Consumptive Water Use Research Articles

Effect of Irrigation System, Tillage System, and Seeding Rates on Wheat (<i>Triticum aestivum</i> L.) Growth, Grain Yield and Its Water Consumption and Efficiency

A field trial was conducted at a private farm in AL-Hashimiya district Babylon Governorate—the republic of Iraq during the 2016-2017 and 2017-2018 growing seasons. This study was conducted using two irrigation methods, sprinkler and surface irrigation, for each of them had three Tillage methods (zero-tillage, medium-tillage, deep-tillage) and each tillage system had four seeding rate of wheat yield (120, 180, 240, 300) kg∙ha-1. Results indicated that the consumptive water use was 557.5 and 535.9 mm for surface irrigation and 460.9 and 442.6 mm for sprinkler irrigation in the 2016-2017 and 2017-2018 growing seasons. Sprinkler irrigation significantly increased the flag leaf area with no significant effect on plant height. However, the minimum tillage and seeding rate (240 kg∙ha-1) significantly increased the plant height and flag leaf area in both growing seasons. For the grain yield, the sprinkler irrigation, minimum tillage, and seeding rate (240 kg∙ha-1) also increased the plant height and flag leaf area by 13%, 10, % 11%, 11%, 12%, and 14% in both growing seasons, respectively, through an increased number of spikes/m2, the number of grain spike-1, and 1000-grain weight in both growing seasons, respectively. Interestingly the grain yield was increased by 33% and 32% in both growing seasons under the effects of these three factors altogether, respectively. It can be concluded that these factors act synergistically, resulting in a significant improvement in the wheat grain-yield of, less consumptive water use, and high water use efficiency.

Monitoring of emerging contaminants of concern in the aquatic environment: a review of studies showing the application of effect-based measures.

Water scarcity is increasingly a global cause of concern mainly due to widespread changes in climate conditions and increased consumptive water use driven by the exponential increase in population growth. In addition, increased pollution of fresh water sources due to rising production and consumption of pharmaceuticals and organic chemicals will further exacerbate this concern. Although surface water contamination by individual chemicals is often at very low concentration, pharmaceuticals for instance are designed to be efficacious at low concentrations, creating genuine concern for their presence in freshwater sources. Furthermore, the additive impact of multiple compounds may result in toxic or other biological effects that otherwise will not be induced by individual chemicals. Globally, different legislative frameworks have led to pre-emptive efforts which aim to ensure good water ecological status. Reports detailing the use and types of effect-based measures covering specific bioassay batteries that can identify specific mode of actions of chemical pollutants in the aquatic ecosystem to evaluate the real threat of pollutants to aquatic lives and ultimately human lives have recently emerged from monitoring networks such as the NORMAN network. In this review, we critically evaluate some studies within the last decade that have implemented effect-based monitoring of pharmaceuticals and organic chemicals in aquatic fauna, evaluating the occurrence of different chemical pollutants and the impact of these pollutants on aquatic fauna with special focus on pollutants that are contaminants of emerging concern (CEC) in urban wastewater. A critical discussion on studies that have used effect-based measures to assess biological impact of pharmaceutical/organic compound in the aquatic ecosystem and the endpoints measurements employed is presented. The application of effect-based monitoring of chemicals other than assessment of water quality status is also discussed.

Management of Water Resources in Agriculture in Chile and its Challenges

Water is a strategic resource for agricultural development, particularly in the arid and semiarid regions of central and northern Chile. Currently, irrigated surfaces contribute between 60 and 65% of the country’s agricultural GDP. Associated with Chile’s economic growth, total consumptive water use has increased, which, together with population growth, urbanization, water contamination and pollution, has led to important water stress situations that are triggering a greater number of conflicts and social, economic, and environmental vulnerability. The above phenomena will be exacerbated by climate change. At present, surface water deficit covering irrigation demands exists in the central and northern regions. This deficit is projected to increase as a result of climate change, which would increase the challenges for satisfying agricultural water requirements. The objective of this article is to integrally review the key aspects of Chilean water and agricultural water management policies, considering their interphases, providing the reader with a general overview of the main features of this model, an evaluation of its effectiveness and the main challenges agricultural water management faces. Resolving the challenges of the future requires a thorough reconsideration of water management policies and institutions and how water is managed in the agricultural sector in the broader context of overall water resource management in Chile.

