Irrigation Management Methods Research Articles

Water-energy-food-greenhouse gas nexus: An approach to solutions for water scarcity in agriculture of a semi-arid region

CONTEXTAgricultural systems involve intricate interdependencies among water, energy, and food. Increasing understanding of these linkages, along with implications for greenhouse gas (GHG) emissions and developing new assessment approaches are critical for achieving key sustainability goals. OBJECTIVES1) Evaluation of the impacts of tillage, irrigation and residue management practices on water and energy consumption, and GHG emission in the cultivation of irrigated wheat and rapeseed, 2) Developing a novel Water-Energy-Food-Greenhouse gas (WEFG) nexus index to provide a holistic assessment of the linkages among water, energy, food, and GHG emissions in agriculture, and 3) Assessing the sustainability of irrigated wheat and rapeseed cultivation under different methods of tillage, irrigation and residue management applying the WEFG nexus index. METHODSThis study formulated a new WEFG nexus index applying eight indicators of water and energy consumption, CO2-eq (CO2 equivalent) emission, water and energy mass productivity, water, energy and CO2-eq economic productivity to evaluate the sustainability of wheat and rapeseed cultivation under two field management practices: 1) furrow irrigation with conventional tillage (FICT), and 2) center pivot irrigation with no-tillage (CPNT), within a semi-arid region in northeastern Iran. Irrigation in both systems was done by applying a deficit irrigation approach. RESULTS AND CONCLUSIONSCPNT resulted on average in 46% and 53% energy consumption reductions from water and diesel usage, respectively, compared to FICT. The mean CO2-eq emission under CPNT was 26% lower than that recorded under FICT. Furthermore, the WEFG nexus index score for wheat and rapeseed under CPNT was 0.91 and 0.73, respectively, out of 1, compared to 0.18 and 0.12 for FICT. These scores suggest that the CPNT approach is a more appropriate strategy than FICT, as it effectively reduced water and energy consumption while aligning better with long-term environmental and economic aims. SIGNIFICANCEThe study applies more accurate GHG emission-based indicators to introduce a new WEFG nexus index, and it uses these for evaluation of different field management at the farm level to reduce the uncertainties in the large-scale studies. The proposed methodology for assessing multiple aspects of the WEFG nexus can change previous perceptions about agricultural management in other regions confronting multiple resources and environmental crises.

Estimating Agricultural Irrigation Water Usage in Delaware, USA

Irrigation is an important agricultural management practice and the second largest consumer of freshwater resources in Delaware. As more farmland is converted to irrigated agriculture, it is crucial that water resource managers be able to determine reasonable estimates of irrigation water usage in order to protect the resource. This study used a soil water balance approach to simulate irrigation for corn and soybeans in Delaware (USA). The simulations were divided into four scenarios to determine which irrigation management method best represents agricultural irrigation water usage in Delaware. Two scenarios utilized an evapotranspiration-based (ET-based) approach using meteorological data from the Delaware Environmental Observing System (DEOS) with a soil water availability threshold to determine when and how much to irrigate. A second set of scenarios used a calendar-based approach and a rain gauge trigger to simulate irrigation. Analyses were performed to examine the seasonal and spatial variability of irrigation in Delaware and to compare simulated irrigation data to reported water use data provided by the Delaware Department of Natural Resources and Environmental Control’s Water Allocation Permit program. Seasonal irrigation varied due to environmental as well as irrigation decision making factors. Spatially, irrigation varied primarily as a result of the soil water holding properties. The ET-based scenario with a fixed amount of irrigation had the best agreement with the reported irrigated water use data. This study demonstrated the utility of high-resolution, environmental data with a soil water balance approach to improve estimates of irrigated water usage at the state and regional scale.

