The Soils of Italy

The present chapter deals with the history of research in pedology in Italy, with a special emphasis on soil survey, since the early stages and until the end of the past century. Early soil scientists were rooted in disciplines like agro-chemistry and geology, and their approach to pedology was conditioned by their cultural background. The first complete Soil Map of Italy is dated 1928. Its Author, the geologist De Angelis d’Ossat, was the president of the organising committee of the 1924 International Soil Conference of Rome, where the International Society of Soil Science was founded. The map was based on the geological map of Italy, drafted in scale 1:1,000,000 after the creation of the Kingdom of Italy in 1861. The internal disputes within the Geological Society, together with the scarce interest of most geologists for soil, did not facilitate the birth of a central soil survey institute. Soil mapping was mainly carried out by universities and research institutes, and we had to wait until 1953 for a new national level soil map (scale 1:3,125,000) to be realised by Principi, based on literature data. In 1966, a new 1:1,000,000 Soil Map of Italy was eventually published by a national committee, led by Fiorenzo Mancini. This was based on literature data and on field surveys, and the mapping units’ limits, based on geomorphology, are still the basis of the most updated European 1:1,000,000 soil map. At the end of the 1980s, soil survey and mapping were taken over by the Italian regional administrations, which set up regional soil surveys working in coordination among them and with the research institutions.

Climate has a potential strong influence on the soil forming processes of Italy. The elongated shape of the Italian peninsula, stretching along 11 parallels in the middle of the Mediterranean Sea, and the presence of two morphological barriers, the Alps and the Apennines, cause great local climatic variations. Actually, in Italy, authors recognized 14 of the 35 climatic regions occurring in Europe. Average climatic conditions are temperate, in particular, long-term mean annual air temperature (MAT) is 12.6 (°C) and total annual precipitation (MAP) 932.5 mm, but variations are much more important than means, in fact, they span about 30 °C and 1,800 mm. The degree of continentality, that is, the difference between summer and winter temperature is on average more than 15 °C, but it reaches more than 17 °C in the Po Plain. Seasonality of the precipitations, that is, the difference between the amount of long-term rainfall fallen in the most and in the least rainy months, proportioned to the total long-term annual rainfall, is on average 11 % and more pronounced in the southern regions. Mean long-term potential evapotranspiration is 1,002 mm, ranging from around 600 mm in the Alps and the Northern Apennines to more than 1,300 mm in some parts of Apulia, Sicily and Sardinia. As a result, climatic deficit dominates Italy. The ustic soil moisture regime is the relatively most widespread udometric regime, while the udic regime dominates the Alps and the Apennines chains, and xeric and dry xeric are well correlated with lands with the highest aridity. The mesic soil temperature regime dominates most part of the country, but the thermic regime dominates southern Italy. The frigid and cryic regimes are present in large areas of the Alps and the Apennines. A general climatic change occurred in Italy in the period 1961–2000, with a general reduction in mean total annual precipitation (MAP) and number of rainy days, and a general increase in mean air temperature (MAT). The climate change had a general low influence on soil organic carbon variations. Nevertheless, the relatively higher climatic influence occurred in meadows and in arable lands with a moderate or high MAP decrease (<−100 mm/y) and a moderate to high MAT increase (>0.62 °C). The decreasing SOC content of lands with increasing hot and arid climate could be a soil indicator of the consequences of the extension of the Mediterranean subtropical climatic regions in Italy.

The chapter describes the importance of vegetation in contributing to the pedogenesis physically, biologically and chemically. Analysis is performed of the different vegetation components and their relations to soil. A special emphasis is reserved to the forms of humus and to their classification. Land use is documented with the positive and negative effects on the pedogenesis. Several paragraphs deal with the influence of vegetation and land use on the soils of Italy. In the Alps altitude, climate and lithology determine the type of vegetation which in turn gives rise to the forms of humus which become fundamental pedogenetic factors. The Po plain presents a variety of soils and landscapes: from the old fluvio-glacial terraces with fragipan to the Po delta with sandy soils or with clay soils cracking during the summer. Other plains of Central and Southern Italy of minor surface but not of minor historical importance are presented. The Apennines range is described in its main features underlining the human influence across the centuries. From the Central Apennines to Sicily appear Andosols, that is, volcanic soils. Soils of the hills of Central Italy have been the base on which the Italian agriculture has developed in the past time advanced practices and techniques. Some considerations concern the difference between the past and the actual land uses. Southern Italy has different soils with the related land management: from the intensively cultivated Andosols of Campania to the stony terra rossa of the Murge with fallow. Sicily and Sardinia are described according to their natural vegetation and to their specificities: cereals cultivation on soil catena of the clay hills of Central Sicily and valuable Holm oak (Quercus ilex L.) and Cork oak (Quercus suber L.) of Sardinia. The chapter concludes with a pedological tour of the Italian coasts.

The nature and working of environmental influences conditioning time as a forming factor for soils of Italy are examined, on the light of updated geological, palaeoecological and archaeological literature. The complex of factors determining the general youth of Italian soils is discussed. The timing of formation of specific soil properties is examined, according to reported evidence from soils which were considered by the authors as firmly dated, either from hard, absolute dating or from very strong, and still presently sustainable, stratigraphic considerations. Investigation on soil age suggests that after the Last Glacial Maximum (LGM), about 18,000 years ago, the soil most likely to form on the most common, fine-textured and calcareous, parent materials of Italy is a partially decarbonated, fully base-saturated Cambisol. Horizons with clear clay illuviation appear to have formed only in favourable conditions. Such results compare very fairly with the analysis of soil pedodiversity in Italy presented elsewhere in this book. On the other hand, it is clear that Italian soils developed Nitic, Fragic, Ferric and Plinthic horizons well within Pleistocene times. The formation of fully developed, carbonate-free but base-saturated, Luvisols appears to have generally been possible starting much later than Marine Isotope Stages (MIS) 5, the last fully fledged interglacial.

