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[EN] Education must prepare students to find solutions for the global and local challenges of today and the future, by conferring students the knowledge, skills and attitudes to address them, including environmental degradation. Soils perform a number of key environmental, social and economic functions (e.g. production of food and biomass, nutrient cycling, water filter, climate control). Various Sustainable Development Goals (SDGs) are connected with soil. Sustainable soil use is crucial for many SDGs. Target 2.4 of SDG 2 (Zero Hunger) mentions the implementation of resilient agricultural practices to improve land and soil quality. Target 3.9 of the SDG 3 (Good Health and Wellbeing) indicates that the number of deaths and illnesses from soil pollution and contamination must be substantially reduced. Target 12.4 of SDG 12 (Responsible Consumption and Production) mentions reducing the release of chemicals to soil to minimize their adverse impacts on human health and the environment. Target 15.3 of SDG 15 (Life on Land) includes the restoration of degraded soil. Although soil is not mentioned in other SDG targets, it is related to other SDGs. We present the results of the analysis of the activity performed by the students related to soil and SDGs and the transversal competence ¿knowledge of contemporary problems¿. In the activity, the students were asked to write down with reasons the SDGs that soil is related to. Afterward, they were asked to write down soil degradation processes and their consequences for people lives and the environment. Next the students worked in groups on the link between soil functions and soil degradation processes using communication material designed by the Food and Agriculture Organization. Finally, they answered a questionnaire, and five open questions to explain the link between soil and the SDGs 2, 3, 6, 13 and 15. The students gave a value of 9.1 out of 10 to the importance of knowledge toward an integrated approach to the environment. The students rated the importance of studying Soil Science to increase their ability to perceive and realize the existence and uniqueness of soils with 8.7 out of 10. The need to raise awareness about soils among people who are not in direct contact with soils was rated with 9.2 out of 10. The students who knew that the SDGs have 169 targets were 85%. The students related the statement ¿Women remain a minority in soil science¿ to SDGs 5 (Gender Equality) and 10 (Reduced inequalities). Ninety-five percent of the students stated that "zero hunger" is not only a question of crop production, but it is also related to the quality of education, malnutrition, etc. All the students stated that there is now scientific evidence that healthy soils support nutritious and healthy food and, therefore, contribute to people's health. When students were asked about the origin of toxicity in the soil that can affect human health, 50% named heavy metals, 35% radioactive elements, 35% organic chemicals, and 15% diseases due to exposure to soil organisms. The students were asked if they knew that zinc deficiency is the fifth leading cause of death and disease in the developing world; only 52% said that they did. Soil science has important links to several SDGs and students must know them to advance in their achievement.

Due to restrictions on pesticide and nitrogen use in high-input European agricultural systems, many of the biostimulants used in horticulture are being incorporated into turfgrass management programs—although often with little understanding. A set of experiments was carried out on perennial ryegrass (Lolium perenne) cultivated in pots in a greenhouse in 2013 and 2014 to test the effect of three biostimulants: two composed of nitrifying bacteria (B1 and B2), and the other a mixture of amino acids, polysaccharides, nitrogen, and micronutrients (B3). Apart from the biostimulant treatment, nutritional stress was incorporated into the study to demonstrate if biostimulants could temporarily replace the fertilization role and so lessen the environmental impact. Turfgrass treated with B1 resulted in an increase in quality compared with untreated turf, and the positive effect lasted 2 and 3 months in 2013 and 2014, respectively. Additionally, an extended benefit was observed when the B1 interval application was longer, even temporarily replacing fertilization when applied on stressed turfgrass. The B2 produced similar results to B1, the effect was longer, and the turf exhibited a darker color—although it caused phytotoxicity at the tip of the leaves. The B3 led to a beneficial effect on turfgrass, especially under nutritional stress; it showed a better quality, darker green color, and more growth and yield than untreated turf (despite adding less nitrogen than during either mineral fertilizer treatment). Overall results show that the tested biostimulants increase turfgrass quality even when inducing a nutritional stress.

The Valencia Anchor Station (VAS) is an Earth Observation super site run by the University of Valencia, where a fair number of satellite remote sensing missions are validated. Within the framework of the Joint ESA-EUMETSAT “OLCI Land Validation (OLCI-Land-Val)” project, and of the Joint Research Center Ground-Based Observations for Validation (GBOV) of Copernicus Global Land Products, the Climatology from Satellites Group (GCS) has installed a total of 16 FAPAR (Fraction of Absorbed Photosynthetic Active Radiation) stations over a large vineyard area, where the GCS has carried out an extended number of field campaigns following the vine phenological cycle to validate the relevant parameters related to chlorophyll and N2 content, LAI (Leaf Area Index), surface temperature and soil moisture together with the Sentinel-3-A and -B more OLCI-specific products OLCI FAPAR and OTCI (OLCI Terrestrial Chlorophyll Index).This presentation shows the work carried out from the design and assembly of the FAPAR fixed stations, and the data series processed for the entire study period (2016-2021), to the different observations and validations carried out during the intensive observation campaigns. carried out in the area. Specifically, the data collection carried out consists of measurements using the SPAD 502 Plus Chlorophyll Meter which instantly measures the chlorophyll content or “greenness” of the plants, and whose calibration is carried out by means of cold extraction in the laboratory. These measurements are also used for the validation of the OTCI product obtained from Sentinel-3, as well as for its correlation with the continuously measured FAPAR and with the corresponding Sentinel-3 OLCI FAPAR product. Additionally, LAI data are included to establish the vegetation cover as well as soil moisture content and radiative surface temperature as a reference for the hydric stress conditions suffered by the vegetation.At the same time, a study of the vegetation cover has been carried out on the study area using the products MCD15A3H, MCD12Q1-2 and MOD-MYD13, to establish a soil correction of the data collected at the plant level.This leads to results where FAPAR and chlorophyll can be observed at three different levels, namely, in-situ plant, in-situ 300m x 300m with correction for the influence of the soil and satellite data. This research is important as a starting point in the validation of new indices with greater physical foundation and as confirmation of the robustness of the sensors on board the Sentinel 3-A, -B satellites for the continuity of the programme.

Climate change increases the occurrence and severity of droughts due to increasing temperatures, altered circulation patterns, and reduced snow occurrence. While Europe has suffered from drought events in the last decade unlike ever seen since the beginning of weather recordings, harmonized long-term datasets across the continent are needed to monitor change and support predictions. Here we present soil moisture data from 66 cosmic-ray neutron sensors (CRNSs) in Europe (COSMOS-Europe for short) covering recent drought events. The CRNS sites are distributed across Europe and cover all major land use types and climate zones in Europe. The raw neutron count data from the CRNS stations were provided by 24 research institutions and processed using state-of-the-art methods. The harmonized processing included correction of the raw neutron counts and a harmonized methodology for the conversion into soil moisture based on available in situ information. In addition, the uncertainty estimate is provided with the dataset, information that is particularly useful for remote sensing and modeling applications. This paper presents the current spatiotemporal coverage of CRNS stations in Europe and describes the protocols for data processing from raw measurements to consistent soil moisture products. The data of the presented COSMOS-Europe network open up a manifold of potential applications for environmental research, such as remote sensing data validation, trend analysis, or model assimilation The dataset could be of particular importance for the analysis of extreme climatic events at the continental scale. Due its timely relevance in the scope of climate change in the recent years, we demonstrate this potential application with a brief analysis on the spatiotemporal soil moisture variability. The dataset, entitled "Dataset of COSMOS-Europe: A European network of Cosmic-Ray Neutron Soil Moisture Sensors", is shared via Forschungszentrum Julich: https://doi.org/10.34731/x9s3-kr48 (Bogena and Ney, 2021)., Earth System Science Data, 14 (3), ISSN:1866-3516, ISSN:1866-3508

