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There is a controversy regarding when it is appropriate to apply the irrigation restriction in almond trees (Prunus dulcis Mill.) to save water without penalizing yield. We hypothesized that knowing when plants demand fewer photoassimilates would be a good indicator of less sensitivity of the crop to water deficit. One parameter that defines the photosynthetic capacity is the triose phosphate utilization (TPU). Due to its connection to the export of sugars from the leaves to other sink organs, it is a good candidate for being such an indicator. The objective was to analyze the seasonal evolution of the photosynthetic capacity of three almond cultivars (cvs Guara, Marta and Lauranne) subjected to water stress during vegetative, kernel-filling and postharvest stages. Two sustained deficit irrigation (SDI) treatments (SDI75 and SDI65 with water reductions of 25 and 35%, respectively) and a control treatment (FI) consisting of fully irrigated trees were applied. The response of curves A(N)-Ci was analyzed to assess the maximum carboxylation rate (V-cmax), maximum rate of electron transport (J(max)), TPU and mesophyll conductance to CO2. In addition, leaf water potential and yield were measured. Our experimental findings showed any significant differences in the variables analyzed among cultivars and irrigation treatments. However, consistent differences arose when the results were compared among the phenological stages. During the kernel-filling and the postharvest stages, a progressive limitation by TPU was measured, suggesting that the demand for photoassimilates by the plant was reduced. This result was supported by the correlation found between TPU and fruit growth rate. As a consequence, a downregulation in J(max) and V-cmax was also measured. This study confirms that the kernel-filling stage might be a good time to apply a reduction in the irrigation and suggests a method to detect the best moments to apply a regulated deficit irrigation in almond trees.

The need to improve agroecosystem sustainability to secure yields, minimize environmental impacts and improve soil health is widely recognized. Organic production systems are one of the strategies that may be used to alleviate the negative environmental repercussions of conventional agriculture. In the present study, we compared the impact of conventional and organic production systems on the almond (Prunus dulcis (Mill.) D.A. Webb) yield and quality of nuts of two cultivars (Marcona and Desmayo largueta), with both systems being managed on marginal hillslopes in the southeast of Spain. Our findings show that the organic production system in rainfed almond trees has positive effects on certain nut quality parameters, with a slight decrease in almond yield, specifically 9.5% for cv. D. largueta and 1.3% for cv. Marcona, with respect to the conventional system. The results obtained have varied depending on the cultivar. Statistically significant differences have been obtained for cv. Marcona in the sugar content (54.4 and 49.8 g kg−1 in organic and conventional, respectively) and the total phenol content (3.41 and 2.46 g GAE kg−1 for organic and conventional, respectively). In the case of cv D. largueta, statistically significant differences were found between the organic and conventional systems for antioxidant activity (14.8 vs. 8.68 mmol Trolox kg−1, DPPH), fatty acid content (229 vs. 188 g kg−1 dw), saturated fatty acids (36 vs. 28.7 g kg−1 dw), monounsaturated fatty acids (113 vs. 110 g kg−1 dw) and polyunsaturated fatty acids (60.3 vs. 49.6 g kg−1 dw ). Here, we show for the first time how a rainfed organic system allows for higher- quality almonds, specifically with a higher content of phytochemicals beneficial for health, which, together with the higher price compared to conventional almonds, could compensate for the yield losses while preserving the sustainability of marginal agroecosystems.

As a network of researchers we release an open-access database (EUSEDcollab) of water discharge and suspended sediment yield time series records collected in small to medium sized catchments in Europe. EUSEDcollab is compiled to overcome the scarcity of open-access data at relevant spatial scales for studies on runoff, soil loss by water erosion and sediment delivery. Multi-source measurement data from numerous researchers and institutions were harmonised into a common time series and metadata structure. Data reuse is facilitated through accompanying metadata descriptors providing background technical information for each monitoring station setup. Across ten European countries, EUSEDcollab covers over 1600 catchment years of data from 245 catchments at event (11 catchments), daily (22 catchments) and monthly (212 catchments) temporal resolution, and is unique in its focus on small to medium catchment drainage areas (median = 43 km2, min = 0.04 km2, max = 817 km2) with applicability for soil erosion research. We release this database with the aim of uniting people, knowledge and data through the European Union Soil Observatory (EUSO).