Manufacturing of Machine for Planting on Wide Ridges Without Tillage in Desert Soils

This research was conducted during three winter seasons (2015-2016), (2016-2017) and (2017-2018) at Ras Sudr Research Station, South of Sinai Governorate, this region suffers from the problems of increasing salinity in soil and irrigation water, in addition to the high level of ground water. Therefore, the cultivation on wide ridges (raised-bed soil) was used for good soil leaching by storing large quantities of irrigation water in these wide ridges and easy drainage it from both sides of the ridges to the adjacent furrows. The wide ridges are considered one of the methods of remedy the rise in ground water level by raising the agricultural soil to a higher level, which helps to move the roots of plants away from the ground water level and to drain the irrigation water through the ridges sides to the adjacent furrows, which does not cause an increase in the ground water level. Also, conservation tillage (no-tillage) reducing the effect of salinity. So that a prototype of combined machine was manufactured which consisted of two units, the first unit to build ridges with the possibility to change the both of width and height of ridges. The second unit to sow wheat seeds on the ridges. The research treatments consisted of two tillage systems (traditional tillage system (TT) and conservation tillage system (CT) i.e., no-tillage), three ridge widths (50cm, 70cm and 90cm) and four ridge heights (0cm, 20cm, 35cm and 50 cm) where, the treatment of (0cm) was indicated to control treatment (flat soil). Also, the effect of three agriculture seasons was studied. Some parameters were measured or estimated as the following; actual field capacity (AFC), field efficiency (FE)), energy requirements (ER), pulling force (PF), fuel consumption rate (FCR), bulk density (BD), average infiltration rate (AIR), soil salinity (SS), water stored in the effective root zone (WS), water consumptive use in root zone (WC), water application efficiency (WA), wheat grain yield (WGY), water productivity (WP) and specific cost of production (SC). When using (CT) system and the largest cross section area of the ridges (90cm width x 50cm height) with continued application of this system for three consecutive seasons achieved the highest values of: (AFC=0.39 ha/h), (FE=93%), (WS=5773 m3/ha), (WC=4834 m3/ha), (WA=89%), (WGY=8.7 Mg/ha) and (WP=1.8 Mg/m3), in addition this treatment achieved the lowest values for both (SS=6.17 ds/m) and (SC=216 L.E/Mg) compared to the other treatments.

АНАЛИЗ ИСПОЛЬЗОВАНИЯ СВЕЖЕЙ ВОДЫ НА ПРОИЗВОДСТВЕННЫЕ НУЖДЫ

The study was conducted on the basis of official data of the State Statistics Service of the Russian Federation for the period from 1993 to 2019. The analysis of the dynamics of the indicator of the use of fresh water for production needs is carried out, the suitability of the data for the construction of the model is veri-fied. A factor field was constructed and its quality was checked according to separate criteria. The cyclicity was checked and a spectral model of the indicator of the use of fresh water for produc-tion needs was constructed. A set of measures aimed at reducing industrial water consumption and rational use of water resources is proposed. At the legislative level, the possibility of establishing differentiated pay-ments for the consumption of water resources by industrial enterprises has been considered.

ПРАВОВЕ РЕГУЛЮВАННЯ ПРОЦЕСІВ ВИДОБУТКУ ПІДЗЕМНИХ ВОД ДЛЯ ЗАБЕЗПЕЧЕННЯ ПОТРЕБ ВІЙСЬКОВИХ ЧАСТИН

The article highlights the legal aspects of groundwater regulation to meet the needs of the Armed Forces of Ukraine. The general tendencies of groundwater extraction to meet the needs of military units as components of national security and defense of Ukraine are considered and revealed. Given the insufficient resource provision, inefficient environmental monitoring system and inefficient use of resources in the security and defense sector, the issue of legal regulation of groundwater extraction processes to meet the needs of the Armed Forces of Ukraine as components of national security and defense of Ukraine is quite relevant and in demand. Currently, the issue of providing water to remote military units of the Armed Forces of Ukraine that do not have the ability to connect to a centralized water supply system and are forced to use wells to meet water supply needs is relevant. Analyzing the state of legal regulation of groundwater extraction processes to meet the needs of the Armed Forces of Ukraine, we note that there are a number of issues that are not regulated by the legislation of Ukraine, there are regulations that contain conflict rules. Achieving a balance of social, environmental and economic interests of military units as components of national security and defense of Ukraine, related to rational and balanced water consumption and water use, is one of the priority areas in improving mechanisms for state regulation of water resources in Ukraine. The means of implementing this direction is the development and implementation of coordinated and interconnected legislative, regulatory, organizational, economic, environmental and technical projects and measures to improve the quality of water resources, their rational and environmentally safe use, balancing economic water needs with resources and environmental opportunities water resource potential.

