Optimizing sustainable agriculture: A comprehensive review of agronomic practices and their impacts on soil attributes.

This study explores agronomic management (AM) effects on soil parameters under diverse conditions. Investigating tillage practices (TP), nutrient management (NM), crop rotation (CR), organic matter (OM), irrigation management (IM), and mulching (MS), it aims to reveal impacts on soil productivity, nutrient availability, microbial activity, and overall health. Varied TP affect soil quality through compaction, porosity, and erosion risk. Proper NM is vital for nutrient cycling, preventing imbalances and acidification. CR disrupts pest cycles, reduces weed pressure, and boosts nutrient recycling. OM management enhances soil quality by influencing organic carbon, nutrient availability, pH, fertility, and water retention. Optimizing IM regulates soil water content without inducing waterlogging. MS contributes to OM content, nutrient retention, soil structure, and temperature-moisture regulation, benefiting soil biota, aggregation, soil health and agricultural productivity. The review emphasizes integrated nutrient, CR, and OM management's positive impact on fertility and microbial activity. Different TP and IM variations impact soil health and crop production. Judicious implementation of these practices is essential for sustainable agriculture. This synthesis identifies uncertainties and proposes research directions for optimizing productivity while ensuring environmental sustainability. Ongoing inquiry can guide a balanced approach between yields and resilient soil stewardship for future generations.

Calibration, testing and application of the AquaCrop model for bean crop under irrigation regimes.

Crop growth simulation models relate the soil-water-plant-atmosphere components to estimate the development and yield of plants in different scenarios, enabling the identification of efficient irrigation strategies. The aim of this study was to calibrate crop coefficients for a common bean cultivar (IAPAR 57) and assess the AquaCrop model's efficacy in simulating crop growth under different irrigation regimes (T0 - non-irrigated, T1-fully irrigated, and T2-deficit irrigated) and sowing dates (S1-March 21, S2-April 24, and S3-August 23). Successful calibration was achieved for crop seasons with suitable temperatures to crop growth (S1 and S3). However, during periods with suboptimal temperatures (April 24 season), coupled with reduced irrigation supply (T0 and T2), the AquaCrop model did not appropriately account for the combined effects of thermal and water stresses. Despite adjustments to stress coefficients, this led to an overestimation of crop growth and yield. In long-term simulations, the model successfully replicated the variability of crop water availability over cropping seasons, reflecting the impact of precipitation variations. It recommended irrigation strategies for the study region (irrigate at depletion of 120 and 170% of readily available water for sowing on March 21 and August 24, respectively) to achieve high crop yield (> 2,769 kg ha-1) and water productivity (1,050 to 1,445 kg m-3) with minimal application depths (< 150 mm). While acknowledging the need for improvements in thermal stress calculations, the AquaCrop model demonstrates promising utility in studies and applications where water availability significantly influences crop production.

Deficit Irrigation with Silicon Application as Strategy to Increase Yield, Photosynthesis and Water Productivity in Lettuce Crops.

In regions where water is a limited resource, lettuce production can be challenging. To address this, water management strategies like deficit irrigation are used to improve water-use efficiency in agriculture. Associating this strategy with silicon (Si) application could help maintain adequate levels of agricultural production even with limited water availability. Two lettuce crop cycles were conducted in a completely randomized design, with a factorial scheme (2 × 3), with three irrigation levels (60%, 80% and 100%) of crop evapotranspiration (ETc), and with and without Si application. To explore their combined effects, morphological, productive, physiological and nutritional parameters were evaluated in the crops. The results showed that deficit irrigation and Si application had a positive interaction: lettuce yield of the treatment with 80% ETc + Si was statistically similar to 100% ETc without Si in the first cycle, and the treatment with 60% ETc + Si was similar to 100% ETc without Si in the second cycle. Photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate and total chlorophyll content increased under water-stress conditions with Si application; in the first cycle, the treatment with 80% ETc + Si increased by 30.1%, 31.3%, 7.8%, 28.46% and 50.3% compared to the same treatment without Si, respectively. Si application in conditions of water deficit was also beneficial to obtain a cooler canopy temperature and leaves with higher relative water content. In conclusion, we found that Si applications attenuate water deficit effects and provide a strategy to ameliorate the yield and water productivity in lettuce crops, contributing to more sustainable practices in agriculture.