Human-caused climate change increases the occurrence and severity of droughts due to increasing temperatures, altered circulation patterns and reduced snow occurrence. For example, Europe has suffered from drought events in the last decade like never since the beginning of weather recording. Here we present soil moisture data from 65 Cosmic-ray neutron sensors (CRNS) in Europe (COSMOS-Europe for short) covering recent drought events. The CRNS sites are distributed across Europe and cover all major land use types and climate zones in Europe. The raw neutron count data from the CRNS stations were provided by 23 research institutions and processed using state-of-the-art methods. The harmonised processing included correction of the raw neutron counts, and a harmonised methodology for the conversion into soil moisture based on available in-situ information. In addition, information on the data uncertainty is provided with the dataset, information that is particularly useful for remote sensing and modelling applications. This paper presents the current spatiotemporal coverage of CRNS stations in Europe and describes the protocols for data processing from raw measurements to consistent soil moisture products as well as first results on how the recent drought events have been captured by the CRNS network. This harmonised European soil moisture dataset will help both hydrologists and climate scientists to study individual drought events, to understand their causes, to evaluate and improve their modelling, and to estimate the extremity of current events. The dataset, entitled “Dataset of COSMOS-Europe: A European network of Cosmic-Ray Neutron Soil Moisture Sensors”, is shared via Forschungszentrum Jülich: https://doi.org/10.34731/x9s3-kr48 (Bogena and Ney, 2021).

In order to assess the sustainability of silvicultural treatments in semiarid forests, it is necessary to know how they affect the nutrient dynamics in the forest. The objective of this paper is to study the effects of silvicultural treatments on the net N mineralization and the available mineral N content in the soil after 13 years following forest clearings. The treatments were carried out following a randomized block design, with four treatments and two blocks. The distance between the two blocks was less than 3 km, they were located in Chelva (CH) and Tuéjar (TU) in Valencia, Spain. Within each block, four experimental clearing treatments were carried out in 1998: T0 control, and T60, T75 and T100 where 60%, 75% and 100 of basal area was eliminated, respectively. Nitrogen dynamics were measured using the resin tube technique, with disturbed samples due to the high stoniness of the plots. Thirteen years after the experimental clearings, T100, T75 and T60 treatments showed a twofold increase in the net mineralization and nitrification rates with respect to T0 in both blocks (TU and CH). Within the plots, the highest mineralization was found in sites with no plant cover followed by those covered by undergrowth. These results can be explained in terms of the different litterfall qualities, which in turn are the result of the proportion of material originating from Pinus halepensis Mill. vs. more decomposable undergrowth residues.

[EN] The effects of a thinning treatment on soil respiration (Rs) were analysed in two dryland forest types with a Mediterranean climate in east Spain: a dry subhumid holm oak forest (Quercus ilex subsp. ballota) in La Hunde (HU); a semiarid postfire regenerated Aleppo pine (Pinus halepensis) forest in Sierra Calderona (CA). Two twin plots were established at each site: one was thinned (T) and the other was the control (C). Rs, soil humidity and temperature were measured regularly in the field at nine points per plot distributed into three blocks along the slope for 3 years at HU and for 2 years at CA after forest treatment. Soil heterotrophic activity was measured in laboratory on soil samples obtained bimonthly from December 2012 to June 2013 at the HU site. Seasonal Rs distribution gave low values in winter, began to increase in spring before lowering as soil dried in summer. This scenario indicates that with a semiarid climate, soil respiration is controlled by both soil humidity and soil temperature. Throughout the study period, the mean Rs value in the HU C plot was 13% higher than at HU T, and was 26% higher at CA C than the corresponding CA T plot value, being the differences significantly higher in control plots during active growing periods. Soil microclimatic variables explain the biggest proportion of variability for Rs: soil temperature explained 24.1% of total variability for Rs in the dry subhumid forest; soil humidity accounted for 24.6% of total variability for Rs in the semiarid forest. As Mediterranean climates are characterised by wide interannual variability, Rs showed considerable variability over the years, which can mask the effect caused by thinning treatment., This study was supported by research projects Hydrological characterisation of forest structures on a plot scale for adaptive management (CGL2011-28776-C02-02) and SILWAMED (CGL2014-58127-C3-2) funded by the Spanish Ministry of Science and Innovation and FEDER funds. CEHYRFO-MED (CGL201786839-C3-2-R), RESILIENT-FORESTS (LIFE17 CCA/ES/000063) and SilvAdapt. net (RED2018-102719-T) are also acknowledged. The authors are grateful to the Valencia Regional Government, VAERSA, ACCIONA and the "Sierra Calderona" Natural Park for their support in allowing us to use experimental forests and for their assistance in fieldwork. We also thank Rafael Herrera from the Centro de Ecologia, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela, and the anonymous reviewers for critically reviewing the manuscript.

Agronomy 2020, 10, 261, Compost represents a sustainable alternative for peat (P) replacement in soilless plant cultivation, but its use can be limited by several inadequate physical and physicochemical properties. Biochar can alleviate some of the limitations of compost for its use as growth media by improving the physical properties, decreasing salinity and making the phytotoxic compounds unavailable for plants. We studied the physical and physicochemical properties of holm oak biochar (B), poultry manure compost (PMC), poultry manure composted with biochar (PMBC), a commercial peat (P) and multiple combinations of these materials as growth media, and their effect on the rooting and growth of rosemary. PMBC and PMC showed similar physical and physicochemical properties as growing media, and they both were phytotoxic when used in a rate above 50% (by volume) in the growing medium. However, when used at proportion of 25%, PMBC was less phytotoxic than PMC and enhanced the percentage of rosemary cutting rooting. The incorporation of B in the growing medium instead of P (either at 50% or 75% in volume) increased the stability of the growing media and the percentage of rooted cuttings, but it did not affect plant growth significantly. Our results demonstrate the potential of substituting peat by a combination of poultry manure compost and biochar for the formulation of growth media., This research was funded by SPANISH MINISTRY OF ECONOMY AND COMPETITIVENESS, grant numbers AGL2012-40143-C02-01 and RTI2018-099417-B-I00, co-funded with EU FEDER funds.