Densidade vegetal no rendimento de tomate Husk (Physalis ixocarpa Brot.) em campo e casa de vegetação

ABSTRACT: Physalis ixocarpa Brot. (tomatillo or Husk tomato) is one of the five major vegetables cultivated in Mexico, but its yield in the field is low. However, greenhouse crops and the enhancement in plant density can promote an increase in yield per area. The aim of this research was to evaluate: yield, water consumption and water use efficiency of variety husk tomato ‘Diamante’. The experiment was conducted under field and greenhouse conditions, during the two crop cycles (autumn-winter and spring-summer), with different planting densities (1.5, 2 and 3 plants m-2), in complete random blocks and three replications. The yield was influenced by the planting density and environments. In both environments, the planting density, with 3 plants m-2 increased yield 32 %, and 25% in water use efficiency (WUE). In greenhouse increased 32% yield m-2 and the WUE it was 18.1 kg m-3 while in the field was 16.4 kg m-3. Crop cycle spring-summer produced differences of 27% in plant length and 15% in stem diameter, probably due to the temperature that was 4 ºC higher with respect to autumn-winter.

A re-look at canal irrigation system performance: a pilot study of the Sina irrigation system in Maharashtra, India

AbstractThe general perception of canal irrigation systems in India is one of built infrastructure with low service performance. This paper presents an analytical framework, applied to the Sina medium irrigation system in Maharashtra state of India, to study the performance of an expanded water influence zone (WIZ) including a buffer zone outside the canal command area (CCA) influenced by the irrigation system's water resources. The framework used satellite-based estimates of land-use and cropping patterns. The results indicate that there is hardly any gap between the irrigation potential created (IPC) and the irrigation potential utilized (IPU) in the CCA. The fraction of consumptive water use (CWU) of irrigation is low in the CCA, but almost one in the WIZ, due to the reuse of return flows in the WIZ. Future investments should focus on increasing economic water productivity ($/m3) in order to enhance the resilience of the farming community in the WIZ, which is frequently affected by water scarcity.

Effect of varying water applications on growth, yield and water use efficiency of okra under drip irrigation in Akure, Ondo state, Nigeria

The conservation of water is crucial to sustainable agricultural production during dry season when there is little or no rainfall to improve crop production. Thus this study is aimed to estimate the effects of different levels of water applications on the growth, yield and water use efficiency of Okra under drip irrigation system during dry season. The sixteen plots consist of four treatments (2 m x 2 m) with four replicates in a complete randomized block design to determine the water consumptive use of Okra. The growth, yield and water use efficiency of Okra under four different irrigation management i.e irrigation water applied at 100FIT (full irrigation treatment), 80FIT, 60FIT and 40FIT were measured. Results showed highest growth parameters being observed at 100FIT and the least at 40FIT. The difference in the growth parameters in all the experimental blocks were not significant (p=0.05) for all the stages of development of okra. Using standard bar errors the yield obtained at 60 and 100FIT was not significantly different but significantly different when compared to other treatment blocks and it ranges from 2.05-3.60 tons/ha. The Irrigation Water Use Efficiency (IWUE) ranges from 0.024-0.041tons/ha.mm while the Crop Water Use Efficiency (CWUE) ranges from 0.0088-0.0139 tons/ha.mm. Okra crop irrigated with drip irrigation at 60FIT recorded the highest IWUE, CWUE and about 73% more yield than the 40FIT of 0.041 tons/ha.mm, 0.0139 tons/ha.mm and 3.56 tons/ha respectively. It was concluded that Okra crop irrigated at 60FIT should be adopted in order to save 40% water to irrigate additional land. Drip irrigation is encouraged during dry season for farmers to produce okra all year round.

