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The Intergovernmental Panel on Climate Change (IPCC) approach is widely used to estimate the C account through the use of standardized coefficients that are not site specific. For these reasons, the aim of the work was to define specific IPCC coefficient taking into account differences in pedological characteristics that affect soil C steady state. In a vineyard area of Sicily, the effectiveness of 5years of recommended management practice (RMP) adoption on soil organic carbon (SOC) stock increases was evaluated by considering 100 paired sites distributed over four functional soil groups. Each site consisted of two neighbouring plots. The soil of one plot was managed with cover crops according to RMP, and the other plot was managed with conventional tillage practices. IPCC coefficients were also derived and specifically adjusted for semiarid environments. SOC changes following RMP adoption and SOC steady-state levels were correlated with functional soil groupings. SOC increased from 24.8 to 28.3tha−1 in conventional and RMP vineyards, respectively, with the highest increases being observed in vertic and the lowest in calcic soils. The management factor (Fmg) ranged from 1.11 for calcaric to 1.44 for vertic functional soil groups. C maintenance requirement (C input) should be estimated in relation to soil functional groups. Findings of this study highlighted how the fine tuning of C steady state in relation to specific environmental characteristics is necessary to avoid overestimation of soil C sequestration. Awareness of correct soil C sequestration potential is useful for policymakers and stakeholders for future C account and land degradation control planning.

No tillage (NT) soil management has been considered a strategy for the implementation of environmental sustainability and a possible tool of soil organic carbon (SOC) sequestration. Considering the wide range of data on SOC change after NT application in relation to conventional tillage (CT) in different studies, further researches are needed over a diverse range of soil and climate before a proper estimation of the benefits can be provided by the NT. A data set composed of cereal cropping system studies, comparing the SOC content under CT and NT was compiled from the literature using the scientific repositories “Scopus” and “Science direct”. This aims to i) discriminate and quantify the variation of SOC in relation to morphology (Flat area (FA) and Slope Area (SA)) and climates (Aridity index (Ai)); ii) provide a reliable forecast of C sequestration by NT in a specific environment. The results from collected datasets showed that SOC ratio between NT and CT was higher in sloping than flat areas and was also in correlation with the Ai. The average annual increase of SOC in NT in comparison to CT was 0.32 Mg ha−1y−1 and 0.21 Mg ha−1y−1 for SA and FA, respectively. The regression of the relative ratio (RRNT/CT) against Ai both for FA and SA showed a high statistical significance for FA. For SA the lack of significance is due to no response of the dependent variables to Ai changes and to the prevalent effect that NT has on the soil C erosion processes. These results highlighted that in SA, the SOC sequestration by NT is overestimated. These results provide concrete examples of the importance to discriminate soil morphology and climate when recommending NT soil management for soil C sequestration in order to individuate areas where NT can maximize its potentiality as a mitigation tool.

The aim of this study is to develop a framework for the evaluation of no-till (NT) yield success probability as a decision tool for farmers or decision makers. The effect of soil management on durum wheat yield has been tested on many long-term field experiments. Results of these researches were collected in a unique dataset to evaluate the success of NT management in comparison to conventional tillage (CT) as influenced by the aridity index, crop residue management and cropping system. A total of 519 observations of long-term experiments (>3years) regarding durum wheat in a number of areas with semi arid climate were included in the present study. The relative ratio of yield under NT and CT was correlated to the aridity index (Ai) for different cropping systems and residue management strategies. No-till performed better with lower values of the Ai. When NT and CT yields were the same, the Ai value was defined as the Ai threshold, and this value resulted as being strongly dependent upon crop management. The developed framework, in any given site, allows us (i) to know the threshold for different managements tecniques, (ii) to estimate the probability of success in adopting NT and CT soil management techniques; (iii) to predict the best management with reference to Ai variation.