Effect of Precision Water and Nitrogen Management on Yield Attributes and Yield of Aerobic Rice under Drip System

A Field experiment was conducted at Indian Institute of Rice Research (IIRR) during Rabi season of 2020 and 2021, with an objective to study the effect of precision water and nitrogen management on yield attributes and yield of aerobic rice under drip system. Treatments included three precision irrigation management methods- {I1 (DRIP irrigation 1.5 Epan in Flat bed system); I2 (DRIP irrigation 1.5 Epan in Raised bed system) and I3 {Surface irrigation (up to saturation)}} and four precision nitrogen management practices- N1 {Recommended practice (RDF)-(120:60:40 N P K kg ha-1)}; N2 {Green seeker (Optical sensor) based N application}; {N3 (LCC based N application) and N4­­ (No Nitrogen)} replicated thrice. Results of experiment shows that, the performance of aerobic rice was better when it was managed with precision ‘N’ management tools like LCC based ‘N’ application with surface method of irrigation in terms of recording higher yield attributes and yield. Among irrigation methods, higher values of yield attributes such as no of panicles m-2 (144), length of panicle (21.7 cm), panicle weight (3.4 g), filled grains panicle-1 (109.3), total grains panicle-1 (128.7), test weight (21.6 g), grain yield (4171 kg ha-1) and lowest sterility percentage (15.6%) were observed under surface irrigation followed by drip irrigation with raised beds during both years (mean). Significantly higher values for above parameters were recorded under LCC based N application (148, 21.7 cm, 3.5 g, 114.5, 132.4, 21.5 g, 4230 kg ha-1 and 13.7%) followed by recommended practice among nitrogen management practices. The experimental data revealed that, cultivating rice under aerobic ecosystem with drip irrigation along with precision nitrogen management tools like LCC and greenseeker aids in recording high yield and yield attributes besides saving water and nutrients.

The impact of cyanobacteria inoculation on soil hydraulic properties at the lab-scale experiment

Ecosystem-based approaches, including soil inoculation, have been considered to improve the soil water behavior, for the purpose of ensuring better irrigation management on farms. This study was, therefore, conducted to assess the responses of the moisture characteristic curve (MCC) and saturated hydraulic conductivity (SHC) to soil inoculation with cyanobacteria. To this end, the most suitable existing cyanobacteria (i.e., Nostoc sp. and Oscillatoria sp.) from the original soil were inoculated on clay, loam and sand textures at a small cylinder scale. After 35 days, the MCC and SHC of the treatments (six control and inoculation treatments in three repetitions) were measured using the sandbox and pressure plate, and constant head method, respectively. The results showed that, in the control treatment, the volumetric water content of the clay, loam and sand textures was 38–69%, 28–58% and 8–24%, respectively. Meanwhile, the inoculation of cyanobacteria led to a significant (P < 0.05) increase in the MCC of the loam and sand soils; their values were 36–65% and 16–31%, respectively. In the control, the SHC of the clay, loam and sand textures was 0.42, 0.54 and 1.21 cm min−1, respectively; meanwhile, this was 0.37, 0.50 and 0.67 cm min−1 for the inoculated treatments, respectively. On the other hand, the inoculated cyanobacteria reduced the SHC of the sand soils by 44%. We also found that the inoculated cyanobacteria perceptibly improved the soil surface physical and chemical properties, which could play a key role in determining the soil hydraulic and hydrologic behavior. Overall, we found that soil inoculation with cyanobacteria could be an effective approach in improving the soil water behavior, especially in coarse texture soils; thus, it could serve as a suitable irrigation and drainage management method in agricultural lands.

Principles and Practices of Plant-based Irrigation Management

Many consider tools for plant-based irrigation management methods to be the most precise way to manage irrigation in either a research or a commercial settings. Although many types of tools are available, they all measure some aspect of water movement along the soil–plant–atmosphere continuum. This article presents some of the more commonly used tools and the methods involved to properly employ them. In addition, recent literature is reviewed to provide context to the methods themselves and also to highlight each one’s specific advantages and disadvantages. Ultimately, there is no clear winner or “best” tool as all have disadvantages, either due to prohibitive cost, the amount of data output, the difficulty of data interpretation, lack of signal resolution, or lack of dynamic ability to provide decision support. Therefore, we conclude that the user should carefully weigh these varied advantages and disadvantages in the context of their production goals before deciding on a given tool for irrigation management.

