Higher Water Use Research Articles

Changes in Blue/Green Water Partitioning Under Severe Drought

AbstractMuch attention has been given to the disproportionate streamflow deficits (relative to rainfall deficits) experienced by many catchments during the Millennium Drought (1998–2009) in southeastern Australia, along with lack of post‐drought streamflow recovery in some cases. However, mechanisms behind the coupled hydrologic and ecosystem dynamics are poorly understood. We applied a process‐based ecohydrologic model (RHESSys) in a Melbourne water supply catchment to examine changes in ecohydrologic behavior during and after the drought. Our simulations suggested that average transpiration (green water) was maintained under drought despite a substantial (12%) decrease in average rainfall, meaning that the entire rainfall deficit translated to reduced streamflow (blue water). Altered spatial patterns of vegetation behavior across the terrain helped the ecosystem maintain this unexpectedly high green water use. Decreased transpiration upland was compensated by increases in the riparian zone, which was less water limited and therefore able to meet higher water demand during drought. In the post‐drought period, we found greater transpiration and reduced subsurface water storage relative to pre‐drought, suggesting a longer‐term persistence in altered water partitioning. The post‐drought outcome was attributed to a combination of warmer climate and the persisting effects of the drought on nutrient availability. Given the importance of shifting ecohydrologic patterns across space, our results raise concerns for applying lumped conceptual hydrologic models under nonstationary or extreme conditions. Additionally, the processes we identified have important implications for water supply in Australia's second largest city under projected drying.

Evaluation of Furrow Irrigation System on Head Cabbage Yield and Water Use Efficiency in Arbegona Woreda, Ethiopia

Available fresh water resources are subjected to an ever-increasing pressure due to extensive agricultural water demand for irrigated lands. A long-term perspective in shortage of fresh water resources, especially in arid and semi-arid area, highlights an urgent solution for innovative irrigation strategies and agricultural water management. The experiment was conducted in Arbegona district, Sidama region of Ethiopia. This experiment was conducted to evaluate and demonstrate of Alternative, Fixed and Conventional furrow irrigations on Head Cabbage yield and water use efficiency. To achieve this objective the treatment were three furrow irrigation method (Conventional, Alternate and Fixed furrow) laid out in a random complete block design (RCBD) with three replications. The result shows that there is no significant difference between alternative and conventional furrow irrigation on Head cabbage yield. But, fixed furrow irrigation system reduces the yield significantly. The maximum yield (48407kg/ha and 43840kg/ha) was obtained from conventional and alternate furrow irrigation method, respectively. The minimum yield (35242kg/ha) was obtained under fixed furrow irrigation. Furrow irrigation method has no significant effect on plant height, head weight and head diameter of head cabbage. The highest water use efficiency was obtained from alternate furrow irrigation and shows significant difference between the other treatments. Therefore, to save water, labour and time without significant yield reduction alternate furrow irrigation is recommended in water scarce area of Ethiopia.

Evaluating greenhouse gas mitigation through alternate wetting and drying irrigation in Colombian rice production

Rice demand in Latin America is increasing rapidly, but few studies have identified management practices to reduce water demand and soil greenhouse gas (GHG) emissions for irrigated rice systems in this region. Therefore, we tested the hypothesis that alternate wetting and drying (AWD) irrigation could maintain crop yields while mitigating global warming potential (GWP) compared to a conventional system with recommended irrigation and nutrient management practices for tropical rice in Colombia. Over four consecutive growing seasons, we monitored CH4 and N2O emissions, grain yield, and water consumption for two AWD treatments (AWD5 cm and AWD10 cm - where water drained to depths of 5 and 10 cm below the soil surface, respectively) and a control, in which the field was drained multiple times during fertilizer applications and then continuously flooded until harvest. The control had the highest water use across all rice seasons, with values ranging from 9260 to 16559 m3 ha−1 harvest−1. Implementation of AWD reduced cumulative water use by 19–56%, especially in dry seasons. Both AWD treatments significantly reduced cumulative CH4 emissions by 72–100%, which is consistent with previous research. A new finding is that AWD also decreased N2O emissions by 12–70%, which was attributed to management of soil moisture during fertilizer application events. In total, AWD reduced GWP by 25–73% compared to the control, with minimal impacts on crop productivity. Rice yields ranged from 5.2 to 8.2 Mg ha−1, with no significant difference among treatments in three of four seasons. This study shows that AWD saves irrigation water while greatly reducing GWP with little agronomic penalty, suggesting this technology could be a promising strategy for GHG mitigation in tropical rice in Colombia. Because there are important barriers to AWD adoption, future work should explore challenges at the farm-level as well as changes in policy, irrigation infrastructure, and institutional arrangements to understand the potential for broader implementation.

