SSS9.4

Smallholder farming is the cornerstone of the agricultural sector in the Global South. It produces 80% of the food in Sub-Saharan Africa and Asia, though it accounts for barely 12% of the global farmland. Its sustainable intensification is therefore paramount in the accomplishment of Sustainable Development Goal 2: Zero Hunger. In this respect, adoption of sustainable water pumping technologies is key to ensure access to irrigation water, thus to secure smallholder production. Sustained uptake of agricultural technologies, however, is a complex process whose attainment is far beyond the sole technology itself. It encompasses a number of intertwined variables of all kinds related to the adopter and the use context: biophysical, financial, institutional, social, cultural, etc.

We argue that innovative business models—like sustainable product-service system (SPSS)—have the potential to ease the adoption process by overcoming many of its constraints (e.g. unaffordable upfront costs, lack of adequate servicing). These business models, unlike traditional linear approaches of technology transfer, have to take into account a broader network of stakeholders. In this way, the technology becomes an agent of interaction between involved parties. It turns into a dynamic element, connected to other products and well-developed services, that caters multiple farming needs. In our paper, we discuss enablers and barriers for the implementation of an SPSS in smallholder contexts under different scenarios. We analyze them based on evidence from Nepali and Indonesian smallholder communities where a novel hydro-powered pumping technology, known commercially as the Barsha pump, has been deployed. The insights gathered reveal many leverage points to create synergies between farmers, entrepreneurs, financial institutions, non-profit organizations and governmental agencies. They also denote the persistent challenges in the required shift of mindset for such an innovative system to come into full operation.

How to cite: Intriago Zambrano, J. C., Diehl, J. C., and Ertsen, M. W.: Sustainable Product-Service Systems: A different approach to secure smallholder production?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-701, https://doi.org/10.5194/egusphere-egu21-701, 2021.

Geostatistical and multivariate techniques have been widely used to identify and characterize the soil spatial variability, as well as to detect possible relationships between soil properties and management. Besides that, these techniques provide information regarding the spatial and temporal structural changes of soils to support better decision-making processes and management practices. Although the Zona da Mata region is a reference for sugarcane production in the northeast of Brazil, only a few studies have been carried out to clarify the effects of different management on soil physical attributes by using geostatistical and multivariate techniques. Thus, the objectives of this study were: (I) to characterize the spatial distribution of soils physical attributes under rainfed and irrigated sugarcane cultivations; (II) to identify the minimum sampling for the determination of soil physical attributes; (III) to detect the effects of the different management on soil physical attributes based on the principal component analysis (PCA). The study was carried out in the agricultural area of the Carpina Sugarcane Experimental Station of the Federal Rural University of Pernambuco, 7º51’13”S, 35º14’10”W, characterized by a Typic Hapludult with sandy clay loam soil texture. The investigated plot, cultivated with sugarcane, included a rainfed and an irrigated treatment in which a sprinkler system was installed according to a 12x12m grid. The interval between consecutive watering was fixed in two days, whereas irrigation depth was calculated to replace crop evapotranspiration (ETc) and accounting for the effective precipitation of the period. Daily ETc was estimated based on crop coefficient and reference evapotranspiration (ETo) indirectly obtained through a class A evaporation pan. In both treatments, the soil spatial variability was determined according to a 56x32m grid, on 32 soil samples collected in the 0.0-0.1m soil layer, spaced 7x8m, and georeferenced with a global position system. The soil was physically characterized according to the following attributes: bulk density (BD), soil penetration resistance (SPR), macroporosity (Macro), mesoporosity (Meso), microporosity (Micro), total porosity (TP), saturated hydraulic conductivity (Ksat), gravimetric soil water content (SWCg), geometric mean diameter (GMD) and mean weight diameter (MWD). The results of the descriptive statistics showed that among the studied attributes, Ksat, SPR, and Macro presented higher CV values, equal to 63 and 69%, 35 and 40%, and 32 and 44%, under rainfed and irrigated conditions, respectively. The minimum sampling, adequate to characterize the different soil attributes, resulted in general smaller in the rainfed area, characterized by higher homogeneity. Thus, the GMD, SWCg (both with 2 points ha^-1), and SPR (with 6 points ha^-1) were identified as the soil physical attributes requiring the lowest sample density; on the other hand, MWD and Ksat, with 14 and 15 points ha^-1, respectively, required the highest number of samples. Pearson’s correlation analysis evidenced that soil BD was the most influential physical attribute in the studied areas, with a significant and inverse effect in most of the investigated attributes. The geostatistical approach associated with the multivariate PCA provided to understand the relationships between the spatial distribution patterns associated with irrigated and rainfed management and soil physical properties.