The potential for expansion of irrigated rice under alternate wetting and drying in Burkina Faso

Achieving rice self-sufficiency in West Africa will require an expansion of the irrigated rice area under water-scarce conditions. However, little is known about how much area can be irrigated and where and when water-saving practices could be used. The objective of this study was to assess potentially irrigable lands for irrigated rice cultivation under water-saving technology in Burkina Faso. A two-step, spatially explicit approach was developed and implemented. Firstly, machine learning models, namely Random Forest (RF) and Maximum Entropy (MaxEnt) were deployed in ecological niche modeling (ENM) approach to assess the land suitability for irrigated rice cultivation. Spatial datasets on topography, soil characteristics, climate parameters, land use, and water were used along with the current distribution of irrigated rice locations in Burkina Faso to drive ENMs. Secondly, the climatic suitability for alternate wetting and drying (AWD), an irrigation management method for saving water in rice cultivation in irrigated systems, was assessed by using a simple water balance model for the two main growing seasons (February to June and July to November) on a dekadal time scale. The evaluation metrics of the ENMs such as the area under the curve and percentage correctly classified showed values higher than 80% for both RF and MaxEnt. The top four predictors of land suitability for irrigated rice cultivation were exchangeable sodium percentage, exchangeable potassium, depth to the groundwater table, and distance to stream networks and rivers. Potentially suitable lands for rice cultivation in Burkina Faso were estimated at 21.1 × 105 ha. The whole dry season was found suitable for AWD implementation against 25–100% of the wet season. Soil percolation was the main driver of the variation in irrigated land suitability for AWD in the wet season. The integrated modeling and water balance assessment approach used in this study can be applied to other West African countries to guide investment in irrigated rice area expansion while adapting to climate change.

Development and Evaluation of a Variable-Rate Irrigation Management Method in the Mississippi Delta

HighlightsWe developed and evaluated a variable-rate irrigation (VRI) management method for five crop years in the Mississippi Delta.VRI management significantly reduced irrigation water use in comparison with uniform-rate irrigation (URI). There was no significant difference in grain yield and irrigation water productivity between VRI and URI management.Soil apparent electrical conductivity (ECa) was used to delineate irrigation management zones and generate VRI prescriptions.Sensor-measured soil water content was used in irrigation scheduling.Abstract. Variable-rate irrigation (VRI) allows producers to site-specifically apply irrigation water at variable rates within a field to account for the temporal and spatial variability in soil and plant characteristics. Developing practical VRI methods and documenting the benefits of VRI application are critical to accelerate the adoption of VRI technologies. Using apparent soil electrical conductivity (ECa) and soil moisture sensors, a VRI method was developed and evaluated with corn and soybean for five crop years in the Mississippi Delta. Soil ECa of the study fields was mapped and used to delineate VRI management zones and create VRI prescriptions. Irrigation was scheduled using soil volumetric water content measured by soil moisture sensors. A center pivot VRI system was employed to deliver irrigation water according to the VRI prescription. Grain yield, irrigation water use, and irrigation water productivity in the VRI treatment were determined and compared with that in a uniform-rate irrigation (URI) treatment. Results showed that the grain yield and irrigation water productivity between the VRI and URI treatments were not statistically different with both corn and soybean crops. The VRI management significantly reduced the amount of irrigation water by 22% in corn and by 11% in soybean (p = 0.05). Adoption of VRI management could improve irrigation water use efficiency in the Mississippi Delta. Keywords: Soil electrical conductivity, Soil moisture sensor, Variable rate irrigation, Water management.

