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Forest soils are recognized to be important organic carbon storage, but the role of surface and subsurface soil horizons on such function and its drivers are still field of debate. In this context, we examined the dynamics of soil organic carbon (SOC) for a chestnut forestry system in a temperate area of northern part of Apennine mountain range in Italy. Specifically, we questioned: what are the main i) SOC forms both in mineral surface and subsurface soil horizons? ii) factors affecting SOC stabilization?. Soil samples were collected by horizon and SOC was separated into organic C of the particulate organic matter (POM_C), sand–size aggregates (sand_C) and the mineral–associated organic C (MAOM_C). The easily oxidizable C (EOC), water–soluble organic C (WSOC), the microbial biomass–C and its respiration, and the total and easily extractable glomalin–related soil protein (T–GRSP and E–GRSP, respectively) were also estimated. Then, the E–GRSP–to–T–GRSP and E-GRSP–to–SOC ratios, the metabolic (qCO2) and microbial (qMIC) quotients were calculated. The POM_C, sand_C and MAOM_C showed the highest concentrations in A horizon (26.5, 14.6 and 13.9 g kg–1, respectively) highlighting the importance of the litter floor on the organic matter pools quantity in the topsoil. Further, the A horizon was enriched of the most labile organic C forms (i.e., EOC and WSOC) indicating the key role of A horizon for the development and growth of chestnut forest ecosystems. In fact, the labile organic C forms provide several ecosystem services, such as plant growth and yield. Unlike A horizon, the subsurface horizons preserved SOC mostly in the most stable form (63.8 %, on average). Because of the role of fungal biomass and its exudates to increase SOC capture and stabilization, the great potential of the subsurface horizons to store MAOM_C can be attributed both to the higher release of exogenous GRSP (higher E–GRSP–to–T–GRSP ratio) by mycorrhizal fungi and fungal mycelium expansion (higher E-GRSP–to–SOC ratio) within such horizons (0.504 and 0.061, respectively) compared to the A horizon (0.244 and 0.034, respectively). Therefore, the subsurface soil horizons seemed to have more favourable conditions for microorganisms compared to surface one as shown by the lower qCO2 and the higher qMIC values found in the former than in the latter. Overall, the present investigation highlighted the importance of subsurface soil horizons of chestnut forests on C stabilization processes compared to the A horizon likely due to the better edaphic conditions for the microbial communities. Thus, our results pointed out the key role that the subsurface soil horizons of chestnut forests could have for mitigating the current climate change.

Soil health is fundamental in maintaining and promoting overall ecosystem health and is defined as the continued capacity of soil to function as a vital living system, sustaining biological productivity as well as maintaining or enhancing the quality of air and water.The aim of this study was to assess the health of soils under orchards where the cultivation of Rosa Romana, a local apple cultivar, is taking place. These orchards were located in the Bologna Apennine farms, ranged in age between 5 and 30 years and were implanted on former cropland. They were all grassed and cultivated following the principles of organic farming.In this context, a comparison between the soils which belonged to orchards of at least 5 years in six farms with loamy texture was made. In each orchard, a morphological study of soils was carried out through the core of soil until 120 cm; then three mini pits were dug and sampled at a depth of 0-15 and 15-30 cm for physicochemical and biological analyses.Soil health assessment was carried out via physicochemical and biological analyses and the calculation of two indexes: Dilly’s index (metabolic quotient to soil organic carbon ratio) that highlights the carbon use efficiency of soil microorganisms and the Index of Biological Fertility (IBF), obtained through the sum of scores assigned to significant parameters such as organic matter, microbial biomass C content and its activity.Soil sampling and analyses were part of the Rural Development 2014-2020 of Emilia Romagna Region Project named “Rosa Romana apple of the Bolognese Apennines: organization of a quality organic supply chain”, which addresses to promote the sustainable management of agricultural areas in the Bologna Apennine by bringing together all actors involved in the cultivation, processing, and commercialization of this local apple cultivar.The indicators related to soil health showed a difference between the orchards of less than ten years compared to the older ones, the latter displaying better overall health. Dilly’s index showed a growing microbial efficiency from the young orchards to the old ones and the same pattern is present in the IBF. This is due to the older orchards having a higher microbial C content and lower metabolic quotient in both soil layers, and higher SOM in the topsoil layer. These differences, which indicate a lower microbial stress and higher efficiency in the old orchards, may be due to the effect of reduced or null disturbance inflicted to the soil after the conversion of cropland into orchard, as they were no longer tilled and have a permanent grass cover. Moreover, in the topsoil the mineralization quotient and the nitrogen isotope ratio are lower in the older orchards, which may indicate respectively a tendency toward carbon accumulation and a higher fresh organic matter input to the soil of orchards of more than ten years.These results may suggest that the promotion of the cultivation of the local Apennine apple variety “Rosa Romana” on former cropland in hill and mountain areas could promote the restoration of soil health.

In soil organic carbon (SOC) survey, the role of sampling approach is crucial andshould not be underestimated. In this sense, the appropriateness of soil sampling bypedogenic horizons (PGH) and fixed depth layers (FDL) in forest is still a field ofdebate. The present work aimed to: (a) study the spatial variability of SOC concentra-tions and C stocks through PGH and FDL samplings in uneven-aged sweet chestnut,European beech and Norway spruce forests of the Apennine chain (Italy); (b) clarifythe major advantages and drawbacks of sampling by PGH and FDL. In a representa-tive area (1818 m) of each forest, a soil profile was investigated and eight addi-tional sampling points were selected. The sampling was performed both by PGH andFDL (0–15 and 15–30 cm). For each forest, no SOC content and C stock differencesin 0–30 cm soil depth were found between PGH (58.8 ± 5.3 g kg1and 103±7gha1, respectively) and FDL (52.7 ± 4.3 g kg1and 117 ± 9 Mg ha1, respec-tively) sampling. However, under Norway spruce, PGH sampling pointed-out that Cwas mainly stored in Oe and Oa horizons (51.1 vs. 146 Mg ha1in the 0–30 cmlayer). The higher coefficient of variation obtained when soil horizons were consid-ered (from 19.2% to 72.8% for PGH and from 16.5% to 25.7% for FDL) suggestedthat PGH sampling preserved the information about the spatial variability within anecosystem. The information loss about SOC vertical and spatial distribution wouldindicate the inability of FDL sampling to support decision-making plans addressed forsustainable use of soil resource

Land capability and suitability maps are useful tools for soil resource conservation. This study aimed to build land capability and suitability maps using a multi-thematic approach by GIS in a salt-affected coastal area of Italy. Topographic, morphological, geological, pedological delineations and land cover maps, remote sensing image and climate data were acquired and the main physical and chemical properties, including electrical conductivity (EC) and available water capacity, were analysed on the soil samples collected in the study area. The acquired information were elaborated through QGIS software to obtain the land capability and suitability maps. The suitability map showed that most of the area (80%) is suitable for cultivation and, therefore, can be addressed for agricultural purposes without risk of degradation. In fact, the land capability map showed that 42% of the investigated area belongs to class I and II indicating that they can be used for a wide range of cultivations. While 44% of the investigated area clustered in class III and IV. In these latter the cultivation should be allowed to a limited range of crops due to the high sand content, which does not allow a good water retention, and due to a strong intrusion of sea water with consequent increase of the soil EC. In our study area, where agricultural productivity and environmental impact are in conflict, to classify the lands on base the land capability and suitability could help to define the best agricultural practices to apply in order to preserve soil functions.

