and decomposition processes regulate global carbon cycling. An increase in the conformational stability of humus may be achieved by increasing the intermolecular covalent bonds among heterogeneous humic molecules through a photo-oxidative coupling mediated by a biomi-metic (enzyme-like) catalyst, such as synthetic water-soluble metal-porphyrins (Piccolo et al. 2005). It was found...

The Stable Isotopes Approach to Study C and N Sequestration Processes in a Plant Soil System

Giuseppe Celano, Francesco Alluvione, Mostafa Abdel Aziz Ali Mohamed, and Riccardo Spaccini Abstract This chapter reviews the main methods for tracing N and C stable isotopes in natural and agricultural systems following organic and mineral amendments to soil. Moreover, we present the results obtained from two field experiments conducted, within the MESCOSAGR project, to evaluate either the fate and flow rate of N added as 15N-compost in a maize-soil system or the contribution of sorghum roots...

Natural Abundance Method

The use of 13C NAM in soil studies provides a highly accurate method to trace carbon transfer among pools, and has been successfully used in studies on SOC dynamics (Martel and Paul 1974 Nissenbaum and Schallinger 1974 Leavitt et al. 1994 Paul et al. 2001 Stevenson et al. 2005). NAM is based on the discrimination of 13C and 12C isotopes during CO2 assimilation by plants due to different photosynthesis pathways, which lead to plants with distinct d13C values. Plants with a C3 photosynthetic...

Cloning of PCR Amplicons

PCR amplicons were cloned by the pGEM -T Easy Vector Systems (II) kit (Promega) (Felske and Weller 2004). 5 U of T4 DNA ligase were used to ligate PCR products for 16 h at 4 C into pGEM-T vector at an insert plasmid ratio of 6 1. The ligation product was added to 50 ml of E. coli JM109 competent cells and the transformation was carried out by heating for 45 s at 42 C, cooling in ice, and incubating at 37 C for 90 min under shaking (750 rpm) in SOC growth medium (20 g Bacto -tryptone, 5 g Bacto...

Soil Properties

Soil properties are different among experimental sites (Table 3.3), with soil texture the most distinct. In top layers, soil texture was sandy loam for TO with a low content of clay (7-8 ), while it was silty clay loam in the other two experimental sites with a clay content of 30-33 at NAP and of 31-40 at BAS. SOM was larger in TO (1.7-1.8 ) than in both NA (1.2 ) and BAS (1.1-1.2 ). Total N was greater and exchangeable K2O smaller in TO than for the other two sites. Soil classification (USDA...

Materials and Methods 1021 Microcosm Style Experiments 10211 Experimental Setup

The microcosm-scale experiment was carried out in a greenhouse facility of the Mediterranean University of Reggio Calabria. The microcosms consisted of 9.5 L PVC pipes (30 cm height x 20 cm diameter) filled with approximately 13 kg of a soil perlite (80 20, v v) mixture. The soil was a clay loam sand 36.0 , silt 32.0 , clay 32.0 bulk density 1.23 0.04 kg dm-3 pH-H2O 7.2 0.2 pHKa 6.4 0.1 total organic C (TOC) 19.3 0.4 g (kg dw dry weight basis soil)-1 total N (TN) 1.8 0.2 g kg-1 C N ratio 10.7...

Model Description 1121 Concept

The SOMDY model presented here has been conceived to represent soil organic matter dynamics taking into account the following major issues - Improved definition of chemical composition of SOM - Assessment of SOM physical structure - Chemical and physical protection effects on mineralization processes - Microbial turnover and chemical evolution of SOM during the decomposition - Impact of agricultural practices on SOM dynamics Then, the general structure and logic of SOMDY model is represented in...

Impact of Different Agricultural Practices on Soil Microbial Communities The Mescosagr Case Study

Within the National project MESCOSAGR, we investigated the impact on soil microorganisms of two innovative technologies applied to sequester carbon in agricultural soils. The hypothesis was that the structure and activity of microbial communities would be influenced by (1) addition of compost, a humified and hydrophobic material that protects the easily degradable organic fraction, and (2) in situ photo-oxidative polymerization of native SOM under the action of a biomimetic catalyst (CAT)...