How to cite: Almeida, B. G. D., Mantovanelli, B. C., Schossler, T. R., Freire, F. J., Souza, E. R. D., Almeida, C. D. G. C. D., Provenzano, G., and Simões Neto, D. E.: Spatial variability of the physical-hydric properties of cohesive soils under rainfed and irrigated sugarcane cultivations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1526, https://doi.org/10.5194/egusphere-egu21-1526, 2021.

In the present work, a selection of drip irrigation emitters used in greenhouse horticultural crops in the province of Almeria, Spain, were hydraulically evaluated, studying their hydraulic behavior and whether they meet with quality standards. Since manufacturers are offering lower flow emitters less spaced, all drippers tested are low flow. The hydraulic characterization will indicate the discharge and emission uniformity of the manufactured emitters, which are the fundamental parameters for the study of water use efficiency in drip irrigation. In the province of Almeria, water is a limiting factor due to the existence of a semi-arid climate, and, in addition, these limited water resources are used by intensive agriculture which causes a high consumption of these resources.

In total, 21 emitters have been evaluated, including all possible drippers according to their type of insertion (inline, pinched or online and interlinea), hydraulic behaviour (non-compensating and self-compensating) and, within the compensating ones, (anti-draining and non anti-draining). Its flow rates are between 1 and 2.4 l/h, except for a non-compensating interlina emitter of 3.8 l/h.

To carry out these tests, the criteria of the ISO 9261:2004 standard have been followed, calculating the coefficient of manufacturing variation and the emitter discharge equation on a test bench located in the La Mojonera Centre (Almeria) of the IFAPA (Andalusian Institute of Agricultural and Fishing Research and Training).

The results of this study show very good behavior in most of the emitters, and, as a consequence, a low coefficient of manufacturing variation has been obtained. The discharge equation obtained in the laboratory shows a low emisión exponent in the self-compensating emitters, being, therefore, the compensation of the pressures very high in all cases. No statistically significant differences have been found between self-compensating and non-compensating emitters by analysing their manufacturing variation coefficients. Nor have any significant differences been found between self-compensating emitters according to whether they are anti-draining or non-anti-draining, considering also the coefficient of variation. In anti-draining emitters, all closing pressures are not satisfied according to the standard, and are exceeded with very high values. The opening pressure is met for two of the four emitters, and one of those that does not meet it does so with a very large value.

How to cite: Moreno-Pérez, M. F., Baeza-Cano, R., Roldán-Cañas, J., Cánovas-Fernández, G., and Reyes-Requena, R.: Hydraulic characterization of low flow drip irrigation emitters used in intensive horticultural crops in Almeria (Spain), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2338, https://doi.org/10.5194/egusphere-egu21-2338, 2021.

The growing need to increase productivity in smaller areas guides agricultural research to develop and improve technologies that seek to meet this demand. The possibility of producing vegetables in areas where land is a limiting factor is something that draws attention, especially for family farmers and residents of urban areas who wish to produce their food. The vertical cultivation system is a technique developed focusing on the production of medicinal, horticultural, and ornamental crops, mainly in places without the ideal space for conventional production, and widely used for those that seek sustainable and organic production. The vertical system build with 200 liters drums allows the farmer to produce 52 plants in about 1 m², and all the researches carried out with these systems shows high productivity and a water use efficiency superior to conventional production systems. The use of wastewater allows the irrigator to produce in places where clean water is scarce, in addition to taking advantage of the nutritional content present in it, thus reducing fertilizer costs. For this, it is necessary to ensure that the effluent undergoes treatments to avoid possible contamination. As treatment options tested that provide safe agricultural reuse of wastewater, we present three solutions: a low-cost and nature-based treatment system compound by the combination of a biological filter bed (BFB) and a solar disinfection (SODIS) reactor, a low-cost anaerobic filter, and the SODIS reactor + H₂O₂. The BFB consists of four equals rectangular fiberglass water tanks presenting the following dimensions: 100 x 35x 31 cm. The water tanks were connected in series by a PVC pipe of 50 mm. Gravel with size ranging from 4.8 to 9.5 mm were used as biofilter media. The wastewater filtered by the BFB was directed to the SODIS reactor. The SODIS reactor was made of concrete and shaped in the form of an inverted truncated cone with the following dimensions: 1.0 m of larger radius, 0.25 m of smaller radius and 0.30 m of height. The anaerobic filter consists of six identical plastic 200 liters drums connected in series through a PVC pipe of 32 mm, filled with gravel that presented an average diameter of 14 mm. In order to speed up the SODIS process in the reactor, in a wastewater depth of 0.10 m, it was added 125 mg L^-1 of H₂O_2. Wastewater treatment can provide wastewater with concentrations of fecal coliform ≤ 1000 MPN 100 mL^-1. The wastewater treated by the treatment options described here can be safely reused to irrigate crops cultivated in vertical systems. Several studies have been showing that in crops irrigated with wastewater, crop yield can be higher than those irrigated with tap water. It is evident the need to combine treatment strategies to better take advantage of the benefits provided by the reuse of wastewater in irrigated agriculture, while using alternative ways of producing food, thus the producer can grow his food even with little available space, and avoids circulation in public places to purchase their food.