The aim of this study was to investigate the effect of soil volume restriction, i.e. root confinement, on below-and-above ground growth of cactus pear (Opuntia ficus-indica (L.) Mill) as well as the effect on root architecture and turnover, and soil carbon turnover. In May 2014, 1- year-old cladodes were planted in five different pots size (50, 33, 18, 9 and 5 L). Soil samples were collected from each pot and dried before SOC and δ13C determination. Roots of each plant were divided visually into three groups depending on their diameter, and then measured and weighed. Results indicated a significant effect of soil volume and sampling dates on total root length, root dry mass and δ13C. Our data showed a linear positive and significant effect of the soil volume on the large and fine roots mass, during the four sampling dates. Roots of the plants placed in the smallest soil volume had higher C root turnover (% per year) and Soil Organic Carbon (SOC) showed a significant increase in relation to sampling dates (6, 12, 18 and 24 months). Our research showed that the significant effect of the interaction between sampling date and soil volume (pot size) clearly indicates how soil availability is relevant SOC contribution. Based on the new findings of our study, cactus pear could enhance accumulation of SOC in soils.

Sustainability in orchard crops is an important goal for farmers, decision-makers and consumers. The United Nations Sustainable Development Goals emphasize the importance of the soils in the Earth System to achieve sustainability and accomplish the Land Degradation Neutrality Challenge. Within the world agriculture land, olive and vineyards are within the eldest crops in the world, and they are also the ones with the highest degree of soil degradation. Cover crops (CC) are widely accepted as sustainable crop management that reduces soil and water losses, restores organic matter, increases biodiversity and fertility in degraded agriculture soils. The agriculture land must shift into a more sustainable agricultural practices for achieving soil and water conservation targets, and CC are of help, but not widely applied by farmers that usually expect subsidies. Runoff and soil water storage are two key processes that determine the crop production, plant health and sustainability. However, after four decades of use, there is not a consistent State-of-the-Art that clarifies the impact of service crops. Our review highlights, in quantitative terms, the role of CC exerted in vineyard and olive grove in runoff reduction and soil water status. Statistical differences were found between the average values of RC (7.37 % and 10.05 % for CC and conventional tillage (CT) management, respectively). For the soil water conservation, the ratio SWCCT/SWCCC is always higher than 1. Water competition was more pronounced in spring and decreased after blooming. The use of CC is a strategy can have a positive influence on water use efficiency, through the reduction of the excessive vine vigour in fertile soils or favouring the growth of roots in deeper layers. In low vigour vineyards, low fertile soils and in dry environment, the water competition should be correctly monitored to avoid negative effect in grape yields. Cover crops are a positive contribution to the agriculture sustainability, although Mediterranean ecosystems, where most of the olive oil and wine is produced should pay attention to their impact on water availability

Climate, soil physical–chemical characteristics, land management, and carbon (C) input from crop residues greatly affect soil organic carbon (SOC) sequestration. According to the concept of SOC saturation, the ability of SOC to increase with C input decreases as SOC increases and approaches a SOC saturation level. In a 12-year experiment, six semi-arid cropping systems characterized by different rates of C input to soil were compared for ability to sequester SOC, SOC saturation level, and the time necessary to reach the SOC saturation level. SOC stocks, soil aggregate sizes, and C inputs were measured in durum wheat monocropping with (Ws) and without (W) return of aboveground residue to the soil and in the following cropping systems without return of aboveground residue to soil: durum wheat/fallow (Wfall), durum wheat/berseem clover, durum wheat/barley/faba bean, and durum wheat/Hedysarum coronarium. The C sequestration rate and SOC content were lowest in Wfall plots but did not differ among the other cropping systems. The C sequestration rate ranged from 0.47 Mg C ha−1 y−1 in Ws plots to 0.66 Mg C ha−1 y−1 in W plots but was negative (−0.06 Mg C ha−1 y−1) in Wfall plots. Increases in SOC were related to C input up to a SOC saturation value; over this value, further C inputs did not lead to SOC increase. Across all cropping systems, the C saturation value for the experimental soil was 57.7 Mg ha−1, which was reached with a cumulative C input of 15 Mg ha−1. Copyright © 2015 John Wiley & Sons, Ltd.

Evaluating the economic damage caused by soil erosion is important. In addition to increasing the awareness of the problem among farmers and policy makers, evaluation of the economic damage caused by erosion can promote the implementation of more sustainable soil management practices. In the present study, we describe a new approach to evaluate incentives for the adoption of agri-environment measure (AEM) in degraded and eroded vineyards. To estimate this incentive, the replacement cost (RC) and the loss of income are calculated when the vineyard is managed with conventional tillage versus a cover crop (AEM). Our findings show that the incentive could range from the loss of income due to AEM adoption to the ecosystem service benefit (RCC − RCAEM). In our case study, the incentive ranged from 315 € ha−1 (loss of income) to 1,088 € ha−1 (ecosystem service benefit). Within this range, the incentive amount is determined according to efficiency criteria based on vineyard slope. We also present a conceptual model of public spending efficiency that should help policy makers decide how to allocate the incentives so as to maximize the economic return associated with ecosystem services. Copyright © 2015 John Wiley & Sons, Ltd.