[EN] The accurate estimation of plant water needs is the first step for achieving high crop water productivity. The main objective of the work was to develop an irrigation scheduling procedure for mandarin orchards under Mediterranean conditions based on replacing the amount of consumed water using reference values of soil moisture according to different phenological periods. The proposed methodology includes a definition part where the threshold values were established relating the trees' stem water potential and the volumetric soil water content measured with Frequency Domain Reflectometry probes. A second part includes the steps for standardizing measurements from capacitance probes by using the LEACHM hydrological simulation model to take into account the sensor-to-sensor variations. Finally, an extrapolation procedure based on soil water retention curves was used for adapting critical soil water content thresholds to different soil conditions. Field evaluations were made in a citrus orchard located in eastern Spain during two seasons. Standardize critical soil water contents were: i) 24 % vol. for post-harvest, bloom - fruit set and phase III of fruit growth; ii) 27 % vol. for phase I of fruit growth, and iii) 29 % vol. for phase II of fruit growth with average daily air vapour pressure deficit values ranging between 0.2 - 0.4; 0.9-1.1 and 1.1-1.3 kPa, respectively. When implemented in the orchard, the sensor-based strategy resulted in water saving of 26 % respect to a control treatment, irrigated using the standard FAO-56 approach, without significant differences in yield and increasing the crop water productivity by 33 %. In conclusion, we suggest that the determination and use of the critical soil water content is a useful tool for scheduling irrigation. The proposed standardization and extrapolation methodology allows the irrigation strategy to be applied to other mandarin orchards under similar climatic conditions., This experiment was funded by European project WEAM4i Water & Energy Advanced Management for Irrigation, grant agreement 619061 and FEDER-MINECO projects EASYRIEGO IPT-2012-0950-310000, RISUB IPT-2012-0480-310000 and RIEGOTEL RTC-2016-4972-2. M.A. Martinez-Gimeno acknowledges the financial support received from the Spanish Ministry of Education, Culture and Sports (MECD) program Formacion Profesorado Universitario (FPU). Juan G. Perez-Perez also gratefully acknowledges the post-doctoral contract in the `Ramon y Cajal' program, supplied by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO). Authors would like to thank M. Jorda, C. Albert, F. Sanz and A. Yeves for the support on installation and maintenance of the equipment. Thanks also to Prof. G. Provenzano (University of Palermo) for his critical comments and suggestions.

Continuity to the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) will be provided by the Ocean and Land Color Instrument (OLCI) on-board the Sentinel-3 missions. To ensure its utility in a wide range of scientific and operational applications, validation efforts are required. In the past, direct validation has been constrained by the need for costly airborne hyperspectral data acquisitions, due to the lack of freely available high spatial resolution imagery incorporating appropriate spectral bands. The Multispectral Instrument (MSI) on-board the Sentinel-2 missions now offers a promising alternative. We explored the synergetic use of MSI data for validation of the OLCI Terrestrial Chlorophyll Index (OTCI) over the Valencia Anchor Station, a large agricultural site in the Valencian Community, Spain. Using empirical and machine learning techniques applied to MSI data, in situ measurements were upscaled to the moderate spatial resolution of the OTCI. An RMSECV of 0.09 g·m−2 (NRMSECV = 20.93%) was achieved, highlighting the valuable information MSI data can provide when used in synergy with OLCI data for land product validation. Good agreement between the OTCI and upscaled in situ measurements was observed (r = 0.77, p < 0.01), providing increased confidence to users of the product over vineyard dominated Mediterranean environments.

[EN] Soil organic carbon pools have an important role in the maintenance of ecosystems as a source of energy for soil microorganisms. Soil biological and biochemical properties are essential for the decomposition of organic matter. These soil properties can be affected by thinning, which is considered sustainable when the soil properties are maintained or improved. We studied the effects of selective thinning and shrub clearing, performed with an ecohydrological approach, in a marginal Holm oak forest in a semiarid area on soil properties. The effects of thinning (T) were compared with an untreated area (control, C). Fine woody debris was ground into mulch onto the thinned area. Forest floor and mineral soil properties were analyzed between five months and seven years after the thinning. In the forest floor, gravimetric water content (GWc(ff)) and water soluble organic carbon (WSOCff) were analyzed and compared between T and C. In mineral soil, GWC(ms), soil organic carbon (SOC), WSOCms, soil basal respiration (BR), soil microbial biomass carbon (MBC) and soil enzymes (acid phosphatase (Acid PA) and urease (URE)) were analyzed. In the early stage, the results showed slightly higher SOC and WSOms in T likely due to fine woody debris left on the forest floor. However, seven years after the thinning the effects of the thinning on all the studied variables were negligible. All variables showed high spatial-temporal variability. Our results suggest that selective thinning and shrub clearing in the studied site do not affect negatively soil properties when woody debris is left on the forest floor., This study is a component of research projects: HYDROSIL (CGL2011-28776-C02-02) and SILWAMED (CGL2014-58+127-C3-2), RESILIENT-FORESTS (LIFE17 CCA/ES/000063) and CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the Spanish Ministry of Science and Innovation, and the FEDER fund and the EU. The authors are grateful to the Valencia Regional Government (CMAAUV, Generalitat Valenciana) for it supports in allowing the use of the experimental forest. We thank Joana Oliver for her laboratory and technical assistance and Dr. Rafael Herrera for valuable comments on the manuscript.

[EN] Trees in semiarid conditions survive despite water scarcity and shallow soils because they commonly have access to subsoil water resources. Currently, conventional models do not include groundwater transpiration and the results frequently underestimate the actual evapotranspiration and overestimate the net recharge. Therefore, in this work we focus on how a multi-variable calibration with a multi-objective approach may improve model robustness leading to a more realistic closure of the water balance in two models (LEACHM and TETIS) of different conceptualisation taking into account the specific characteristics of a facultative phreatophytic forest. The results suggest that the common single-variable and single-objective calibration is not able to measure all system¿s characteristics. However, the multi-variable and multi-objective calibration proved a good option to reproduce the water dynamics of a facultative phreatophytic forest and confirmed that groundwater transpiration is an important water source for them. Therefore, hydrological models should include this mechanism and both LEACHM and TETIS proved an acceptable tool to be applied in the regions covered by this species., This work was supported by the Spanish Ministry of Science and Innovation through the research projects: TETISMED (CGL2014-58127-C3-3-R), SILWAMED (CGL2014-58127-C3-2-R) and TETISCHANGE (RTI2018-093717-B-100), and by the project LIFE17 CCA/ES/000063 RESILIENTFORESTS.

Rainfed Mediterranean agriculture is characterized by low water input and by soil water content below its field capacity during most of the year. However, erratic rainfall distribution can lead to deep drainage. The understanding of soil-water dynamics is essential to prevent collateral impacts in subsuperficial waters by leached pollutants and to implement suitable soil management (e.g., agronomic measures to avoid nitrate leaching). Soil water dynamics during two fallow years and three barley crop seasons was evaluated using the Leaching estimation and chemistry model in a semiarid Mediterranean agricultural system. Model calibration was carried out using soil moisture data from disturbed soil samples and from capacitance probes installed at three depths. Drainage of water from the plots occurred in the fall and winter periods. The yearly low drainage values obtained (&lt, 15 mm) indicate that the estimated annual nitrate leaching is also small, regardless of the nature of the fertilizer applied (slurries or minerals). In fallow periods, there is a water recharge in the soil, which does not occur under barley cropping. However, annual fallow included in a winter cereal rotation, high nitrate residual soil concentrations (~80 mg NO3&minus, N L&minus, 1) and a period with substantial autumn-winter rains (70&ndash, 90 mm) can enhance nitrate leaching, despite the semiarid climate.

