It's well known the degradation of many Italian soils, both in hill and in plain environments, due to the increasing anthropic pressure on natural resources. Soil erosion and organic matter loss are recognized as the main processes responsible of such degradation and of the rising risk of desertification, to which land use changes and politics for agriculture not suitable for land specificities often contribute. The knowledge of land use impact on soil quality is, thus, essential to preserve environmental integrity and to obtain sustainable agricultural productions.

The investigated areas are located in Pisa and Siena (Tuscany, Central Italy), Catanzaro (Calabria, South Italy) and Verona (Veneto, North Italy). The soils of the first two regions, classified as Vertic Cambisols (Soil Taxonomy), developed from the same pedogenetic substrate (Pliocene clay) and lie on hill slopes with incline from 8 to 40% and altitude from 100 to 300 m a.s.l.. In the third region, plain soils were selected from three different cartographic units: CB1 (Aquic Ustipsamment, S.T.), IS1+IS3 (Fluventc Ustochrept, S.T.), MA1 (Cumulic Haplaquol,  S.T.). Soil texture and soil use are reported in table 1. The climatic characteristics of the considered areas are shown in table 2. Each soil was sampled in three points, at the depths of 0-10 cm, 10-20 cm and 20-40 cm. Soil samples were analyzed for: texture, pH, cation exchange capacity, total organic carbon (TOC), total extractable carbon (TEC) and humified carbon (HC), total and mineral N. The percentage ratio HC/TEC was used as a measure of the organic matter humification degree (DH). The differences between the compared soil uses were evaluated within each environment and at each depth level by ANOVA.

 

Table 1 – Soil texture and compared soil uses in the investigated areas.
	Soil texture (g kg-1)			Soil Use
	Sand	Silt	Clay
Pisa	99	427	474	alfalfa/wheat rotation ;meadow; mediterranean bush
Siena	50	495	455	continuous wheat; meadow; mediterranean bush
Catanzaro	79	455	466	continuous wheat; pasture; mediterranean bush
Verona  (CB1)	730	170	100	continuous maize; meadow; locust  wood  (Robinia Pseudoacacia L.)
Verona (IS1+IS3)	400	440	160	tobacco; meadow; poplar wood(Popolus Alba L.)
Verona (MA1)	640	36	0	continuous maize; pear wood  (Pyrus comunis L)

 

Table 2 – Climate of the studied areas.
Location	Temperature and moisture regimes	Mean annual air temperature (°C)	Mean annual rainfall (mm)
Tuscany	Mesothermal, Humid	12.7	678
Calabria	Thermal, Xeric	16.2	632
Veneto	Temperate, Humid	13.0	684

In all the studied environments, the differences in TOC, TEC and HC between the compared soil uses mainly concerned the first centimetres depth. The decrease of TOC content as a result of soil use change differed between the considered regions. For soils developed on Pliocene clays, it varied between 85% (from mediterranean bush to continuous wheat in Calabria) and 63% (from mediterranean bush to continuous wheat in Tuscany). In Veneto it ranged between 65% (from locust wood to tobacco) and 36% (from poplar wood to continuous maize); nevertheless, the highest TOC content measured in this region (19 g kg^-1 under locust wood) was largely below those measured under mediterranean bush in Tuscany (30 g kg^-1) and in Calabria (62 g kg^-1). In all the areas, the meadow, compared to the more intensive soil uses, allowed a greater accumulation of TOC (18 g kg^-1 in Siena, 15 g kg^-1 in Verona), with a higher humification degree. This latter parameter proved to be a valid indicator of soil quality.