How to cite: Ventura, K., Silva, T., Pitoro, V., and Sánchez-Román, R.: Systems alternative for treating wastewater for irrigation in a vertical production system, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15431, https://doi.org/10.5194/egusphere-egu21-15431, 2021.

The problem of obtaining consistently high yields of early potatoes while minimizing the cost per unit of production is very serious. Improving the technology of growing potatoes in the dry steppe zone with the integrated irrigation and fermentation systems is aimed not only at meeting the needs of the population in these products in the region, but also at reducing the demand for the purchase of potatoes abroad.

The dynamics of the main factors of plant life associated with the state of the environment, and the needs of plants at different stages of development may differ significantly from each other, which leads to a decrease in the intensity of the production process and yield. Regulation of the hydrothermal regime of crop during the critical periods of plant vegetation can be a useful agrotechnical method in managing the water regime and productivity of potatoes in the conditions of the dry steppe zone.

The use of digital technology for regulating the water-thermal regime of irrigated crops with using simulation models is caused not only by the specifics of the problem being solved, but also by the requirements for updating irrigation and drainage systems based on the modern technical advances and fundamental knowledge in order to implement highly efficient and environmentally friendly farming on reclaimed land.

Results of multifactor experiments on potatoes cultivation under drip irrigation and finely divided sprinkling in the conditions of the Volgograd region did not allow us to identify optimal technological parameters with apply of statistical methods. In addition to the small number of field experiments over a number of years, the high variation of weather conditions was the dominant factor, that is leading the shifts in vegetative growth period duration and the most significant stages of potato growing.

The prospect to solve this problem is recognized in application of a dynamic model for the potato crop growing that considers the ability to control soil moisture in the root zone and temperature regime of the vegetation cover and simulate them depending on the emerging weather conditions and the actual state of the plants. Using the J. Richie algorithm to determine evaporation and transpiration, it is easy to reconcile the design scheme with soil moisture distribution under drip irrigation, and also consider the agrocenosis water balance with periodic fine dispersion water sprinkling when the set air temperature is exceeded in the hottest hours of the day. Preliminary numerical experiments, based on the retrospective data of earlier field experiments, indicate sufficient flexibility of the model in terms of the formed water-temperature regime simulation and its influence on potato growth processes.

In 2019, the technology of growing early potatoes was tested using a dynamic model in the Ryazan region for the temperate climate of the forest-steppe area. The model showed adequate results of its application to control the hydrothermal regime in irrigation by sprinkling.

The research is carried out under the Grant of the RFBR 19-416-343004 р_мол_а with the support of the Committee for Economic Policy and Development of the Volgograd Region.

How to cite: Buber, A. and Dobrachev, Y.: Hydrothermic regime management of the irrigated field while growing early potatoes in the arid zone, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5322, https://doi.org/10.5194/egusphere-egu21-5322, 2021.

Italy is Europe’s leading rice producer, with over half of the total production, almost totally concentrated in a large paddy rice area in the north-western part of the country, stretching across the border between the Lombardy and Piedmont regions in the Po river valley. In this area, rice irrigation has been traditionally carried out by wet seeding and continuous flooding. The introduction of alternative water-saving irrigation strategies could reduce water needs and environmental impacts; however, before extensively adopting them, their effects at both the field and irrigation district scales must be quantified.

In the context of the MEDWATERICE project (PRIMA-Section2-2018), in the agricultural season 2019 an experimental platform was set-up in a location within the paddy area (Pavia province), to compare different irrigation strategies: wet seeding and traditional flooding (WFL), dry seeding and delayed flooding (DFL), and a ‘safe' wet seeding and alternated wetting and drying (AWD). Six plots of about 20 m x 80 m each were set-up, with two replicates for each irrigation option. One out of the two replicates was instrumented with: water inflow and outflow meters, piezometers, tensiometers, and water tubes for the irrigation management in the AWD plots. A soil survey was conducted before the agricultural season (EMI sensor and physico-chemical analysis of soil samples). Periodic measurements of crop biometric parameters were conducted. Nutrients (N, P, K) and two widely used pesticides (Clomazone, MCPA) were measured in irrigation water (inflow and outflow), groundwater, and porous cups installed at two soil depths (20 and 70 cm, above and below the plough pan). Finally, rice grain yields and quality (As and Cd in the grain) were determined. The experimental activity in the platform was carried out for two years (2019 and 2020), and an upscaling of the results at the irrigation district scale is foreseen in the project.