[EN] Mediterranean drylands are often nutrient poor, but parameter requirements of forest ecosystem models are usually high. Therefore, there is a need for developing parsimonious nutrients models. In that sense, this study aims to contribute to a better understanding and modelling of the hydrological and biogeochemical (carbon and nitrogen) cycles and their interactions in semiarid conditions and to test the capability of a new parsimonious model to satisfactorily reproduce them. The proposed model (TETIS-CN) and two additional widely used models were implemented in a Quercus ilex forest, and no noteworthy differences were found. Results suggest that: (1) it is important to include carbon observations in the calibration process and to consider all the existing vegetation species in the simulation; (2) a fixed daily potential uptake may not be appropriate to reproduce plant nitrogen uptake; and (3) TETIS-CN, with a lower number of parameters, proved an acceptable tool., This work was supported by the Spanish Ministry of Science and Innovation through the research projects: TETISMED (CGL2014-58127-C3-3-R), SILWAMED (CGL2014-58127-C3-2-R), CEHYRFO-MED (CGL2017-86839-C3-2-R) and TETISCHANGE (RTI2018-093717-B100), and by the project LIFE17CCA/ES/000063 RESILIENTFORESTS.

Continuity to the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) will be provided by the Sentinel-3 Ocean and Land Colour Instrument (OLCI), and to ensure its utility in a wide range of operational applications, validation efforts are required. In the past, these activities have been constrained by the need for costly airborne hyperspectral data acquisition, but the Sentinel-2 Multispectral Instrument (MSI) now offers a promising alternative. In this paper, we explore the synergetic use of Sentinel-2 MSI data for validation of the Sentinel-3 OLCI Terrestrial Chlorophyll Index (OTCI) over the Valencia Anchor Station, a large agricultural site in the Valencian Community, Spain. High retrieval accuracy (RMSE = 0.20 g m-2) was obtained by applying machine learning techniques to Sentinel-2 MSI data, highlighting the valuable information it can provide when used in synergy with Sentinel-3 OLCI data for land product validation.

[EN] Gypsum areas are stressful environments inhabited by gypsophytes, plants that are exclusive for such habitats, and by plants that grow on gypsum but also on other soil types, the so-called gypsovags. To investigate possible differences between gypsovags and gypsophytes with respect to basic stress response mechanisms, two common osmolytes, glycine betaine and total soluble sugars, as well as monovalent (Na+ and K+) and bivalent (Ca2+ and Mg2+) cations, were quantified, under field conditions, in two Iberian endemic gypsophytes (Gypsophila struthium subsp. hispanica and Ononis tridentata) and two common Mediterranean gypsovags (Rosmarinus officinalis and Helianthemum syriacum). Their spatial variation according to a topographic gradient and their temporal variation over a period of three successive seasons were correlated with climatic data and soil characteristics. This analysis confirmed that water stress is the main environmental stress factor in gypsum habitats, whereas the percentage of gypsum in the soil does not seem to play any relevant role in the activation of stress responses in plants. Glycine betaine may contribute to stress tolerance in the gypsophytes, but not in the gypsovags, according to the close correlation found between the level of this osmolyte and the gypsophily of the investigated taxa. Cation contents in the plants did not correlate with those present in the soil, but the gypsophytes have higher levels of Ca2+ and Mg2+ than the gypsovags, under all environmental conditions, which may represent an adaptation mechanism to their specific habitat, This work has been supported by the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund.

[EN] Water-oriented forest management is an urgent need in semiarid catchments. In the case of low-biomass forests and shrublands, the magnitude, efficiency and temporal duration of thinning effects on rainfall partitioning needs further attention. This work studies the effects of juvenile thinning and shrub clearing on stemflow (Stf), throughfall (Thr) and interception (It) in two low-biomass forests (CAL: post-fire Aleppo pine saplings with 74% of basal area, BA, removed; and HU: evergreen oak coppice with 41% of BA removed), as well as the relative contribution of the event meteorology. The effects are compared with a control plot during the first 3¿4¿years. Stf rate (%) decreased with density and, on a tree scale, it was enhanced by the treatment only in the bigger oaks. Event Thr increased from 55 to 81% and from 68 to 86% of gross rainfall (Pg) for CAL and HU respectively after thinning, resulting in about 15% less intercepted Pg. High evaporative conditions and an open (ventilated) forest structure led to high It rates in the controls when comparing with other studies, thus making the treatments more efficient in net precipitation (Pn) gain (Pg intercepted decreased 17% or 2.3% per unit of LAI or BA removed respectively). In general, depths (mm) were mostly explained (>75%) by the rainfall characteristics of the event (e.g. amount, duration, intensity), with a limited contribution from forest structure (e.g. cover, LAI) and event meteorology (e.g. temperature, wind speed, vapor pressure deficit). On the contrary, when expressed as rates (% of Pg), forest structure and event-meteorology gained importance (explaining 25¿65%), especially in the drier site (CAL). In this site, the low gain in Pn (~25¿mm per year on average) was offset with no temporal dampening during the span of this study, as observed in the wetter site (HU), where plant growth tended to mitigate the effect of the treatment by the end of the study. The results presented here make a contribution to a better understanding of the effects of water-oriented forest management in low-biomass semiarid forests., This study is a component of research projects: HYDROSIL (CGL2011-28776-C02-02), SILWAMED (CGL2014-58127-C3-2) and CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the Spanish Ministry of Science and Innovation and the FEDER fund of the EU. The authors are grateful to the Valencia Regional Government (CMAAUV, Generalitat Valenciana), Serra municipality, VAERSA and ACCIONA for their support in allowing the use of the experimental forest and for their assistance in carrying out the fieldwork.

BACKGROUND Environmentally friendly agriculture needs to reduce the use of synthetic fertilizers and to reclaim nutrients from organic wastes. In this study the effect of five doses (0, 12, 24, 48 and 96 t ha−1) of two two-phase olive mill waste (TPOMW)-based composts on the bioactivity and chemical characteristics of an agricultural soil and their potential to fertilize alfalfa (Medicago sativa) and stimulate nodulation were assessed during a two-year incubation experiment. The two composts were prepared either with the olive mill waste alone (compost A), which served as control, or mixed with a liquid fatty-proteinaceous hydrolyzate waste (FPH) from the pharmaceutical industry (compost AH). RESULTS Compost AH resulted in greater N immobilization than compost A because the former supplied the soil with easily degradable C and N, which increased microbial biomass and activity. Both compost mineralizations during the first year of incubation supplied the soil with more nutrients (mainly N), more so with A than with AH. Nevertheless, plant growth was similar in soils amended with either A or AH. Both composts induced nodulation similarly and the highest dose (96 t ha−1) increased the formation of nodules by a factor of 11 compared with the four lower doses. CONCLUSION TPOMW serves as an effective ground material for co-composting with liquid wastes such as FPH. TPOMW supplies key nutrients and stimulates nodulation in alfalfa. © 2014 Society of Chemical Industry

[EN] Biosynthesis of proline¿or other compatible solutes¿is a conserved response of all organisms to different abiotic stress conditions leading to cellular dehydration. However, the biological relevance of this reaction for plant stress tolerance mechanisms remains largely unknown, since there are very few available data on proline levels in stress-tolerant plants under natural conditions. The aim of this work was to establish the relationship between proline levels and different environmental stress factors in plants living on gypsum soils. During the 2-year study (2009¿2010), soil parameters and climatic data were monitored, and proline contents were determined, in six successive samplings, in ten taxa present in selected experimental plots, three in a gypsum area and one in a semiarid zone, both located in the province of Valencia, in south-east Spain. Mean proline values varied significantly between species; however, seasonal variations within species were in many cases even wider, with the most extreme differences registered in Helianthemum syriacum (almost 30 lmol g-1 of DW in summer 2009, as compared to ca. 0.5 in spring, in one of the plots of the gypsum zone). Higher proline contents in plants were generally observed under lower soil humidity conditions, especially in the 2009 summer sampling preceded by a severe drought period. Our results clearly show a positive correlation between the degree of environmental stress and the proline level in most of the taxa included in this study, supporting a functional role of proline in stress tolerance mechanisms of plants adapted to gypsum. However, the main trigger of proline biosynthesis in this type of habitat, as in arid or semiarid zones, is water deficit, while the component of ¿salt stress¿ due to the presence of gypsum in the soil only plays a secondary role., This work has been supported by the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund.