ASCD: Automatic sensing and control device for crop irrigation scheduling.

Traditional agricultural irrigation systems suffer from wasting a lot of water allocated for irrigation through evaporation and drainage. To address water waste and increase crop productivity, irrigation scheduling is used, as irrigation scheduling depends on four elements: soil moisture, soil characteristics, weather conditions, and plant type. This paper proposes a new design for monitoring agricultural conditions and controlling the amount of soil moisture by determining the required irrigation water ratios and the ideal time period for irrigating crops. An intelligent control and monitoring algorithm was created using experimental data for a wide range of plants (for soil moisture from 21 to 80 kPa), where plants were classified into three groups according to their common irrigation starting point. Based on the proposed plant classification, three models were provided, where irrigation ratios as the required parameter, soil moisture, plant type, and time interval as input parameters. This algorithm was used to program a custom-made automatic sensor and control device (ASCD). The ASCD is equipped with two input ports to communicate with two types of soil moisture sensors (a resistive sensor and a capacitive sensor) and with three output ports to drive three types of electronic irrigation valves. The ASCD can read from one sensor and drive one electronic valve at a time, the choice of which is made by the farmer. ASCD based the new algorithm showed high accuracy compared to a number of experimental results. The average absolute relative deviation (AAPD) of the new models and experimental data is 5.46 %. The application of the new algorithm shows a reduction in the amount of water used for crop irrigation during the day versus irrigation at night. On the other hand, ASCD has proven its success in sensing and controlling, and it works automatically and independently.

Water strategy improves the inflorescence primordia formation of 'Arra 15' grapevine in the Brazilian semiarid region.

Failure in irrigation management of grapevines grown in the Brazilian semiarid region can affect bud fertility. Adequate irrigation, considering both the development of bunches in the current cycle and the formation of fertile buds for subsequent cycles, can bring significant advances to viticulture. Therefore, the objective of this research was to investigate the effect of different irrigation levels during flowering on the formation of buds and potential bunches of 'Arra 15' grapevine and its relationship with metabolic processes. A field experiment was carried out in a commercial vineyard in Petrolina, Pernambuco, Brazil, during the 2021 and 2022 seasons. The experiment was designed in randomized blocks with four replications and five irrigation levels (70; 85; 100; 115 and 130% of crop evapotranspiration - ETc) during three production cycles. The variables fertile bud, vegetative bud, dead bud, potential fertility of the basal, median, and apical regions of the branches, number of potential bunches, reducing sugar, total soluble sugar, net photosynthesis, stomatal conductance, transpiration, and relative chlorophyll index were evaluated. The 115% ETc irrigation level improved the number of fertile buds and number of potential bunches. Irrigation level above 115% ETc increased gas exchange and relative chlorophyll index, while 70% ETc increased leaf sugar content. The most appropriate irrigation strategy is the application of 115% ETc during the flowering stage, for the increase of fertile buds and potential bunches of the next cycle, without influencing the vine metabolism. Total soluble sugars are a promising indicator of water deficit during flowering and as an indicator of vegetative bud formation for the next cycle.

Optimizing evapotranspiration and crop irrigation requirements of tropical forages cropping systems in Southern Brazil.