In a dryland Mediterranean agrosystem (Sicily, Italy) a comparative study was carried out among two crop systems (wheat/wheat and wheat/bean) after 19 years under three most used tillage managements (conventional, dual layer and no-tillage), in order to ascertain the effects of those experimental factors, single and combined, on various soil organic C pools (total and extractable organic C, microbial biomass C, basal respiration). Field CO 2 fluxes from soil, throughout a year, were also determined. Moreover, C input and output were assessed, as well as microbial and metabolic quotients. Tillage management more than cropping system affected the soil organic C stored in the first 15 cm of soil. After 19 years, no-tillage caused a 3.6 Mg ha −1 increase of C content in wheat/faba rotation while of 5.6 Mg ha −1 in wheat monoculture. The higher soil total organic C content in wheat monoculture was ascribed to a lower quality of residues supplied (higher both C/N ratio and acid detergent fibre (ADF) content). Moreover, wheat/bean rotation increased soil microbial biomass C, basal respiration and microbial quotient, thus suggesting that crop rotation more than tillage management was the driving factor in improving soil biochemical indicators.

In the field of conservative agriculture, no-till (NT) management has been receiving increasing interest, with 45 million ha of land under no-till management in 1999 to 155 million ha in 2014. Up until now, no-till has only been observed to perform better under rainfed conditions, especially in dry climates mainly because the reduced tillage system retains more soil moisture. However, the adoption of alternative agricultural practices (NT) can be improved only if uncertain and consequent assumption of risk is well known and accepted. For these reasons, the aim of this research is (i) to define durum wheat suitability under NT soil management in terms of yield success probability and (ii) to determine the suitable area for NT wheat cultivation within three climatic periods (the past, present, and future). The probability distribution of the aridity index (AI) was used to derive the non-exceedance conditional probability of NT yield success in comparison to conventional tillage (CT) on arable land in the Sicilian Region (southern Italy). The probability of NT management resulting in a higher yield than CT management for each specific environment was predicted. The latter made it possible to determine the probability of a higher yield under NT practice in comparison to CT, considering both the environment (aridity index) and different management practices (cropping system and residue management). An analysis of the relationship between the crop yield and the AI showed that the probability of NT success in durum wheat yield is affected by cropping systems and residue management and that Sicilian climatic trends will determine an increase in the areas suitable for NT durum wheat management. The uncertainty quantification or the success yield probability of NT could be used to target incentives for NT durum wheat cultivation in areas (within a region) where the mean yield and non-exceedance probability are low.

The aim of this work was to investigate the effect of an experimental fire used for grassland management on soil organic carbon (SOC) stocks. The study was carried out on Hyparrhenia hirta (L.) Stapf (Hh) grassland and Ampelodesmos mauritanicus (Desf.) T. Durand & Schinz (Am) grasslands located in the north of Sicily. Soil samples were collected at 0–5 cm before and after the experimental fire, and SOC was measured. During the grassland fire, soil surface temperature was monitored. Biomass of both grasses was analysed in order to determine dry weight and its chemical composition. The results showed that SOC varied significantly with vegetation type, while it is not affected in the short term by grassland fire. Am grassland stored more SOC compared with Hh grassland thanks to lower content in the biomass of the labile carbon pool. No significant difference was observed in SOC before and after fire, which could be caused by several factors: first, in both grassland types the measured soil temperature during fire was low due to thin litter layers; second, in a semiarid environment, a higher mineralization rate results in a lower soil carbon labile pool; and third, the SOC stored in the finest soil fractions, physically protected, is not affected by fire.