The role of forests on the provision and regulation of non-marketed ecosystem services is well known (Thorsen et al. 2014). This is especially important in areas like the Mediterranean, where protective forests play a major role against soil erosion and degradation, landscape quality and stabilization of the hydrological cycle. Socio-economic and cultural changes affecting rural society from the 1960s have produced a demographic decline, and with it, an abandonment of rural activities, leading to an expansion and densification of forest and scrub. Forest encroachment may decrease the streamflow from upper catchments (Gallart and Llorens 2004); this study reports a decrease in average annual flow of major Spanish rivers between 37 and 59%, partly explained by the densification of upstream forests, and increasing interception loss. Moreover, some Mediterranean basins (e.g. Segura and Jucar in Spain) present very serious problems of water scarcity, because of a combination of low/irregular rainfall and high rates of evapotranspiration, that has resulted in overuse of groundwater resources (Estrela et al. 2000a, b). These problems may even endanger urban water supply (approx. 15% of the total water supply in Spain). In addition, the Mediterranean region is already suffering some significant impacts of the climate change, such as longer dry seasons, or lower soil moisture content (Giorgi and Lionello 2008; Garcia-Ruiz et al. 2011). All these issues have raised concern about the importance of forests and water interactions in the Mediterranean (Birot et al. 2011).

Compartmentalization of toxic ions in the vacuole and accumulation of osmolytes in the cytoplasm is a common response of halophytes to high soil salinity. Soluble carbohydrates, such as sugars and polyols, are some of the compatible solutes used for osmotic adjustment and osmoprotection. Major carbohydrates were identified and quantified by high-performance anion-exchange chromatography, combined with pulsed amperometric detection (HPAEC-PAD), in five halophytic species from a Mediterranean salt marsh (Juncus acutus, Juncus maritimus, Plantago crassifolia, Inula crithmoides and Sarcocornia fruticosa). Sucrose, followed by glucose and fructose were the more representative sugars detected in J. acutus and J. maritimus, and sorbitol the only soluble carbohydrate present at significant levels in P. crassifolia. In the other two taxa analyzed, no clearly predominant carbohydrates were observed: polyols (myo-inositol and glycerol) seemed to be the most representative in I. crithmoides, albeit at relatively low concentrations, and sugars (sucrose and glucose) in S. fruticosa. Multivariate statistical analysis was used to correlate soil properties and meteorological conditions increasing soil salinity, with seasonal changes in carbohydrate contents, to establish their possible function as osmolytes and their contribution to salt tolerance in the investigated species. The obtained results confirmed sorbitol as the major functional osmolyte in P. crassifolia-as it has been described previously for other species of the genus-and suggested the participation of sucrose and, to a lesser extent, glucose and fructose in osmoregulatory mechanisms in J. acutus and J. maritimus., This study was supported by the Spanish Ministry of Science and Innovation (project CGL2008-00438/BOS), with contribution from the European Regional Development Fund.

A simple model that represents the soil nitrogen dynamics in a citrus orchard is studied. This model consists of several compartments of organic and inorganic nitrogen representing the main processes that occur among the compartment of the soil column. Some of these processes are coupled to the carbon dynamics in the soil, thus, the evolution of organic carbon in the soil has been also described in the model. The dependence of these processes with soil moisture requires the coupling of a nitrogen model with a model of soil water dynamics. A compartmental model for the water has been used to simulate the dynamics of water in the root profile. The proposed model has been used to predict the soil mineral nitrogen content and the nitrate leaching in a citrus orchard placed in the area of Valencia and the obtained results have been compared with the results obtained with the nitrogen component of the widely used Leaching Estimation and Chemistry Model (LEACHM).

BACKGROUND: The production of biodegradable wastes and their disposal cause a major financial problem in many industrial activities. Co-composting was thought to be a feasible alternative for disposing of a strongly alkaline waste from the pharmaceutical industry (AW), mainly consisting of animal fats and partially hydrolysed proteins in a stable emulsion. The AW was added gradually, during the early phase of the composting process, to a substrate made up of ‘alperujo’ (AL), the wet, lignocellulosic, solid by-product of the olive oil industry, and fresh horse manure, which was added to improve the physical structure of the composting substrate. RESULTS: The addition of AW reduced organic matter degradation during composting, enriched the amount of organic compounds in the water- and alkali-soluble fractions and increased mineral salt contents. Thus, significantly higher electrical conductivity, humification indices and contents of organic matter, P, K and Na were recorded in the end-composts resulting from AW treatments. However, the application of one AW-based compost led to soil N immobilisation, as revealed by an incubation experiment, which must be considered in order to avoid potential N starvation in the short term. CONCLUSION: According to these results, composting can be used as a disposal alternative for AW, leading to end-products with potential uses as organic amendments or fertilisers for agricultural systems. In addition, these composts could be used to produce alternative liquid organic fertilisers, based on the extraction of their humic-like fraction. Copyright © 2009 Society of Chemical Industry

[EN] Recently, biochars and hydrochars have been proposed as soil amendments and, to a lesser degree, as substrate constituents for soilless cultivation. These materials are interesting because their use is a means to reclaim organic matter and because, in some instances, they have been proved to sequester CO2 from the atmosphere. Myrtle and mastic are native to Mediterranean ecosystems and are grown for their essential oil production. This study aims to assess the properties of two biochars from different feedstock and a hydrochar from the same feedstock as one of the biochars as substrate constituents, in order to partially substitute either coir or soil in the cultivation of myrtle and mastic. Although the physical properties of the four organic materials are reasonably adequate for their use in substrate mixes, the biochar of olive mill waste is extremely saline as a pure material and remains very saline in a 50% mix with coir. The hydrochar showed less easily available water for the plants and a lower pH than the others. In incubation experiments using mixes with soil, biochars absorbed more 02 than CO2 emitted, which suggests they were sequestering CO2. The hydrochar showed O-2 consumption and CO2 emission of one order of magnitude larger than the biochars. It also showed that an outstanding amount of organic carbon was being metabolized in anaerobic routes. The biochar of forest waste and the coir displayed N immobilization when mixed with soil, whilst the biochar of olive mill waste had little microbial activity. Although hydrochars had been proved not to immobilize N as pure materials, they did immobilize N when mixed with soil. When tried for plant growth, mixes of the local soil with the biochar of forest waste and with hydrochar produced the best mastic plants. However, unmixed soil gave the best results for myrtle. The biochar of olive mill waste proved phytotoxic for myrtle in mixes with coir, whilst the biochar of forest waste gave optimal results for both species. Depending on their production process and the feedstock from which they are produced, biochars and hydrochars can vary in their characteristics and therefore in their effect on plants. (C) 2016 Elsevier B.V. All rights reserved.