Impact of Evaluation of Different Irrigation Methods with Sensor System on Water Consumptive Use and Water Use Efficiency for Maize Yield

The sensor system is one of the modern and important methods of irrigation management in arid and semi-arid areas, which is water as the limiting factor for crop production. The study was applied for 2016 and 2017 seasons out in Al-Yousifya, 15 km Southwest of Baghdad. A study was conducted to evaluate coefficient uniformity, uniformity distribution and application efficiency for furrow, surface drip and subsurface drip irrigation methods and it was (98, 97 and 89)% and (97, 96 and 88)% for 2016 and 2017 seasons; respectively. And control the volumetric moisture content according to the rhizosphere depth for depths of 10, 20 and 30 cm by means of the sensor system. The results indicated that the height consumptive water use of furrow 707.91 and 689.69 mm·season-1 and the lowest for subsurface drip with emitter deep at 20 cm 313.93 and 293.50 mm·season-1 for 2016 and 2017 seasons; respectively. As well, the highest value of water use efficiency for subsurface in drip irrigation at a depth of 20 cm, was 2.71 and 2.99 kg·m-3 and the lowest value for furrow irrigation was 1.12 and 1.20 kg·m-3 for the 2016 and 2017 seasons; respectively.

Study of drought manifestation and its effect on the thermal regime of vegetation surface of crops under irrigation

Relevance of the topic. In recent years, irrigation management practices have faced new challenges related to climate change and the increase in the frequency and intensity of droughts in the southern regions. In addition, the latest technical and technological capabilities have emerged in irrigated agriculture to more effectively manage technological processes. All these processes occurring in real production and in the market of scientific and technical products, have determined the possibility and necessity of studying the influence of natural and agricultural conditions on the processes of energymass transfer in the "soil-plant-atmosphere" environment to improve management methods in modern irrigation conditions. Purpose of research is to investigate the features of formation of crop thermal regime in the conditions of air and soil drought manifestation under irrigation during 2018-2019. Research object. The research was carried out at the production fields of the farm “Freedom Farm International” in the Kakhovsky district of Kherson region during 2018-2019. Two experimental sites were equipped to carry out experimental studies on the crop rotation of "Gornostayevske -2". Methodology and Research methods. The methodology for the conduct of thermal water balance and phenological observations on the growth and development of crops at the experimental sites was applied. Standard field research techniques were used. Analytical, field, simulation modeling, mathematical statistics, geoinformation technologies (GIS), remote sensing of the Earth (RS) methods were used. Research results. As a result of the research in 2018-2019 a database of farm fields (crops, sowing dates, soil conditions, initial moisture reserves, irrigation machines and their characteristics) was created; phenological observations of plant growth and development were performed, heat and water balance calculations were made. It was established that to ensure optimal conditions for the use of thermal energy in different drought conditions, it is necessary to improve models and algorithms for operational planning of crop irrigation. Thus, to mitigate the influence of atmospheric drought, it is recommended to conduct refreshing irrigation, the timing of which can be determined on the basis of monitoring the temperature of the vegetation surface, using the data from the space images or ground-based observations. In addition, under drought conditions, in the case of applying water-balance methods used in irrigation management, it is necessary to adjust the biological coefficients of water consumption by crops, based on modeling the production process using the WOFOST model and identifying its parameters with the help of space images. The obtained new knowledge is aimed at improving irrigation management methods in modern conditions.

Effect of A200 super absorbent polymers on corn growth and yield under Partial Root-Zone Drying Irrigation

