Irrigation alternatives for avocado (Persea Americana Mill.) in the Mediterranean Subtropical region in the context of climate change: a review

Due to congenital features, avocado (Persea Americana Mill.) trees are substantial water users relative to other fruit trees. The current growing deficiency of water resources, especially in arid and semi-arid avocado-producing areas, has led to the demand for more sustainable water-saving measures. The objective of this review was to analyze the role of deficit irrigation as a strategy to face climate change and water scarcity through achieving efficiency, saving water, and maximizing the benefits that could be achieved at the level of the irrigated agricultural system. Particular attention is devoted to studies performed in the subtropical Mediterranean climate, in which irrigated avocado orchards are common. These studies analyzed irrigation demand, deficit irrigation, and determination of water status through physiological parameters, leading to possible sustainable irrigation programs for avocado in the context of water shortage scenarios. Through these insights, we conclude that under the current climatic circumstances with respect to available water resources, avocado farming requires sustainable resilience strategies to reduce irrigation water consumption without affecting the yield and quality of the fruits. Water stress inevitably affects the physiological processes that determine yield. Therefore, an admissible yield loss is required with smaller fruits and water savings made through deficit irrigation strategies. In addition, modern consumers tend to prefer foods based on sustainability, i.e., there is a high demand for socially responsible and environmentally friendly products

Conservation Agriculture as a Sustainable System for Soil Health: A Review

Soil health is a term used to describe the general state or quality of soil, and in an agroecosystem, soil health can be defined as the ability of the soil to respond to agricultural practices in a way that sustainably supports both agricultural production and the provision of other ecosystem services. Conventional agricultural practices cause deterioration in soil quality, increasing its compaction, water erosion, and salinization and decreasing soil organic matter, nutrient content, and soil biodiversity, which negatively influences the productivity and long-term sustainability of the soil. Currently, there are many evidences throughout the world that demonstrate the capability of conservation agriculture (CA) as a sustainable system to overcome these adverse effects on soil health, to avoid soil degradation and to ensure food security. CA has multiple beneficial effects on the physical, chemical, and biological properties of soil. In addition, CA can reduce the negative impacts of conventional agricultural practices on soil health while conserving the production and provision of soil ecosystem services. Today, agricultural development is facing unprecedented challenges, and CA plays a significant role in the sustainability of intensive agriculture. This review will discuss the impact of conservation agricultural practices on soil health and their role in agricultural sustainability

Impacts of a hydroinfiltrator rainwater harvesting system on soil moisture regime and groundwater distribution for olive groves in semi-arid Mediterranean regions

Dry periods in semi-arid regions constitute one of the greatest hazardous features that agriculture faces. This study investigates the effects of using a new device called ‘Hydroinfiltrator Rainwater Harvesting System (HRHS) on the water balance of soils. It was designed for arid and semi-arid zones affected by long periods of drought punctuated by heavy rainstorms. The new hydroinfiltrator consists of a net-like shell filled mainly with biochar. It is cylindrical in shape, is placed vertically and is half-buried in the soil around the crop tree to facilitate the infiltration of rainwater, irrigation or runoff water deep into the soil. The experimental plot is located in Baena (Córdoba, southern Spain) in an olive grove where the hydroinfiltrator was installed in 90 olive trees while 10 were left as a control group. In the xeric climate (bordering on arid), typical of the region, soils without a hydroinfiltrator have had a low infiltration rate, which reduces the effectiveness of precipitation and significantly increases the risk of water erosion. The effects of infiltration assisted by the device were analysed by simulating a torrential rain in which 600 L of water were passed through the hydroinfiltrator on an olive tree which had been installed 3 years previously. Geophysical methods (electrical resistivity tomography, ERT), direct analyses of soil samples, both in situ and in the laboratory, and theoretical flow models indicated a very significant increase in soil moisture (which nearly tripled in respect to the control group) because water was absorbed into the soil quickly, preventing runoff and water erosion. The soil moisture at 20 cm depth was 2.97 times higher with the HRHS than in the control plots. In addition, olive production increased by 211% and was higher in fat yield by 177%. Moreover, the resistivity profiles, taken by ERT showed that the water that entered the soil accumulated in the root zone of the olive tree, encouraged by the preferential pathways created by the roots and away from the surface, which prevented rapid evaporation during the high temperatures of spring and summer. Here we show for the first time that the use of the hydroinfiltrator rainwater harvesting system represents a significant improvement in the use of scarce water resources caused by climate change, providing agronomic and environmental benefits for rainfed, Mediterranean agricultural systems

Can Sustained Deficit Irrigation Save Water and Meet the Quality Characteristics of Mango?