[EN]: Climate change, water resources reduction, or land degradation and abandonment are some limitations to overcome within the new model of achieving competitive and sustainable agriculture. Among the possible strategies, the implementation of drought tolerant crops with high profitability, and the application of water saving strategies such as deficit irrigation (DI) should be considered. In this regard, almond (Prunus dulcis Mill.) would be an excellent alternative under water scarcity and climate change scenarios. However, it is essential to reach an equilibrium between crop management to enhance its productivity and the water availability; defining its water requirements and the relationships between irrigation needs and crop development. In this sense, the general objective of this doctoral thesis was to improve the almond irrigation management, specifically in three of the most traditional cultivars in south Spain (cvs. Guara, Marta and Lauranne) using two DI strategies; regulated deficit irrigation (RDI) and sustained deficit irrigation (SDI). In order to optimize the irrigation water management for each studied cultivar and increase the quality of almonds, [ES]: El cambio climático, la reducción de los recursos hídricos o la degradación y el abandono de la tierra son algunas de las limitaciones que hay que superar en la búsqueda de una agricultura competitiva y sostenible. Dentro de las posibles estrategias, debe considerarse la implementación de cultivos tolerantes a la sequía con alta rentabilidad y la implementación de estrategias de ahorro de agua como las estrategias de riego deficitario (RD). Dentro de las posibilidades de cultivo, el almendro (Prunus dulcis Mill.) sería una excelente alternativa ante un escenario de escasez de agua y cambio climático. Sin embargo, es esencial alcanzar un equilibrio entre la gestión de cultivos y la disponibilidad de agua, definiendo sus necesidades hídricas y las relaciones entre las necesidades de riego y las prácticas agronómicas. En este sentido el objetivo general de esta tesis doctoral fue mejorar el manejo del riego del cultivo del almendro, concretamente en tres de las variedades más implementadas en el sector almendrero (cvs. Guara, Marta y Lauranne) usando dos estrategias de RD diferentes; riego deficitario controlado (RDC) y riego deficitario sostenido (RDS). Con el objetivo de optimizar el manejo del agua de riego para cada variedad estudiada y aumentar la calidad de la almendra obtenida

Deficit irrigation (DI) strategies are considered essential in many arid and semi-arid areas of Mediterranean countries for proper water management under drought conditions. This fact is even more necessary in crops such as almond (Prunus dulcis Mill.), which in the last recent years has been progressively introduced in irrigated areas. An essential aspect to be considered would be the ability to improve fruit-quality parameters when DI strategies are imposed, which can boost the final almond price and ensure the sustainability and competitiveness of this crop. This work examines the effects of sustained deficit irrigation (SDI) on three almond cultivars (Marta, Guara, and Lauranne) on parameters related to almond functionality, aroma and sensory profile, which consequently influence its marketability and consumers acceptance. SDI strategies allowed the improvement of physical parameters such as unit weight, kernel length, kernel thickness or color. Moreover, higher total phenolic compounds, organic acids and sugars were found in SDI almonds. Finally, the highest concentrations of volatile compounds were obtained under SDI, this being a clear advantage in relation to almond flavor. Thus, moderate SDI strategy offered relevant improvements in parameters regarding the marketability, by enhancing the final added value of hydroSOStainable almonds with respect to those cultivated under full irrigation conditions.

Terracing is a soil conservation strategy applied worldwide to prevent erosion and runoff on sloping lands. Orchard terraces can considerably reduce soil loss due to water erosion if they are well planned, correctly constructed and properly maintained. Terraces have to be combined with additional soil conservation practices, of which the most important is the maintenance of a soil cover, especially during the rainy period. On the coastal strip of the provinces of Granada and Malaga (south-eastern Spain), irrigated subtropical fruit species have been introduced and cultivated on terraces with a considerable importance as the only European producer region. The subtropical farming in this zone also has strong socio-economic impact. In the present chapter, land-use changes were analysed in a selected representative watershed over 29 years. According to the findings, formerly, 97.5% of the watershed was devoted to traditional Mediterranean crops; however, after this period, due to abandonment, this area was reduced to 17.6% and increased in subtropical fruit crops (26.6%), shrubland (29.8%) and abandoned cropland (24.6%). The main driving force in land-use change has been intensive irrigation on terraces planted with subtropical crops, which are economically more profitable than traditional rainfed crops, almond and olive, which have been replaced or abandoned. The intensification of subtropical farming in terraces provokes environmental effects, especially those regarding soil and water resources, which need to be minimized. The results support the recommendation of using plant covers on the taluses of subtropical crop terraces in order to control soil erosion and improve the soil quality in the taluses of orchard terraces. In this sense, compared to bare soil, thyme and native spontaneous vegetation plant covers reduced the runoff with 94% and 93% and declined erosion with 71% and 79%, respectively. That is to avoid the collapse of the structure and make more feasible

Mango (Mangifera indica L.) is one of the most important fruit crops in tropical and subtropical regions worldwide. On the coast of Granada and Malaga (SE Spain), irrigated subtropical fruit species have been introduced and cultivated on terraces with a considerable economic importance as the only European production region. The subtropical fruit production in this zone is possible with intensive irrigation on terraces, which are economically more profitable than traditional rainfed crops (almond and olive), which have been replaced or abandoned. A 2-year monitoring period was conducted using drainage lysimeters to determine the crop coefficients (Kc) and fruit yield in mango (Mangifera indica L. cv. Osteen) orchards. Also, some quality parameters such as titratable acidity, total soluble solids, and vitamin C were evaluated under these conditions. The averaged Kc values of mango trees varied within production cycle of 0.43, 0.67, and 0.63 at flowering, fruit set, and fruit growth, respectively. In this study, the fruit yield under full water requirements (100% ETC) averaged 24.1 kg tree−1, amounting to 21.2 kg ha−1 mm−1 in terms of water-use efficiency. The quality parameters of the mango fruits harvested in the study area were satisfactory. Thus, this study highlights the need to optimize the irrigation-water use according to actual mango requirements, thereby achieving more sustainable Mediterranean subtropical farming in orchard terraces.