Water crisis: One of the most important and effective solutions to cope with water crisis is optimum use of consuming water in agriculture section. In other word, increasing “agricultural water productivity” is unavoidable in future planning and decision making as an effective factor. Therefore, deficit irrigation is stated as a proper solution in water limitation aiming to maximally use water volume unit. In addition to applying irrigation management methods, using developed techniques to save soil moisture is of the effective measures to increase irrigation efficiency and achieving sustainable agriculture. One of the strategies for optimal use of water resources and its preservation is using super absorbent polymers. This study was conducted during two growth seasons and within 2014-2015 in the farm and in Sari University of agricultural sciences and natural resources on single cross 704silage maize. The treatments included three irrigation regimes (as the main plot) and three levels of super absorbent (as subplots) with three replications. Irrigation treatments included complete and partial root irrigation in two levels of 55 and 65% (PRD65, PRD55) and three levels of water super absorbent polymer of A200 type, including 20, 40 and 60kg/hectare. Based on the obtained results, the plants, were regularly irrigated during their growth period and cultivated in the conditions of 60kg/hectare of super absorbent, had the most rate of yield components but they weren’t significantly different from those plants, irrigated with 55 and 65% volume. In other word, the function of super absorbent in these treatments increased the efficiency of water use and partial irrigation in 55 and 65% volume has been able to generate an equal yield with the conditions of complete irrigation.

Effects of Oxygation on Super Rice under Different Irrigation and Drainage Management Modes in Rice Field

The management mode of irrigation and drainage in field during the growth period of super rice will directly affect its growth trend, yield and water consumption. Increasing the oxygen content of irrigation water will help to promote the growth of rice and increase the yield. To understand the effect of oxygation on growth and yield of super rice, 7 irrigation and drainage management modes were designed and carried out in the super hydrid early rice field during the whole growth period by using oxygation and non-oxygation, so as to find a better management mode under different conditions. The results showed that the oxygation with the same irrigation in field had a significant effect on promoting the growth and increasing the yield of rice compared with that non-oxygation. However, the results of increasing the yield of rice by oxygation were very different among the modes. Under the oxygation condition, the Drought-tolerant II had the best growth trend and yield increase, and the irrigation water quantity was in the middle level, which had better water conservation and drainage reduction effect compared with the conventional mode. The Drought-tolerant II is “controlled irrigation and storage” mode, which is moderate water shortage controls irrigation and moderate rain storage controls drainage. The moderate water shortage controls irrigation mean that the soil moisture content is lower than 70% of the saturated water capacity as the irrigation control parameter during the drought in rice field. The moderate rain storage controls drainage the maximum rain storage depth of 200 mm as the field drainage control parameter during the rain in rice field. The results indicated that the Drought-tolerant II is a relatively optimal irrigation and drainage management method for rice field in southern China.

Yield, water use efficiency and water productivity of rice (Oryza sativa L.) relative to irrigation management and crop establishment methods

A field experiment was conducted at Crop Research Centre, RPCAU, Pusa, Bihar during Kharif, 2017. The soil of the experimental plot was sandy loam in texture with low in available N, P2O5 and K2O. The experiment was laid out in split plot design and replicated thrice. A total of twelve treatment combinations were used viz., three irrigation levels (I) in main plots and four crop establishment methods (E) in sub-plots. Irrigation level includes I1 - Continuous submergence throughout crop growth, I2-Saturation maintenance upto PI and (5±2cm) after PI and I3 -Alternate wetting and drying (5 cm irrigation at 3 DADPW) up to PI and (5±2 cm) after PI while the methods of establishment includes E1- Normal transplanting, E2- Direct w.et seeding on puddled soil, E3- Direct dry seeding and E4- Broadcasting on un-puddled soil. Grain as well as straw yield were significantly influenced by different crop establishment methods but not significantly affected by different irrigation levels. Water use efficiency and water productivity were also significantly affected by different crop establishment methods but water productivity was not significantly affected by different irrigation managements.