When soil nitrate levels are low, plants suffer nitrogen (N) deficiency but when the levels are excessive, soil nitrates can pollute surface and subsurface waters. Strategies to reduce the nitrate pollution are necessary to reach a sustainable use of resources such as soil, water and plant. Buffer strips and cover crops can contribute to the management of soil nitrates, but little is known of their effectiveness in semiarid vineyards plantations. The research was carried out in the south coast of Sicily (Italy) to evaluate nitrate trends in a vineyard managed both conventionally and using two different cover crops (Triticum durum and Vicia sativa cover crop). A 10 m-wide buffer strip was seeded with Lolium perenne at the bottom of the vineyard. Soil nitrate was measured monthly and nitrate movement was monitored by application of a 15N tracer to a narrow strip between the bottom of vineyard and the buffer and non-buffer strips. Lolium perenne biomass yield in the buffer strips and its isotopic nitrogen content were monitored. Vicia sativa cover crop management contributed with an excess of nitrogen, and the soil management determined the nitrogen content at the buffer areas. A 6 m buffer strip reduced the nitrate by 42% with and by 46% with a 9 m buffer strip. Thanks to catch crops, farmers can manage the N content and its distribution into the soil over the year, can reduced fertilizer wastage and reduce N pollution of surface and groundwater. © 2013 Author(s).

Summary Soil organic matter (SOM) is an important factor in ecosystem stability and productivity. This is especially the case for Mediterranean soils suffering from the impact of human degradation as well as harsh climatic conditions. We used the carbon (C) exchange resulting from C3-C4 and C4-C3 vegetation change under field conditions combined with incubations under controlled conditions to evaluate the turnover and availability of soil organic C under different land-uses. The 40-year succession of Hyparrenia hirta L. (C4 photosynthesis) after more than 85 years of olive tree (Olea europaea L.; C3 photosynthesis) growth led to the exchange of 54% of soil organic C from C3 to C4 forms. In contrast, 21 years of vine (Vitis vinifera L.) growing after H. hirta decreased the organic C content to 57%. Considering this exchange and decrease as well as the periods after the land-use changes, we calculated the mean residence time (MRT) of soil C of different ages. The MRT of C under grassland dominated by H. hirta was about 19 years, but was 180 years under the vineyard. The rates of C accumulation under the H. hirta grassland were about 0.36 Mg C ha −1 year −1 . In contrast, the rates of C losses after conversion from natural grassland to a vineyard were 1.8 times greater and amounted to 0.65 Mg C ha −1 year −1 . We conclude that changes of land use from natural Mediterranean grassland to a vineyard lead to very large C losses that cannot be compensated for over the same periods.

Previous studies have documented that, relative to conventional tillage (CT), alternative soil management (reduced tillage, mulching, or cover crops) decreases soil erosion and increases soil organic matter (SOM) in vineyards. These previous studies, however, failed to consider the loss of soil organic carbon (SOC) with erosion that could occur with the adoption of agro-environmental measures (AEM) in a semiarid environment. Accordingly, the aims of this study were to determine whether changes in SOC content under AEM management are always positive and to develop a conceptual model for estimating the “SOC threshold”. The SOC threshold was defined as that level of SOC in an AEM-managed vineyard above which erosion will result in greater loss of C than occur in a comparable vineyard with CT management. SOC was analyzed at a 100 paired sites (vineyards with AEM management vs. CT). The results showed that in some cases the loss of C was higher with AEM than with CT. Overall, the results indicate that the SOC threshold may be a key parameter in determining the best AEM measures for vineyards that are on slopes and therefore vulnerable to erosion.

Background and aims: Carpobrotus spp. are amongst the most impactful and widespread plant invaders of Mediterranean habitats. Despite the negative ecological impacts on soil and vegetation that have been documented, information is still limited about the effect by Carpobrotus on soil microbial communities. We aimed to assess the changes in the floristic, soil and microbial parameters following the invasion by Carpobrotus cfr. acinaciformis within an insular Mediterranean ecosystem. Methods: Within three study areas a paired-site approach, comparing an invaded vs. a non-invaded plot, was established. Within each plot biodiversity indexes, C and N soil content, pH and microbial biomass and structure (bacterial and fungal) were assessed. Results: Invaded plots showed a decrease of ?-species richness and diversity. The least represented plant species in invaded plots were those related to grassland habitats. In all invaded soils, a significant increase of carbon and nitrogen content and a significant decrease of pH were registered. Carpobrotus significantly increased bacterial and fungal biomass and altered soil microbial structure, particularly favoring fungal growth. Conclusions: Carpobrotus may deeply impact edaphic properties and microbial communities and, in turn, these strong modifications probably increase its invasive potential and its ability to overcome native species, by preventing their natural regeneration.