Extraction and Purification of Nucleic Acids

Total DNA was extracted adopting the direct lysis method by using the FastPrep System, a bead beater that allows to desorb microbial cells from soil particles and provides a large lysis yield. In combination with the commercial FastSPIN kit Fig. 8.1 Flow sheet of employed molecular techniques Fig. 8.1 Flow sheet of employed molecular techniques for Soil (MoBio) this method gives a highly purified DNA from small amount (0.5 g) of soil. One milliliter of sodium phosphate buffer and 0.1 ml lysis...

References

Abdelbasset L, Scelza R, ben Achiba W, Scotti R, Rao MA, Jedidi N, Abdelly C, Gianfreda L (2011) Effect of municipal solid waste compost and sewage sludge on enzymatic activities and wheat yield in a clayey-loamy soil. Soil Sci 176 15-21 Albiach R, Canet R, Pomares F, Ingelmo F (2000) Microbial biomass content and enzymatic activities after the application of organic amendments to a horticultural soil. Bioresour Technol 75 43-48 Amann RI, Ludwig W, Schleifer KH (1995) Phylogenetic...

Nitrogen Dynamics in Soil Plant Systems

The 15N tracer technique can be applied to evaluate both the net gross mineralization rates of indigenous or added N, and the efficiency of plants to assimilate added N (Barraclough 1995). If the objective is to estimate the plant assimilation of added N, it is usually not convenient to use N tracers, and a lower cost alternative is to apply non-isotopic techniques (Powlson and Barraclough 1993). There are two methods (a) Control plot method N uptake of the unfertilized crop is subtracted from...

Microbial Activity

Soil microbial activity can be estimated by measuring CO2 respired from soil, as a well-established parameter to monitor SOM decomposition (Anderson 1982). Soil respiration is highly variable and its natural fluctuation depends on substrate availability, moisture, and temperature (Alvarez et al. 1995 Brookes 1995). For valid comparisons among soils, respiration measurements must be conducted under controlled laboratory conditions (Anderson 1982). Here, the basal respiration of soil samples was...

Conclusion and Future Recommendations

First of all, our results highlight the importance of combining different approaches to obtain complementary information on the microbiological status of agricultural soils. Amendment with compost appears to have a promising environmental application, although its use depends on soil texture and clay content, as shown by our studied sites. In fact, compost was found to decrease cultivable microorganisms, microbial carbon, and coefficient of SOM mineralization in clayey soils, possibly due to an...

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 6,326 Da) as hypothesized by Stevenson (1994). (a) Upper picture humic polymer having an energy of 627.40 Kcal mol_1 (b)...

The Kyoto Protocol and European and Italian Regulations in Agriculture

Davide Savy, Antonio Nebbioso, Roc o Danica Condor, and Marina Vitullo Abstract Climate change represents the most important challenge for the international scientific community, for the inherent and irreversible modification brought about in natural ecosystems. International institutions increasingly adopt measures to promote preservation of ecosystems and counteract the social and economical consequences of environmental decline. Here we review the actions undertaken by both the...

Italian Greenhouse Gas Emissions

Emission estimates comprise ten GHG carbon dioxide, methane, nitrous oxide, HFCs, PFCs, sulfur hexafluoride, nitrogen oxides, carbon monoxide, non-methane volatile organic compounds, sulfur dioxide. The first six GHGs directly contribute to climate change owing to their positive irradiative forcing effect. The national Kyoto target is a reduction in the period 2008-2012 of 6.5 of GHG, as compared to the 1990 base year level. In spite of it, total GHG emissions, in CO2 equivalent, decreased by...

Concluding Notes on Soil Physical Quality

As mentioned earlier, the yields of aggregate fractionation and values of soil stability index suggested a predominant influence of specific texture and clay content on the physical and structural properties of soils. However, all treatments in each site, despite the specific soil structural properties, showed a comparable macroaggregate dynamics throughout the experimental period, consisting first in a decrease and then in a recovery of soil stability. In fact, our results revealed a similar...

Active Fungal Mycelium

Metabolically active hyphae were estimated by fluorescence microscopy. Soil samples were sieved through a 2-mm mesh, suspended in a solution (1 g of fresh soil in 100 ml) of phosphate buffer (60 mM, pH 7.5), and homogenized at 6,000 rpm for 2 min. 0.5 ml of suspension were collected and filtered under vacuum on nitrocellulose filter with a pore size of 0.45 mm. The sample was treated with fluorescein diacetate (FDA) (Soderstrom 1977, 1979). This stain penetrates rapidly in cells and is...