Assessment of Main Cereal Crop Trade Impacts on Water and Land Security in Iraq

Growing populations, socio-economic development, the pollution of rivers, and the withdrawal of fresh water are all signs of increasing water scarcity, and with 85% of global use, agriculture is the biggest freshwater user. The water footprint (WF) and virtual water (VW) are concepts used recently for freshwater resources assessment. The WF reflects how much, when and where the water was used whereas VW reveals the volume of water embedded in goods when traded. The first goal of this research is to determine the WF per ton and the WF of production (Mm3/yr) of wheat, barley, rice, and maize in Iraq. The second goal is estimating the quantities of the 4 main cereal crops imported into Iraq and assessing the impact on reducing WF and land savings for 10 years from 2007 to 2016. The results showed that the WF per ton was 1736, 1769, 3694, 2238 m3/ton and the WF of production was 5271, 1475, 997, 820 Mm3/yr for wheat, barley, rice, and maize, respectively. The median total VW imported was 4408 Mm3/yr, the largest volume was 3478 Mm3/yr from wheat, and Iraq saved about 2676 Mm3 of irrigated water and 1,239,539 M ha of land by importing crops every year during 2007–2016. The study revealed the significance of better irrigation management methods to decrease the WF through a selection of crops that need less water and cultivation in rain-fed areas, as well as the use of cereal import to conserve scarce water resources, which is crucial both in terms of water resource management and preservation of the environment. The results of this research could be used as a guideline for better water management practices in Iraq and can provide helpful data for both stakeholders and policymakers.

OPERATIONAL IRRIGATION MANAGEMENT: MODERN CHALLENGES, REALITIES AND VISIONS

Introduction. The current challenges in water and agriculture management in Ukraine wield major influence on the development of reclamation science and practice. These challenges and the realities of irrigated farming require a revision of traditional decision-making methods and criteria to ensure resource-efficient irrigation management. Analytical and experimental studies were conducted to evaluate existing irrigation practices, develop a vision for its development over the next 20-30 years, and evaluate the prospects for the use of certain innovative products that can be implemented for irrigation management under existing economic conditions and in the future. The purpose of the research was to improve the methods of operational irrigation management and support the adoption of appropriate strategic decisions to achieve resource efficiency in irrigated agriculture. The following tasks were solved: to investigate the temporal and spatial variability of the natural and economic conditions of irrigation use; to determine the basic directions of models and algorithms improvement for operational irrigation planning taking into account the spatial and temporal variability of natural and economic conditions of real production; to evaluate perspective directions of development of irrigation planning methods to ensure resource efficiency of management in the current agricultural practice. Methods and methodologies. The research was conducted during 2012-2019 at the farms of Kherson and Zaporizhzhya regions. Testing and pilot implementation of the operational irrigation planning information system “GIS Polyv” has been carried out. The studies were carried out on 306 fields, the total area of which was 9266.09 ha, the main crops were soybean, sunflower, winter wheat, alfalfa and winter rape. Research methods included on-site observations, modelling, remote sensing, and method of system analysis. Results and discussion. The role of on-site and space agro-monitoring for the correction of bioclimatic coefficients of crop water consumption taking into account the space-time variability of the actual biomass has been substantiated and demonstrated. For the adaptation of irrigation management to the conditions of air drought, it is proposed to use an additional criterion for making decisions on crop cooling, which is determined by the maximally permissible temperature duration at the vegetation surface above the physiologically acceptable level. It is established that under conditions of air drought, in addition to slowing the growth of biomass, physiological processes occur in the leaves and reproductive organs of plants, due to the increase in the temperature of the vegetation surface. According to studies of energy transfer processes in crops during periods of atmospheric drought, an increase in the use of a share of thermal energy for turbulent exchange has been found compared to the volumes of energy that is evaporated. The vision of the future development of methods of operational irrigation planning based on modern agricultural information platforms has been presented. It will allow to choose a method of operational irrigation management, based on the capabilities of each farm economy and to provide "on-line" consulting for water user organizations or farm personnel.