Soils release more carbon, primarily as carbon dioxide (CO2), per annum than current global anthropogenic emissions. Soils emit CO2 through mineralization and decomposition of organic matter and respiration of roots and soil organisms. Given this, the evaluation of the effects of abiotic factors on microbial activity is of major importance when considering the mitigation of greenhouse gases emissions. Previous studies demonstrate that soil CO2 emission is significantly affected by temperature and soil water content. A limited number of studies have illustrated the importance of bulk density and soil surface characteristics as a result of exposure to rain on CO2 emission, however, none examine their relative importance. Therefore, this study investigated the effects of soil compaction and exposure of the soil surface to rainfall and their interaction on CO2 release. We conducted a factorial laboratory experiment with three soil types after sieving (clay, silt and sand soil), three different bulk densities (1.1?g cm3, 1.3?g cm3, 1.5?g cm3) and three different exposures to rainfall (no rain, 30 minutes and 90 minutes of rainfall). The results demonstrated CO2 release varied significantly with bulk density, exposure to rain and time. The relationship between rain exposure and CO2 is positive: CO2 emission was 53% and 42% greater for the 90 minutes and 30 minutes rainfall exposure, respectively, compared to those not exposed to rain. Bulk density exhibited a negative relationship with CO2 emission: soil compacted to a bulk density of 1.1?g cm3 emitted 32% more CO2 than soil compacted to 1.5?g cm3. Furthermore we found that the magnitude of CO2 effluxes depended on the interaction of these two abiotic factors. Given these results, understanding the influence of soil compaction and raindrop impact on CO2 emission could lead to modified soil management practices which promote carbon sequestration. Copyright (C) 2012 John Wiley & Sons, Ltd.

Understanding soil water erosion processes is essential to evaluate the redistribution of soil organic carbon (SOC) within a landscape and is fundamental to assess the role of soil erosion in the global carbon (C) budget. The main aim of this study was to estimate the C redistribution and losses using (13)C natural abundance. Carbon losses in soil sediment, dissolved organic carbon (DOC) and CO2 emission were determined. Four bounded parallel plots were installed on a 10% slope. In the upper part of the plots, C3soil was replaced with C4soil. The SOC and δ(13)C were measured after 145.2mm rainfall in the upper (2m far from C4strip), middle (4m far from C4strip) lower (6m far from C4strip) trams of the plot and in the sediments collected in the Gerlach collector at the lower part of the plot. A laboratory incubation experiment was performed to evaluate the CO2 emission rate of soils in each area. OC was mainly lost in the sediments as 2.08g(-)(2) of C was lost after 145.2mm rainfall. DOC losses were only 5.61% of off-site OC loss. Three months after the beginning of the experiment, 15.90% of SOC in the upper tram of the plot had a C4 origin. The C4-SOC content decreased along the 6m length of the plot, and in the sediments collected by the Gerlach collector. CO2 emission rate was high in the upper plot tram due to the high SOC content. The discrimination of CO2 in C3 and C4 portion permitted to increase our level of understanding on the stability of SOC and its resilience to decomposition. The transport of sediments along the plot increased SOC mineralization by 43%. Our study underlined the impact of rainfall in C losses in soil and water in abandoned Mediterranean agriculture fields and the consequent implications on the C balance.

The mechanisms of litter decomposition, translocation and stabilization into soil layers are fundamental processes in the functioning of the ecosystem, as they regulate the cycle of soil organic matter (SOM) and CO2 emission into the atmosphere. In this study the contribution of litters of different stages of Mediterranean secondary succession on carbon sequestration was investigated, analyzing the role of earthworms in the translocation of SOM into the soil profile. For this purpose the δ13C difference between meadow C4-C soil and C3-C litter was used in a field experiment. Four undisturbed litters of different stages of succession (45, 70, 100 and 120 since agriculture abandon) were collected and placed on the top of isolated C4 soil cores. The litter contribution to C stock was affected by plant species and it increased with the age of the stage of secondary succession. One year after the litter position, the soil organic carbon increased up to 40% in comparison to soils not treated with litter after 120 years of abandon. The new carbon derived from C3 litter was decomposed and transferred into soil profile thanks to earthworms and the leaching of dissolved organic carbon. After 1 year the carbon increase attributed to earthworm activity was 6 and 13% in the soils under litter of fields abandoned for 120 and 45 years, respectively.