Water scarcity in many semi-arid agricultural areas, in particular for the Mediterranean basin, is promoting changes in irrigated agriculture, with alternative strategies being introduced for water-use optimization. The coast of Granada and Malaga (Southeast Spain) is an economically important area for subtropical fruit cultivation. This intensively irrigated agriculture is characterized by requiring extra amounts of water and the adoption of sustainable practices to improve agricultural water management. A two-season experiment was conducted to assess (1) the water use in terraced cherimoya (Annona cherimola Mill. cv. Fino de Jete) orchards under conventional and organic production systems with drainage lysimeters, and (2) the impact on fruit yield and nutritional effects between the two considered production systems. Crop coefficient (Kc) values for cherimoya were 0.60–0.66, 0.64–0.71, and 0.48–0.62 at flowering, fruit set, and fruit growth, respectively. Fruit yield was similar in both systems, ranging from 47.1 for conventional to 44.1 kg tree−1 for organic farming, averaging 13.2 and 12.3 t·ha−1, respectively. No differences between these systems were observed in terms of leaf nutrient status, with variations in the N, P, and K contents during the different phenological stages. The N, P, and K lessen during flowering and fruit growth; the highest levels of these nutrients were fixed at harvest. These patterns were the opposite in Ca and Mg, ascribable to the antagonism between K and both Ca and Mg. Thus, these findings highlight the need to establish the optimal use of irrigation water with respect to crop requirements, thereby encouraging sustainable subtropical farming in terraces.

Water is the most limiting resource in many semi-arid areas of Mediterranean countries. Among the strategies to improve water productivity, the implementation of deficit irrigation (DI) strategies and the introduction of drought-tolerant crops in irrigated areas (such as almond) are being widely studied. Recently, the use of biostimulants to enhance crop tolerance to drought under water-scarcity scenarios is increasing. This work examines the response of three almond cultivars (‘Guara’, ‘Marta’, and ‘Lauranne’) in terms of yield and associated physiological responses in the main phenological stages to biostimulants (HYT® A and HYT® B plus) applied to young trees subjected to different irrigation levels: (i) a full irrigation treatment (FI), irrigated at 100% of crop evapotranspiration (ETC); and (ii) sustained-deficit irrigation (SDI75), irrigated at 75% of ETC. Significantly higher yields were obtained with HYT applications in 2 of 3 cultivars; these differences were most evident in the SDI75 treatment. In particular, ‘Guara’ registered the most significant improvements in nut yield when the HYT product was applied (15–20% higher). With regard to crop physiological responses, higher values of leaf water potential and stomatal conductance were noted with the HYT application in some cultivars and phenological stages. These results indicated that the use of biostimulants can be a feasible strategy for almond cultivation, especially when SDI is used.

Almond (Prunus dulcis Mill. [D.A. Webb]) is the third most widely spread crop in Spain and has traditionally been cultivated in marginal areas and shallow soils under rainfed conditions. However, it recently has been progressively introduced in flat irrigated areas. The implementation of cover crops in the inter-rows of woody crops has been proven as a suitable strategy to reduce the runoff and soil erosion but they also can boost soil quality and health. A field experiment was conducted during two-monitoring seasons to examine the soil nitrogen and carbon sequestration potential of three seeded cover crops [barley (Hordeum vulgare L.), hairy vetch (Vicia villosa Roth), and a mixture of 65% barley and 35% vetch] and a control of spontaneous flora in irrigated almond orchards (SW Spain). Here, we show that barley provided the highest biomass amount, followed by mixture covers, vetch, and the control treatment. Also, vetch covered the soil faster in the growing stage, but its residues were decomposed easier than barley and mixture treatments during the decomposition period after mowing, providing less soil protection when the risk of water erosion with autumn rainfall is high. On the other hand, vetch improved soil nitrate content by over 35% with respect to barley and mixture treatments at 0–20 cm soil depth throughout the studied period. In addition, a greater carbon input to the soil was determined in the barley plot. That is, the mixture and barley cover crops had higher potential for carbon sequestration, augmenting the soil organic carbon by more than 1.0 Mg ha−1 during the study period. Thus, taking into consideration the findings of the present experiment, the establishment of a seeded cover crop would be more advisable than spontaneous flora to mitigate soil erosion, enhancing soil fertility and carbon sequestration in irrigated almond plantations in Mediterranean semi-arid regions.