Soil health is defined as the continued capacity of soil to function as a vital living system, sustaining biological productivity and maintaining or enhancing the quality of air and water, thus promoting the overall ecosystem health.Erosion, incorrect forestry practices, excessive grazing and a changing climate are major threats to soil health in temperate forest ecosystems. Correct forest management is necessary to enhance the soil’s capacity to provide essential ecosystem services such as water regulation, carbon storage and plant productivity.Because of the growing interest on forest ecosystem services, the Rural Development 2014-2020 of Emilia Romagna Region Project “Technical innovation and carbon capture on management of state-owned forests of high Apennine (BOSCHIAMO)” addresses to strengthen the sustainable management and multi-functionality of some publicly owned forests in the high Apennine, mainly managed by park authorities, while monitoring carbon sequestration in the soil and plant biomass. Within this project, our specific aim was to assess the soil health of three forest sites located in state-owned forests in the Northern Apennines in Emilia-Romagna region (Italy), overlying sandstone formations at a height of approximately 1500 m. The land use was coppice or high forest beech (Fagus sylvatica), high forest spruce (Picea abies), high forest beech and silver fir (Abies alba) and included an area of moorland (Vaccinium myrtillus, Vaccinium uliginosum, Juniperus nana).In each site, soil profiles, till BC horizon, were dug and each horizon was described, sampled, and analysed for physicochemical and biological parameters.Soil health assessment was carried out via physicochemical and biological analyses and the calculation of two indexes: Dilly’s index, which highlights the carbon use efficiency of soil microorganisms, and the index of biological fertility (IBF), which is obtained through the sum of scores assigned to significant parameters such as organic C, microbial biomass C content and its activity linked to basal respiration.These ecosystems showed overall good health, scoring average, good or excellent IBF; Dilly’s index was variable both in space and in depth but directed towards the efficiency of the use of C by microbial biomass. Significant differences in these indexes were found mainly in the subsoil, where the site over the most alterable parent material performed better than sites with a higher coarse fragment content, and the coniferous or mixed forest performed better than the beech forest, while the moorland often showed the worst values. In these cases, the differences in IBF scores were linked to indicators of soil microbial activity. Carbon stock at 0-30 cm was very variable as it depends on many different processes and conditions and was heavily influenced by slope and the quantity of coarse fragments in the soil.These results will serve as a baseline to quantify the impact on soil health of different logging techniques thus evaluating the best practices to preserve and enhance the ecosystem services provided by the soil.

The role of soil organic carbon (SOC) in avoidance, mitigation and control land degradation in forest ecosystems is largely recognized. For these reasons, a satisfactory SOC monitoring aimed to drive sustainable SOC management is necessary to avoid soil forest degradation. In this work we thus aimed to a) compare the soil organic carbon stock (OC stock) obtained by pedogentic horizons (PED) and fixed depth layer (FIX) in different forest ecosystems; b) discuss the differences in SOC data provided by the two soil sampling approaches, clarifying their major advantages and drawbacks; and c) to assess the ability of PED and FIX sampling approaches to keep information about horizontal and vertical SOC distribution. On the Apennine chain (North Italy), uneven–aged sweet chestnut, European beech and Norway spruce forests were selected. In each site, a representative area (18 m × 18 m) has been selected and, in the centre of the area, a soil profile has been investigated. Further, within the representative areas 8 additional sampling points were identified. Both for soil profiles and the additional sampling points, soil collection was performed both by PED and FIX (0–15 and 15–30 cm). For each forest stand, no difference of OC stock in 0–30 cm soil depth was found between PED and FIX sampling approaches, however SOC distribution along 0-30 cm provided by PED sampling was more informative on SOC dynamics. The findings obtained through the sampling by FIX would indicate a positive effect of conifers on SOC storage, the PED sampling allowed to assess that SOC under spruce forest was greatly stored in the organic horizons (Oe and Oa) because of the recalcitrant nature of the spruce litter, that does not allow the organic carbon stabilization through the association with mineral particles. Therefore, the spruce forest soil would not lead structural stability and resilience to soil degradation. Sampling by PED also preserved the information about the spatial variability within each study site. In fact, we noted higher coefficient of variation when soil horizons were considered compared to FIX (from 19.2 to 72.8% and from 16.5 to 25.7%, respectively). Overall, in a view of SOC monitoring, our findings demonstrated that the sampling by PED draws a better picture of SOC distribution along depth and its potential susceptibility to external factors leading to degradation. Further, the loss of information about SOC stabilization process and spatial variability would indicate the inability of FIX sampling to support decision–making plans addressed for sustainable use of soil resource.