Management of sea reclamation land using drip irrigation with treated effluent and its effect on Rosa chinensis

The field experiment was conducted to develop a drip irrigation management method using treated wastewater effluent for Chinese rose (Rosa chinensis) cultivation in coastal saline soil during 2015–2016. Five irrigation treatments were evaluated consisting of treated effluent (electrical conductivity, 4.2–6.9 dS/m) blended with fresh water (effluent proportions of 0%, 25%, 50%, 75% and 100%). Chinese rose was planted in ridges above a gravel-sand layer at the depth of 100 cm. Irrigation was based on soil matric potential (SMP) and managed in three stages, including enhanced salt leaching stage (continuous irrigation), water-salt regulation stage (SMP, −5 kPa) and normal irrigation stage (SMP, −10 kPa). The study showed drip irrigation with different proportions of treated effluent could enhance salt leaching. After the first two stages (about 3.5 months), soil salinity above the gravel-sand layer was reduced from 37.4 dS/m to 2.16–3.86 dS/m. Throughout one year of the normal irrigation stage, salinity increases that exceeded 1 dS/m in the root-zone soil were observed in the treatments of 75% and 100% treated effluent, and mainly during a dry season. In Bohai region, the survival rate of Chinese rose decreased by 0–5% in the first two stages of irrigation, depending on treatments, but a notable reduction in plant survival rate was found in the first month of a new growing period under normal irrigation. Therefore, in saline soil typical of sea reclamation land, drip irrigation with different levels of treated effluent can be used for Chinese rose cultivation in the enhanced salt leaching and water-salt regulation stages of irrigation. Irrigation water containing ≤50% treated effluent is feasible in the normal irrigation stage, except for the first month of the new growing period, for which water containing 25% treated effluent should be used.

Produção de pimentão em ambiente protegido com água residuária

Objetivou-se estudar o desempenho agronômico do pimentão cv. Ikeda, irrigado com diferentes qualidades de água, sob dois métodos de manejos de irrigação: reflectometria no domínio da frequência e tensiometria, sob ambiente protegido. O delineamento estatístico utilizado foi o inteiramente casualizado, em esquema de parcelas subdivididas, constituído de três qualidades de água nas parcelas, e dois manejos de irrigação nas subparcelas. Foram avaliadas a produtividade total; produtividade comercial; eficiência do uso da água; massa média dos frutos; comprimento; diâmetro; relação comprimento/diâmetro; teor de sólidos solúveis; acidez titulável e pH. Os resultados obtidos permitem concluir que a produtividade e qualidade físicas dos frutos de pimentão não foram afetadas pela qualidade da água de irrigação, enquanto a menor demanda hídrica quantificada pela tensiometria influenciou significativamente apenas nos pH dos frutos.

Irrigation of ‘Hass’ avocado: effects of constant vs. temporary water stress

The main objectives of the present study were to assess the water demand for heavy fruit load of ‘Hass’ avocado throughout the growth periods and to investigate the effects of deficit irrigation during sensitive phenological phases on yield. The experimental set-up allowed the comparison between trees responses to three irrigation strategies during the entire growth period (no water stress; excessive irrigation; constant water stress) as well as the comparison between regulated deficit irrigation (RDI) managements applied during the early or the late growth period. The yield of no water stress treatments during three experimental years was very high (25–31 t ha−1) while the yields of water-stressed trees were significantly lower (16–21 t ha−1). More importantly, the yield of no water stress trees was not susceptible to alternate bearing while the yield of water-stressed trees was considerably reduced during off-crop years. Irrigation rates and the actual evapotranspiration coefficient KL = ET/ET0 for the no water stress treatment may serve as a reasonable guide for irrigation management. Fruit load should be taken into account while planning irrigation and fertilization management and plant-based methods should be used for controlling the irrigation management (scheduling and quantities). Analyses of trunk diameter variation data that lead to evaluation of trunk growth rate and maximum daily shrinkage reflect phenological stages and periodicity of shoot, fruit and root growth, and also may provide an integrative, “holistic viewpoint” of overall tree status.