Abandonment of agricultural land and the subsequent recolonization by natural vegetation is known to cause increases in C contents, contributing to reduction in atmospheric CO2 concentrations. Assessment of the possible mitigation of CO2 excess requires understanding the SOC dynamics, the origin of C pools and the pathways of their transformation. The aims of this work were to assess, by using the δ13C signature, the changes of old and new organic C in total (soil organic carbon, SOC) and labile (microbial biomass C, MBC, dissolved organic C, DOC, CO2 efflux from soil) pools after vegetation change from vineyard (C3) to grassland (C4) under semiarid Mediterranean climate. Colonization of abandoned vineyard by the perennial C4-grass Hyparrhenia hirta after 15 or 35 years increased topsoil C stocks by 13% and 16%, respectively. Such an increase was attributed to new above- and below-ground biomass C input from H. hirta. The maximal incorporation of new C was observed in MBC, whereas the DOC derived mainly from old SOC. Based on d13C values of SOC, MBC, DOC and CO2 in C3 soil and in soils after 15 and 35 years of C4 grass colonization, 13C fractionation per se from changes in isotopic composition by preferential utilization of substrateswith different availability was separated. MBC in C3-C4 soil used more recent (13C-enriched) versus old C (relatively 13C-depleted) sources. The δ13C by decomposition of SOC to CO2 (δ13C of CO2 minus d13C of SOC) was higher than δ13C by microbial respiration (CO2 minus MBC), demonstrating that under semiarid climate, soil microorganisms do not always preferentially decompose themost available SOC pools. The use of δ13C signature of SOC after C3-C4 vegetation change combinedwith soil incubation is a powerful tool to assess the exchange between old and new C in pools of various availability. © 2014 Elsevier B.V.

Clarifying which factors cause an increase or decrease in soil organic carbon (SOC) after agricultural abandonment requires integration of data on the temporal dynamics of the plant community and SOC. A chronosequence of abandoned vineyards was studied on a volcanic island (Pantelleria, Italy). Vegetation in the abandoned fields was initially dominated by annual and perennial herbs, then by Hyparrhenia hirta (L.) Stapf, and finally by woody communities. As a consequence, the dominant photosynthetic pathway changed from C3 to C4 and then back to C3. Conversion of a plant community dominated by one photosynthetic pathway to another changes the 13C/12C ratio of inputs to SOC. Using the time since abandonment and the shift in belowground δ13C of SOC relative to the aboveground δ13C plant community, we estimated C3-C and C4-C changes during secondary succession. SOC content (g kg− 1) increased linearly (R2 = 0.89 and 0.73 for 0–15 and 15–30 cm soil depth) with the age of abandonment, increasing from 12 g kg− 1 in cultivated vineyards to as high as 26 g kg− 1 in the last stage of the succession. δ13C increased in the bulk soil and its three aggregate fractions (> 250, 250–25, and < 25 μm) during succession, but the effect of soil depth and its interaction with succession age were significant only for soil aggregate fractions. Polynomial curves described the change in δ13C over the chronosequence for both depths. δ13C in the bulk soil had increased from − 28‰ to − 24‰ by 35 years after abandonment for both depths but then decreased to − 26‰ at 60 years after abandonment (corresponding with maturity of the woody plant community). Overall, the results indicate that abandoned vineyards on volcanic soil in a semi-arid environment are C sinks and that C storage in these soils is closely related to plant succession.

Carpobrotus spp. are amongst the most impactful and widespread plant invaders of Mediterranean habitats. Despite the negative ecological impacts on soil and vegetation that have been documented, information is still limited about the effect by Carpobrotus on soil microbial communities. We aimed to assess the changes in the floristic, soil and microbial parameters following the invasion by Carpobrotus cfr. acinaciformis within an insular Mediterranean ecosystem. Within three study areas a paired-site approach, comparing an invaded vs. a non-invaded plot, was established. Within each plot biodiversity indexes, C and N soil content, pH and microbial biomass and structure (bacterial and fungal) were assessed. Invaded plots showed a decrease of α-species richness and diversity. The least represented plant species in invaded plots were those related to grassland habitats. In all invaded soils, a significant increase of carbon and nitrogen content and a significant decrease of pH were registered. Carpobrotus significantly increased bacterial and fungal biomass and altered soil microbial structure, particularly favoring fungal growth. Carpobrotus may deeply impact edaphic properties and microbial communities and, in turn, these strong modifications probably increase its invasive potential and its ability to overcome native species, by preventing their natural regeneration.