IMPACT OF LAND LEVELING AND CUT-OFF IRRIGATION ON COTTON YIELD AND WATER PRODUCTIVITY IN NORTH MIDDLE NILE DELTA REGION

A field trial was conducted through successive the two summer growing seasons 2018 and 2019 at Sakha Agricultural Research Station Farm, Kafr-El-Sheikh Governorate. The objective of this current study was to investigate the impact of three land leveling levels and three irrigation treatments on some water relationships, cotton yield and also some its components. The experiments were designed as split plot with three replications. The main plots were occupied by land leveling with three levels namely; traditional leveling farmers practices (L1), Dead level (0.0%) slope (L2) and 0.10% ground surface slope (L3). while sub plots were devoted t cut-off irrigation with three level namely, cut-off at 100% of furrow length (I1),cut-off irrigation at 90% of furrow length (I2) and cut-off irrigation at 80% furrow length(I3). The main results can be summarized as follows: Land leveling and cut-off irrigation treatments have highly significant effect on increasing the cotton yield. its components and fiber technological properties. The interaction between the two factors resulted in the highest values of cotton yield i.e. The highest mean values of seed cotton yield, boll weight, leaf area, plant height, lint percentage, lint index and seed index were obtained under I3 and L3 The highest mean values of fiber fineness, fiber strength, length 2.5%, length 50% and uniformity index were obtained from interaction between I3 and L3 . Cut-off irrigation at 80% from furrow length (I3) and 0.1%ground surface slope ( L3) decreased seasonal applied water, water consumptive use and water stored in the effective root zone by 20.11, 12.11 and 10.90%, respectively compared with cut-off irrigation at 100% of furrow length ( I1) and L1 (traditional land leveling). Also, the highest mean values of water application efficiency, water consumptive use efficiency (71.65, 67.84%) respectively were obtained with I3 and L3 treatments. The highest mean values of water productivity (WP) and productivity of irrigation water (PIW) were recorded under the I3 and L3.

Evaluation of the Public Pipe-borne Water supply in Ilorin West Local Government Area of Kwara State, Nigeria

This paper assesses the residents’ access to public pipe-borne water in Ilorin West Local Government Area of Kwara State, Nigeria. The authors analyzed spatial distribution and functionality of public pipe-borne water. They also examined intra-urban variation in the distribution of public pipe-borne water in the study area. The study used primary data which were obtained through random sampling techniques of 400 households, using structured questionnaire in the twelve political administrative wards of the examined area. Physical enumeration was also adopted to identify the functional and non-functional public pipe-borne water points. Descriptive statistics in the form of frequency table and percentages with chi-square were used to describe residents’ demand and accessibility of public pipe-borne water. Analysis of Variance (ANOVA) was used to examine intra-urban variations in the functionality of public pipe-borne water. The results revealed that distribution of public pipe-borne water cut across different localities in the twelve political administrative wards that Ilorin West Local Government consisted of. Although the highest proportion (60.24%) of public pipe-borne water points were observed to be functioning, a significant proportion (39.26%) were not functioning. The highest proportion (95.5%) of the respondents were of the opinion that public pipe-borne water is not regularly available. The findings from Analysis of Variance (ANOVA) revealed significant differences (F=2.702, P=0.004) in the functioning of public pipe-borne water infrastructural elements existing in the examined area. The study concludes by suggesting the need for the government to ensure regular public water supply to meet the residents’ daily needs for water consumption and domestic use, which continue to increase every day.

Remote Sensing and Modelling Based Framework for Valuing Irrigation System Efficiency and Steering Indicators of Consumptive Water Use in an Irrigated Region