Pedodiversity of Italy, that is, the diversity of soil genetic types, their geographic distribution, and the statistical variability of their properties, is depicted by means of maps and information stored in the national soil database. Soil regions on hills are the most lithologically and climatically variable environments, and host the greatest soil variability and endemisms. A vast majority of the WRB reference soil groups (25 out of 32), as well as soil orders of Soil Taxonomy (10 out of 12), are represented in the main Italian soil typological units (STUs), but the clear skewness and lognormal distribution of STUs demonstrate the utmost endemic nature of many Italian soils. In particular, more than a fourth of STUs belongs to Cambisols, more than a half to only four reference soil groups, and 88 % to nine RSGs, while the remaining 16 RSGs are represented in 12 % of STUs. A similar trend is depicted by considering single soil profile classification, although a larger number of main soil types are represented as soil profiles than as STUs. Ferralsols (Oxisols for Soil Taxonomy) and Durisols are the only main kind of soils that have not yet been found in Italy. Likewise RSGs, the distribution of WRB qualifiers shows an evident concentration in relatively few cases, followed by a long tail. In particular, 138 out of the 180 types foreseen by WRB are represented in Italy. Thus, it is possible to say that in Italy, there is about three quarters of the global pedodiversity. Although the most common qualifiers (that is, Calcaric, Haplic, Skeletic, Eutric) are all related to the nature of parent material and to incipient pedogenesis, a second group (namely Chromic, Calcic, Stagnic, and Luvic) indicates the main soil-forming mechanisms that typify current Italian pedogenesis.

Soil functions are closely related to soil ecosystem services, defined as the complex of actions sustained by soils to guarantee life on the earth. Briefly, they can be summarized as: biodiversity and habitat, nutrient cycling, water regulation, filtering and buffering, physical stability and support.

Over the past decades Italians—as well as other European inhabitants—have loaded their soilscapes more intensely and quicker than ever before. This anthropic pressure has such a strong impact on the environment that it sets off degradation processes in soils endangering them in various ways. In particular, (i) huge areas of the Italian landscape are exposed to soil erosion that still remain a concern because of the scarce adoption of soil conservation practices; (ii) soil consumption is much more evident in the main metropolitan areas and in the coastal areas and recently boosted also by the spread of photovoltaic ground-mounted installations that are preferentially established in flat areas, regardless of any aspect of soil quality; (iii) soil pollution/contamination is mainly due to industrial and urban settlements and concerns almost 1 % of the national area; (iv) soil salinization/alkalization is mainly due to irrigation with saline waters and is particularly diffused in the plains and along the coastal areas; (v) Italian soils are generally poor in organic matter, and its decline is mainly due to changes in land use and in soil managements; (vi) finally, it is to mention the soil diversity loss, a new soil threat that is mainly linked to large-scale farming in growing high remunerative crops.

This chapter begins with a short recollection of the general concepts of soil management and, thus, reports of the different methods to rate soil quality. Both these sections set the stage to a wide presentation of an historical overview of soil management that in Italy has been going on from the beginning of agriculture to nowadays. In this way, recent archaeological observations have allowed to proposed original theories about the genesis of badland landscapes, so diffuse in Italy. Particular attention has also been done on the impact of European directives on the soil and land management, taking into consideration all the directives promulgated from the beginning of the European Union. The chapter also reports of the land set-up systems devoted to soil and water conservation, many of them invented in Italy, and of the different soil managements adopted in different Italian physiographic agro-ecosystems: high-alpine environments, pre-alpine fringe, Po plain, Apennines, southern Italy and the two great islands of Sardinia and Sicily.

Urban soils appear as very complex ecosystems in which the anthropic pressures give them unique features that render them different from natural or agricultural soils. Although the soil classification systems provide for the description of anthropogenic or technogenic soils, a number of drawbacks has hindered a systematic taxonomic studies. In Italy, the interest has been directed mainly on the contamination of urban soils. The studies have started in the 1970s, and data are now available for a number of cities. The soils of large cities like Rome, Naples and Turin have been studied in view of their size and the intensity of the polluting sources therein, but also mid-sized cities such as Ancona or Palermo have been investigated. A common trait of all cities is the high spatial variability of their soils together with a high level of contamination. Numerical classification appears then to be preferable to the classic systems for application in urban areas.

This chapter aims to address future soil issues from a specific viewpoint, namely the need of our country. It starts by analysing both Italy’s physical landscape along with the social and economic structure and its population. From this basis, the chapter focuses on country limitations and potentialities and identifies the most important country-specific contributions by soil science aiming towards the well-being of Italy. We claim that future soil scientist must give major contributions in the followings: (1) spatial planning of the landscape (oriented to urban planning), (2) archaeology and natural heritage, (3) agriculture and forestry combining productivity and environmental protection, (4) hydrogeological risks, (5) integrated landscape management. In order to get these results, the authors anticipate that soil science requires a novel vision, novel approaches and most importantly a novel education combining in-depth specialized knowledge with a very good but broad and basic soil knowledge.