Crop irrigation requirements are usually estimated based on crop evapotranspiration (ETc) as determined by the reference evapotranspiration (ETo) and crop coefficient (Kc). There is a lack of knowledge on the irrigation requirements of tropical forage crops in Brazil, contrasting with the increasing use of irrigation in pastures. The effort of this study was to investigate what would be the water needs of tropical forages in Southern Brazil, based on a robust experimental database. The study was carried out in São Paulo State-Brazil using different forages species and their combinations [Guinea grass (GG); Guinea grass + black oat + ryegrass (GOR); Bermuda grass (BG), and Bermuda + black oat + ryegrass (BOR)]. The experimental fields were fully irrigated, and the Kc values were derived from ETc measurements on lysimeters; ETo was estimated using daily data from a nearby weather station and the standard FAO56 parameterization. Mean daily ETc values for GG, GOR, BG and BOR were 4.1, 2.9, 3.6, and 3.4 mm, respectively, and respective mean Kc values were 0.99, 0.90, 1.0, and 0.94. Average Kc values for all plots decreased as ETo increased, producing a negative Kc-ETo relationship, mainly when ETo reached values greater than 5 mm d-1. This was most likely due to internal plant stomatal resistance to vapor release from the leaves diffusing to the atmosphere at high ETo. So, the time-based Kc curves described by FAO 56 manual should be adjusted for the analyzed crops considering different ranges of ETo to improve the required irrigation depth.

Identifying robust adaptive irrigation operating policies to balance deeply uncertain economic food production and groundwater sustainability trade-offs.

Increasing irrigation demand has heavily relied on groundwater use, especially in places with highly variable water supplies that are vulnerable to drought. Groundwater management in agriculture is becoming increasingly challenging given the growing effects from overdraft and groundwater depletion worldwide. However, multiple challenges emerge when seeking to develop sustainable groundwater management in irrigated systems, such as trade-offs between the economic revenues from food production and groundwater resources, as well as the broad array of uncertainties in food-water systems. In this study we explore the applicability of Evolutionary Multi-Objective Direct Policy Search (EMODPS) to identify adaptive irrigation policies that water agencies and farmers can implement including operational decisions related to land use and groundwater use controls as well as groundwater pumping fees. The EMODPS framework yields state-aware, adaptive policies that respond dynamically as system state conditions change, for example with variable surface water (e.g., shifting management strategies across wet versus dry years). For this study, we focus on the Semitropic Water Storage district located in the San Joaquin Valley, California to provide broader insights relevant to ongoing efforts to improve groundwater sustainability in the state. Our findings demonstrate that adaptive irrigation policies can achieve sufficiently flexible groundwater management to acceptably balance revenue and sustainability goals across a wide range of uncertain future scenarios. Among the evaluated policy decisions, pumping restrictions and reductions in inflexible irrigation demands from tree crops are actions that can support dry-year pumping while maximizing groundwater storage recovery during wet years. Policies suggest that an adaptive pumping fee is the most flexible decision to control groundwater pumping and land use.

Evapotranspiration adjustment for irrigated maize-soybean rotation systems in Nebraska, USA.

Irrigation water requirements are commonly estimated based on the estimated crop evapotranspiration (ETc) as determined by the reference evapotranspiration (ETr) and crop coefficient (Kc). Recent studies show that, at high evaporative demand (high ETr), Kc tends to decrease, creating an inverse ETr-Kc relationship. The focus of this long-term study is to, if at high atmosphere demand, there is the same inverse ETr-Kc relationship in Nebraska, USA, one of the most intensely irrigated regions in the world, and as a result, propose an adjustment to the Kc-ETr approach. The study was carried out in eastern Nebraska for maize-soybean rotation fields for the period 2002-2012. The Kc was estimated based on energy balance data from eddy covariance flux towers installed in the field and a nearby automated weather station throughout the growing seasons. We found that average Kc values varied depending on the year under high ETr; measured ETc agreed reasonably well with the FAO-56 manual predicted values, but in years with high ETr such as 2012 and 2002 affecting ETc values over the growing season. It was observed that Kc decreased as ETr increased, mainly when ETr reaches values greater than 6 mm d-1 (P values < 0.001). This most likely was due to internal plant stomatal resistance to vapor release from the leaves diffusing to the atmosphere at high atmospheric demands. So, the time-based Kc curves described by FAO 56 manual should be adjusted for the analyzed crops considering different ranges of ETr to improve the required irrigation depth and irrigation management.