Water crises are becoming severe in recent times, further fueled by population increase and climate change. They result in complex and unsustainable water management. Spatial estimation of consumptive water use is vital for performance assessment of the irrigation system using Remote Sensing (RS). For this study, its estimation is done using the Soil Energy Balance Algorithm for Land (SEBAL) approach. Performance indicators including equity, adequacy, and reliability were worked out at various spatiotemporal scales. Moreover, optimization and sustainable use of water resources are not possible without knowing the factors mainly influencing consumptive water use of major crops. For that purpose, random forest regression modelling was employed using various sets of factors for site-specific, proximity, and cropping system. The results show that the system is underperforming both for Kharif (i.e., summer) and Rabi (i.e., winter) seasons. Performance indicators highlight poor water distribution in the system, a shortage of water supply, and unreliability. The results are relatively good for Rabi as compared to Kharif, with an overall poor situation for both seasons. Factors importance varies for different crops. Overall, distance from canal, road density, canal density, and farm approachability are the most important factors for explaining consumptive water use. Auditing of consumptive water use shows the potential for resource optimization through on-farm water management by the targeted approach. The results are based on the present situation without considering future changes in canal water supply and consumptive water use under climate change.

Attributing Terrestrial Water Storage Variations across China to Changes in Groundwater and Human Water Use

AbstractThis study investigated the attribution of terrestrial water storage (TWS) variations across China to changes in groundwater and human water use. As one vital storage component, the groundwater storage (GWS) derived from the Jet Propulsion Laboratory’s GRACE (Gravity Recovery and Climate Experiment) mass concentration solution compared reasonably well with the in situ groundwater table depth, with the correlation coefficients ranging from −0.83 to −0.18, all of which were statistically significant at the 95% confidence level. About 71% of the trends in derived GWS had the same sign as those of observations, without systematic deviation, across China. The GWS variation contributed a large portion of the TWS trend in most regions of China, and the majority of contribution values reached 50%–150% in the Hai River basin, the Loess Plateau, and the middle portion of the Yangtze River basin. The dominant role of GWS is closely related to the detected long-term “memories” in both TWS and GWS. The increase of irrigation consumption accelerated the TWS depletion trend by 13.4% in the Huai River basin, while the decrease of consumptive agricultural water use alleviated the TWS decline rate by 4.1% in the Hai River basin. Importantly, the correlation coefficients reached 0.74–0.95 between the TWS change and the residual of precipitation, evapotranspiration, flow into the sea, and irrigation consumption in the four river basins of particular interest. The findings of this study are helpful for understanding regional water cycles in China.

Effect of Deficit Irrigation and Weed Control Treatments on Grain Yield and Water Productivity for Three Bread Wheat Genotypes

A field experiment was conducted during two winter seasons 2018/2019 and 2019/2020 at Sakha Agricultural Research Station, Kafr El-Sheikh Governorate, Egypt to study the effect of deficit irrigation and weed control treatments on grain yield and water productivity of three bread wheat genotypes. The experimental design was stripe split-plot, with three replicates. Irrigation treatments were in the vertical plots which include I1 irrigation at all stages (full irrigation), while I2, I3 and I4 were deficit irrigation through withholding one irrigation at elongation, booting, and anthesis stages, respectively. Four weed control treatments were allocated in horizontal plots that include, W1 (Gerostar + Action), W2 (Atlants), W3 (hand weeding twice), and W4 control (untreated), Sub-Subplots were three wheat genotypes G1 (Giza 171), G2 (Sakha 95) and G3 (promising Line). The results revealed that the highest values of plant height, number of spikes m2, number of kernels spikes-1, 1000-kernel weight, biological yield, grain yield and straw yield were recorded under I1 compared to all the studied irrigation treatments, as well as under W1 compared to other weed control treatments and G2 compared to others genotypes in the two seasons. The highest values of water consumptive use (CU), and applied water (AW) were recorded under I1 to be 37.67, and 48.26 cm respectively, the values of AW under I2, I3 and I4 were reduced by 18.5%, 17.6%, and 22.3% respectively compared to I1 as mean of the two seasons. The values of productivity of irrigation water (PIW), and water productivity (WP) were taken the descending order W1> W2 > W3 > W4 and G2 > G1 > G3 for weed, and genotypes respectively. It could be recommended the I2 × W1 × G2 interaction which recorded the highest grain yield, PIW and WP, moreover saved a reasonable amount of irrigation water.