The Mediterranean region is one of the most water-scarce areas worldwide and is considered a climate-change hotspot. To assure the viability and competitiveness of irrigated agriculture, it is vital to implement strategies that can maximize water saving without compromising yield. Deficit irrigation (DI) for cultivating drought-tolerant species such as almond (Prunus dulcis (Mill.) D.A. Webb) can help in achieving this goal, while at the same time improving fruit chemical composition. This work evaluated the effect of DI techniques and cultivars on the chemical composition of almonds (cvs. Marta, Guara, and Lauranne) in order to elucidate the most suitable irrigation dose under water-scarcity scenarios. Three irrigation regimes were imposed: a control treatment (FI), which was fully irrigated, receiving 100% of the irrigation requirement (IR), and two sustained-deficit irrigation (SDI) strategies that received 75% (SDI75) and 65% (SDI65) of IR. Significant differences among cultivars and irrigation treatments were observed for antioxidant activity and organic acid, sugar, and fatty acid content, which were increased by the SDI strategies. In addition, highly significant correlations were found between leaf-water potential and components such as fumaric acid, sugars, and fatty acids. In terms of the cultivars, cv. Marta showed the highest antioxidant activity, cv. Guara was the richest in organic acids, and cv. Lauranne had the highest fatty acid content. Consequently, SDI strategies improved almond quality parameters related to their nutritional and sensory composition, with significant water savings (reductions of 25–35%) and without important yield loss.

Climate change, water resources depletion, or land degradation and abandonment are some constraints to overcome within the new paradigm of achieving competitive and sustainable agriculture. Within the possible strategies, the introduction of drought-tolerant crops with high profitability, and the implementation of water-saving strategies such as deficit irrigation (DI) should be considered. Within the crop possibilities, almond (Prunus dulcis Mill.) would be an excellent alternative under water scarcity and climate change scenarios. However, it is essential to reach an equilibrium between crop management and water availability, defining its water requirements and the relationships between irrigation needs and the agronomical practices. Once done, adaptation strategies to water scarcity should be considered, especially in those cases of lack to cover the total irrigation needs by DI practices. In this agreement, the success of these strategies will depend on the proper knowledge respect to crop phenological development and the assessment of physiological status using different available tools. Thus, different crop physiological responses to water stress will be observed and different taking decisions should be considered. Finally, implementing water-saving strategies will be done not only from the perspective of preserving maximum yields but also for product quality improvements, and hence providing a final added value.

The climate change is already affecting many agricultural systems and human environments, and the implementation of adaptation strategies, especially those related to irrigated agriculture in semiarid regions, is urgent. In this regard, deep knowledge about the effects that irrigation has on the food quality parameters will allow us to estimate the potential benefits of deficit irrigation (DI) strategies. This work presents the effects on the quality parameters of three almond cultivars (Marta, Guara, and Lauranne) subjected to three irrigation doses: (i) full-irrigated treatment (FI) at 100% crop evapotranspiration (ETC), (ii) an overirrigated treatment at 150% ETC (150% ETC), and (iii) regulated deficit irrigation (RDI65) treatment, in which irrigation was done as in FI, expect during the kernel-filling period when this treatment received 65% ETC. According to experimental findings, the cultivar most sensitive to water stress was Marta, having the most significant improvements for RDI65. In general, the effects of the irrigation dose on the morphological and physicochemical parameters were not huge but some improvements were observed in key parameters such as the color and contents of specific sugars, organic acids, and unsaturated fatty acids. Thus, it can be concluded that the irrigation dose did not drastically affect the fruit almond quality, although it is possible to improve several key parameters when a moderate RDI strategy is applied.

The demand for aromatic and medicinal plants (AMPs) is growing worldwide, and most of them are from the wild collection. Today there is a consensus that for industrial purposes the AMPs must be cultivated. Many studies have shown the importance of the collection strategy used to guarantee the plant regeneration, and soil protection against erosion process in mountainous areas in the Mediterranean region. In this work, during three-year monitoring period we compared in four AMPs two harvest strategies by cutting biomass in 25% (BHI25) and 50% (BHI50) of oregano (Origanum bastetanum L.), lavender (Lavandula lanata L.); sage (Salvia lavandulifolia V.); and santolina (Santolina rosmarinifolia L.) in order to assess their effect on essential-oil content, and to be consistent with both plant and soil conservation in Mediterranean steeply sloping areas. The experimental plots were located in Lanjarón (Granada, SE Spain), on a 20% slope. According to the findings the strategy BHI50 of fresh herb of oregano, lavender, sage, and santolina produced essential-oil yield of 13.2 ± 1.74, 17.3 ± 1.69, 9.7 ± 5.21, and 10.8 ± 2.00 L·ha-1, respectively. Since significant differences were found between BHI25 and BHI50 strategies for harvest and distillation of aromatic plants, we recommend a rational harvest, leaving the 50% of the plant biomass in the field to avoid the soil degradation. In addition, with this rational harvest strategy encourages the sustainable AMP cultivation without significant alterations for essential-oil yields, and at the same time guaranteeing the regrowth, and conservation of them in its habitat. Therefore, encouragement local decision-making measures regarding environmental compatibility, social acceptability and economic viability in land use and management will be crucial. Otherwise, the inappropriate harvest of aromatic shrubs in mountain areas compromises land conservation.