Forest soils contain a large amount of carbon and play an important role in its global cycle. As forest soil organic carbon (SOC) mineralization is one of the major sources of atmospheric carbon, small changes of SOC can have effects on climate. Therefore, the Rural Development Programme (RDP) of Emilia-Romagna Region (Northeastern Italy) financed our SuoBo project, which aims to assess and preserve the quantity and quality of soil organic matter (SOM) in mountainous forest ecosystems located on the Apennine chain of the Emilia-Romagna Region. Our specific goal was to explore the response of SOC pools to forest thinning under two vegetation types. For this purpose, a chestnut forest of Beghelli farm (BEG), located at about 550 m a.s.l., and a mixed forest of Branchicciolo farm (BRA), located at about 225 m a.s.l, were selected. Soil samples were collected from each forest stand at 0-15 cm and 15-30 cm depths, in October 2020 in both farms and then in July 2021 in BRA farm and September 2021 in BEG farm. The soil samples were analyzed for the elemental contents and isotopic ratios (δ13C) of the soil total (TC), organic (SOC) and inorganic (SIC) carbon using an elemental analyzer coupled with an isotope ratio mass spectrometer. In October 2020, forest soil in BRA had higher TC, SOC, and SIC content in 0-30 cm (average: 7.1, 4.8 and 2.3 wt%, respectively) than in BEG (3.0, 2.8 and 0.1 wt%, respectively). The δ13CTC of the BRA soil is less negative than that of the BEG farm (–17.3‰ and –25.9‰, respectively) due to the higher SIC content, inherited by the parent rock mainly composed by limestones. In 2021, after one year since the thinning intervention, the TC and SOC contents in BEG soil were like those recorded in 2020, whereas those in BRA soils showed lower values. In particular in the superficial layer of BRA soils (0-15 cm), the SOC decreased from 6.9% to 4.1% in 2020 and 2021, respectively, while SIC content was unchanged (2.0 vs 2.1 wt%). Even in the deepest layer (15-30 cm) SIC remained the same over time (2.5 vs 2.4 wt%), while SOC decreased (2.5 vs 1.2 wt%). Also, the changes of δ13CSOC underlined a loss of organic matter from 2020 to 2021 (0-15 cm: –27.0 vs –26.2‰; 15-30 cm: –26.2 vs –25.9‰). Different concomitants may be contributing to this significant decrease in SOC: a) the different period of soil sampling (autumn vs summer), considering that the year 2021 is one of the seven warmest years on record globally and BRA has a lower altitude than BEG; b) the high slope (>45°) and the triggering of erosion process after the thinning intervention, which took away the surface soil, mainly characterized by organic hemitransformed horizons (e.g., Oe horizons). The future planned analyses of the quality of the SOM through i) chemical extraction and separation of the different humic fractions and ii) stability of the C fractions at different temperatures with a SoliTOC analyzer will shed a light on the prevailing phenomenon.

Availability of georeferenced yield data involving different crops over years, and their use in future crop management, are a subject of growing debate. In a 9 hectare field in Northern Italy, seven years of yield data, including wheat (3 years), maize for biomass (2 years), sunflower, and sorghum, and comprising remote (Landsat) normalized difference vegetation index (NDVI) data during central crop stages, and soil analysis (grid sampling), were subjected to geostatistical analysis (semi-variogram fitting), spatial mapping (simple kriging), and Pearson’s correlation of interpolated data at the same resolution (30 m) as actual NDVI values. Management Zone Analyst software indicated two management zones as the optimum zone number in multiple (7 years) standardized yield data. Three soil traits (clay content, total limestone, total nitrogen) and five dates within the NDVI dataset (acquired in different years) were shown to be best correlated with multiple- and single-year yield data, respectively. These eight parameters were normalized and combined into a two-zone multiple soil and NDVI map to be compared with the two-zone multiple yield map. This resulted in 83% pixel agreement in the high and low zone (89 and 10 respective pixels in the soil and NDVI map; 73 and 26 respective pixels in the yield map) between the two maps. The good agreement, which is due to data buffering across different years and crop types, is a good premise for differential management of the soil- and NDVI-based two zones in future cropping seasons.

Temperate soils are threatened by degradation and soil organic matter (SOM) loss due to a combination of geomorphology, soil types, and anthropic pressure. In 54 sites in Northern Italy, characterized by different land uses, climates, geological substrates, and soils, we assessed (i) the soil quality, (ii) the SOM accumulation/degradation patterns, and (iii) whether land use and related soil management practices are sustainable based on changes in soil quality. Soil samples from the 0–15 and 15–30 cm deep layers were collected and analyzed for the soil parameters recommended by the FAO (bulk density, pH, organic and microbial C, total N, and soil respiration rate) and for the chemical SOM pools. Parameters related to the efficient use of soil microbial C were also calculated. The findings showed that agricultural lands where organic material was added had good soil quality and used microbial C efficiently. Reclaimed peaty soils degraded because the conditions were too stressful for the soil microbial biomass as supported by high metabolic quotient and the low values of mineralization quotient, microbial quotient, and soil biofertility index. Conservative management practices carried out in chestnuts were found to have a decreased soil degradation risk. An investigation of the soil parameters recommended by the FAO can be used to evaluate sustainable practices and soil quality on microbial activity and SOM dynamics.

Recently, several hectares of abandoned chestnut forests (ACF) were recovered into chestnut stands for nut or timber production, however, the effects of such practice on soil mineral horizon properties are unknown. This work aimed to (1) identify the better chestnut forest management to maintain or to improve the soil properties during the ACF recovery, and (2) give an insight into the effect of unmanaged to managed forest conversion on soil properties, taking in consideration sweet chestnut (Castanea sativa Mill.) forest ecosystems. The investigation was conducted in an experimental chestnut (Castanea sativa Mill.) forest located in the northern part of the Apennine chain (Italy). We identified an ACF, a chestnut forest for wood production (WCF), and chestnut forests for nut production with a tree density of 98 and 120 plants ha&minus, 1 (NCFL and NCFH, respectively). WCF, NCFL and NCFH stands are the result of the ACF recovery carried out in 2004. After 15 years since the ACF recovery, generally, the effects on the main soil chemical properties were negligible. Some differences occurred for the water-soluble organic carbon (WSOC) and microbial biomass and its activity. NCFL showed the highest WSOC content in the uppermost soil horizon likely due to higher amount of roots which are source of labile organic compounds. The higher WSOC amount might explain the greatest amount of microbial biomass in the A horizon of NCFL. Furthermore, the microbial biomass harboring in the A horizon of NCFL has also shown both a better C use efficiency and a larger soil organic carbon immobilization in the microbial biomass itself. Our data would indicate that the ACF recovery into pure chestnut forests did not have negative impacts on soil chemical and biochemical properties, though chestnut stands for nut production with a low plant density are the most suitable ones.