Soil water balances at the field scale were computed through an approach integrating field measurements of irrigation flows and storages with hydrological modelling, to compare the three irrigation management strategies under similar soil conditions. Results for 2019 showed that DFL allowed a water saving of 10% compared to WFL, while a higher water saving (19%) was achieved with AWD, as expected. Rice grain yield was found to be comparable for all the investigated irrigation treatments. Also, the grain N content was not significantly affected by the water management strategy adopted: the highest values were obtained in WFL and AWD (1.4 N%), while the lowest in DFL (1.2 N%). Total As in grain was not significant for any of the irrigation strategies, but rice Cd level was statistically higher in AWD, although under the legal limits set in the EU even for baby food. As far as water quality is concerned, in surface water, soil solution and groundwater, concentrations for both herbicidesdid not reach significant values, even after treatments, except in limited cases that could depend on relevant concentrations already present in the irrigation inflow. Data for 2020 are under elaboration and first results will be illustrated during the conference.

How to cite: Gharsallah, O., Romani, M., Ricciardelli, A., Rienzner, M., Mayer, A., Chiaradia, E., Ortuani, B., Gilardi, G., Gandolfi, C., Ferrari, F., Voccia, D., Tediosi, A., Botteri, L., Botteon, E., Lamastra, L., Trevisan, M., and Facchi, A.: Alternate wetting and drying irrigation for rice: first experimental activities in northern Italy, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15130, https://doi.org/10.5194/egusphere-egu21-15130, 2021.

In Ecuador, tomato (Solanum lycopersicum L.) is a main crop which production has been increase in the latest decade. The crop is grown throughout the country, although it is in the Sierra region where locate the greenhouse production areas. Tomato manufacturers face the water scarcity problems and in addition, the small and medium producers have little knowledge regarding the amount of water they should apply to the crop, and how they should manage. Considering this framework, this study first is aimed at determining the optimal water doses for tomato crop cultivated under greenhouse conditions in the Sierra region and second, it is aimed at establishing the best irrigation frequency. The experimental study was carried out from June to December 2020, in a metallic greenhouse with plastic cover, located in the Natabuela’s parish which belong to the city of Antonio Ante in the Imbabura province. The variables studied were:  two water doses (100% and 120% of the of the evapotraspiration, ET) and four irrigation frequencies (two irrigations and one irrigation a day, one irrigation every other day and one irrigation every two days). In total, eight treatments were evaluated in an 2 x 4 factorial design, under a completely random block distribution, with four repetitions. The results show that the 120% ET irrigation dose produces the highest plant vigor and total and commercial production, while the 100% ET irrigation dose presents a higher citric acid percentage and total soluble solids content. Likewise, both doses do not showed significant differences in their water use efficiency and pH. Therefore, if the increase in production is searching then, it would be advisable to apply the 120% ET dose, although if the search is for the production quality it would be better to apply 100% ET. Regarding the irrigation frequency, one or two irrigations a day produced higher plant vigor as well as higher production and water use efficiency. None of the irrigation frequencies studied had significant differences in plant height and fruit quality variables.

How to cite: Colimba Limaico, J. E., Zubelzu Minguez, S., and Rodriguez Sinobas, L.: Assessing water doses, water use efficiency and tomato quality under greenhouse conditions in Natabuela-Ecuador, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2911, https://doi.org/10.5194/egusphere-egu21-2911, 2021.

Due to climate change, extreme weather conditions such as droughts may have an increasing impact on the water demand and the productivity of irrigated agriculture. For the purpose of adaptation to changing climate conditions, the value of information about irrigation control strategies, future climate development and soil conditions for the operation of deficit irrigation systems is evaluated. To treat climate and soil variability within one simulation optimization framework for irrigation scheduling we formulated a probabilistic framework that is based on Monte Carlo simulations. The framework can support decisions when full, deficit and supplemental irrigation strategies are applied. For the a global analysis the Deficit Irrigation Toolbox (DIT) is now adapted for a global analysis using ERA5 reanalysis data and large ensemble CESM scenarios for the global climate . It allows the analysis of the impact of information of (i) different scheduling methods (ii) different crop models, (iii) climate variability using recent and future climate scenarios. The results show a prove of concept which facilitates the development of an easy-to-use support tool for decisions about the value of management, climate and soil data and/or a cost benefit analysis of farm irrigation on a local scale.

How to cite: Schuetze, N.: Prove of concept of a global evaluation of the value of information for the management of deficit irrigation systems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14820, https://doi.org/10.5194/egusphere-egu21-14820, 2021.