The conservation of the soil resource in semi-arid environments is one of the major challenges of agricultural systems, particularly in the Mediterranean region. In the present study, two types of soil management were compared: minimum tillage (ML) and minimum tillage with spontaneous vegetation cover (MLVE). The comparison was conducted in a rainfed almond plantation at slope (35%), under an extraordinary event in 2015 (91.3 mm and EI30 of 2,719.89 mm ha-1 h-1). In this situation in MLVE plots, the development of furrows in contrast to ML were not recorded; the total soil loss was more than 12 times lower than that recorded in the latter. This fact demonstrated the effectiveness of the vegetal cover in the protection of the agricultural soil against the erosion during extreme events. Also, for ML management, furrow erosion represented more than 60% of the total soil loss, demonstrating the dominance of this type of erosion. Finally, it should be noted that this event represents the almost total loss of soil recorded in the experimental plots during the period 2012-2015; and this consequently shows the significant impact of extreme events on erosion rates in the Mediterranean region., La conservación del recurso suelo en ambientes de tipo semiárido constituye uno de los mayores retos de los sistemas agrícolas y, en particular, en la región mediterránea. En el presente estudio se han comparado dos tipos de manejos de suelo, mínimo laboreo (ML) y mínimo laboreo con cubierta vegetal espontánea (MLVE), en una plantación de almendro en secano y en pendiente (35%), ante un evento extraordinario durante el año 2015 (91,3 mm y EI30 de 2 719,89 mm ha-1 h-1). Ante esta situación, en las parcelas de MLVE no se registró la formación de surcos en contraste con las de ML, donde la pérdida de suelo total fue más de 12 veces inferior a la registrada en estas últimas. Este hecho demuestra la eficacia de la cubierta vegetal en la protección del suelo agrícola frente a la erosión con eventos extremos de esta naturaleza. Asimismo, para el manejo de ML, la erosión por surcos representó más del 60% de la pérdida de suelo total, lo que indica el dominio de este tipo de erosión. Finalmente, cabe señalar que este evento supone la práctica totalidad de la pérdida de suelo registrada en las parcelas experimentales durante el período 2012-2015, lo que, en consecuencia, muestra el impacto significativo de los eventos extremos en las tasas de erosión en la región mediterránea.

The coast of Granada, in southeast Spain, has a zone of subtropical fruits in hillsides, distributed in terraces. Nitrogen (N) breakdown and release rates for litter were assessed in two ecosystems: (1) unaltered hillside ecosystem (ELI) without agricultural crops, with indigenous vegetation cover and (2) altered hillside ecosystem (ELA) with mango (Mangifera indica L.), avocado (Persea americana Mill.), cherimoya (Annona cherimolia Mill.), loquat (Eriobotrya japónica (Thunb.) Lindl.) and covered with aromatic and medicinal plants (PAM) in terrace slopes. In the ELA, the cherimoya litter breakdown rate was higher; among the PAM, fringed lavender (Lavandula dentata L.), mástic thyme (Thymus mastichina L.) and savory (Satureja obovata Lag.) recorded high Nitrogen release rates. In ELI, olive (Olea europea L.) and bolina (Genista umbellata (L’Hér.) Dum., had low breakdown rates. The PAM and ELA may contribute to resetting natural nutrient recycling cycles, minimizing the effects of change in land use., En la costa de Granada, sureste de España, se encuentra una zona de frutales subtropicales en laderas, distribuidos en terrazas. Se evaluaron tasas de descomposición y liberación de nitrógeno (N) de hojarasca, en dos ecosistemas: (1) ecosistema de ladera inalterado (ELI) sin cultivo agrícola, con cubierta de vegetación autóctona, y (2) ecosistema de ladera alterado (ELA) con frutales de mango (Mangifera indica L.), aguacate (Persea americana Mill.), chirimoyo (Annona cherimolia Mill.), níspero (Eriobotrya japónica (Thunb.) Lindl.), y cubiertas de plantas aromáticas y medicinales (PAM) en los taludes de las terrazas. En ELA la tasa de descomposición de hojarasca de chirimoyo fue la más alta, y entre las PAM la alhucema rizada (Lavandula dentata L.), así como la mejorana (Thymus mastichina L.), alhucema rizada (Lavandula dentata L.) y ajedrea (Satureja obovata Lag.) registraron altas tasas de liberación de N. En ELI acebuche (Olea europea L.) y bolina (Genista umbellata (L’Hér.) Dum., tuvieron bajas tasas de descomposición. Las PAM en ELA pueden contribuir a restablecer los ciclos naturales de reciclado de nutrientes, minimizando los efectos del cambio de uso del suelo.