Soil organic carbon (SOC) content is the major indicator used for soil quality evaluation because provides several ecosystem functions. However, SOC content does not allow to understand the soil potential to deliver the key ecosystem functions because most of soil processes are linked to soil biota. This research aimed to demonstrate the importance of soil indicators related to the SOC cycle rather than SOC content for soil quality evaluation. To reach this goal, three farms characterized by diverse soil types (Fluvisol and Cambisol) were selected in the Po plain of Emilia-Romagna Region, Italy. Moreover, different agricultural practices were performed: three-year-old pear trees using conventional management for Maccanti farm (MAC), 10-year pear orchard with integrated management for Zani (ZAN) and 10-year peach orchard with organic management for Biondi (BIO). MAC is located in ancient reclamation area, where Fluvisols are enriched of peat and organic matter. In each farm, soil samples from 0–15 (hereafter called topsoil) and 15–30 cm (hereafter called subsoil) depth were collected and analysed for the contents of SOC, labile organic carbon (Clab), fulvic acids, humic acids, humin and microbial biomass–C (Cmic), and for microbial respiration (Resp). In order to evaluate the soil processes related to C cycle, the humification rate (HR), metabolic quotient (qMET) and microbial quotient (qMIC) were calculated. MAC soil showed the highest SOC content without differences between topsoil and subsoil, due to ancient reclamation and agricultural management. BIO and ZAN showed similar SOC contents and it was higher in the topsoil than in subsoil due to grassy turf. Compared to BIO and ZAN, MAC soil showed a higher amount of Clab, and SOC was composed by a lower percentage of stable organic carbon (humin). Despite the higher Clab concentration, which is an easily available C source for microbes, no differences of Resp were observed among the sites, and MAC showed the lowest Cmic content. These data would indicate the presence in MAC of stress conditions which do not allow the growth of microbial biomass. The occurrence of stress conditions is clearly showed by the lowest qMET indicating how the conventional agricultural practices in peaty Fluvisol negatively affect the carbon use efficiency of microbial biomass. As a consequence, these stress conditions do not allow the C stabilization as suggested by the lowest qMIC. Further, the low C stabilization processes are highlighted by the highest HR. Conversely, despite the lowest content of Clab, BIO soil showed the lowest qMET and the highest qMIC suggesting how organic managements tend to improve the soil quality. Hence, the present study highlighted the importance of indicators linked to soil microbiome for soil quality evaluation in order to preserve its ecosystem functions. Indeed, organic carbon rich soils as those of MAC would indicate high quality soils but, because of the highly impacting practices, they showed stress conditions when the indicators linked to soil microbiome are taken in account. Therefore, if these indicators are not considered for soil quality evaluation, several fields used for agricultural purposes could become degraded.

ABTRACT: Soil and weather data were used to analyse spatio-temporal yield patterns of winter cereals (wheat) and spring dicots (sunflower and coriander) in an 11-ha field in Northern Italy (44.5° N, 12.2° E), during 2010–2014. Three yield stability classes (YSCs) were established over multiple years, based on spatio-temporal characteristics across the field: high yielding and stable (HYS), low yielding and stable (LYS), and unstable. The HYS class (46% of field area) staged a 122% relative yield with low temporal variability. The unstable class (24% of field area) was slightly more productive (83% relative yield) than the LYS class (30% of field area, and 80% relative yield), but less consistent over time. Crop yields evidenced negative correlations with sand content; positive correlations with silt and clay content. Soil properties were quite consistently classified among YSCs: the LYS and unstable classes were associated with higher sand content and lower cation exchange capacity, suggesting that these characteristics lead to fluctuation and depression of final yield. Establishing YSCs based on spatio-temporal yield appears a sound approach to appraise field potential. It results in strategic and tactical decisions to be taken, depending on the profile of spatial and temporal productivity in different field areas.

Industrial farming without considering soil biological features could lead to soil degradation. We aimed to evaluate the biochemical properties (BPs) and biological fertility (BF) of different soils under processing tomato cultivation, estimate the BF through the calculation of a simplified BF index (BFIs), determine if the crop was affected by BP and BF. Three farms were individuated in Modena (MO), Ferrara (MEZ) and Ravenna (RA) provinces, Italy. Soil analysis included total and labile organic C, microbial biomass-C (Cmic) and microbial respiration measurements. The metabolic (qCO2), mineralization (qM) and microbial (qMIC) quotients, and BFIs were calculated. Furthermore, plant nutrient contents were determined. The low Cmic content and qMIC, and high qCO2 found in MEZ soils indicate the occurrence of stressful conditions. The high qMIC and qM, and the low qCO2 demonstrated an efficient organic carbon incorporation as Cmic in MO soils. In RA soils, the low total and labile organic C contents limited the Cmic and microbial respiration. Therefore, as confirmed by the BFIs, while MO showed the healthiest soils, RA soils had an inefficient ecophysiological energy state. However, no effects on plant nutrient contents were observed, likely because of masked by fertigation. Finally, BP monitoring is needed in order to avoid soil degradation and, in turn, crop production decline.

The aim of the study was to assess if pedogenic processes such as mineral weathering and lessivage, other than organic matter accumulation, can affect soil microbial population and enzyme activities. This study examines six soil profiles located in a karst region of the North-Eastern Italian Alps and characterized by a vertical textural differentiation due to lessivage. For each soil, four pedological layers were recognized according to the dominant soil forming process: i) the top soil (Tp layer), formed by A and AB horizons, characterized by organic matter accumulation; ii) the subsurface eluviated layer (Elu layer), comprising AE and EB horizons; iii) the layer dominated by the in-situ mineral weathering (Wh layer), made by Bw horizons; iv) the deepest layer (Ls), subjected to clay illuviation and comprised by Bt horizons. In the upper layers (Tp and Elu), because of the low pH, weathering also occurred, as indicated by the presence of disordered smectite and by the high values of pedogenic Fe oxi-hydroxides to pseudo-total Fe ratio. The microbial biomass content and structure, and the enzyme activities significantly differed in the four pedological layers. The amount of microbial biomass was, as expected, most abundant in the Tp layer, where bacteria and actinomycetes abounded. Conversely, in Elu and Wh we observed a fungal-to-bacterial biomass ratio significantly higher than in Tp and Ls; in Elu, also the gram (+)/gram (−) ratio was the highest. In the upper layer, the interaction between enzymes and minerals like disordered smectite and pedogenic Fe-oxides appeared as responsible for the inhibition of the total enzyme activity per unit of organic C, and of the lipase activity. In Ls layer, where clay illuviation and high organo-minerals interaction occurred, the potential hydrolysis of organic matter was low, as revealed by the SEI/TOC ratio, the reduced lipase activity, and the inhibited activity of α-fucosidase and α-mannosidase. Even if the activity of most enzymes depends on the substrate availability, which decreases with soil depth, those involved in lipid degradation displayed the maximum activities in Elu and Wh layers, where a relative increase of the fungal population was observed. In conclusion, our findings showed that the soil functionality, expressed by the microbial community structure and enzymes activity, can vary according to organic matter–mineral interaction following the weathering and lessivage gradients along the soil profiles.