Impact of Soil Water Quality on Yield, Qualities and Water Consumptive Use of Melon (Cucumis Melo L)

Indonesia has two seasons. These are wet season and dry season; in the dry season, water from rainfall decreases and demand for water as irrigation resources decrease. Soil water is expected to supply irrigation in the agriculture sector. Water quality at Universitas Padjadjaran can be affected by poor water disposal planning and the location of the surrounding industrial estate, animal farms, farm activities and domestic wastewater. Poor water quality can affect the quality and quantity of crops. Melon is commonly not needed much water as a consumptive use but needs water in whole life and usually applied irrigated, especially if growth in the greenhouse. Poorly applied water qualities of the melon can will impact the quality and quantity to decrease. Research on the impact of soil water quality on yield and quality and consumptive use of melon was conducted at the greenhouse located in Universitas Padjadjaran Campus, West Java Province, Indonesia, from July to November 2019. The research method is descriptive analysis, and melon is planted in containers called autopot and fertigation daily applied by control of autopot smart valve. The results show that TSS of soil water were 200.2 mg/al; TDS 300.2 mg/L; EC 0.75 mS/cm; pH 7,0 and turbidity is 4.75 NTU. The quality of melon shows that water 95.19%; Fat 0.88%; ash 0.57%; protein 1.37%; carbohydrate 1.99% vitamin C 6.91% and sweeteners is 9.4 Brix. In conclusion, that soil water meets requirements as resources irrigation to applied melon.

Experimental investigation of Versa Tyle GRP for solar thermal system

ABSTRACT Solar thermal systems have encountered a high level of interest over the last ten years due to their low cost and convenience in reducing energy load for domestic hot water. This paper aimed to introduce a new panel’s material (Versa Tyle GRP Tiles) for solar thermal system and a prototype was built in a small shed at a site in Liverpool (UK), in order to assess its performance. The experiment was run for 12 months for the purpose of collecting and analyzing thermal data in terms of heat capacity, solar energy, and solar fraction. To simulate the daily use of water consumption and provide realistic outputs, the system was emptying every day at different durations in order to investigate the recovery period of the temperatures. The results proved the feasibility and efficiency of the Versa Tyle GRP as the maximum recorded temperature on the tiles was 68°C, and 51°C for the hot water in July; while winter months recorded a maximum of 26°C for the hot water. The system achieved average solar fraction of 36.52–47.43% between May to September, while in the rest of the months in the year, average solar fraction of 2.95%-18.59% were detected.

Influence of Irrigation Regimes on the Performance of Groundnut (Arachis hypogaea) under Intercropping Situation

Background: The system output of groundnut based intercropping system depends on the selected companion crop as well as the frequency with which irrigation is supplied. This initiates a requisite to evaluate the performance of present traditional intercropping systems and thereby optimize the level of irrigation for both the crops under the system.Methods: A two-year field experiment was conducted during the rabi season 2017-2019 at Oilseeds Research Station, Tamil Nadu Agricultural University, Tindivanam, Tamil Nadu, India The experiment was laid out in split plot design with three replications. Main plot comprised of five treatments with four intercrops viz., castor (TMV 5), blackgram (VBN 8), sesame (TMV 7), pearl millet (CO 10) and sole groundnut (TMV 13). The sub plot was assigned with three irrigation regimes based on IW/CPE ratio of 0.50, 0.75 and 1.0. Result: Groundnut + blackgram combination recorded higher pod yield (6.31 g plant-1), equivalent pod yield (1986 kg ha-1) with increased water use efficiency (5.49 kg ha-1 mm-1) and economic water productivity (` 309 ha-1 mm-1) over sole groundnut while other intercropping combinations failed to express. Soil moisture extraction pattern was higher at top layers and decreased with soil depth. More frequent irrigations (IW/CPE 1.0) mismatched with the crop water requirement and resulted in higher consumptive water use (500.8 mm) with moisture extraction pattern from initial layers favouring evaporation losses. At peak growth stage (60 days after sowing) higher light interception was observed in groundnut + pearl millet (41.4%) followed by castor (38.2%) combinations which was the prime reason for decreased yields as groundnut is susceptible to shading. Therefore, groundnut + blackgram combination under rabi season when supplied with six irrigations at twenty days interval (based on IW/CPE 0.50) could significantly increase the productivity and monetary returns from the system.