[EN] Different adverse environmental conditions cause oxidative stress in plants by generation of reactive oxygen species (ROS). Accordingly, a general response to abiotic stress is the activation of enzymatic and non-enzymatic antioxidant systems. Many phenolic compounds, especially flavonoids, are known antioxidants and efficient ROS scavengers in vitro, but their exact role in plant stress responses in nature is still under debate. The aim of our work is to investigate this role by correlating the degree of environmental stress with phenolic and flavonoid levels in stress-tolerant plants. Total phenolic and antioxidant flavonoid contents were determined in 19 wild species. Meteorological data and plant and soil samples were collected in three successive seasons from four Mediterranean ecosystems: salt marsh, dune, semiarid and gypsum habitats. Changes in phenolic and flavonoid levels were correlated with the environmental conditions of the plants and were found to depend on both the taxonomy and ecology of the investigated species. Despite species-specific differences, principal component analyses of the results established a positive correlation between plant phenolics and several environmental parameters, such as altitude, and those related to water stress: temperature, evapotranspiration, and soil water deficit. The correlation with salt stress was, however, very weak. The joint analysis of all the species showed the lowest phenolic and flavonoid levels in the halophytes from the salt marsh. This finding supports previous data indicating that the halophytes analysed here do not undergo oxidative stress in their natural habitat and therefore do not need to activate antioxidant systems as a defence against salinity., This work has been funded by the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund. Thanks to Dr. Rafael Herrera for critical reading of the manuscript.

[EN] Our knowledge about the influence of silvicultural treatments on nutrient cycling processes in Mediterranean forests is still limited. Four levels of tree removal were compared in an Aleppo pine forest in eastern Spain to determine the effects on litterfall, litter decomposition and the associated nutrient fluxes after 12 years. Removal treatments included clearfelling, two shelterwood intensities (60 and 75 % of basal area removed) and untreated controls. Twelve years later, the basal area removed still explained 60 % of litterfall mass variance and 60 % of C, 52 % of N, 45 % of P, 17 % of K, 47 % of Ca and 60 % of Mg return variances. Litter decomposed somewhat more slowly in clearfellings compared to controls (p = 0.049), accumulated more Ca and released less K compared to the other three treatments. This was explained by contamination with mineral particles due to the poorly developed O horizon in clearfellings. We conclude that the management practices reduced the nutrient return via litterfall, but the nutrient release through decomposition seems poorly sensitive to canopy disturbance. In order to accurately quantify the harvesting impacts on nutrient cycling in this Mediterranean forest system, it is necessary to measure the litterfall of the understory layer., This work has been supported by a fellowship from the Generalitat Valenciana, Conselleria de Educacion, Formacion y Empleo awarded to L. Lado-Monserrat (BFPI/2008/041). Silvicultural treatments were carried out by the Mediterranean Centre for Environmental Studies (CEAM) through programme "I + D en relacion con la restauracion de la cubierta vegetal y otros aspectos de investigacion forestal". Dataloggers and probes were provided by the Generalitat Valenciana through Project "Efecto de diferentes sistemas de aclareo de masa forestal sobre la disponibilidad de agua, nutrientes y la regeneracion de la masa arborea y arbustiva en parcelas de pinar" (GV06/126). We acknowledge Joana Oliver, Ruth M. Tavera and Daniel Fortanet for their help in the laboratory and in the field. The authors wish to thank Francisco Galiana for his assistance, including help in fieldwork and providing information about the experimental design of the silvicultural treatments. Thanks also go to Rafael Herrera from the Centro de Ecologia, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela and two anonymous reviewers for critically reviewing the manuscript.

[ES] El uso de modelos de simulación de la dinámica del agua en el suelo requiere del conocimiento de un gran número de parámetros, algunos de los cuales son difíciles de medir y es necesaria su calibración a partir de medidas experimentales. Por ello, es conveniente elegir aquellos parámetros que mayor incidencia tienen en los procesos a estudiar, simplificando con ello el proceso de calibración del modelo. En este trabajo se propone la utilización de métodos de análisis de sensibilidad global para determinar los parámetros más influyentes en los errores de la predicción del contenido de humedad del suelo de dos modelos de simulación con diferente grado de complejidad, LEACHM y EU-Rotate_N. Se ha hecho uso de los valores medidos de la humedad del suelo en dos ensayos de cultivo de coliflor en dos años consecutivos, utilizando los datos del primer ensayo para la calibración de ambos modelos y los datos del segundo ensayo para evaluar la capacidad predictiva de los mismos una vez calibrados. Los resultados muestran que es posible obtener buenas predicciones calibrando solo un número reducido de parámetros., Este trabajo ha sido subvencionado parcialmente por el Ministerio de Economía y Competitividad mediante el proyecto INIA-RTA 2011–00136-C04-01.

[ES] Las interacciones entre cubierta forestal y agua son complejas ya que afectan a diferentes variables tales como reparto de los flujos de agua, cosecha de agua y calidad de la misma. El crecimiento forestal en suelos de baja fertilidad requiere que los ciclos de nutrientes dentro del ecosistema sean eficientes, especialmente en bosques mediterráneos, en los que además de los problemas de escasez de agua, el nitrógeno y el fósforo son a menudo nutrientes limitantes. El objetivo de este trabajo es analizar el impacto de la gestión hidrológico forestal sobre los flujos de nutrientes (C, N, P y K) asociados al ciclo hidrológico. Se seleccionó un bosque de encina situado en el monte público de La Hunde, Valencia (NE España). Se establecieron dos parcelas contiguas, control y tratamiento, de 1800 m2, respectivamente. En la parcela de tratamiento se reduce la densidad de 861 a 414 árboles por ha, siguiendo los requisitos del gestor forestal. Se han medido los flujos de transcolación, escorrentía cortical y se han instalado zanjas de drenaje para recoger la escorrentía superficial y subsuperficial. Durante más de un año hidrológico se han recogido muestras de agua en ambas parcelas, con una periodicidad aproximadamente quincenal, y se han medido los contenidos de C, N, P y K disueltos en el agua, tanto en forma orgánica como inorgánica, para analizar los efectos del tratamiento en el ciclo de nutrientes., Este trabajo se ha realizado en el marco del proyecto de investigación CGL2011-28776-C02-02 financiado por el Ministerio de Economía y Competitividad.

[EN] Two biochars, one from forest waste (BCH-FW) and the other from olive mill waste (BCH-OMW), and one hydrochar from forest waste (HYD-FW) were analyzed from the horticultural and environmental point of view. Several incubation assays were performed to foresee the material evolution when used as soilless growth media. HYD-FW was slightly alkaline and rich in nutrients and showed high microbial respiration Moreover, it did not caused N immobilization but N mineralization which contradicts previous reports. Biochars were highly alkaline. BCH-FW was poor in nutrients whilst BCH-OMW was saline and rich in soluble cations. Both materials had low respiratory activity, similar to that of coir fibre (CF). Whilst BCH-FVV and CF immobilize N, BCH-OMW did not. Both biochars captured CO2 from the atmosphere, particularly BCH-OMW, which concomitantly showed a decrease in soluble cations. We conclude that pure hydrochar does not immobilize N and that alkaline biochars act as CO2 traps. (C) 2014 Elsevier Ltd. All rights reserved., This study was funded by the Universitat Politecnica de Valencia (Proyectos de nuevas Lineas de Investigacion Multidisciplinares; SP 20120433-PAID-05-12). We thank INGELIA S.L. for giving the hydrochar for free and to Mr Manuel Sanchez-Perales and Mrs Joana Oliver for their technical assistance.