To improve knowledge on salt leaching suitability on different soils, in Arenosols and Cambisols croplands in the coastal area of Ravenna (Italy), soil samples were collected in the non-irrigation winter period and irrigation summer period. Concurrently, waters of the canal network were also investigated. Soil samples were analyzed for pH, carbonate, total organic carbon (TOC), particle size distribution, electrical conductivity (EC), bulk density (BD) and water content at field capacity (FC). Water samples were investigated for pH, EC, biological and chemical oxygen demand, sodium adsorption ratio, phosphorus, nitrogen, sulfates and chlorides. All soils had low TOC concentrations and Arenosols showed the lowest clay content, BD and FC. Soils had similar EC values in winter, but in summer the lowest ones were observed in Arenosols, suggesting that irrigation mitigated salinization in Arenosols, while the high clay content, BD and FC prevented or limited the salt leaching in Cambisols. In summer, the increase of total nitrogen and biological oxygen demand, especially in drainage channels, might suggest the leaching of soluble nutrients and organic matter from soils due to the high irrigation water volumes. Finally, our findings stress the need to consider soil type and properties to contrast soil salinization without negative effects on soil C leaching caused by salt leaching practice.

The agricultural European Innovation Partnership (EIP-AGRI) Focus Group on Soil Organic Matter (SOM) content in Mediterranean regions highlighted the poor organic carbon (OC) content in the investigated soils, with some areas, especially in Southern Europe, showing low (≤2%) or even very low (≤1%) OC values. For this reason Emilia-Romagna Region (Northeastern Italy) invested heavily in the Rural Development Programme (RDP), which financed projects addressed to the needs of specific geographical areas. Among these, SaveSOC2 project (Save Soil Organic Carbon) aims to evaluate the quantity and quality of SOM in both conventional and organic farms from distinct pedo-climatic setting of Emilia-Romagna Region and with possible critical issues, in order to identify the best agricultural practices which could contribute to i) carbon conservation and sequestration in soil and ii) mitigation of SOM mineralization responsible for the greenhouses emissions. Here we report the data of the “Tassinari” organic farm located at Bondeno, near Ferrara city in Padania Plain, an area characterized by soil with very low amount of OC. In the selected organic farm, topsoil samples (0-15 cm and 15-30 cm depth) were collected from strawberry fields and orchards converted from conventional to organic production since 1992. The soils have loam and silt loam texture, they are subalkaline (pH: 7.9-8.7) and nonsaline (EC: 0.1-0.2 dS m-1). To characterize the soil inorganic (SIC) and organic (SOC) carbon, for each sample, elemental and isotopic analyses were performed using the Thermally Based Separation protocol tested by Natali et al. (2018) with an EA-IRMS. As expected, the vertical distribution of carbon along each site showed a negative correlation between SIC and SOC contents, as IC slightly increase over depth while OC show a clear decline. Moreover, irrespectively of the sampling depth, the OC values (0.90-1.14 wt.%) are always lower than those of IC (1.04-2.50 wt.%). The relatively low negative δ13C values of the total carbon (from -12.1‰ to -9.0‰) reflect the predominance of SIC in the investigated topsoils. The low storage of organic matter in this area is also confirmed by the OC stock value in the topsoils, which is on average 42.6 Mg/ha. A Soli TOC Cube® was also used to discriminate the labile organic carbon (TOC400) and the residual oxidizable carbon (ROC) fractions, which are oxidized at temperature below and above 400°C, respectively. In all the investigated topsoils, the TOC400 values (0.60-0.84 wt.%) are higher than those of ROC (0.21-0.28 wt.%), indicating large amount of “fresh” organic matter, and low amount of residual organic carbon. The high relative presence of labile OC pools, probably due to the soil fertilisation with easy available organic compounds, can be critical for SOM sequestration, preventing the accumulation of stabilised organic compounds. Natali C., Bianchini G., Vittori Antisari L. 2018. Thermal separation coupled with elemental and isotopic analysis: A method for soil carbon characterisation. Catena 164, 150-157.

The exploitation of soils due to farming has produced a progressive loss of soil organic matter (SOM) over the years. At the same time, the degradation of SOM has led to a decline of several ecosystem services provided by soil, especially in mountain. Against this background, the partnership between Department of Physics and Earth Sciences of University of Ferrara and Department of Agricultural and Food Sciences of University of Bologna led to the creation of the SaveSOC2 project (Save Soil Organic Carbon), funded by Rural Development Programme of Emilia-Romagna Region. This project primarily seeks to investigate and promote carbon storage processes in agricultural soils of Emilia-Romagna Region (NE Italy). The present study outlines an overview about the SOM dynamics of “I Rodi” organic farm, located in the Modena Apennine. “I Rodi” produces and processes small organic fruits, especially raspberries. Three different sites (grassland -G, very low productive raspberries -LR, and good productive raspberries -GR) have been selected and the topsoils (0-15 cm and 15-30 cm) have been investigated. Elemental and isotopic analyses of soil C were performed using an EA-IRMS. In particular, the application of the Thermally Based Separation protocol [1] allowed the determination of both inorganic (IC) and organic (OC) carbon contents in each soil sample. OC accounted for 93.50% of the total carbon (1.72-4.84 wt.%). The negative δ13C values of the total carbon (from -27.8 to -19.7 ‰) confirmed the predominance of OC over IC in the investigated soils. The average values of OC isotopic C signature showed a decreasing trend among the three sites (-28.2, -27.2 and -25.8‰ for GR, G and LR, respectively), with the low productivity site having the highest δ13C value. The isotopic C signature of separated organic C fractions (0-15 cm topsoils) showed that humin (832-879 g/kg), which is the SOM fraction mostly interacting with the soil mineral phase and the largest pool, confirmed the observed trend (-27.5, -27.0, -26.4‰, GR, G and LR). The humic acids (6-17 g/kg) showed similar trend but lower δ13C values in all sites (-28.5, -28.0, -26.8 ‰, GR, G and LR). Finally, fulvic acids (5-10 g/kg) differed, having dissimilar trend and values of δ13C (-27.1, -26.8, -26.0 ‰ for G, GR and LR). Comparing to G, the GR data suggested that organic management i) did not decrease quantity and quality of organic matter, and ii) it was more efficient in OC stabilisation, increasing the amount of less transformed OC in both humin and humic acids (more negative δ13C values). In the LR site, instead, the observed trend can be due to low suitability of this soil to raspberries production, negatively affecting both crop yields and organic C dynamics. In our opinion, in order to combine agricultural productivity and its sustainability, more attention should be paid both to soil management and suitability in the area.[1] Natali C., Bianchini G., Vittori Antisari L. 2018. Thermal separation coupled with elemental and isotopic analysis: A method for soil carbon characterisation. Catena 164, 150-157.

