Effects of maquis clearing on the properties of the soil and on the near-surface hydrological processes in a semi-arid Mediterranean environment

Mediterranean environment have been cleared in recent decades. There is little information on what effect this has on the hydrology of the soil. We compared the hydraulic properties of the soil and the subsurface hydrological dynamics on two adjacent sites on a hillslope. One site was covered with maquis, the other with grass. The grass started to grow some 10 years ago, after the maquis had been cleared and the soil had been ploughed. Our study found that the hydraulic properties and the hydrological dynamics of the maquis and the grassed soil differed greatly. The grassed soil had less organic matter and higher apparent density than did the soil covered in maquis. Moreover, the maquis soil retained more water than the grassed soil in the tension range from saturation to 50 cm of water. Infiltration tests performed in summer and in winter indicated that the field saturated hydraulic conductivity (Kfs) of the maquis soil was higher than that of the grassy soil. However the data showed that the Kfs of the two soils changed with the season. In the maquis soil the Kfs increased from summer to winter. This was assumed to be due to water flowing more efficiently through wet soil. By contrast, in the grassy soil the Kfs decreased from summer to winter. This was because the desiccation cracks closed in the wet soil. As result, the influence of the land use change was clear from the Kfs measurements in winter, but less so from those in the summer. Changes in land use altered the dynamics of the infiltration, subsurface drainage and soil water storage of the soil The maquis soil profile never saturated completely, and only short-lived, event based perched water tables were observed. By contrast, soil saturation and a shallow water table were observed in the grass covered site throughout the wet season. The differences were assumed to be due to the high canopy interception of the maquis cover, and to the macropores in the grassed soil being destroyed after the maquis had been cleared and the soil ploughed. The results of this work are helpful for predicting the changes in the hydraulic properties of the soil and in the near-surface hydrological processes in similar Mediterranean environments where the natural vegetation has been cleared. These changes must be taken into consideration when developing rainfall-runoff models for flood forecasting and water yield evaluation.</br

Temporal variability of physical quality of a sandy loam soil amended with compost

Compost can enhance the soil's ability to retain water, resulting in an overall improvement of soil physical quality (SPQ). The purpose of this study was to evaluate the temporal variability of physical and hydraulic properties of a sandy loam soil amended with a compost obtained from orange juice processing wastes and garden cleaning. The soil water retention curve of repacked soil samples at varying compost to soil ratios, r, was determined at the time of compost embedding (M0) and after six months (M6), and twelve months (M12). Indicators of SPQ linked to soil water retention curve such as air capacity (AC), macroporosity (Pmac), plant available water capacity (PAWC), relative field capacity (RFC) and Dexter S-index (S), were estimated. The effect of compost addiction of the pore volume distribution function was also evaluated. The elapsed time from compost application influenced all SPQ indicators but the maximum beneficial effects of compost amendment were achieved within approximately the first six months. Indicators linked the macro- and mesoporosity (Pmac and AC) decreased with r whereas indicators linked to plant water availability (PAWC and RFC) increased with r. The combined effect of time and rate was statistically observed only for Pmac, PAWC and S. Compost addiction reduced the soil compaction and modified the pore system, as the fraction of structural porosity (i.e., macropores) decreased and the fraction of textural porosity (i.e., micropores) increased. It was concluded that even a single application of compost could have a significant impact on soil water retention and microstructure with positive implications for soil health, precision agriculture and crop productivity

Influence of the pressure head sequence on the soil hydraulic conductivity determined with tension infiltrometer

An increasing and a decreasing sequence of pressure head, h0, values were applied with the tension infiltrometer (TI) to determine the corresponding hydraulic conductivity, K0. The pressure head sequence is expected to influence the K0 results given the hysteretic nature of the hydraulic conductivity relationship. The objective of this study was to evaluate the influence of the selected pressure head sequence on the hydraulic conductivity of a sandy loam soil measured by a multipotential TI experiment. Twenty experiments were carried out by applying h0 values varying between -150 and +5 mm (site A). The h0 values ranged from -150 to -10 mm in another 20 spots (site B). Both wetting and drying values of K0 corresponding to h0 = -150, -75, and -30 mm were calculated for each experiment using the measured steady-state flow rates. At both sites, higher K0 results were obtained with the descending h0 sequence than with the ascending one. The deviations between the two sequences were more noticeable in site A (deviations by a factor ranging from 2.1 to 3.3, depending on h0) than in site B (deviations by a factor ranging from 1.0 to 2.2), and the values decreased as h0 increased. For most of the considered type of site/pressure head combinations, the differences between the K0 results were statistically significant (P = 0.05). In all cases, the coefficients of variation of the K0 data obtained with the two sequences differed at most by a factor of 1.2, suggesting that the applied h0 sequence did not affect appreciably the relative variability of the K0 results. It was concluded that the dependence of the K0 estimates on both the pressure head sequence (ascending or descending) and the highest value of h0 used within a descending sequence experiment may be neglected for a rough hydraulic characterization of the selected area. However, both factors should be maintained constant in order to obtain truly comparable K0 data from different experiments