Drip irrigation in agricultural saline-alkali land controls soil salinity and improves crop yield: Evidence from a global meta-analysis.

Saline-alkali land, a precious candidate arable land resources, plays a critical role in achieving agricultural sustainability. Drip irrigation (DI) is an effective method for rationalizing of saline-alkali land. Nevertheless, the inapposite application of DI increases the risk of secondary salinization, significantly leading to severe soil degradation and yield decline. In this study, we conducted a meta-analysis to quantify the impacts of DI on soil salinity and crop yield to determine the appropriate DI management strategies for an irrigated agricultural system in saline-alkali land. The results showed that DI generally decreased soil salinity in the root zone by 37.7 % and increased crop yield by 37.4 % relative to flooding irrigation (FI). Drip emitters with a flow rate of 2-4 L h-1 were recommended to obtain positive effects on soil salinity control and agricultural production when an irrigation quota was below 50 % crop evapotranspiration (ETc), and the salinity of irrigation water was between 0.7 and 2 dS m-1. Further, we also found that drip-irrigated cotton had a higher yield on fine-textured saline soils. Our study provides scientific recommendations for applying DI technology worldwide in the saline-alkali land.

Monitoring Irrigation in Small Orchards with Cosmic-Ray Neutron Sensors.

Due to their unique characteristics, cosmic-ray neutron sensors (CRNSs) have potential in monitoring and informing irrigation management, and thus optimising the use of water resources in agriculture. However, practical methods to monitor small, irrigated fields with CRNSs are currently not available and the challenges of targeting areas smaller than the CRNS sensing volume are mostly unaddressed. In this study, CRNSs are used to continuously monitor soil moisture (SM) dynamics in two irrigated apple orchards (Agia, Greece) of ~1.2 ha. The CRNS-derived SM was compared to a reference SM obtained by weighting a dense sensor network. In the 2021 irrigation period, CRNSs could only capture the timing of irrigation events, and an ad hoc calibration resulted in improvements only in the hours before irrigation (RMSE between 0.020 and 0.035). In 2022, a correction based on neutron transport simulations, and on SM measurements from a non-irrigated location, was tested. In the nearby irrigated field, the proposed correction improved the CRNS-derived SM (from 0.052 to 0.031 RMSE) and, most importantly, allowed for monitoring the magnitude of SM dynamics that are due to irrigation. The results are a step forward in using CRNSs as a decision support system in irrigation management.

A Review on Regulation of Irrigation Management on Wheat Physiology, Grain Yield, and Quality.

Irrigation has been pivotal in sustaining wheat as a major food crop in the world and is increasingly important as an adaptation response to climate change. In the context of agricultural production responding to climate change, improved irrigation management plays a significant role in increasing water productivity (WP) and maintaining the sustainable development of water resources. Considering that wheat is a major crop cultivated in arid and semi-arid regions, which consumes high amounts of irrigation water, developing wheat irrigation management with high efficiency is urgently required. Both irrigation scheduling and irrigation methods intricately influence wheat physiology, affect plant growth and development, and regulate grain yield and quality. In this frame, this review aims to provide a critical analysis of the regulation mechanism of irrigation management on wheat physiology, plant growth and yield formation, and grain quality. Considering the key traits involved in wheat water uptake and utilization efficiency, we suggest a series of future perspectives that could enhance the irrigation efficiency of wheat.

A simplified model for analyzing rainwater retention performance and irrigation management of green roofs with an inclusion of water storage layer.