[ES] El Manejo Forestal Adaptativo (MFA) en entornos semiáridos tiene como objetivo adaptar el bosque a la escasez de agua mediante una regulación artificial de la estructura y la densidad del mismo. En el presente trabajo se aplica el MFA a una masa marginal de Quercus ilex con el fin de optimizar los recursos hídricos y tratando de evitar a su vez el posible impacto negativo derivado de una pérdida excesiva de suelo y nutrientes. La masa se encuentra en la Cuenca Mediterránea, dentro del Monte Público de La Hunde, Valencia (E de España), donde dos parcelas contiguas, control y tratamiento, de 1800 m2 cada una, fueron establecidas. La orientación (NO), pendiente (30 %) y densidad (861 árboles por ha) fueron las mismas en ambas parcelas. La parcela tratamiento fue aclarada en Mayo del 2012, reduciendo la densidad de 861 a 414 árboles por ha. La parcela control no fue aclarada. Los efectos del aclareo en los ciclos hidrológico y biogeoquímico fueron caracterizados en ambas parcelas y comparados entre sí. Los resultados indicaron un efecto temprano del aclareo que optimiza el ciclo hidrológico. Se encontró un incremento significativo de la transpiración, escorrentía cortical y humedad del suelo en la parcela tratada. Por el contrario, no se observaron efectos ni en la escorrentía superficial ni en la trascolación. De la misma forma, el MFA parece no afectar significativamente al ciclo biogeoquímico del bosque, ya que no se encontraron diferencias significativas en el contenido de C, N y P en el agua de ambas parcelas. La removilización de nutrientes parece verse afectada por el resalveo. La parcela tratada muestra una menor eficiencia en el uso de los nutrientes, probablemente derivada de una mayor disponibilidad de agua. Con estos resultados, podemos afirmar que la aplicación de un adecuado MFA posibilita la optimización del ciclo hidrológico sin dañar significativamente el ciclo de los nutrientes. De la misma forma, además de la satisfacción de las necesidades hídricas y nutricionales del ecosistema, el MFA incrementa la disponibilidad de agua para el resto de la cuenca.

[EN] Simulation models for the transport of water and nitrogen in the soil are useful tools for evaluating the consequen-ces of di erent crop management practices without waiting until the end of the crop cycle. Particularly, simplecompartmental models for the transport of water and nitrogen are based on the solution of mass balance equationsfor the water and a system of ordinary di erential equations for the nitrogen cycle. In this work, these modelsare used to evaluate di erent possible scenarios of irrigation and nitrogen fertilization in a cauli ower crop, as apractical work for the students of Horticulture course. The results show that di erent irrigation and fertilizationstrategies lead to di erent results for the nitrate leaching, water drainage and nitrogen uptake, [ES] Los modelos de simulación del transporte de agua y nitrógeno en el suelo son herramientas útiles para evaluar distintas prácticas de cultivo sin necesidad de tener que esperar a que se complete el ciclo de crecimiento. En concreto, los modelos compartimentales sencillos para el agua y el nitrógeno en el suelo se basan en ecuaciones de balance de masa y en la resolución de un sistema de ecuaciones diferenciales ordinarias. Se plantea la posibilidad de utilizar este tipo de modelos en las prácticas de la asignatura Horticultura, evaluando distintos escenarios posibles de riego y abonado en un cultivo de coliflor. Los resultados muestran que distintas prácticas de cultivo producen diferencias en la lixiviación de nitrato y en la extracción de nitrógeno por el cultivo.

The Birch effect is a pulse in soil C and N mineralization caused by the wetting of dry soils, but the role of the soil moisture increment (Delta SWC) is still poorly understood. We quantified the relationship between Delta SWC and the Birch effect, and its interactions with pre-wetting soil moisture (preSWC) and substrate supply. Two soils (clay loam and sandy loam) under a Pinus halepensis forest were subjected to rewetting in laboratory treatments combining different Delta SWC and preSWC values, with or without additional substrate (5 mg g(-1) P. halepensis needles). Respiration flush (Delta R), changes in microbial biomass C (MBC) and net N mineralization (NMIN) were measured. Overall, we found a relationship with the form: Delta R = a Delta SWC + b, where the slope (a) was significant only when pre-wetting water potential was below a threshold value in the range of -100 to -1,200 kPa. However, the threshold alone does not fully describe the role of preSWC in slope variability. Substrate addition modified the Delta SWC sensitivity of Birch effect, enhancing it in the clay loam and suppressing it in the sandy loam. The intensity of the wetting is a dominant factor regulating Birch effect, and Delta SWC is useful for its quantification., This work was supported by a fellowship from Generalitat Valenciana, Conselleria de Educacion, Formacion y Empleo awarded to L. Lado-Monserrat (BFPI/2008/041). Thanks are due to Antonio del Campo for help in data analyses and to Antonio Lloret for laboratory work. The authors wish to thank Joana Oliver for invaluable laboratory support. The authors also thank two anonymous reviewers and Professor Stephan Glatzel from the University of Rostock, Germany, for the critical review of the manuscript.

Three different methods of measuring drainage were selected and applied to two irrigated citrus orchards for 3 years. The methods were: (1) a simple soil water capacity model, (2) a chloride balance, and (3) the LEACHM model. In the first method, the soil is assumed to have a given water holding capacity, plants cannot extract water from soil below a certain level, and evapotranspiration varies with soil water content in a well-defined pattern. In the second method, drainage in a given period of time is estimated from the chloride input to soil (mainly with the irrigation and rain water), the changes in soil chloride, and the average chloride concentration of soil solution at the depth where drainage is estimated. In the LEACHM model, water transport in soil is assumed to follow Richards equation, and evapotranspiration depends in soil water content, soil hydraulic properties, the evaporative conditions of the air, and root properties and distribution. Two citrus orchards planted with mature trees, under flood irrigation, were used for the comparison of methods. The three methods provided drainage estimates that differed in most cases by less than 13%, although in some particular season and plot, a given method deviated from the other two by up to 56%. The soil water capacity model is appealing because it only needs a few parameters for calibration, and can be easily programmed in a spreadsheet. The main advantage of the chloride balance approach is that it requires neither calibration nor an estimate of evapotranspiration; this latter fact converts the chloride balance into a good alternative method of measuring evapotranspiration. The precision of the drainage estimates by chloride balance is mainly determined by the spatial variability of soil chloride relative to the chloride input to the soil in the measurement period; in most cases, to obtain a reasonable precision, this period should be longer than 1 or 2 months. The LEACHM model requires more data for calibration, but it can provide additional information on water and solute distribution in the soil profile with time.