Mediterranean crops favour high erosion rates. Vineyards use to reach the highest soil and water losses due to the lack of vegetation cover. A topographical approach by means of the use of vineyards poles as fixed reference point as erosion markers allowed to quantify high and non-sustainable soil erosion rates on the Sicilian vineyards during 9 years. In order to develop strategies to control the soil losses, seven land management were selected and applied in a typical blanc wine grape vineyard located in southwestern Sicily. Comparable plots were managed traditionally using conventional tillage and alternatively using various cover crops: 1) Vicia faba; 2) Vicia faba and Vicia sativa; 3) Trifolium subterraneum, Festuca rubra, and Lolium perenne; 4) Trifolium subterraneum, Festuca rubra, and Festuca ovina; 5) Triticum durum; and 6) Triticum durum and Vicia sativa. To estimate the soil losses the C factor of the USLE was calculated. And to monitor the water and sediment yield, Gerlach troughs were installed on the vineyard inter-row. Runoff was measured after each rainfall event from November 2005 to April 2007. Both runoff and erosion were significantly reduced when cover crops of Trifolium subterraneum, Festuca rubra, and Lolium perenne; and Trifolium subterraneum, Festuca rubra, and Festuca ovina were sown. The least effective management systems for soil erosion were conventional tillage and alternative management using the Vicia faba cover crop. Our results suggest that planting the appropriate cover crops provides an effective soil and water management system for Sicilian vineyards which will make sustainable the wine and grapes production under Mediterranean climate conditions.

Soil organic matter (SOM) changes affect the CO2 atmospheric levels and is a key factor on soil fertility and soil erodibility. Fire affects ecosystems and the soil properties due to heating and post-fire soil erosion and degradation processes. In order to understand fire effects on soil organic carbon (SOC) balance research was undertaken on a fire-prone ecosystem: the Mediterranean maquia. The spatial distribution of SOC was measured in a Burnt site 6 months after a wildfire and in a Control site. Samples were collected at two different depths (0–3 and 3–10 cm) and SOC was determined. The results show that 41·8 per cent of the SOC stock was lost. This is due to the removal of the burnt material by surface wash. No significant differences in SOC content were found for the subsurface samples between burnt and control plots. Those results show that ashes and charcoal are transported by runoff downslope and are subsequently deposited in the valley bottom and this is the key process that contributes the burial of SOC after a forest fire. SOC redistribution by water erosion is accelerated after forest fires and contribute to the degradation of soils located at the upper part of the hillslopes but causes the enrichment with SOM of the soils located at the valley bottom. Buried SOC in the bottoms valley terraces will contribute to the sequestration of carbon for longer. Conservation of abandoned terraces is a key policy to avoid land degradation and climate change. Copyright © 2010 John Wiley & Sons Ltd.

A calcareous and clayey xeric Chromic Haploxerept of a long-term experimental site in Sicily (Italy) was sampled (0–15 cm depth) under different land use management and cropping systems (CSs) to study their effect on soil aggregate stability and organic carbon (SOC). The experimental site had three tillage managements (no till [NT], dual-layer [DL] and conventional tillage [CT]) and two CSs (durum wheat monocropping [W] and durum wheat/faba bean rotation [WB]). The annually sequestered SOC with W was 2·75-times higher than with WB. SOC concentrations were also higher. Both NT and CT management systems were the most effective in SOC sequestration whereas with DL system no C was sequestered. The differences in SOC concentrations between NT and CT were surprisingly small. Cumulative C input of all cropping and tillage systems and the annually sequestered SOC indicated that a steady state occurred at a sequestration rate of 7·4 Mg C ha−1 y−1. Independent of the CSs, most of the SOC was stored in the silt and clay fraction. This fraction had a high N content which is typical for organic matter interacting with minerals. Macroaggregates (>250 µm) and large microaggregates (75–250 µm) were influenced by the treatments whereas the finest fractions were not. DL reduced the SOC in macroaggregates while NT and CT gave rise to higher SOC contents. In Mediterranean areas with Vertisols, agricultural strategies aimed at increasing the SOC contents should probably consider enhancing the proportion of coarser soil fractions so that, in the short-term, organic C can be accumulated. Copyright © 2010 John Wiley & Sons, Ltd.