Rainwater retention and water content in green roofs are primarily influenced by structural configurations (i.e., soil layer, vegetation layer, and water storage layer) and climatic factors (i.e., rainfall and evapotranspiration (ET)). Based on the principle of water balance, this study proposes a conceptual model for simulating water flow in green roofs with water storage layers. Three green roof model experiments were conducted from August 1st, 2020 to July 31st, 2021 for calibrating and verifying the conceptual model. The proposed model was solved iteratively using a newly developed program in Visual Basic. The results showed that the conceptual model can capture the dynamic variations in the rainwater retention and water content of green roofs well. The average Nash-Sutcliffe efficiency coefficient is 0.65 and the average error is 6%. The annual rainwater retention capacity (RRC) of green roofs in the perennial rainy climate model was on average 28% higher than that in the seasonal rainy climate model. At the expense of water stress, high ET plants significantly increased the annual RRC of green roofs at a low level. As the water storage layer depth increased from zero to 150 mm, the annual RRC of green roofs increased by 41%, and the water stress decreased by 49%. Compared with an increase in water holding capacity and soil depth, the response of the annual RRC and water stress of green roofs for increasing water storage layer depth is much greater. As per climate of Southern China region, the water storage layer depth of 100 mm is found to obtain optimal rainwater retention and irrigation management in green roof with similar soil thickness (100 mm).

Water Stress Identification of Winter Wheat Crop with State-of-the-Art AI Techniques and High-Resolution Thermal-RGB Imagery.

Timely crop water stress detection can help precision irrigation management and minimize yield loss. A two-year study was conducted on non-invasive winter wheat water stress monitoring using state-of-the-art computer vision and thermal-RGB imagery inputs. Field treatment plots were irrigated using two irrigation systems (flood and sprinkler) at four rates (100, 75, 50, and 25% of crop evapotranspiration [ETc]). A total of 3200 images under different treatments were captured at critical growth stages, that is, 20, 35, 70, 95, and 108 days after sowing using a custom-developed thermal-RGB imaging system. Crop and soil response measurements of canopy temperature (Tc), relative water content (RWC), soil moisture content (SMC), and relative humidity (RH) were significantly affected by the irrigation treatments showing the lowest Tc (22.5 ± 2 °C), and highest RWC (90%) and SMC (25.7 ± 2.2%) for 100% ETc, and highest Tc (28 ± 3 °C), and lowest RWC (74%) and SMC (20.5 ± 3.1%) for 25% ETc. The RGB and thermal imagery were then used as inputs to feature-extraction-based deep learning models (AlexNet, GoogLeNet, Inception V3, MobileNet V2, ResNet50) while, RWC, SMC, Tc, and RH were the inputs to function-approximation models (Artificial Neural Network (ANN), Kernel Nearest Neighbor (KNN), Logistic Regression (LR), Support Vector Machine (SVM) and Long Short-Term Memory (DL-LSTM)) to classify stressed/non-stressed crops. Among the feature extraction-based models, ResNet50 outperformed other models showing a discriminant accuracy of 96.9% with RGB and 98.4% with thermal imagery inputs. Overall, classification accuracy was higher for thermal imagery compared to RGB imagery inputs. The DL-LSTM had the highest discriminant accuracy of 96.7% and less error among the function approximation-based models for classifying stress/non-stress. The study suggests that computer vision coupled with thermal-RGB imagery can be instrumental in high-throughput mitigation and management of crop water stress.

Responses of microbial community composition and function to biochar and irrigation management and the linkage to Cr transformation in paddy soil.