SUAS Remote Sensing of Vineyard Evapotranspiration Quantifies Spatiotemporal Uncertainty in Satellite-Borne ET Estimates

Small Unmanned Aerial Systems (sUAS) show promise in being able to collect high resolution spatiotemporal data over small extents. Use of such remote sensing platforms also show promise for quantifying uncertainty in more ubiquitous Earth Observation System (EOS) data, such as evapotranspiration and consumptive use of water in agricultural systems. This study compares measurements of evapotranspiration (ET) from a commercial vineyard in California using data collected from sUAS and EOS sources for 10 events over a growing season using multiple ET estimation methods. Results indicate that sUAS ET estimates that include non-canopy pixels are generally lower on average than EOS methods by >0.5 mm day−1. sUAS ET estimates that mask out non-canopy pixels are generally higher than EOS methods by <0.5 mm day−1. Masked sUAS ET estimates are less variable than unmasked sUAS and EOS ET estimates. This study indicates that limited deployment of sUAS can provide important estimates of uncertainty in EOS ET estimations for larger areas and to also improve irrigation management at a local scale.

Evaluation of Two Irrigation Scheduling Methods and Nitrogen Rates on Corn Production in Alabama

Regulations on nutrient application amounts and environmental impacts of fertilizers are promoting advances in agricultural management strategies to optimize irrigation application and N fertilization in corn. Previous studies have found a relationship between irrigation application, available water in the soil, and N fertilizer uptake. The objective of this study was to evaluate interactions between two irrigation scheduling methods and four N rate applications (0-control, 202, 269, and 336 kg ha−1) on grain yield, aboveground biomass, plant N concentration, N uptake, and nitrogen use efficiency in corn. The study was conducted at the Tennessee Valley Research and Extension Center (TVREC) during two growing seasons (2014 and 2015). The irrigation scheduling methods consisted of (i) the pan evaporation method, which is based on managing the crop’s estimated evapotranspiration (ET) using pan evaporation values and the crop’s consumptive water use and (ii) the sensor-based irrigation scheduling method based on soil matric potential values recorded by soil moisture tension sensors installed in the field. Irrigation amounts from both irrigation scheduling methods indicated that less water was applied with the sensor-based method. The different amounts of irrigation applied associated with the two irrigation scheduling methods did not impact grain yield, aboveground biomass, and NUE. In general, NUEs values decreased with increased N rates, which means that additional N fertilizer added to the soil was not converted into grain yield or/and adsorbed by plants; therefore, more N remained in the soil, increasing the risk for environmental problems.

Restoring the ecological integrity of a dryland river: Why low flows in the Barwon–Darling River must flow

SummaryFor dryland rivers globally, understanding hydro‐ecological function is fundamental to informing trade‐offs between consumptive water use and aquatic ecosystem integrity. The Barwon–Darling is an Australian dryland river system recognised for its hydrological variability, which is considered a primary driver of the riverine ecosystem. Emphasis has been placed on extremes of zero flow and flood but examining low flow hydrology and hydraulics – through historical and modern droughts – demonstrates that under natural conditions, the river system also exhibits persistent and predictable flow characteristics. From 1885 to 1950, prior to flow regulation, the Barwon–Darling flowed 92% of the time, and throughout severe droughts (1895–1903 and 1939–1945) the river system was characterised by: near‐perennial flows (85% of the time), with lotic (flowing water) habitats; and near‐annual, in channel, flow pulses. Furthermore, evidence of lotic biota is found consistently in Aboriginal middens dating over the past 15,000 years, thus indicating the long‐term persistence of lotic conditions. We propose these consistent hydrological and hydrodynamic features have shaped the ecology of aquatic biota in the Barwon–Darling River but are now experiencing unprecedented change. Flow storage and diversion have increased the frequency and duration of zero flows in some reaches, but arguably the most substantial impacts, along the entire river, are on: (i) low flows, which are now frequently below lotic thresholds, and (ii) the magnitude of near‐annual flow pulses, which are reduced by over 90%. Consequently, in modern droughts, the river becomes predominantly lentic (still‐water), an impact that is exacerbated by weirpools which create artificial lentic conditions for approximately 1000 km (40%) of river. The ecological impacts of these changes are increasingly apparent, with the loss of lotic biota and a reduction in biodiversity. An ecohydraulic perspective explains present impacts, provides new directions and some immediate solutions for river management, and clarifies choices for stakeholders.