In a low water availability scenario, as is increasingly frequent in Mediterranean areas threatened by climate change and endemic water scarcity, to achieve the best irrigation water efficiency is of vital importance. This study aimed to assess the feasibility of an automated irrigation scheduling strategy based on real-time threshold volumetric soil water content values (VSWC), monitored with capacitance probes, in adult early-maturing nectarine orchard (Prunus persica (L.) Batsch cv. `Flariba’, on GxN-15 rootstock). Two drip irrigation practices were tested: one control treatment (T-0) based on conventional crop evapotranspiration calculations (ETc, FAO-56), and one automated treatment (T-A) based on management allowed depletion (MAD) threshold values, derived from VSWC data, with a feed-back control system. Furthermore, for both treatments agro-physiological responses were evaluated under two different water availability scenarios (each one comprised of three consecutive growing seasons): no water restrictions (high water availability), and deficit irrigation (low water availability), in which reduced water to irrigate nectarine trees involved regulated deficit irrigation criteria.  In the high water availability scenario, T-A (MAD = 10%) and T-0 (ETc = 100%) irrigation treatments showed no significant differences in the plant-soil water status, vegetative growth, yield, and nectarine fruit quality parameters. The VSWC was not a limiting factor and full irrigating to achieve a maximum yield was a profitable option. In the low water availability scenario, the T-A treatment (subjected to MAD = 10% during pre-harvest and 30% during post-harvest) received 43% less water than the control, which promoted moderate plant and soil water deficits, leading to a decrease in vegetative growth (winter pruning weight and tree canopy cover), without compromising the total yield and nectarine fruit quality parameters (including an increase in the total soluble solid content). The crop water use efficiency increased by an average of 34%. The proposed automated irrigation strategy, based on MAD seasonal threshold values, combined with regulated deficit irrigation phenological criteria could be considered a promising tool that could be eventually extrapolated to other stone fruit orchards under water scarcity conditions. Acknowledgements: This work was funded by Spanish Agencia Estatal de Investigación (PID2019-106226RB-C21/AEI/10.13039/501100011033) and Fundacion Séneca, Región de Murcia (19903/GERM/15) projects.

How to cite: Conesa, M. R., Conejero, W., Vera, J., and Ruiz-Sánchez, M. C.: Automated soil water content-based irrigation under high and low water availability scenarios for a nectarine orchard, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11033, https://doi.org/10.5194/egusphere-egu21-11033, 2021.

In water scarcity areas, it is necessary not only reducing the water applied as much as possible, but also optimizing nutrients application to avoid soil salinization and aquifers pollution because of leaching bellow the root zone. Increasing the sustainability of fertirrigation needs technology to adjust the irrigation time, knowing more precisely the soil water retention capacity and facilitate water absorption by the crop. The aim of this trial was to establish protocols for sustainable fertirrigation in melon crop under semi-arid conditions, both at an environmental and economic level, based on the use of soil water status indicators measured by sensors that allow us to increase the irrigation water use efficiency. Two irrigation treatments were established: i) Control (CTL), irrigated to satisfy the water requirements of the crop, according to the farmer's criterion throughout the crop cycle and ii) DI, deficit irrigation, irrigated to allow a maximum soil water depletion of 20%, with respect to field capacity throughout the crop cycle, from sensors located below the 20 cm depth horizon, in order to limit water leaching into the soil. An experimental design was established with 4 repetitions per treatment distributed at random, with 5 plants per repetition. Macro and micronutrients concentration of soil solution, leaves and fruits were analysed. The crop water status was determined fortnightly by measurements taken at solar midday of stem water potential, net photosynthesis, evapotranspiration rate and leaf conductance. Whereas photosynthetically active radiation absorption, basal stem and fruit equatorial diameters were determined to estimate plant and fruit growth. The physical (longitudinal and equatorial fruit diameters, fruit weight, pulp width and firmness) and chemical (titratable acidity, pH and total soluble solid of the juice, total phenolic content, total antioxidant capacity and total ascorbic acid) characteristics of harvested fruits were determined. Total water applied in CTL treatment was 3,254 m³ ha^-1 throughout the crop cycle whereas DI received 2,284 m³ ha^-1, a 29.8% lower. In both cases, the volume of water applied was lower than recommended by FAO. The regulation of the irrigation time in the DI treatment respect to the CTL promoted a reduction of the soil water content from 30 cm depth, mitigating the water loss below the root system, along with a lower contribution of nutrients, around of 43, 41.8 and 22% of N, P and K, respectively, and less salinization of the soil profile. No significant difference between treatments was detected in the concentration of these nutrients at leaf level. No difference was observed at harvest, with 0.53 and 0.59 g fruit g^-1 total dry mass of harvest index in CTL and DI, respectively. Fruit quality was not negatively affected in DI but improved since ascorbic acid was higher. This means that DI treatment not only did not negatively affect the crop water status and the amount and quality of the yield, but also improved its biochemical quality while reducing water and nutrients use and leaching.

How to cite: Martínez-Pedreño, S. M., Berríos, P., Temnani, A., Zapata, S., Forcén, M., Lopez, J. A., Pavón, N., and Pérez-Pastor, A.: Optimisation of fertigation scheduling based on indicators of soil water status in melon growing in semi-arid areas, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15032, https://doi.org/10.5194/egusphere-egu21-15032, 2021.