Combining biochar with irrigation management to alter the microbial community is a sustainable method for remediating soils contaminated by heavy metals. However, studies on how these treatments promote Cr(VI) reduction are limited, and the corresponding microbial mechanisms are unclear. Therefore, we conducted a pot experiment to explore the responses of soil microbial communities to combined biochar amendment and irrigation management strategies and their involvement in Cr transformation in paddy soils. Six treatments were established using varying concentrations of biochar (0, 1, and 2% [w/w]) combined with two irrigation management strategies (continuous flooding [CF] and dry-wet alternation [DWA]). The results showed that the combined biochar addition and irrigation management strategy significantly altered soil pH, redox potential, organic matter content, and Fe(II) and sulfide concentrations. In addition, the Cr(VI) concentration under CF irrigation management was conspicuously lower (48.2-54.4%) than that under DWA irrigation management. Biochar amendment also resulted in a substantial reduction (8.8-27.4%) in Cr(VI) concentration. Moreover, the changes in soil physicochemical properties remarkably affected the soil microbial community. The microbial diversity and abundance significantly increased with biochar amendment. Furthermore, the combined biochar amendment and CF strategy stimulated the growth of Geobacter- and Anaeromyxobacter-related Fe(III)-reducing bacteria, Gallionella-related Fe(II)-oxidizing bacteria, and Desulfovibro- and Clostridium-related sulfate-reducing bacteria, which simultaneously facilitated the generation of Fe(II) and sulfide, thereby enhancing Cr(VI) reduction. Consequently, our results suggest that the effectively increased abundance of Fe-reducing/oxidizing bacteria and sulfate-reducing bacteria via combined CF irrigation management and biochar addition may be a key factor in reducing Cr(VI) in paddy soil. The keystone genera responsible for Cr(VI) reduction were Geobacter, Anaeromyxobacter, Gallionella, Desulfovibro, and Clostridium. This study provides novel insights into the coupling mechanism of the Fe/S/Cr transformation mediated by Fe-reducing/oxidizing bacteria and sulfate-reducing bacteria.

Characterisation and Effects of Different Levels of Water Stress at Different Growth Stages in Malt Barley under Water-Limited Conditions.

Malt barley is typically grown in dryland conditions in South Africa. It is an important grain after wheat, but little is known about its water requirements and, most importantly, how it responds to water stress. Determining when water stress sets in and how malt barley responds to water deficit during its growing season is crucial for improved management of crop water requirements. The objectives of this study were to evaluate the response of transpiration (T), stomatal conductance (SC), and leaf water potential (LWP) to water stress for different growth stages of malt barley and to characterise water stress to different levels (mild, moderate, and severe). This was achieved by monitoring the water stress indicators (soil- and plant based) under greenhouse conditions in well-watered and water-stressed lysimeters over two seasons. Water stress was characterised into different levels with the aid of soil water content 'breaking points' procedure. During the first season, at the end of tillering, flag leaf, and milk/dough growth stages, which represent severe water stress, plant available water (PAW) was below 35%, 56%, 14%, and 36%, respectively. LWP responded in accordance to depletion of soil water during the growing season, with the lowest recorded value to -5.5 MPa at the end of the milk/dough growth stage in the first season. Results also show that inducing water stress resulted in high variability of T and SC for both seasons. In the second season, plants severely stressed during the anthesis growth stage recorded the least total grains per pot (TGPP), with 29.86 g of grains. The study suggests that malt barley should be prevented from experiencing severe water stress during the anthesis and milk/dough stages for optimum malt barley production. Quantification of stress into different levels will enable the evaluation of the impact of different levels of stress on the development, growth, and yield of barley.

Enhancing water use efficiency and grain yield of wheat by optimizing irrigation supply in arid and semi-arid regions of Pakistan.

The lack of good irrigation practices and policy reforms in Pakistan triggers major threats to the water and food security of the country. In the future, irrigation will happen under the scarcity of water, as inadequate irrigation water becomes the requirement rather than the exception. The precise application of water with irrigation management is therefore needed. This research evaluated the wheat grain yield and water use efficiency (WUE) under limited irrigation practices in arid and semi-arid regions of Pakistan. DSSAT was used to simulate yield and assess alternative irrigation scheduling based on different levels of irrigation starting from the actual irrigation level up to 65% less irrigation. The findings demonstrated that different levels of irrigation had substantial effects on wheat grain yield and total water consumption. After comparing the different irrigation levels, the high amount of actual irrigation level in semi-arid sites decreased the WUE and wheat grain yield. However, the arid site (Site-1) showed the highest wheat grain yield 2394 kg ha-1 and WUE 5.9 kg-3 on actual irrigation (T1), and with the reduction of water, wheat grain yield decreased continuously. The optimal irrigation level was attained on semi-arid (site-2) with 50% (T11) less water where the wheat grain yield and WUE were 1925 kg ha-1 and 4.47 kg-3 respectively. The best irrigation level was acquired with 40% less water (T9) on semi-arid (site-3), where wheat grain yield and WUE were 1925 kg ha-1 and 4.57 kg-3, respectively. The results demonstrated that reducing the irrigation levels could promote the growth of wheat, resulting in an improved WUE. In crux, significant potential for further improving the efficiency of agricultural water usage in the region relies on effective soil moisture management and efficient use of water.

