RICERCA ITALIANA     

Evolution, Stability and Dynamic of Soil Organic Components for a Genetic and Functional Definition

Università Cattolica del Sacro Cuore

Abstract

Humic substances are a group of macromolecules involved in numerous chemical and biochemical processes, important for soil fertility and for environmental equilibria and they represent an important source of carbon, essential for soil biomass and, more generally, for the ecosystem (Stevenson, 1994).
The quali-quantitative characterization of OM employing chromatographic, spectroscopic, potentiometric, thermogravimetric, differential scanning calorimetry (DSC) and isotipic techniques, besides the humification parameters, can give an essential contribution to an update classification of diagnostic horizons.
The total organic carbon (TOC) is believed a "static indicator" of processes at the equilibrium, in that only allows the determination of changes in the long run. Other indicators, defined as "dynamic" are particularly suitable for pointing out changes in short times and, among these, are the kinetics of mineralization of total organic carbon of microbial biomass.
In order to complete the characterization of humic substances will be evaluated also the stability rate of organic-mineral compounds, the microbial biomass, enzymatic activities, the availability of heavy metals and their relations as useful tools for achieving the objectives of this research program.
The quantification of dynamic of soil organic matter and its role in better understanding the pedological processes and their properties, is particularly important since it can be stated >>>

Principal Investigator

Sandro SILVA Università Cattolica del Sacro Cuore

Research Objectives

Individuation, characterization and dynamic evolution of organic matter (OM) in all its forms in the pedogenesis of the investigated profiles.
1. Identification of the most representative types of soils to investigate; characterization of the most important horizons for the O.M. dynamics through quali-quantitative balances of the organic components and humified fractions; interlaboratory check among the analytical units for what concerns some official methods of analysis (C org. N Kjeldahl, particle size analysis) for the determination of accuracy and precision;
2. General picture of the chemical, biological and microbial characterization coming from the estimation of suitable parameters/indicators determined by the analysis of soil material from pedogenetic horizons of the investigated profiles;
3. Evaluation of the new indicators for agricultural and forestry soils, for dating genetic and operative riclassification criteria, in order to integrate the classic parameters (e.g., color, C org content) of the most commonly used taxonomic classification.

First Results

Step 1:
Characterization of soil profiles representative of the present study, with horizons typical of the type of chosen soils. One of the expected result will be the evaluation of accuracy and precision of the methods employed to determine some standard soil parameters by all the Working Units.Step 2.
Expected result in to come to an analytical multidisciplinary (chemical, biological, microbiological) approach which allows a better characterization and identification of the investigated soils.Step 3.
Ridefinition or riclassification of the investigated soils on the basis of indicators characterized in the step 2, even in terms of enviromnental sustainability.

Timescale

24 months

National and international background

The release of gases produced by human activity has led to a significant increase in the atmospheric temperature of the Earth with dramatic consequences for the whole planet.
The most important responsible is carbon dioxide, mainly released into the atmosphere when fossil fuels are burnt,and whose concentration in the atmosphere has increased by 30% with respect to the pre-industrial era.
Deforestation has also substantially added to the increase in CO2. In 1990, the World Resources Institute reported that CO2 emissions caused by deforestation amounted to 6 Gt (gigatons).
This alarming data call for urgent intervention at different levels by means of mitigation actions that can reduce and absorb a high quantity of carbon dioxide, as established by the Kyoto agreement and the Bonn Conference on climatic change. Since the soil represents the most important C sink, a good knowledge of the evolution, stability and dynamics of its organic components could drive to guarantee its conservation, so reducing the levels of carbon dioxide in the atmosphere and preserve those soil properties which are strongly affected by organic matter (OM), so contributing to a complete guarantee of its functions.
The OM plays a fundamental role in guaranteeing a good soil quality in that it represents a nutritive and energy substratum for living organisms (Schnitzer, 1986; Stevenson, 1994) , and a nutrient source for plants, has a positive action on soil c.e.c., affects >>>