Lime tree growing area is increasing in Mediterranean temperate regions. In these areas, climate change scenario is expected to raise air temperature and water shortages. Such scenario requires new approaches to implement a precision irrigation in agriculture. In order to use water more efficiently, it becomes necessary to accurately determining the crop water needs, which are estimated by crop evapotranspiration computations (ETc). In this study the ETc of young lime trees grown under Mediterranean conditions were determined using the soil water balance method. For this purpose, two-year old lime trees (Citrus latifolia Tan., cv. Bearss) grafted on C. macrophylla rootstock were cultivated in pot-lysimeters, equipped with capacitance and granular matric sensors for real-time monitoring of the soil water status. Irrigation, drainage, and pot weight were also monitored continuously. All measurements were integrated into a telemetry platform. Agro-meteorological variables, plant water status (stem (Ψ_stem) and leaf (Ψ_leaf) water potentials), and leaf gas exchange parameters (stomatal conductance (g_s) and net photosynthesis (P_n)) were measured. Along the experiment, an automated irrigation protocol based on volumetric soil water content (θ_v) threshold values were programmed, guaranteeing an adequate lime tree water status. Irrigation dose was calculated based on a feed-back strategy maintaining θ_v within 30% management allowed depletion.

During the experimental period, the lime trees were well irrigated as revealed midday Ψ_stem values that were maintained above -0.8 MPa. Also, the mean seasonal values of ≈ 7 µmol m⁻² s⁻¹ and 80 mmol m⁻² s⁻¹, for P_n and g_s, respectively, indicated optimal gas exchange values. The computed water balance parameters yielded values for the crop evapotranspiration from 0.25to 2.56 mm day^-1, in winter and summer months, respectively, with maximum values in July when evaporative demand conditions were the highest. This soil water balance was daily validated by the pot weight balance through the year.

In conclusion, the automated irrigation of young potted lime trees, using soil water content as a control system variable, has ensured an adequate lime tree water status. A simple, robust weighing/drainage lysimeter, with real-time monitoring of the soil water balance parameters, has been proved practical and economical tool for crop evapotranspiration measurements.

Acknowledgments: This work was funded by Spanish Agencia Estatal de Investigación (PID2019-106226RB-C2-1/AEI/10.13039/501100011033) and Fundación Séneca, Región de Murcia (19903/GERM/15) projects.

How to cite: Mira-García, A. B., Vera, J., Conejero, W., Conesa, M. R., and Ruiz-Sánchez, M. C.: Young lime tree evapotranspiration measurements in lysimeters with automated irrigation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11027, https://doi.org/10.5194/egusphere-egu21-11027, 2021.

The estimation of the water status in the vineyard, is a very important factor, in which every day the winegrowers show more interest since it directly affects the quality and production in the vineyards. The situation generated by COVID-19 in viticulture, adds importance to tools that provide information of the hydric status of vineyard plants in a telematic way.

In the present study, the stem water potential in the 2018 and 2019 seasons, is analysed in a vineyard belonging to the Rias Baixas wine-growing area (Vilagarcia de Arousa, Spain), with 32 sampling points distributed throughout the plot, which allows the contrast and validation with the remote sensing methodology to estimate the water status of the vineyard using satellite images.

The satellite images have been downloaded from the Sentinel-2 satellite, on the closets available dates regarding the stem water potential measurements, carried out in the months of June to September, because this dates are considered the months in which vine plants have higher water requirements.

With satellite images, two spectral index related to the detection of water stress have been calculated: NDWI (Normalized Difference Water Index) and MSI (Moisture Stress Index). Stem water potential measurements, have allowed a linear regression with both index, to validate the use of these multispectral index to determine water stress in the vineyard.

Determination coefficients of r²=0.62 and 0.67, have been obtained in July and August 2018 and 0.54 in June of 2019 for the NDWI index, as well as values of 0.53 and 0.63 in July 2018 and June 2019 respectively, when it has been analysed the MSI index.

Between both seasons, the difference observed, that implies slightly greater water stress in 2019, is reflected in the climate conditions during the summer months, with an average accumulated rainfall that doesn’t exceed 46 mm of water. Although, the NDWI index has allowed to establish better relationships in the 2018 season respect to the MSI index and the 2019 season, (r²=0.60 NDWI in 2018), as well as greater differences in terms of water stress presented in the vineyard.

With the spectral index calculated, it has been possible to validate the use of these index for the determination of the water stress of the vineyard plants, as an efficient, fast and less expensive method, which allows the application of an efficient irrigation system in the vineyard.

How to cite: Rodríguez-Fernández, M., Fandiño, M., González, X. P., and Cancela, J. J.: Estimation water status of the vineyard by calculating multispectral index from satellite images, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2187, https://doi.org/10.5194/egusphere-egu21-2187, 2021.