Mango is one of the most cultivated tropical fruits worldwide and one of few drought-tolerant plants. Thus, in this study the effect of a sustained deficit irrigation (SDI) strategy on mango yield and quality was assessed with the aim of reducing irrigation water in mango crop. A randomized block design with four treatments was developed: (i) full irrigation (FI), assuring the crop’s water needs, and three levels of SDI receiving 75%, 50%, and 33% of irrigation water (SDI75, SDI50, and SDI33). Yield, morphology, color, titratable acidity (TA), total soluble solids (TSS), organic acids (OA), sugars, minerals, fiber, antioxidant activity (AA), and total phenolic content (TPC) were analyzed. The yield was reduced in SDI conditions (8%, 11%, and 20% for SDI75, SDI50, and SDI33, respectively), but the irrigation water productivity was higher in all SDI regimes. SDI significantly reduced the mango size, with SDI33 generating the smallest mangoes. Peel color significantly changed after 13 days of ripening, with SDI75 being the least ripe. The TA, AA, and citric acid were higher in SDI75, while the TPC and fiber increased in all SDI levels. Consequently, SDI reduced the mango size but increased the functionality of samples, without a severe detrimental effect on the yield

Soil-management strategies in organic almond orchards: implications for soil rehabilitation and nut quality

The implementation of soil conservation measures is essential to promote sustainable crop production in the Mediterranean region. In an organic rainfed almond orchard located in Lanjarón (SE, Spain), a study carried out during 2016–2021 analyzed the influence of different soil management strategies (SMSs) (TT, traditional tillage; NT, no tillage; VF, cover of Vicia faba; VS, cover of Vicia sativa; VS-VE, cover of Vicia sativa and Vicia ervilia) on some selected physical (bulk density, available water content, and aggregate stability), chemical (pH, electrical conductivity, soil-organic content, N, P, K, and micronutrients), and biological (microbial activity) soil properties, relevant to soil health, and their implications for yield and almond quality (physical and chemical). Our results showed that the SMS with legume cover improves soil properties, which had a favorable effect on soil health. The mean almond yield was not significantly affected by the SMS applied, being 315.9, 256.4, 229.1, 212.5, and 176.6 kg ha−1 year−1 for TT, VF, VS-VE, VS, and NT, respectively. Regarding the almond nut quality, the strategy based on implementation of legume cover increased the almond antioxidant activity and the total polyphenol content, which would improve their nutritional value. Here we showed how the use of sustainable SMSs improved the soil properties compared to traditional tillage in rainfed organic almonds, allowing the long-term sustainability of agroecosystems while at the same time obtaining higher nutritional quality almonds

EUSEDcollab: a network of data from European catchments to monitor net soil erosion by water

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=43km2, min=0.04km2, max=817km2) 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)

High reduction of erosion and nutrient losses by decreasing harvest intensity of lavender grown on slopes

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High reduction of erosion and nutrient losses by decreasing harvest intensity of lavender grown on slopes

In Mediterranean countries, where rainfall is scarce and irregular, intensive agriculture promotes erosion and nutrient losses from soil, ending eventually in contamination of water bodies. Wild shrubs may protect the soil against the erosivity of raindrops. However, some shrubs such as wild lavender are traditionally harvested by uprooting the entire plant. Thus, we studied here the impact of harvesting only a part of the plant biomass. Cultivating lavender, Lavandula lanata L., in erosion plots in Lanjarón, Granada, Spain, we studied the effect of two harvest intensities of 25% and 50% of the plant biomass, on soil erosion, runoff, nutrient loss (NPK) and soil-water dynamics. Our results show that decreasing the harvest intensity from 50% to 25% reduced soil loss by 67%: from 143 to 46 kg soil ha$^{-1 }$yr$^{-1}$. Water runoff was also decreased by 59%: from 13 to 5 mm yr$^{-1}$. These findings demonstrate that the rational harvest of cultivated aromatic plants protected the soil against erosion due to the reduction of soil-particle detachment by raindrop impact, and consequently avoided mechanical soil movement. Further, decreasing the harvest intensity from 50% to 25% reduced N losses by 65%, P losses by 42% and K losses by 64%. Soil-water content at 5, 10 and 20 cm deep was also higher for a harvest intensity of 25% than for a harvest intensity of 50%. In conclusion, this study supports the cultivation of lavender instead of wild harvest, following a rational harvest of biomass for reducing erosion and pollution as well as conserving soil-water content

La cubierta vegetal y la erosión de suelos por surcos por eventos lluviosos extremos en ambientes semiáridos

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 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

Cover Crop Effects on Surface Runoff and Subsurface Flow in Rainfed Hillslope Farming and Connections to Water Quality

Surface runoff and subsurface flow patterns were monitored in hillside runoff plots in almond and olive orchards with soils covered with spontaneous plants over two hydrological years. The experimental runoff plots were located on the south flank of the Sierra Nevada (Lanjarón, SE Spain) at 580 m a.s.l. with an area of 40 m2 (10 m × 4 m). The surface and subsurface discharge were collected and measured at different soil depths (0, 5, 10, 25, and 50 cm), and the dissolved nutrient concentrations (NO3–N, NH4–N, PO4–P, and K) were determined. According to the findings, the subsurface flow pathways drained most of the rainfall water compared with surface runoff, which was affected by plant cover. The influence of rainfall intensity (I30) on surface runoff was more meaningful than that on subsurface flow. Throughout the monitoring period, the runoff coefficients at soil depths of 0, 5, 10, 25, and 50 cm averaged 0.04, 0.11, 0.14, 0.17, and 0.18, respectively. Subsurface flow was one of the dominant pathways for N and K loss, whereas P loss mainly occurred via surface runoff. Moreover, the concentrations in subsurface flow were higher than the recommended level for standard water quality for NO3–N, NH4–N, and PO4–P. Subsurface flow was the main route of dissolved nutrient delivery, making these nutrients available to the root systems of trees, where nutrient uptake is more likely to occur. Thus, by lessening surface runoff and encouraging surface vegetation coverage to facilitate the recycling of nutrients and buffer the rainfall’s impact on the soil surface, nutrient loss control can be achieved