Sustainable agricultural management is needed to promote carbon (C) sequestration in soil, prevent loss of soil fertility, and reduce the release of greenhouse gases. However, the influence of agronomic practices on soil C sequestration depends on the existing pedoclimatic features. We characterized the soils of three farms far away each other in the Emilia-Romagna region (Northern Italy): an organic farm in the Northern Apennines, a biodynamic farm, and a conventional farm on the Po Plain. The total, inorganic, and organic carbon in soil, as well as the distinct humic fractions were investigated, analyzing both the elemental and isotopic (13C/12C) composition. In soils, organic matter appears to be variously affected by mineralization processes induced by microorganisms that consume organic carbon. In particular, organic carbon declined in farms located in the plain (e.g., organic carbon down to 0.75 wt%, carbon stock0-30 cm down to 33 Mg/ha), because of the warmer climate and moderately alkaline environment that enhance soil microbial activity. On the other hand, at the mountain farm, the minimum soil disturbance, the cold climate, and the neutral conditions favored soil C sequestration (organic carbon up to 4.42 wt%, carbon stock0-30 cm up to 160 Mg/ha) in humified organic compounds with long turnover, which can limit greenhouse gas emissions into the atmosphere. This work shows the need for thorough soil investigations, to propose tailored best-practices that can reconcile productivity and soil sustainability.

In mountain areas, water erosion plays an important role on soil structure and can strongly affect its functions. Suitable management practices, namely choice of crops, may be able to improve aggregate stability and reduce soil loss by surface runoff. To study the effects of cover crops on aggregation in mountain soils, we investigated a soil planted with wheat (site C) compared to two soils under alfalfa (sites A and B). All investigated soils were Typic Ustorthents. The soil aggregates were isolated by a physical-functional procedure defined on the basis of aggregates resistance against specific breakdown mechanisms such as slaking and water abrasion. One year after alfalfa plantation, its effect on wet aggregate stability and the amount of organic carbon (OC) and nutrients retained by the isolated aggregates were measured. In the less degraded soils (site B) organic matter decomposition was stimulated, and after 1 year the TOC and TOC/N declined. Consequently a reduction in aggregate stability and ability to preserve elements occurred, as shown by the decrease of wet aggregate stability indexes and total nutrients (e.g. N, P and K) retained by stable aggregates. In more degraded soil (site A), alfalfa generally positively affected the investigated properties. The effect of alfalfa in the studied crop rotation depends on the degree of land degradation due to water erosion. As regards the investigated breakdown mechanisms, our data showed that the aggregate resistance to water abrasion was related to TOC, while the resistance against fast wetting breakdown is correlated to the microbial biomass.

The purpose of this study was to investigate the in situ characterization of organic matter (OM) within soil macroaggregates, and to assess the relationships between OM characteristics and macroaggregate size indicating different OM stabilization mechanisms. Optical micro-morphological investigations, coupled to SEM-EDS (scanning electron microscopy and energy X-ray spectroscopy) technique, were carried out on thin sections of 1–4 and 0.25–1 mm soil aggregates (coarse and fine macroaggregates, respectively) from 0 to 20 cm soil layer corresponding to A horizon of four different sites in which soil structure were not disturbed by tillage. The intraggregate porosity, measured by image analysis of four different size classes (200 µm), showed that fine macroaggregates were significantly less porous (3.70–6.71% of total porosity) and had higher presence of the finest pore class (

Assessing the spatial variation of soil and crop properties is the basis for site specific management of crop practices in precision agriculture applications. To this aim, proximal and remote spectral vegetation indices are increasingly replacing soil physical-chemical analysis. In this study the spatial variation of soil properties, proximal and remote spectral vegetation indices were compared in a winter wheat ( Triticum aestivum L.) crop grown in a 4.15 ha field in northern Italy. Soil analysis (particle size distribution, pH, carbonates, C, total N, available P, exchangeable cations and electrical conductivity) was geo-referentially carried out; the proximal indices chlorophyll content by N-Tester and normalized difference vegetation index (NDVI) through GreenSeeker were determined in three dates during stem elongation; the remote indices PurePixel TM Chlorophyll Index and PurePixel TM Vegetation Index were determined through the Landsat 8 satellite in three dates during the same wheat stage. Dry biomass yield (DBY), grain yield (GY) and yield components were determined at harvest. Soil, proximal and remote data were submitted to principal component analysis (PCA), and the retained PCs were clustered to delineate areas at low, intermediate and high yield potential, based on soil parameters (CLU sp ), proximal (CLU pi ), and remote vegetation indices (CLU ri ). DBY and GY were significantly correlated with several soil parameters and vegetation indices. Spatial distribution of soil and crop data consistently depicted a low performing area (GY 8 Mg ha -1 ). CLU sp determined a lower GY difference between low and high performing area (+60%), compared to CLU pi and CLU ri (almost + 100%). In CLU sp and CLU pi the low and high performing area were of similar size (25 and 29% for the two respective areas in CLU sp ; 25 and 33% in CLU pi ), whereas in CLU ri they were quite different (16 and 46%). Lastly, yield potential levels determined by vegetation indices (CLU pi and CLU ri ) exhibited a better degree of agreement with DBY and GY levels, than soil parameters (CLU sp ). In exchange for this, the above referred soil parameters are quite consistent in time, allowing soil data to be used for more years. On concluding, PCA followed by clustering resulted in a robust delineation of field areas at different yield potential. This is the premise for developing research driven strategies of practical use.

Maintaining multiple ecological functions (“multifunctionality”) is crucial to sustain viable ecosystems. To date most studies on biodiversity-ecosystem functioning (BEF) have focused on single or few ecological functions and services. However, there is a critical need to evaluate how species and species assemblages affect multiple processes at the same time, and how these functions are interconnected. Dung beetles represent excellent model organisms because they are key contributors to several ecosystem functions. Using a novel method based on the application of 15N-enriched dung in a mesocosm field experiment, we assessed the role of dung beetles in regulating multiple aspects of nutrient cycling in alpine pastures over appropriate spatial (up to a soil depth of 20 cm) and temporal (up to 1 yr after dung application) scales. 15N isotope tracing allowed the evaluation of multiple interrelated ecosystem functions responsible for the cycling of dung-derived nitrogen (DDN) in the soil and vegetation. We also resolved the role of functional group identity and the importance of interactions among co-occurring species for sustaining multiple functions by focusing on two different dung beetle nesting strategies (tunnelers and dwellers). Species interactions were studied by contrasting mixed-species to single-species assemblages, and asking whether the former performed multiple functions better than the latter. Dung beetles influenced at least seven ecological functions by facilitating dung removal, transport of DDN into the soil, microbial ammonification and nitrification processes, uptake of DDN by plants, herbage growth, and changes in botanical composition. Tunnelers and dwellers were found to be similarly efficient for most functions, with differences based on the spatial and temporal scales over which the functions operated. Although mixed-species assemblages seemed to perform better than single-species, this outcome may be dependent on the context. Most importantly though, the different functions were found to be interconnected sequentially as reveled by analyzing 15N content in dung, soil and vegetation. Taken together, our current findings offer strong support for the contention that the link between biodiversity and ecosystem functions should be examined not function by function, but in terms of understanding multiple functions and how they interact with each other.