Olive is the main fruit tree in Spain representing 50% of the fruit trees surface, around 2,751,255 ha. Due to its adaptation to arid conditions and the scarcity of water, regulated deficit irrigation (RDI) strategy is normally applied in traditional olive orchards and recently to high density orchards. The application of RDI is one of the most important technique used in the olive hedgerow orchard. An investigation of the detection of water stress in nonhomogeneous olive tree canopies such as orchards using remote sensing imagery is presented.

In 2018 and 2019 seasons, data on stem water potential were collected to characterize tree water state in a hedgerow olive orchard cv. Arbequina located in Chozas de Canales (Toledo). Close to the measurement’s dates, remote sensing images with spectral and thermal sensors were acquired. Several vegetation indexes (VI) using both or one type of sensors were estimated from the areas selected that correspond to the olive crown avoiding the canopy shadows.

Nonparametric statistical tests between the VIs and the stem water potential were carried out to reveal the most significant correlation. The results will be discussing in the context of robustness and sensitivity between both data sets at different phenological olive state.

ACKNOWLODGEMENTS

Financial support provided by the Spanish Research Agency co-financed with European Union FEDER funds (AEI/FEDER, UE, AGL2016-77282-C3-2R project) and Comunidad de Madrid through calls for grants for the completion of Industrial Doctorates, is greatly appreciated.

How to cite: Atencia, L. K., Gómez del Campo, M., Camacho, G., Hueso, A., and Tarquis, A. M.: Estimation of water stress in olive orchards through remote sensing data analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9521, https://doi.org/10.5194/egusphere-egu21-9521, 2021.

Mandarin is one of the most important Citrus cultivated in Spain and the sustainability of the crop is subject to a constant pressure for water resources among the productive sectors and to a high climatic demand conditions and low rainfall (about 250 mm per year). The availability of irrigation water in the Murcia Region is generally close to 3,500 m³ per ha and year, so it is only possible to satisfy 50 - 60% of the late mandarin ETc, which requires about 5,500 m³ per ha. For this reason, it is necessary to provide tools to farmers in order to control the water applied in each phenological phase without promoting levels of severe water stress to the crop that negatively affect the sustainability of farms located in semi-arid conditions. Stem water potential (SWP) is a plant water status indicator very sensitive to water deficit, although its measurement is manual, discontinuous and on a small-scale.  In this way, indicators measured on a larger scale are necessary to achieve integrating the water status of the crop throughout the farm. Thus, the aim of this study was to determine the sensitivity to water deficit of different hyperspectral single bands (HSB) and their relationship with the midday SWP in mandarin trees submitted to severe water stress in different phenological phases. Four different irrigation treatments were assessed: i) a control (CTL), irrigated at 100% of the ETc throughout the growing season to satisfy plant water requirements and three water stress treatments that were irrigated at 60% of ETc throughout the season – corresponding to the real irrigation water availability – except  during: ii) the end of phase I and beginning of phase II (IS IIa), iii) the first half of phase II (IS IIb) and iv) phase III of fruit growth (IS III), which irrigation was withheld until values of -1.8 MPa of SWP or a water stress integral of 60 MPa day^-1. When these threshold values were reached, the spectral reflectance values were measured between 350 and 2500 nm using a leaf level spectroradiometer to 20 mature and sunny leaves on 4 trees per treatment. Twenty-four HVI and HSB were calculated and a linear correlation was made between each of them with SWP, where the ρ940 and ρ1250 nm single bands reflectance presented r-Pearson values of -0.78** and -0.83***, respectively. Two linear regression curves fitting were made: SWP (MPa) = -11.05 ∙ ρ940 + 7.8014 (R² =0.61) and SWP (MPa) = -13.043 ∙ ρ1250 + 8.9757 (R² =0.69). These relationships were obtained with three different fruit diameters (35, 50 and 65 mm) and in a range between -0.7 and -1.6 MPa of SWP. Results obtained show the possibility of using these single bands in the detection of water stress in adult mandarin trees, and thus propose a sustainable and efficient irrigation scheduling by means of unmanned aerial vehicles equipped with sensors to carry out an automated control of the plant water status and with a suitable temporal and spatial scale to apply precision irrigation.

How to cite: Berríos, P., Temnani, A., Zapata, S., Forcén, M., Martínez-Pedreño, S., López, J. A., Pavón, N., and Pérez-Pastor, A.: Single hyperspectral bands are highly sensitive to water stress in adult mandarin trees, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12594, https://doi.org/10.5194/egusphere-egu21-12594, 2021.

Several methodologies and techniques are available for irrigation management in protected environments. Despite the cultivation of vegetables in the greenhouse is largely present in the northeastern region of Brazil, not many research has been aimed at supporting growers for accurate irrigation management.

The objective of this study is to evaluate yield and irrigation water use efficiency of Capsicum crop cultivated in a greenhouse under different methods to define the daily irrigation depth, based on the soil water status and the atmospheric evaporative demand. Moreover, two different strategies to apply the estimated irrigation depths (single or double daily application) were also examined.