Enzymatic Activities and Soil Carbon Sequestration Strategies

The expression enzymatic activities is usually preferred to enzymes, the reason being that applied methods do not isolate and measure the enzyme itself in soils, but quantify (mainly by absorbance or fluorescence) the rate of transformation of an enzyme substrate added to soil. Already in the 1940s a paper was published reporting the effect of copper nitrogen complex on soil potential nitrification, as assessed by this substrate-induced approach (Lees 1946), and it was followed by a series of...

Contributors

Maria Rosa Abenavoli Dipartimento BIOMAA, Universita Mediterr nea, 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, Italy Maurizio Badiani Dipartimento BIOMAA, Universita Mediterranea, Reggio Calabria, Italy Chiara Bertora Dipartimento di Agronomia, Selvicoltura e Gestione...

Carbon Sequestration References

Aita C, Recous S, Angers DA (1997) Short-term kinetics of residual wheat straw C and N under field conditions characterization by 13C15N tracing and soil particle size fractionation. Eur J Soil Sci 48 283-294 Angers DA, Voroney RP, Cote D (1995) Dynamics of soil organic matter and corn residues affected by tillage practices. Soil Sci Soc Am J 59 1311-1315 Bakken LR (1990) Microbial growth and immobilization mineralization of N in the rhizosphere. Symbiosis 9 37-41 Balesdent J, Balabane M (1992)...

The Supramolecular Structure of SOM

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...

Effects of Cover Crops Mulching and Green Manure

Cover and catch crops, mulch, residue, and green manure provide many services to agroecosystems, from erosion and weed control to deposition and protection of organic matter (Jackson 2000) and promotion of genes for disease resistance (Kumar et al. 2004). Some of such services reduce yield of the main crop, especially in intercropping systems and in environments where water and or nutrients availability are limited. Therefore appropriate management is required, and trade-offs between ecological...

SOM Chemical Composition and Physical Aggregation

In the model, soil organic matter is a state variable represented by the sum of dissolved (DOM) and aggregated organic matter (AOM). Addition of exogenous organic matter (EOM) is also taken into account with external inputs added to DOM and partitioned according to their specific chemical composition. Solid-state 13C NMR spectroscopy has been used to assess the chemical composition of organic matter in litter decomposition studies, with different classes of organic-C compounds related to...

Soil Amendment with Biomimetic Catalyst Under Wheat Trials

The action of the iron-porphyrin biomimetic catalyst, at the rate of 10 kg ha-1, was tested at TO and NA in soils cropped with wheat (Triticum aestivum L., cv. Blasco). In 10 m2 plots (three replications per site), aim2 soil surface was identified where iron-porphyrin was distributed before wheat emergence at the rate of 1 g m-2 (previously dissolved in 21 of water). All plots were plowed at 30 cm and wheat was fertilized at the rate of 130 kg N ha-1 with ammonium nitrate. Phosphorus and K...

Effects of Carbon Sequestration Methods on Soil Respiration and Root Systems in Microcosm Experiments and In Vitro

Antonio Gelsomino, Maria Rosaria Panuccio, Agostino Sorgona, Maria Rosa Abenavoli, and Maurizio Badiani Abstract In the framework of an interdisciplinary research devoted at increasing soil capacity to act as carbon sink by means of innovative and sustainable strategies (the MESCOSAGR Project), we studied, in microcosm-scale model systems, changes of selected soil chemical properties, soil CO2 efflux, and root morpho-topology after addition of either mature compost or a biomimetic catalyst...

Sustainable Agriculture to Reduce Environmental Impact Soil Organic Matter as a Source and Key Factor of Greenhouse

Croplands play a key role for the sustainability of world's life. The exponential growth of global population and the need to produce alternative energy to fossil fuel has placed increased demands on agriculture to produce more food and biomass. For these reasons the agriculture poses a huge challenge for the sustainability at global and local environments, because of the different forms of environmental impacts related to agricultural management. The loss of soil organic matter (SOM) through...