Lâminas de irrigação e hidrogel nas taxas de crescimento e produção de tomateiro / Irrigation depths and hydrogel on tomato growth and production rates / Láminas de riego e hidrogel en las tasas de crecimiento y producción de tomate

O tomateiro é uma das hortaliças de maior importância econômica a nível mundial. No entanto, sua produção pode ser limitada por diversos fatores, sendo o manejo da água o principal fator limitante. Dessa forma, o uso de tecnologias que melhorem a eficiência no uso da água é de extrema importância, destacando-se entre estas o uso de hidrogel. Nesse sentido, objetivou-se nesse trabalho avaliar as taxas de crescimento e produção do tomateiro sob lâminas de irrigação e volumes de hidrogel. O experimento foi conduzido em esquema fatorial 3x4, em blocos ao acaso com quatro repetições, sendo os fatores: três volumes de hidrogel previamente hidratado (0, 50 e 100 ml por planta); e 4 lâminas de irrigação (40, 60, 80 e 100% da evapotranspiração da cultura). Foram avaliadas as taxas de crescimento absoluto e relativo da altura de planta e diâmetro do caule, massa média dos frutos e a produtividade por planta. Os resultados evidenciaram que a redução das lâminas de irrigação levou a redução linear das taxas de crescimento absolutas e relativas de altura e diâmetro. Perante essas mesmas condições, também houve redução da massa média dos frutos e da produtividade por planta. O uso de hidrogel não afetou nenhuma das características avaliadas, dessa forma, recomenda-se a sua não utilização nas condições desse estudo. Indica-se a utilização da lâmina de reposição de 100% da ETc.(AU)

Tomato is one of the most economically relevant vegetables worldwide. However, its production can be limited by several factors, with water management being the main limiting factor. Thus, the use of technologies that improve efficiency in the use of water are extremely important, with emphasis on the use of hydrogel. In this sense, the objective of this study was to evaluate the growth and production rates of tomato under irrigation depths and hydrogel volumes. The experiment was carried out in a 3x4 factorial scheme, in randomized blocks with four replications, with the following factors: three volumes of previously hydrated hydrogel (0, 50 and 100 ml per plant); and 4 irrigation depths (40, 60, 80 and 100% evapotranspiration of the crop). The absolute and relative growth rates of plant height and stem diameter, average fruit mass, and productivity per plant were evaluated. The results showed that the reduction of irrigation depths led to a linear reduction in absolute and relative growth rates in both height and diameter. Under these same conditions, there was also a reduction in the average fruit mass and productivity per plant. The use of hydrogel did not affect any of the evaluated characteristics; therefore, it is recommended not to use it under the conditions of this study. It is recommended to use the 100% ETc replacement blade.(AU)

