Niro, Elisa (2016) Sustainability and impact on C storage and soil quality of different cropping systems and agricultural managements. [Tesi di dottorato]

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Item Type: Tesi di dottorato
Lingua: English
Title: Sustainability and impact on C storage and soil quality of different cropping systems and agricultural managements
Creators:
CreatorsEmail
Niro, Elisaelisaniro@live.it
Date: 31 March 2016
Number of Pages: 194
Institution: Università degli Studi di Napoli Federico II
Department: Agraria
Scuola di dottorato: Scienze agrarie e agro-alimentari
Dottorato: Scienze delle risorse ambientali
Ciclo di dottorato: 28
Coordinatore del Corso di dottorato:
nomeemail
Rao, Maria Antoniettamariarao@unina.it
Tutor:
nomeemail
D'Ascoli, RosariaUNSPECIFIED
Mora, María de la LuzUNSPECIFIED
Marzaioli, FabioUNSPECIFIED
Date: 31 March 2016
Number of Pages: 194
Uncontrolled Keywords: C storage; SOM fractions; soil amendment
Settori scientifico-disciplinari del MIUR: Area 05 - Scienze biologiche > BIO/07 - Ecologia
Area 02 - Scienze fisiche > FIS/07 - Fisica applicata (a beni culturali, ambientali, biologia e medicina)
Date Deposited: 14 Apr 2016 14:12
Last Modified: 10 May 2017 01:00
URI: http://www.fedoa.unina.it/id/eprint/11004

Abstract

In the global C cycle of terrestrial ecosystems, soil is considered a very important C sink, and it has been estimated that approximately 1500 Gt of organic C is stored in the first meter of soils. Given the importance of the soil C storage and environmental and agronomic implications of organic C content in soil, the preservation and implementation of soil C stock is necessary, especially in managed ecosystem where organic C is often strongly depleted. Adequate management practices could be useful in attempts to meet C-emission reduction targets, as reported in Article 3.4 of Kyoto Protocol. In this perspective, specific studies are necessary because soil C storage is affected in different way by environmental conditions (soil properties, climate, topography, land use change). This PhD thesis focused on three different aspects regarding the SOM stability topic: a) the potential in C sequestration of tree crop systems vs non-tree crop systems, to understand if in Italian contest they could be a valid strategy in climate change mitigation; b) the soil organic amendment, with olive-oil extraction solid waste, and the relative hypothetical beneficial effects in term of improvement in organic C and soil quality; c) the organic C stability and distribution among different size aggregates in Andisols (soils developed in particular geographic and pedogenic conditions), in which the specific soil properties strongly affect the C storage compared to other kinds of soils. The potential in C sequestration was evaluated in olive groves compared to crop land, being this tree crop systems one of the most important in Italy and whole Mediterranean region, by the measure of OC stock in bulk soil and SOM fractions, separated by physic-chemical fractionation method in both soil top layer and soil profiles and the measure of 14C activity, as a trace of the C dynamic in soil. The results highlight that in long period (>30 years) olive grove management are able to improve the OC stock in soil top layer, an increase that corresponded not only to an increase in more labile SOM fraction, as well as light fraction that respond quickly to land use change but also in more stable pools, such as hydrolyzate and recalcitrant fractions. In fact the OC in this fractions appeared enriched in 14C compared to control, sing that modern C was fixed in this stable fractions during the recent history. The beneficial effects of the olive pomace as soil amendment on both OC stock and general soil quality were evaluated in soil sample in an olive grove, where some plots were amended since 2006 with olive pomace and other were lefts as control. Both kind of soils were utilized in laboratory incubation experiment in order to evaluate the effects of pomace amendment in short and long period. The short period did not affect the chemical parameters essayed (pH, EC, OC,TN) but the yearly amendment (8 years) caused an significant improvement of the OC and TN content in bulk soil associated to an increase in more stable SOM fractions, an increase in EC and a reduction in soil pH. As concern the soil biological parameters, the pomace caused in short period an increase in soil microbial biomass, respiration rate either in soil yet amended in field and in soil never amended before and in long period also a significant increase in fungal biomass and a significant decrease in the index of enzyme activities indicating a higher soil quality. However the soil amended showed lower value in microbial quotient and coefficient of endogenous mineralization compared to soil never amended, indicating an accumulation of organic matter not minerizable by soil microorganisms and also an inhibition in N mineralization (as well as nitrification activity essayed in potential conditions). Generally the results underline the really improvement in SOC stock after the employment of pomace as organic amendment, with positive effects on soil microbial community. Andisols are a kind of andic soils characterized by high SOM content due to sorption of organic matter on short range order (SRO) minerals and interaction with Al-oxides. As consequence of this characteristics, the separation of soil aggregates is very difficult and in general they don’t follow the aggregates hierarchy suggested by Tisdall and Oades in 1982. The content and the distribution of organic C was analysed in four SOM fractions separated by dry saving from the top layer of three Andisols (Puerto Fonk, Pemehue and Piedras Negras). Data showed no differences in organic C, total N contents, C:N ratio and total P among the fraction for all soils, comparing macro- and microaggregates. The images obtained by laser scan confocal microscope showed, through the autofluorescence of soil organic matter, a homogeneous distribution of OM among aggregates before and after oxidation, indicating a similar efficiency of OM removal during the oxidation. This observation allows us to affirm that in these three Andisols it is not verify the aggregate hierarchy, and that the stabilizing mechanisms (such as the interaction of SOM with SRO inerals) act independently of all aggregates classes.

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