The conservation of the soil resource in semi-arid environments is one of the major challenges of agricultural systems, particularly in the Mediterranean region. In the present study, two types of soil management were compared: minimum tillage (ML) and minimum tillage with spontaneous vegetation cover (MLVE). The comparison was conducted in a rainfed almond plantation at slope (35%), under an extraordinary event in 2015 (91.3 mm and EI30 of 2,719.89 mm ha-1 h-1). In this situation in MLVE plots, the development of furrows in contrast to ML were not recorded; the total soil loss was more than 12 times lower than that recorded in the latter. This fact demonstrated the effectiveness of the vegetal cover in the protection of the agricultural soil against the erosion during extreme events. Also, for ML management, furrow erosion represented more than 60% of the total soil loss, demonstrating the dominance of this type of erosion. Finally, it should be noted that this event represents the almost total loss of soil recorded in the experimental plots during the period 2012-2015; and this consequently shows the significant impact of extreme events on erosion rates in the Mediterranean region., La conservación del recurso suelo en ambientes de tipo semiárido constituye uno de los mayores retos de los sistemas agrícolas y, en particular, en la región mediterránea. En el presente estudio se han comparado dos tipos de manejos de suelo, mínimo laboreo (ML) y mínimo laboreo con cubierta vegetal espontánea (MLVE), en una plantación de almendro en secano y en pendiente (35%), ante un evento extraordinario durante el año 2015 (91,3 mm y EI30 de 2 719,89 mm ha-1 h-1). Ante esta situación, en las parcelas de MLVE no se registró la formación de surcos en contraste con las de ML, donde la pérdida de suelo total fue más de 12 veces inferior a la registrada en estas últimas. Este hecho demuestra la eficacia de la cubierta vegetal en la protección del suelo agrícola frente a la erosión con eventos extremos de esta naturaleza. Asimismo, para el manejo de ML, la erosión por surcos representó más del 60% de la pérdida de suelo total, lo que indica el dominio de este tipo de erosión. Finalmente, cabe señalar que este evento supone la práctica totalidad de la pérdida de suelo registrada en las parcelas experimentales durante el período 2012-2015, lo que, en consecuencia, muestra el impacto significativo de los eventos extremos en las tasas de erosión en la región mediterránea.

Lateral transfer of organic carbon and phosphorus by water erosion at hillslope scale can be a key component in understanding their budget in agricultural areas, particularly those located in areas where erosion rates are high. In this study dissolved organic carbon (DOC) and dissolved reactive phosphorus (DRP) in runoff, and organic carbon (OC) and total phosphorus (TP) in sediment were measured in three olive orchards. These measurements were carried out in a three year runoff plots trial under two different soil management systems (temporary cover crop in the lanes, CC, and conventional tillage, CT). DOC losses (7.8–13.6 kg ha-1 yr-1) were equivalent, and OC losses (101–432 kg ha-1 yr-1) were higher than those measured in other agricultural and forest systems. Thus, both sources of OC, dissolved in runoff and in sediment, should not be neglected as a relevant flux to water bodies in the region and in the soil organic carbon (SOC) balance at hillslope scale. Losses of DRP (0.03–0.21 kg ha-1 yr-1) were in the lower to medium range of published values in agricultural areas, while losses of TP in sediment (2–39 kg ha-1 yr-1) were in the higher range of those reported form agricultural areas in the Mediterranean region, as the combined result of enrichment in sediment and high sediment losses. There is the scope for a large reduction of TP by reducing sediment losses through appropriate CC management. Average annual concentration of DOC in runoff and OC and TP in sediment was correlated with that of the top 5 cm of the soil in the lanes of the orchards. When analyzed at event scale, in DOC, OC and DRP presented a moderated trend towards a larger concentration for runoff events of low magnitude, below 10 to 20% runoff coefficient approximately. However, these trends at event scale presented a large scattering that precludes the determination of robust correlations for prediction and model calibration purposes.

Dissolved organic C (DOC) and dissolved reactive P (DRP) in runoff and total organic C (TOC) and total P (TP) in sediment were measured in three olive (Olea europaea L. ) orchards, during a 3-yr runoff plot experiment under two soil management systems (temporary cover crop in lanes [CC]; conventional tillage [CT]). Losses of DOC (7.8–13.6 kg ha−1 yr−1) were equivalent and losses of TOC (101–432 kg ha−1 yr−1) were higher than those measured in other agricultural systems, so both sources of organic C, dissolved and in sediment, should not be neglected when accounting fluxes to water bodies in the region and soil organic C (SOC) balances at the hillslope scale in olive orchards. Losses of DRP (0.03–0.21 kg ha−1 yr−1) were in the lower to medium range, while losses of TP (2–39 kg ha−1 yr−1) were in the higher range than those reported from agricultural areas. The average annual concentration of DOC in runoff was similar for both systems (20.9–9.1 vs. 21.4–8.7 mL L−1 for CC and CT, respectively) and also for DRP (0.45–0.02 vs. 0.20–0.02 mg L−1 for CC and CT, respectively). Concentrations of TOC and TP were higher under CC, but under CC the TOC and TP fluxes were lower because of reduced sediment losses. To achieve a large reduction in TP and TOC, CC management should provide early ground cover beginning in early fall, the start of the rainy season. A conceptual model of TOC and TP losses was developed to estimate the impact of different cover crop soil conservation strategies.