Runoff generation processes in a Mediterranean research catchment (Sardinia)

In recent decades the hydrological community has increasingly improved its understanding of the runoff generation in river basins. Since Horton (1933), numerous studies have investigated these mechanisms at the plot, hillslope and catchment scale (e.g.: Betson, 1964; Dunne and Black, 1970; Pilgrim et al., 1978; Kirkby, 1978; Mosley, 1979; Beven, 1989; Anderson and Burt, 1991). The primary processes that have been observed and described to explain runoff generation in a catchment area are: (1) Hortonian Overland Flow (HOF), which occurs when rainfall intensity exceeds the infiltration capacity of the soil; (2) Saturation Overland Flow (SOF), which occurs when the storage capacity of the soil is exceeded and defines the concept of contributing saturated areas, which expand as rainfall volume increases; Saturated Subsurface Flow (SSF), which occurs when the water in the soil flows along lateral paths and thus contributes to streamflow as return flow from the groundwater aquifer.</br

Comparing physical quality of tilled and no-tilled soils in an almond orchard in southern Italy

No-tillage (NT) is an alternative way of reducing costs and lessening the burden of working the land, but in essence it is a method of sustainable land use in dryland cropping systems. The physical quality of the soil is the fundamental factor that defines the sustainability of agro-ecosystems, and its evaluation can be obtained using both capacitive and dynamic indicators. The main objectives of this study were: i) to assess the physical quality of the soil in an almond orchard where long-term different soil tillage systems and weed control methods, such as NT with chemical control and surface tillage (ST), were used; and ii) to compare the indicators under consideration with the proposed reference values, using the information gathered to evaluate the effects of NT and ST. The following physical properties were determined: bulk density, air capacity, macroporosity, plant available water capacity, relative field capacity, Dexter's index, field saturated hydraulic conductivity, as well as the location (modal, median, and mean pore diameter) and shape (standard deviation, skewness, and kurtosis) parameters which corresponded to the equivalent pore size distribution functions. Our results showed that the physical soil indicators adopted were sufficiently sensitive to identify tillage-induced changes and then to quantify the physical quality of rigid to moderately expansive agricultural soils. After thirty years of NT, a set of capacitive indicators, along with measurements of hydraulic conductivity, used in conjunction with an optimal pore volume distribution and the water release curve, unanimously classified the quality of the studied soil as optimal or near optimal

Application of EMI and FDR sensors to assess the fraction of transpirable soil water over an olive grove

Accurate soil water status measurements across spatial and temporal scales are still a challenging task, specifically at intermediate spatial (0.1-10 ha) and temporal (minutes to days) scales. Consequently, a gap in knowledge limits our understanding of the reliability of the spatial measurements and its practical applicability in agricultural water management. This paper compares the cumulative EM38 (Geonics Ltd., Mississauga, ON, Canada) response collected by placing the sensor above ground with the corresponding soil water content obtained by integrating the values measured with an FDR (frequency domain reflectometry) sensor. In two field areas, characterized by different soil clay content, two Diviner 2000 access tubes (1.2 m) were installed and used to quantify the dimensionless fraction of transpirable soil water (FTSW). After the calibration, the work proposes the combined use of the FDR and electromagnetic induction (EMI) sensors to measure and map FTSW. A strong correlation (R2= 0.86) between FTSW and EM38 bulk electrical conductivity was found. As a result, field changes of FTSW are due to the variability of soil water content and soil texture. As with the data acquired in the field, more structured patterns occurred after a wetting event, indicating the presence of subsurface flow or root water uptake paths. After assessing the relationship between the soil and crop water status, the FTSW domain includes a critical value, estimated around 0.38, below which a strong reduction of relative transpiration can be recognized

Subsurface flow and large-scale lateral saturated soil hydraulic conductivity in a Mediterranean hillslope with contrasting land uses