El tomate es una de las hortalizas de mayor importancia económica a nivel mundial. Sin embargo, su producción puede verse limitada por varios factores, siendo la gestión del agua el principal factor limitante. Por ello, el uso de tecnologías que mejoren la eficiencia en el uso del agua es de suma importancia, con énfasis en el uso de hidrogel. En ese sentido, el objetivo de este estudio fue evaluar las tasas de crecimiento y producción de tomate en láminas de riego y volúmenes de hidrogel. El experimento se realizó en un esquema factorial 3x4, en bloques al azar con cuatro repeticiones, siendo los factores: tres volúmenes de hidrogel previamente hidratado (0, 50 y 100 ml por planta); y 4 láminas de riego (40, 60, 80 y 100% evapotranspiración del cultivo). Se evaluaron las tasas de crecimiento absoluto y relativo de la altura de la planta y el diámetro del tallo, la masa promedio de frutos y la productividad por planta. Los resultados mostraron que la reducción de las láminas de riego condujo a una reducción lineal en las tasas de crecimiento absoluto y relativo en altura y diámetro. En estas mismas condiciones, también se redujo la masa media de frutos y de la productividad por planta. El uso de hidrogel no afectó ninguna de las características evaluadas, por lo que se recomienda no utilizarlo en las condiciones de ese estudio. Se recomienda utilizar la lámina de repuesto del 100% del ETc.(AU)

Designing Low-Cost Capacitive-Based Soil Moisture Sensor and Smart Monitoring Unit Operated by Solar Cells for Greenhouse Irrigation Management.

Precise and quick estimates of soil moisture content for the purpose of irrigation scheduling are fundamentally important. They can be accomplished through the continuous monitoring of moisture content in the root zone area, which can be accomplished through automatic soil moisture sensors. Commercial soil moisture sensors are still expensive to be used by famers, particularly in developing countries, such as Egypt. This research aimed to design and calibrate a locally manufactured low-cost soil moisture sensor attached to a smart monitoring unit operated by Solar Photo Voltaic Cells (SPVC). The designed sensor was evaluated on clay textured soils in both lab and controlled greenhouse environments. The calibration results demonstrated a strong correlation between sensor readings and soil volumetric water content (θV). Higher soil moisture content was associated with decreased sensor output voltage with an average determination coefficient (R2) of 0.967 and a root-mean-square error (RMSE) of 0.014. A sensor-to-sensor variability test was performed yielding a 0.045 coefficient of variation. The results obtained from the real conditions demonstrated that the monitoring system for real-time sensing of soil moisture and environmental conditions inside the greenhouse could be a robust, accurate, and cost-effective tool for irrigation management.

Assessment of Irrigation Water Use Efficiency in Citrus Orchards Using AHP.

Irrigation water use efficiency, the small size of the orchards, and part-time farmers are major issues for Spanish citriculture. How should irrigation water use efficiency be assessed? Does irrigation water use efficiency improve when increasing the size of the orchards? Are full-time farmers more efficient in irrigation water use than part-time ones? To address these three questions, we propose to apply a new multicriteria approach based on the analytic hierarchy process (AHP) technique and the participation of a group of experts. A new synthetic irrigation efficiency index (IEI) was proposed and tested using data from an irrigation community (IC) and a cooperative of farmers in the East of Spain. The results showed that the size of the orchards had no relation with the IEI scoring but full-time farmers tended to have better IEI scores and, thus, were more efficient. These results were obtained from a sample of 24 orchards of oranges, navelina variety, growing in a very similar environment, and agronomical characteristics. The proposed methodology can be a useful benchmarking tool for improving the irrigation water management in other ICs taking into account the issues related to farm data sharing recorded during the case study.

Managing Crop Diseases Under Water Scarcity.

The significance of water scarcity to crop production and food security has been globally recognized as a pivotal sustainability challenge in the UN Sustainable Development Goals (86). The critical link between water scarcity and sustainability is adaptation. Various changes in water use practices have been employed to alleviate production constraints. However, the potential for these changes to influence crop diseases has received relatively little attention, despite the circumglobal importance of diseases to agricultural sustainability. This article reviews what is known about the realized effects of scarcity-driven alterations in water use practices on diseases in the field in order to raise awareness of the potential for both increased disease risk and possible beneficial effects on crop disease management. This is followed by consideration of the primary mechanistic drivers underlying disease outcomes under various water use adaptation scenarios, concluding with a vision for disease-water co-management options and future research needs.