Olive growing is a centenarian activity in Andalusia, Southern Spain.,alusia holds the largest olive tree growing area in the world. In spite of the relevance of olive growing for the Mediterranean economy, the influence of soil biodiversity on olive crops has been seldom studied. We hypothesized that soil diversity must be well preserved because the Andalusian olive groves are low-input and no-till systems. Soil depth should also help to structure soil diversity. We tested the effect of site features and soil management on nematode diversity, soil properties and soil food webs. Site features included use, position, orientation, radiation, slope, altitude and regional scale. Soil management included tillage and herbicide use. Results show that at the large scale, nematode abundance and soil food web structure were reduced under the tree canopy affected by herbicides by 57.9 and 14.2 %, respectively, in comparison to areas not treated with herbicides. Nematode abundance decreased by 47.7 %, taxa richness by 12.4 % and soil food web structure by 23.4 % in areas where herbicides are applied, in comparison to surrounding oak woodlands. The absence of vegetation in bare soils impacted the lower levels of the soil food web, depleting bacterial and fungal-mediated decomposition channels. This depletion spread up in turn to microbivore nematodes and nematodes in the upper level. We also found that nematode abundances decreased with soil depth on average by 73.2 % from the top soil layer (0–2 cm) to the deepest one (10–20 cm), irrespectively of the tillage practice. © 2014, INRA and Springer-Verlag France.

La degradación de suelos en los agroecosistemas mediterráneos implica una pérdida de utilidad actual y una reducción de sus funciones potenciales, tanto por procesos naturales, como aquellos especialmente inducidos e intensificados por las acciones humanas. Se evalúa el impacto de la erosión y escorrentía en diferentes tipos de uso del suelo (TUS): agrícola (olivar, almendro y cereal), bosque (Pinus halepensis y Pinus sylvestris), matorral, pastizal y tierras de cultivo abandonadas, en Sierra Nevada (SE España). Las parcelas cerradas de erosión-escorrentía con dos repeticiones fueron instaladas en las laderas en cada TUS, registrándose tasas de erosión y escorrentía durante 22 eventos lluviosos. De acuerdo con los resultados obtenidos en el marco del presente estudio, los TUS consistentes en P. halepensis y P. sylvestris minimizaron de forma significativa la erosión y escorrentía, en contraste con los suelos agrícolas abandonados. En relación a los TUS con actividad agrícola se determinó una mayor incidencia de la erosión en el olivar respecto al almendro y cereal. El matorral registró tasas de erosión y escorrentía intermedia entre los Pinus spp. y agrícolapastizal. En consecuencia, la alteración de la cubierta vegetal es crucial para interpretar la degradación de la productividad de los suelos, así como para planificar estrategias sostenibles con el objeto de mitigar los procesos de degradación del suelo en agroecosistemas mediterráneos., Land degradation in Mediterranean agroecosystems implies the loss of current utility and reduction of its potential functions, by both natural processes and those specifically induced and intensified by human actions. The impact of erosion and runoff on different land-use types (LUT): farmland (olive, almond and cereal), forest (Pinus halepensis and Pinus sylvestris), shrubland, grassland and abandoned farmland in Sierra Nevada (SE Spain) have been assessed. The erosion plots twice replicated were located on the slopes for each land-use type, monitoring the erosion and runoff rates for 22 rainfall events. According to the results of the present study the LUT consisting in P. halepensis and P. sylvestris significantly minimized soil erosion and runoff, in contrast to the abandoned farmland. In relation to farmland activity important impact of erosion has been found in olive plots than in almond and cereal. The shrubland generated intermediate erosion and runoff rates between Pinus trees and agriculture-grassland plots. Consequently, plant cover change is crucial in interpreting the productivity degradation of soils, as well as in planning sustainable strategies to mitigate soil degradation processes in Mediterranean agroecosystems.

A water balance model developed to simulate the effect of different soil management alternatives, as for instance conventional tillage or cover crop, on soil water balance has been implemented in a user friendly interface in order to allow its use by technicians and other stakeholder in the olive sector. In spite of this simplified interface for the user, the model uses process-based methodologies to describe the key processes controlling water balance in rainfed olive orchards, such as runoff, deep percolation, cover crop growth, soil evaporation and olive and cover crop transpiration. Model predictions were evaluated using 3-year period of runoff and soil moisture data for different soil managements from an experimental field located in an olive orchard in Southern Spain. Comparison of simulated results with experimental data suggests that the model predicts satisfactorily runoff losses and soil moisture. Thus, annual runoff simulation provided a RMSE of 4.4 mm and the model efficiency was in general higher than 0.5. This suggests that the described model could be a useful tool for stakeholders to carry out a complete evaluation of different soil management alternatives in olive orchards. Finally, an example of an application of the model is presented. In this example, the model is used to evaluate the impact of using a cover crop, including different mowing dates, on the different components of the soil water balance compared to conventional tillage for the conditions of Cordoba, Southern Spain, using a 50 year long record. This exercise indicates that the use of a cover crop in these conditions have a negative impact on olive transpiration (25% average reduction), although this impact can be mitigated using an early date killing of the cover crop, March 15th for the conditions simulated in this exercise.