The experiment was carried out in a greenhouse in the Federal Rural University of Pernambuco (UFRPE), northeastern of Brazil (8° 01’ 07” S and 34° 56’ 53” W, altitude 6.50 m). Based on a completely randomized design, the experimental units were distributed according to a 4 x 2 factorial scheme with eight replications, with a total of 64 experimental units. Four methods to estimate daily irrigation water requirement were evaluated: two based on soil sensors (soil water content sensors EC-5, SWS, and tensiometers, TS), whereas the other two were based on the atmospheric evaporative demand (weighing lysimeter, WL, and Piché evaporimeter, PE). Moreover, the daily irrigation depths were applied with a single watering (at 8:00 am) or split into two applications (the half at 8:00 am and the half at 4:30 pm). The commercial yield of the examined crop was calculated through the relationship between the weight of fresh fruit and the area occupied by the plant.

The statistical analysis showed that the water use efficiency, the total water volume applied and the commercial yield of capsicum were significantly influenced by the method used to estimate crop water requirement, as well as the irrigation strategies. The total irrigation depth applied during the entire crop cycle resulted in equal to 509 mm, 678 mm, 716 mm, and 790 mm for treatments with WL, PE, SWS, and TS, respectively. The seasonal applied irrigation depths corresponded to an average daily crop water requirement ranging, according to the treatments, from 5.4 to 8.3 mm day^-1; these values are consistent for the examined crop cultivated under protected conditions. The highest yields of commercial fruits were obtained in the treatments in which the highest irrigation depth (SWS and TS) was applied. On the other hand, the highest values of water use efficiency were obtained in those treatments in which the irrigation depth was defined based on SWS and WL. Splitting the estimated daily irrigation depth in two applications promoted greater commercial productivity and water use efficiency (10.73 t ha^-1 and 1.60 kg m^-3) compared to a single application (8.14 t ha^-1 and 1.22 kg m^-3), with an increase of both variables of about 31%. These results evidenced that splitting the daily irrigation depth is a promising strategy to increase water use efficiency for vegetable crops in protected environments.

How to cite: Almeida, C. D. G. C. D., Gordin, L. C., Almeida, A. C. D. S., Santos Júnior, J. A., Almeida, B. G. D., and Provenzano, G.: Assessing yield and water use efficiency of Capsicum annuum L. cultivated in a greenhouse under different irrigation strategies, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8349, https://doi.org/10.5194/egusphere-egu21-8349, 2021.

This study presents a novel method for controlling and monitoring irrigation of urban green areas based on Geographical Information Systems (GIS). The proposed procedure was applied to the Spanish Valdebebas Urban Development, located in Madrid, which comprises 18 ha occupied by urban parks irrigated by subsurface drip irrigation fully automated. Its irrigation network conveys water to 67 different irrigation units, irrigating very heterogeneous plants typology. The GIS model considered the smallest irrigation unit, as the pixel size and it was fed with the information on: discharging flow, irrigated area and irrigation times of each irrigation unit. The study was performed with data from the three irrigation seasons from 2017 to 2019. Likewise, daily information from the weather station located at the urban development, used for the irrigation network operation, was also incorporated into the GIS. The results showed the spatial and temporal variability of the garden coefficients (and water needs) and the water use efficiency. The study also estimate the evolution of irrigation rates and water use efficiency indices under three different climate change forecasting scenarios (namely Representative Concentration Pathways– RCP–45, RCP 6 and RCP85). This method can assist technicians and irrigation managers to make better decisions on operating the parks’ irrigation network.

How to cite: Rodriguez-Sinobas, L., Canales-Ide, F., and Zubelzu, S.: Mapping irrigation efficiency in large urban green areas, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11074, https://doi.org/10.5194/egusphere-egu21-11074, 2021.

Abstract: The development of the wet bulb under drip irrigation in stratified (sand covered soils) presents a different behavior from that observed under homogeneous soils. The presence of a very active crop as it happens in intensive greenhouses also imposes a series of variations that have not been fully characterized. The aim of this work is to present the data acquisition methodology to calibrate and validate the Hydrus-3D model to safely define the evolution of moisture in wet bulbs generated in stratified “sanded” soils characteristic of greenhouses with tomato and pepper crops grown intensively under drip irrigation.

The procedure for collecting and processing moisture data in stratified soils has been defined. The soil and permeability curve has been adjusted experimentally for each material. It has been proved that the Hydrus-3D model can reproduce the behavior of a sand covered soils and it has been possible to verify that the predictions are adequate to what has been observed in the field.

How to cite: Roldán-Cañas, J., Zapata-Sierra, A. J., Reyes-Requena, R., and Moreno-Pérez, M. F.: Application of the Hydrus 3D model to determine the wet bulb in drip-irrigated soils of intensive greenhouses, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14512, https://doi.org/10.5194/egusphere-egu21-14512, 2021.