Purpose: Canal dredging and shaping produce considerable amounts of sediments whose reuse on- and off-site depends on their pollution level. This study explores the potential of a calcium chloride washing to remove potentially toxic elements (PTEs) from a freshly dredged calcareous sediment and to affect the aggregate stability of the washed sediment. Materials and methods: The ability of 0.5-M CaCl2 washing to restore the sediment samples polluted with Cu and Zn dredged from a freshwater canal was assessed. The distribution of the two metals among the sediment geochemical phases, the potential availability to plants (DTPA), and the water aggregate stability of particles were evaluated on the washed samples and compared to control. Results and discussion: In the most polluted sample (similar to 200 and 500mgkg(-1) of Cu and Zn, respectively), the washing decreased the amount of Cu by 26%, mainly in the sulfide/organic fraction, and of Zn by 10%, mainly in carbonates. A decrease in the dispersivity of clay fraction was observed due to the well-known effect of Ca2+ ions on flocculation of colloidal clay particles. At large scale, the aggregates formed by the interaction between large particles and flocculated clay showed lower water stability with respect to the control, thus suggesting the need to improve the physical properties of the treated material. Noteworthy, after 1 year of dry storage from washing, the average percentage of potentially bioavailable (DTPA) Cu and Zn (23 and 13% of pseudo-total amount, respectively) dropped with respect to the control (40 and 19%) and a concomitant carbonate increase (+33%) was observed. Conclusions: The CaCl2 washing is a promising method to reduce Cu and, to a minor extent, Zn in wet calcareous sediments dredged from freshwater canals. However, there is still room for improvement. The PTE fractions remaining in carbonates and organic component of washed sediment clearly indicate the potential of combining mild acidic pH values with calcium chloride in the washing to enhance the PTE removal.

A Fragipan (Bx) is a soil horizon hard when dry and brittle when moist, that undergoes slaking upon water immersion, forming a barrier to roots and limiting land use. Brittleness and slaking depend on soil porosity and particle arrangement, but still no agreement exists on the inorganic components responsible for such arrangement. We hypothesized that the same kind of particle arrangement may originate from different soil components, ultimately depending on the lithology of parent material, and evaluated the soil and clay characteristics that best differentiate Bx from B horizons. Thirty-six samples were taken from Typic Fragiudalfs developed on the two sides of an alluvial fan characterized by different amounts of ultramafic materials. Discriminant Analysis evidenced that pedogenic Fe oxides were fundamental in discriminating Bx from B horizons on pure ultramafic parent material, while clay mineralogy was more important in soils with less ultramafic materials. In the first case, the association between clay minerals and self-assembling oxides systems may lead to brittleness, while in the second case the higher abundance of kaolinite may contribute to weak associations between pH-dependent sites and negatively charged surfaces. The only common feature to fragipans on both river sides was a higher degree of weathering.

Chestnut plantations are worldwide distributed and they are often subjected to intensive management practices such as the removal of the organic residues from the soil surface. The present study aimed to investigate the effect of such practices on soil properties at different depths and on nutrient contents in chestnut leaves. To reach our goal, 6 pits down to 30 cm soil depth were dug in European chestnut (Castanea sativa Mill.) stands where the organic residues such as burrs, leaves and pruned materials are yearly removed (REM), and 9 pits in stands where the organic residues are chopped and left on soil surface (CONS). Both practices began about 30 years ago. The nutrient contents in leaves were assessed on chestnut trees close to each pit. Our findings showed a more intense soil development in CONS than in REM. At soil surface, CONS had thicker mineral horizon than in REM probably due to the protection acted by the organic residues against erosion. In subsoil, organic residues conservation promoted the organic C (soil organic C, water–extractable organic C, fulvic–like C and soil organic C stock) accumulation which further promoted horizon development. Since the role of soil organic matter (SOM) as source of nutrients, the subsoil of CONS study sites had a greater stock of Ca, P and S and a higher exchangeable Ca content than REM. Furthermore, the higher SOM and nutrient contents in CONS subsoil compared to REM promoted the microbial respiration. The organic residues conservation effects on the surface soil horizon properties were, instead, negligible. Despite the generally better soil conditions in CONS than in REM, no differences were observed for the leaf nutrient contents likely due to the chestnut trees adaptability also to the scarcely fertile soils. Overall, our findings highlighted the importance of organic residues conservation for the improvement in deeper soil horizons of the chemical and biological fertility in chestnut plantations. Furthermore, this research pointed out to pay more attention on subsoil since it is a good indicator of the changes caused by external factors.

Technosols are soils developed on non-traditional substrates and containing large quantities of materials mostly due to intensive human industrial activity, such as artefacts. The increasing number of sites affected by Technosols and their impact on the environment as growing media for plants or as source of pollutants require an understanding of their functioning and evolution, above all the knowledge on the transport of toxic substances from contaminated technogenic soils to groundwater. A case study on properties, remediation and evaluation of Technosols made up by vitrified fly ash and glass–ceramics in Italy was carried out. Original technogenic soils, classified as Spolic Technosols (ecotoxic), were pedotechnically in situ remediated by adding smectitic marlstone and Ca(OH)2. Chemical analysis on samples from piezometers showed the presence of harmful heavy metals in groundwater. By means of boreholes and soil profiles the new soils generated, after remediation, were physically and chemically characterized and classified as Spolic Technosols (calcaric). Analysis on soil toxicity and leaching tests showed the effectiveness of the remediation and the mobility reduction of some potentially harmful elements according to the environmental Italian regulation.

Soil characteristics, proximal and remote spectral vegetation indices were geo-referentially assessed in a 4.15 ha wheat field in northern Italy. Data obtained in the three separate domains were submitted to principal component analysis (PCA), and the retained PCs were clustered to delineate homogeneous areas at low (L), intermediate (I) and high (H) potential, based on soil parameters (CLUsp), proximal (CLUpi) and remote spectral vegetation indices (CLUri). Spatial distribution of soil and crop data showed a low performing area (GY < 3 Mg ha-1) and a high performing one (GY > 8 Mg ha-1). CLUsp staged a lower GY difference between L and H area (60%) than CLUpi and CLUri (ca. 100%). Area levels (L, I, H) based on vegetation indices outlined a better degree of agreement with GY, compared to area levels based on soil parameters. In exchange for this, the above referred soil parameters are quite consistent in time, allowing soil data to be used for more crop seasons.