The conservation and sustainable management of soil and water resources are some of the biggest challenges in rainfed agricultural systems. During two hydrological years, we have studied the rates of erosion and soil runoff from hillside farming in three types of vegetation: barley (Hordeum vulgare), vetch (Vicia sativa) and thyme (Thymbra capitata), in an extensive planting of almond (Prunus amygdalus). The esperiment was conducted in Lanjaron (Granada, SE Spain) with closed erosion plots of 144 m2 (24 mx 6 m) on a hillside with a slope of 35%. Three meter wide vegetable strips were arranged intermittently and across the slope between rows of almond trees. The records of erosion and agricultural runoff were significantly lower in plots covered with thyme, in contrast to those recorded with vetch. The effectiveness of the thyme-covered over the barley and vetch ones in controlling erosion and runoff exceeded 69 and 67%, respectively. Cover crops while cutting and stopping the path of surface runoff retained transported sediments and promote their infiltration into the soil. Besides, the remaining runoff with much less energy can reinfiltrate on the ground before being intercepted by the next swath. We have concluded that the combination of growing woody plant and cover stripes represents an efficient model of adaptation to the traditional systems to improve productivity and sustainability of mountain agriculture in semiarid climate., La conservación y gestión sostenible de los recursos suelo y agua constituyen uno de los mayores retos de los sistemas agrícolas de secano. Durante dos años hidrológicos se han estudiado las tasas de erosión y escorrentía de un suelo de cultivo en ladera con tres tipos de cubierta vegetal: cebada (Hordeum vulgare), veza (Vicia sativa), y tomillo (Thymbra capitata) en una plantación extensiva de almendros (Prunus amygdalus). El ensayo se realizó en Lanjarón (Granada, SE España) con parcelas cerradas de erosión de 144 m2 (24 m x 6 m) en una ladera con pendiente del 35%. Las franjas vegetales de 3 m de ancho se dispusieron de forma intermitente y transversal a la pendiente entre hileras de árboles de almendro. Los registros de erosión y escorrentía agrícolas fueron significativamente inferiores en las parcelas con cubiertas de tomillo, en contraste con las registradas con veza. La efectividad de las cubiertas de tomillo respecto a las de cebada y veza en el control de erosión y escorrentía superaron el 69 y 67%, respectivamente. Las cubiertas vegetales al recortar y frenar la trayectoria de la escorrentía superficial retienen los sedimentos transportados y promueven su infiltración en el suelo. Asimismo, la escorrentía remanente con mucho menos energía puede reinfiltrarse en el suelo antes de ser interceptada por la siguiente franja. Se concluye que la asociación de cultivo leñoso con franjas de cubiertas vegetales representa un modelo eficiente de adaptación a los sistemas tradicionales para la mejora de la productividad y sostenibilidad de la agricultura de montaña de clima semiárido.

O experimento foi realizado na região costeira de Granada (SE España). Estudou-se a decomposição das folhas caídas sobre o solo e a ciclagem de nitrogênio a partir de folhas de frutas de origem tropical e subtropical: manga (Mangifera indica L.), cherimóia (Annona cherimola Mill.), nêspera (Eriobotrya japonica Lindl.) e abacate (Persea americana Mill.), empregando a técnica das bolsas. A atemóia apresentou as maiores taxas de decomposição para as folhas, ao passo que as de manga apresentaram-se como as mais persistentes. As constantes de decomposição (k) para as de manga, nêspera, abacate e cherimóia foram de 0,64, 0,84, 0,80 e 1,30 anos-1, respectivamente. O nitrogênio nas folhas de cherimóia e de manga foi imobilizado durante os primeiros meses em 73 e 21%, respectivamente, sendo liberado mais tarde. Em contraste com as folhas de cherimóia e de abacate, que não experimentaram o período de imobilização. O estudo da dinâmica de liberação de nutrientes em solo agrícola e, particularmente, em terras de cultivo é muito importante para prever a disponibilidade e a ciclagem de nutrientes para plantas e, em conseqüência, suas implicações junto ao meio-ambiente., El experimento se realizó en la costa de Granada (SE España). Se estudiaron la descomposición de la hojarasca y el reciclado del nitrógeno en cuatro tipos de hojas de frutales de origen subtropical y tropical: mango (Mangifera indica L.), chirimoyo (Annona cherimola Mill.), níspero (Eriobotrya japonica Lindl.) y aguacate (Persea americana Mill.), empleando la técnica de las bolsas. El chirimoyo tuvo las mayores tasas de descomposición de hojarasca, mientras que la de mango fue la más persistente. Las constantes de descomposición (k) para mango, níspero, aguacate y chirimoyo fueron 0,64, 0,84, 0,80 y 1,30 años-1, respectivamente. El nitrógeno en níspero y mango fue inmovilizado durante los primeros meses en un 73 y 21%, respectivamente, siendo liberado más tarde. En contraste con la hojarasca de chirimoyo y aguacate, que no experimentaron periodos de inmovilización. El estudio de la dinámica de liberación de nutrientes en un suelo agrícola y en particular en terrazas de cultivo es muy importante para predecir la disponibilidad y el

La agricultura de regadío cuenta hoy en día con un peso específico importante en el desarrollo económico de Andalucía, ocupando aproximadamente un 23% del total de la superficie agraria de la Comunidad, generando el 57% de la producción total y el 60% d