Experimental SetUp and Soil Climatic Conditions for Maize Trials

Maize (TO and NA) and sorghum (BA) were grown in the field sites because their large N demand is liable to better reveal the treatment effects. Soil treatments at the TO and NA sites were the following 1. TRA traditional soil tillage (moldboard plowing, 30 cm deep), mineral fertilization with urea at the rate of 130 kg ha-1 of N. 2. MIN minimum tillage (rotary hoeing, 10 cm deep), mineral fertilization with urea at the rate of 130 kg ha-1 of N. 3. GMAN green manure with hairy vetch (Vicia...

Impact of Innovative Agricultural Practices of Carbon Sequestration on Soil Microbial Community

Valeria Ventorino, Anna De Marco, Olimpia Pepe, Amalia Virzo De Santo, and Giancarlo Moschetti Abstract This chapter deals with the impact on soil microbiology of innovative management techniques for enhancing carbon sequestration. Within the MESCOSAGR project, the effect of different field treatments was investigated at three experimental sites differing in pedo-climatic characteristics. Several microbiological parameters were evaluated to describe the composition of soil microbial communities...

Pulse Labelling Method

The pulse labelling method (PLM) is based on the artificial labelling of plants. The technique can be roughly divided into three methods based on the levels of 13C enrichment achieved in the plant-soil system natural abundance (Heim and Schmidt 2007 Klumpp et al. 2007 Thornton et al. 2004), near natural abundance (50-500 ) (Evershed et al. 2006 Leake et al. 2006) or (highly) enriched > 500 (Zak and Kling 2006). Shoots are exposed to CO2 in an atmosphere labelled with 14C, 13C or C. The shoots...

The Concept of Humification

It has been increasingly proved that simple, mainly alkyl, recalcitrant organic compounds deriving from both plant residue decomposition and microbial resyn-thesis are progressively incorporated into the most stable SOM fractions (Piccolo 1996 Lichtfouse 1998). Piccolo (1996) proposed that hydrophobic humic components in soil protect easily degradable compounds. He postulated that incorporation of polar molecules in associations of hydrophobic components may contribute to prevent an otherwise...

N2O Production and Emission from Soils

Soil N2O production and emission is directly related to land use and soil management practices, since it is the biogenic product of microbial processes of denitrifi-cation and nitrification, as affected by physical-chemical characteristics of soil. Bacterial denitrification is a respiratory reduction of nitrate and or nitrite to gaseous NO, N2O and N2, coupled to phosphorylation electron transport. Many aerobic microorganisms use NO3 as electron acceptor to derive energy from organic compounds...

Microbial Parameters as Indexes of Soil Quality

Because of the fundamental role in mediating soil processes and the responsiveness to soil managements, microbial abundance, diversity, and activity are among the most important soil quality parameters (Andrews and Carroll 2001 Karlen et al. 2001, 2003 Andrews et al. 2003 Anderson and Domsch 2010). In fact, the effect of agricultural management on microbial community is directly related to changes in soil quality (Schloter et al. 2003), that encompass the size and diversity of specific...

Tracing N in Landscapes

Bedard-Haughn et al. (2003) reviewed the use of 15N as a tracer for N cycling in landscapes. They concluded that natural 15N abundance can provide valuable estimates of the contribution of different sources or identify variation in landscape processes. Unfortunately, the large 15N spatial and temporal variabilities can limit source discrimination by masking sources' differences, whereas 15N-enriched materials are widely accepted as tracers. The use of N-enriched materials is limited by their...

Scaling Up Innovative Concepts into Agricultural Field Experiments

The described innovative concepts whose theoretical mechanism and functioning were derived from laboratory experiments, need not only to be verified in real field scale conditions, but also to be proved harmless to the physical, chemical, nutritional, and biomolecular quality of soils. This overall objective was looked for in the MESCOSAGR project. At the basis of this project there was the intention to go beyond the traditional practices for carbon sequestration and put in practice the...

Units of Measurement

The units of measurement for 15N tracer materials are aimed at expressing the relative abundance of 15N compared to 14n using different notations. There are two main units of measurement one is commonly used with 15N-enriched materials, while the other approach is more useful when natural variations in 15N abundance are used to trace N. The unit expresses the isotope abundance as a percentage It is also common to express the 15N abundance as a variation with respect to N2 natural abundance,...