Soil aggregation and organic matter (OM) conservation are important in the prevention of land degradation. Aggregation processes and OM turnover influence each other and depend on the characteristics of both minerals and organic pools. We assessed the relative importance of the organic and mineral phases at the macroaggregate and colloidal scale in two soils (CHL and SRP, chlorite and serpentine-rich, respectively) where Mg-silicates dominated, by incubating them with a relatively degraded and oxidized organic fraction, that is the humic acids (HAs) extracted from the organic horizons of both CHL and SRP. The HA from SRP were more aromatic and richer in phenolic groups, whereas HA from CHL were N-richer, more aliphatic and richer in carboxyl groups. The SRP soil formed larger amounts of macroaggregates, more stable than in CHL. At the colloidal scale, SRP was more flocculated and clay had a lower electrophoretic mobility than CHL. HA enhanced aggregate formation in both samples but improved aggregate stability only in CHL. In CHL, slight differences in electrophoretic mobility were visible, while in SRP, differences were more pronounced, with a point of zero charge at lower pH and larger hydrodynamic diameter. The abundance of Mg in SRP may have favoured the formation of weaker outer-sphere interactions and the release of clay-HA associations upon water dispersion, while in CHL Ca formed more stable bonds with HA. In SRP, ligand exchange reactions can be ruled out, conversely to the dominant bonding mechanism occurring in Al-silicate dominated soils, with important consequences on the release of OM-loaded clay particles. Copyright © 2016 John Wiley & Sons, Ltd.

Soil needs a long time for its development, and traces of the past effects of climate, vegetation cover, and human activity can persist through time. Thus, paleosols are widely studied for paleo-environmental reconstructions, so to understand the effects of climate changes and/or human activities that for millennia transformed the land and interacted with soil formation. The aim of this work was to assess the influence of both ancient and modern environmental conditions on the pedogenesis at Mt Cimone, Northern Apennines, Italy. In particular, we compared buried paleosols and the overlying modern soils separated by a charcoal enriched horizon (Aub) along an altitudinal (climatic) sequence from 1553 to 1939 m above sea level. The radiocarbon age of the Aub horizon was 3040-2940 calibrated years before present, therefore it was taken as a chronological marker for the beginning of soil formation of the modern soil unit. The horizons thickness of the modern soil varied among the sites, suggesting the occurrence of accumulation/erosion processes, with a differential redistribution over the Aub horizon of the soil material transported by surface water runoff. The soil horizon sequence in the paleosol at lower altitudes (1553–1700 m) was rather simple (Bw-C horizons), indicating the occurrence of a moderately intense paleo-pedogenesis. Instead, from 1700 to 1900 m (mostly above the actual tree line) the paleosol showed well-expressed processes of eluviation-illuviation of organic matter and Fe/Al oxyhydroxides, which led to the formation of E-Bs or Bhs-C horizons sequences (podzols). These findings agree with previous studies dealing with climatic and palynological changes occurred in this area in the last seven millennia. At altitudes >1700 m, the ancient pedogenetic phase occurred during the Atlantic climatic period, with a cryic soil temperature regime, no permafrost, presence of seasonal snow, and a progressive tree species transition from Abies alba to oaks of warm temperate climate. The modern pedogenetic phase seemed to be affected by local wetter conditions and human induced forest disturbance, as it is testified by the change in the pollen abundance.

Erosion is a relevant soil degradation factor in mountain agrosilvopastoral ecosystems that can be enhanced by the abandonment of agricultural land and pastures left to natural evolution. The on-site and off-site consequences of soil erosion at the catchment and landscape scale are particularly relevant and may affect settlements at the interface with mountain ecosystems. RUSLE (Revised Universal Soil Loss Equation) estimates of soil erosion consider, among others, the soil erodibility factor (K), which depends on properties involved in structure and aggregation. A relationship between soil erodibility and aggregation should therefore be expected. However, erosion may limit the development of soil structure; hence aggregates should not only be related to erodibility but also partially mirror soil erosion rates. The aim of the research was to evaluate the agreement between aggregate stability and erosion-related variables and to discuss the possible reasons for discrepancies in the two kinds of land use considered (forest and pasture). Topsoil horizons were sampled in a mountain catchment under two vegetation covers (pasture vs. forest) and analyzed for total organic carbon, total extractable carbon, pH, and texture. Soil erodibility was computed, RUSLE erosion rate was estimated, and aggregate stability was determined by wet sieving. Aggregation and RUSLE-related parameters for the two vegetation covers were investigated through statistical tests such as ANOVA, correlation, and regression. Soil erodibility was in agreement with the aggregate stability parameters; i.e., the most erodible soils in terms of K values also displayed weaker aggregation. Despite this general observation, when estimating K from aggregate losses the ANOVA conducted on the regression residuals showed land-use-dependent trends (negative average residuals for forest soils, positive for pastures). Therefore, soil aggregation seemed to mirror the actual topsoil conditions better than soil erodibility. Several hypotheses for this behavior were discussed. A relevant effect of the physical protection of the organic matter by the aggregates that cannot be considered in $K$ computation was finally hypothesized in the case of pastures, while in forests soil erodibility seemed to keep trace of past erosion and depletion of finer particles. A good relationship between RUSLE soil erosion rates and aggregate stability occurred in pastures, while no relationship was visible in forests. Therefore, soil aggregation seemed to capture aspects of actual vulnerability that are not visible through the erodibility estimate. Considering the relevance and extension of agrosilvopastoral ecosystems partly left to natural colonization, further studies on litter and humus protective action might improve the understanding of the relationship among erosion, erodibility, and structure.

Background and Aim: Biotic and abiotic factors contribute in shaping the distribution through the soil profile of elements released by mineral weathering; among them, leaching and biocycling dominate in temperate environments. We evaluated if the intensity of leaching and biocycling of nutrients can be modulated by element deficiencies linked to the abundance of serpentine in the soil parent material, i.e. if the most deficient elements are more efficiently retained. Methods: We selected twelve poorly developed soils from Northern Italian beech stands, with variable amounts of serpentinites in the parent material, and determined total and exchangeable Ca, Mg and K, as well as an index of abundance of serpentine minerals. Results: The total element content depended on the abundance of serpentines, while only exchangeable Mg was related to the parent material. The vertical trend of Ca and K indicated the role of biocycling in all soils, but the relative availability of Ca (ratio between exchangeable and total content) was much higher in the top horizons of serpentine-rich soils. Conclusions: The different element availability among soils suggested that the vertical distribution of available elements was linked to the parent material and that losses were limited in serpentine-rich soils, probably because plants take up the deficient elements as soon as they are released from litter and thus limit their leaching in deeper soil horizons.