This article assesses the effect of management practices on the environmental and economic performance of tigernut production. Tigernut is a horticultural crop grown in a very limited and homogeneous area. Results show that the environmental variability among farms was greater than variability in costs. A selection of practices can reduce impacts per kilogram tigernut by factors 252.5 (abiotic depletion), 33 (aquatic ecotoxicity), or 6 (global warming) and costs by factors of between 2 and 3. The analysis shows a positive relationship between economic and environmental performance. Results highlight how proper management leads to both relatively low environmental impacts and costs., The authors acknowledge the support of the Conselleria d'Empresa, Universitat i Ciencia de la Generalitat Valenciana (GV/2007/211) and the Universitat Politecnica de Valencia (PAID05-08-316).

We have studied the responses to changing environmental conditions of five halophytes in a Mediterranean salt marsh, during a 2-year period. Salt tolerance in succulent dicotyledonous halophytes is mostly dependent on compartmentalisation of toxic ions in vacuoles and biosynthesis of osmolytes for osmotic adjustment – mechanisms that appear to be constitutive in the most tolerant taxa – while monocots avoid excessive ion transport to the plant aerial parts. Contrary to what has been described for salt treatments under artificial conditions, the selected halophytes are not affected by oxidative stress in their natural habitat, and do not need to activate antioxidant defence mechanisms., In their natural habitats, different mechanisms may contribute to the tolerance of halophytes to high soil salinity and other abiotic stresses, but their relative contribution and ecological relevance, for a given species, remain largely unknown. We studied the responses to changing environmental conditions of five halophytes (Sarcocornia fruticosa, Inula crithmoides, Plantago crassifolia, Juncus maritimus and J. acutus) in a Mediterranean salt marsh, from summer 2009 to autumn 2010. A principal component analysis was used to correlate soil and climatic data with changes in the plants' contents of chemical markers associated with stress responses: ions, osmolytes, malondialdehyde (MDA, a marker of oxidative stress) and antioxidant systems. Stress tolerance in S. fruticosa, I. crithmoides and P. crassifolia (all succulent dicots) seemed to depend mostly on the transport of ions to aerial parts and the biosynthesis of specific osmolytes, whereas both Juncus species (monocots) were able to avoid accumulation of toxic ions, maintaining relatively high K+/Na+ ratios. For the most salt-tolerant taxa (S. fruticosa and I. crithmoides), seasonal variations of Na+, Cl−, K+ and glycine betaine, their major osmolyte, did not correlate with environmental parameters associated with salt or water stress, suggesting that their tolerance mechanisms are constitutive and relatively independent of external conditions, although they could be mediated by changes in the subcellular compartmentalization of ions and compatible osmolytes. Proline levels were too low in all the species to possibly have any effect on osmotic adjustment. However—except for P. crassifolia—proline may play a role in stress tolerance based on its ‘osmoprotectant’ functions. No correlation was observed between the degree of environmental stress and the levels of MDA or enzymatic and non-enzymatic antioxidants, indicating that the investigated halophytes are not subjected to oxidative stress under natural conditions and do not, therefore, need to activate antioxidant defence mechanisms.

Environmentally friendly agriculture needs to reduce the use of synthetic fertilizers and to reclaim nutrients from organic wastes. In this study the effect of five doses (0, 12, 24, 48 and 96 t ha(-1) ) of two two-phase olive mill waste (TPOMW)-based composts on the bioactivity and chemical characteristics of an agricultural soil and their potential to fertilize alfalfa (Medicago sativa) and stimulate nodulation were assessed during a two-year incubation experiment. The two composts were prepared either with the olive mill waste alone (compost A), which served as control, or mixed with a liquid fatty-proteinaceous hydrolyzate waste (FPH) from the pharmaceutical industry (compost AH).Compost AH resulted in greater N immobilization than compost A because the former supplied the soil with easily degradable C and N, which increased microbial biomass and activity. Both compost mineralizations during the first year of incubation supplied the soil with more nutrients (mainly N), more so with A than with AH. Nevertheless, plant growth was similar in soils amended with either A or AH. Both composts induced nodulation similarly and the highest dose (96 t ha(-1) ) increased the formation of nodules by a factor of 11 compared with the four lower doses.TPOMW serves as an effective ground material for co-composting with liquid wastes such as FPH. TPOMW supplies key nutrients and stimulates nodulation in alfalfa.

A simple compartmental model using a tipping bucket approach for the water dynamics coupled with a nitrogen¿carbon transformations model has been adapted to simulate the soil nitrogen and water balance in mature orange groves on a daily step. This model has been compared with the more mechanistic LEACHN model (the N module of the LEACHM model), which uses Richards¿ equation to simulate soil water movement in unsaturated conditions, the convection¿dispersion equation for solute transport, and that, in addition to including evapotranspiration, N transformations and N plant uptake as in the compartmental model, it also considers gaseous losses due to denitrification and ammonia volatilization, that are not considered in the compartmental model. This comparison was made using data from a three-year experiment in a citrus orchard with two nitrogen fertilization rates. After calibration using the first year data, a reasonable match between simulated and measured values in both models was observed for soil water storage in the whole profile for the validation period (2nd and 3rd year), but the agreement was not so good for the soil mineral nitrogen content. In spite of the differences in the nature and in the complexity of the two models, the soil water dynamics and drainage were well simulated during the whole period by both models. However, the LEACHN model predicted nitrate leaching better than the compartmental model, probably because it considers the nitrogen cycle in a more detailed way. This work is the first calibration and performance evaluation of the LEACHN model for citrus in the Mediterranean area and the results obtained in this study indicate that this model can be a valid tool to evaluate the effects of irrigation and N management on nitrate leaching. The compartmental model has a lower data requirement and calibration is less complex than the LEACHN model and, therefore, may be more appealing for advisory N management purposes., This work has been partially supported by the Spanish Ministerio de Ciencia e Innovacion under projects, MTM2007-64477-AR07 and INIA-RTA 2011-00136-C04-01.

[EN] A general response of plants to high soil salinity relies on the cellular accumulation of osmolytes, which help the plant to maintain osmotic balance under salt stress condition and/or act as osmoprotectants with chaperon or reactive oxygen species (ROS) scavenging activities. Yet the ecological relevance of this response for the salt tolerance mechanisms of halophytes in their natural habitats remains largely unknown. In this review, we describe and discuss published data supporting the participation of compatible solutes in those mechanisms, with especial focus on soluble carbohydrates. Evidence for a functional role of carbohydrates in salt tolerance include: (i) relatively high levels of specific sugars and polyols have been detected in many halophytic taxa; (ii) an increase in salt tolerance has often been observed in parallel with increased intracellular levels of particular soluble carbohydrates, in transgenic plants overexpressing the corresponding biosynthetic enzymes; (iii) there are several examples of genes involved in carbohydrate metabolism which are induced under salt stress conditions; (iv) specific sugars or polyols have been shown to accumulate in different halophytes upon controlled salt treatments; and (v) although very few field studies on environmentally induced carbohydrate changes in halophytes exist, in general they also support the involvement of this type of osmolytes in salt stress tolerance mechanisms. We also highlight the complexities of unequivocally attributing carbohydrates a biological role in salt tolerance mechanisms of a given tolerant species. It is proposed that research on halophytes in their natural ecosystems should be intensified, correlating seasonal changes in carbohydrate contents with the degree of environmental stress affecting the plants. This could be an important complement to experiments made under more controlled (but artificial) conditions, such as laboratory set-ups., Work in the authors' laboratories was funded by a grant to O.V. from the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution by the European Regional Development Fund.