The lateral saturated hydraulic conductivity, Ks,l, is the soil property that mostly governs subsurface flow in hillslopes. Determinations of Ks,lat the hillslope scale are expected to yield valuable information for interpreting and modeling hydrological processes since soil heterogeneities are functionally averaged in this case. However, these data are rare since the experiments are quite difficult and costly. In this investigation, that was carried out in Sardinia (Italy), large-scale determinations of Ks,lwere done in two adjacent hillslopes covered by a Mediterranean maquis and grass, respectively, with the following objectives: i) to evaluate the effect of land use change on Ks,l, and ii) to compare estimates of Ks,lobtained under natural and artificial rainfall conditions. Higher Ks,lvalues were obtained under the maquis than in the grassed soil since the soil macropore network was better connected in the maquis soil. The lateral conductivity increased sharply close to the soil surface. The sharp increase of Ks,lstarted at a larger depth for the maquis soil than the grassed one. The Ks,lvalues estimated during artificial rainfall experiments agreed with those obtained during the natural rainfall periods. For the grassed site, it was possible to detect a stabilization of Ks,lin the upper soil layer, suggesting that flow transport capacity of the soil pore system did not increase indefinitely. This study highlighted the importance of the experimental determination of Ks,lat the hillslope scale for subsurface modeling, and also as a benchmark for developing appropriate sampling methodologies based on near-point estimation of Ks,l

Cover Crop for a Sustainable Viticulture: Effects on Soil Properties and Table Grape Production

Cover crops are increasingly adopted in viticulture to enhance soil quality and balance the vegetative and reproductive growth of vines. Nevertheless, this sustainable practice has been only recently used for table grape viticulture, with results often contrasting. The aim of this study was to assess the effect of a fescue (Festucaarundinacea Schreb.) cover crop on soil quality, yield, and grape qualitative parameters in a table grape vineyard (cv "Italia") located in southern Italy, comparing results with the conventional tillage. Soil organic carbon (C), total nitrogen (N), microbial biomass C (MBC), β-glucosidase (BGLU) and alkaline phosphomonoesterase (APME) activities were assessed during three growing seasons (2012–2014) and three phenological stages. The trend of soil chemical and microbiological properties was jointly influenced by the soil management system, growing season and phenological stage. Compared to conventional tillage, cover crops increased, on average, soil organic C, total N, MBC, BGLU and APME by 136%, 93%, 112%, 100% and 62%, respectively. Slight or no effects of cover crops were observed on grape quality and yield, except for 2012 (the driest season), when a yield reduction occurred. This study reveals that cover crops strongly enhance soil quality in the short-term, with potential advantages for grape production in the long-term

Open questions and research needs in the adoption of conservation agriculture in the mediterranean area

This article aims to provide a review of major challenges and research needs for the diffusion of conservation agriculture (CA) and the improvement of crop–soil–water conditions in Southern Europe and Northern Africa. A multidisciplinary study and a participatory approach are at the basis of an international project of research and innovation action, “Research-based participatory approaches for adopting conservation agriculture in the Mediterranean Area-CAMA”. It aims to understand the reasons and the research needs that limit a large CA diffusion in the Mediterranean countries. CAMA aims to provide significant advances to CA through multidisciplinary research at the field and farm scales (with main emphasis on smallholder), encompassing a socio-economic analysis of the reasons that obstacle the CA diffusion, legume crop improvement as a component of improved CA cropping systems, and a network of long-term experiments on CA and soil characteristic modification. Its results will be available to scientific and farming communities.This research received the financial funding by PRIMA (Grant Agreement n. 1912), a programme supported by the European Union, research project “Research-based participatory approaches for adopting Conservation Agriculture in the Mediterranean Area – CAMA”, coord. Dott. Michele Rinaldi. Special thanks to Fabrice Dentressangle, CAMA Project Officer and to “Italian PRIMA Secretariate” office

The small satellite NINA-MITA to study galactic and solar cosmic rays in low-altitude polar orbit

Abstract The satellite MITA, carrying on board the scientific payload NINA-2, was launched on July the 15th, 2000 from the cosmodrome of Plesetsk (Russia) with a Cosmos-3M rocket. The satellite and the payload are currently operating within nominal parameters. NINA-2 is the first scientific payload for the technological flight of the Italian small satellite MITA. The detector used in this mission is identical to the one already flying on the Russian satellite Resurs-O1 n.4 in a 840-km sun-synchronous orbit, but makes use of the extensive computer and telemetry capabilities of MITA bus to improve the active data acquisition time. NINA physics objectives are to study cosmic nuclei from hydrogen to iron in the energy range between 10 MeV/n and 1 GeV/n during the years 2000–2003, that is the solar maximum period. The device is capable of charge identification up to iron with isotope sensitivity up to oxigen. The 87.3 degrees, 460 km altitude polar orbit allows investigations of cosmic rays of solar and galactic origin, so to study long and short term solar transient phenomena, and the study of the trapped radiation at higher geomagnetic cutoff