Chemical and Spectroscopic Investigation of Different Soil Fractions as Affected by Soil Management

Francesco De Mastro,Claudio Cocozza,Andreina Traversa,Gennaro Brunetti

doi:10.3390/app10072571

Francesco De Mastro, Claudio Cocozza + Show 2 more

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https://doi.org/10.3390/app10072571

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Abstract

The interaction of organic matter with the finest soil fractions (<20 μm) represents a good way for its stabilization. This study investigates the effects of conventional (CT), minimum (MT), and no (NT) tillage, fertilization, and non-fertilization, and soil depth (0–30, 30–60, and 60–90 cm) on the amount of organic carbon (OC) in four soil fractions. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) was performed to obtain information about the OC quality and the mineralogical composition of these fractions. The CT shows the highest amount of the finest fraction while the fertilization enhances the microbial community with the increase of soil micro-aggregates (250–53 μm). The coarse fraction (>250 μm) is highest in the upper soil layer, while the finest fraction is in the deepest one. The greatest OC content is observed in the topsoil layer and in the finest soil fraction. DRIFT analysis suggests that organic components are more present in the finest fraction, calcite is mainly localized in the coarse fraction, quartz is in micro-aggregates and 53–20 μm fraction, and clay minerals are in the finest fraction.

Highlights

Previous studies have used the particle size fractionation for obtaining information about the influence of land use and depth on the distribution of soil organic carbon (SOC) [1,2]
The physical fractionation recovered 98% of the mass and 99% of the OC from all samples. Such percentages were comparable to those previously reported by other authors [26,27,28], which indicates that the loss of material was very low and confirms the efficiency of the fractionation method adopted
The soil management influenced the quantity of soil fractions since the CT enhanced the finest ones, whereas the fertilization increased the B fractions, which possibly fuels the development of a microbial community that fosters microaggregate formation

Summary

Introduction

Previous studies have used the particle size fractionation for obtaining information about the influence of land use and depth on the distribution of soil organic carbon (SOC) [1,2]. The various soil fractions can differently immobilize organic carbon (OC) through the formation of organo-mineral complexes [3,4]. OM represents the active pool of soil organic matter (SOM), the OM linked to the silt size fraction is the intermediate pool, and the clay related OM represents the passive and the older SOM pool [4]. The microaggregates, composed mainly of clay minerals, represents the most efficient way to stabilize the SOM [6,7] by forming bridges between the exchangeable cations of layer silicates and functional groups of organic compounds [8]. The SOM in the macroaggregates is available for microbial utilization while the protected microaggregates form a long-term reserve of mineral-associated C that is not “humified” and can be attacked by microorganisms once exposed [9]

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