Quality Management for Research Weather Data: USDA‐ARS, Bushland, TX

Core Ideas Several redundant sensors for the same variable are required for quality control. Weighing lysimeters record rainfall more accurately than do tipping bucket gauges. Southern High Plains rainfall is variable, even within a 1‐km radius. Scatterplots and time‐series graphical and statistical analyses aid quality control. Weather mediates the complex interactions of soil, water, plants, atmosphere, and agricultural and environmental interventions. Accurate and representative weather data are thus important to agricultural and environmental research, but particularly to simulation model development and testing. USDA‐ARS research using large weighing lysimeters at Bushland, TX, has produced 30 yr of evapotranspiration and ancillary data related to different methods of irrigation application and management, dryland cropping, crop choice, and agronomic management and weather. To support crop simulation modeling, weather data were gathered on a 15‐min basis at a research weather station adjacent to the weighing lysimeters since the inception of the project in 1987, as well as at nearby stations. The goal of this article is to review and demonstrate Conservation and Production Research Laboratory (CPRL) weather data quality management procedures. Data quality management has involved both quality assurance planning and operations as well as quality control methods. Data analysis revealed the importance of having multiple sensors replicating the same weather measurement because sensor failure or degradation often created gaps in data that required another data source to fill, but also because replicate sensors aided in detecting sensor error. Data from multiple stations also revealed issues of datalogger time keeping and spatial variation of weather. And, comparisons of data on the same weather measurement from various sensors that used different operating principles revealed systematic errors in some sensors. Methods of quality assurance and control involved long‐term planning for sensor calibration, maintenance and replacement, and daily and longer‐term quality control efforts based on data stream analysis.

Irrigation management methods for the production of bell pepper in agricultural substrates

This study’s objective was to assess the response and effectiveness of irrigation management systems for the production of bell pepper with different agricultural substrates, under protected conditions. The current study was conducted in a greenhouse located in Juazeiro, BA, in the northwest of Brazil. The experiment design was completely randomized in a split-plot system, with two irrigation treatments as the main plots (the drainage lysimeter and the Piché evaporimeter) and two substrates in each sub-plot (coconut fiber and pinus bark), with 5 replications per treatment. Harvest was conducted from 86 to 151 days after transplanting, and the following characteristics were evaluated: total, marketable and unmarketable yields, production per plant, fresh mass of fruits, fruit number per plant, length and diameter of fruits, length/diameter ratio, water use efficiency, pulp thickness, fruit pH, soluble solids, and titratable acidity. No interaction effects between irrigation treatments and substrates were observed on the following variables: total yield, marketable yield, non-marketable yield, production per plant, mean mass, and diameter of marketable fruits. Irrigation treatments and substrates did not show a significant effect on bell pepper yield. Drainage lysimeter-based management and coconut fiber substrate had the best results in terms of the physical quality of fruits, whereas pinus bark-based substrate positively influenced all chemical variables and the Piché evaporimeter-based irrigation management showed a good performance raising fruit pH in relation to fruits cultivated in lysimeter with pinus bark. Additional research is required under different environmental conditions so that this crop fully expresses its yield potential.

Real-time irrigation: Cost-effectiveness and benefits for water use and productivity of strawberries

Although California is experiencing permanent water deficits compensated by irrigation, the state accounts for more than 90% of total strawberry production in the United States. There is a critical need to optimize yield and crop water productivity (CWP), as influenced by irrigation management. Although studies have reported that irrigation management based on soil matric potential (ѱ) has the potential to increase yield and CWP compared to conventional practices, the cost of this technology may be a limiting factor for some growers. In this study, we assessed the cost-effectiveness of wireless tensiometer technology (WTT) for field-grown strawberries in California in comparison with the conventional irrigation management. As a second step, we evaluated the cost-effectiveness of deficit irrigation. Using data from eight sites, we calculated multiple linear regressions (MLR) to describe the relationship between: (1) fresh market yield and average soil matric potential reached before irrigation initiation (ѱirr) and (2) water use and ѱirr. Based on MLR results, we evaluated the technical performance of each irrigation management method and conducted an economic analysis. Our results showed that adopting a precise irrigation scheduling tool such as WTT is cost-effective and leads to water savings relative to conventional irrigation. Our results also revealed that any water savings associated with a deficit irrigation strategy are costly for strawberry growers.