Effects of Drip Tape Layout and Flow Rate on Water and Nitrogen Distributions within the Root Zone and Summer Maize Yield in Sandy Tidal Soil

Drip tape layout and flow rate are crucial variables that impact the effects of drip fertigation. To investigate the influence of drip tape layout and flow rate on the soil water and nitrogen transport in summer maize in sandy tidal soil, field experiments were conducted for two years. Two drip tape layouts were set: one tape serving for two crop rows (N) and one tape serving for each crop row (E), with two levels of drip flow rate, i.e., high (2 L/h; H) and low (1.3 L/h; L). The results show that under the same drip tape layout, the lower the drip emitter flow rate, the more upright the shape of wetted soil volume. The maximum vertical and horizontal water transport distance under NL treatment was higher than that under NH, EH, and EL treatments. After surface drip fertigation, nitrate nitrogen accumulated near and at the edge of the wetted soil volume. In 2020, under NL treatment, nitrate nitrogen transported to a 55 cm soil layer, which was 22.22%, 71.42%, and 57.14% deeper than that under NH, EH, and EL treatments, respectively. In 2021, nitrate nitrogen could transport to a 60 cm soil layer in both NL and NH treatments. The maximum concentration of ammonium nitrogen was nearby the emitter. Under NL treatment, ammonium nitrogen was transported to 48 and 60 cm soil layers below the emitter in 2020 and 2021, respectively, which was deeper than that observed under NH, EH, and EL treatments. The soil inorganic nitrogen residue of the NL was lower than that of the NH, EH, and EL treatments. Compared with NH, EH, and EL treatments, the two-year maize yield under NL treatment increased by 11.09%, 13.47%, and 8.66% on average, respectively. NL treatment exhibited the highest water use efficiency and nitrogen fertilizer productivity. Therefore, NL treatment (one drip tape serving for two rows with 1.3 L/h flow rate) could promote the absorption of water and nutrients, reduce inorganic nitrogen residue, and to obtain high maize yield in sandy tidal soil.

Development and evaluation of the first automated irrigation system for alternate wetting and drying technique in rice cultivation in Bangladesh

Rice stands as one of the most water-intensive crops in agriculture, demanding a substantial volume of water annually for cultivation in Bangladesh. To address this considerable water requirement, the International Rice Research Institute (IRRI) introduced the alternate wetting and drying (AWD) irrigation method. This approach necessitates consistent manual oversight to maintain the desired water levels in the field. In pursuit of reducing this manual effort, a study was conducted at Bangabandhu Sheikh Mujibur Rahman Agricultural University. The study aimed to develop an automated version of the AWD irrigation system, assess its impact on plant growth and yield-contributing factors, and investigate water use efficiency through using that automated system. The automated AWD system incorporated water level controllers, solenoid valves, and water level detection probes to regulate water levels in the paddy field. The experiment followed a Randomized Complete Block Design (RCBD) with three treatments: T1 (Conventional Irrigation - CI), T2 (AWD), and T3 (Automated Alternate Wetting and Drying - AAWD), each replicated four times. The findings indicated minimal variation in growth and development parameters of the rice plants between the CI and AWD treatments. Likewise, yield components demonstrated no significant differences among the various treatments. Notably, the treatment with automated alternate wetting and drying (AAWD), namely T3, displayed the highest water use efficiency (WUE) at 65.20 kg/ha/cm, while the lowest WUE of 52.56 kg/ha/cm was observed in the conventional irrigation (CI) treatment T1. The results underscore the clear advantage of adopting an automated AWD system, yielding a 20% reduction in irrigation water usage compared to the conventional approach. This transition also minimizes the need for labor-intensive interventions in the paddy fields of Bangladesh, illustrating the potential for more efficient and sustainable rice cultivation practices.

Influenece of Different Irrigation Scenario's under Mulched and Non-mulched Condition on Soil Moisture, Yield and Wue of Ridge Gourd (Luffa acutangula, L.)

A field experiment was conducted on Ridge gourd during rabi season of 2021-22 and 2022-23 at the Experimental Research Plot Soil and Water Engineering, CAE, Raichur. The study aimed to assess the efficacy of a sensor and evapotranspiration based irrigation system in varying irrigation levels, comparing the performance between mulched and non-mulched conditions. The use of sensor-based irrigation at 100% field capacity under mulched has shown positive outcomes, leading to a notable enhancement in crop production by about 9.40% additionally, this approach has resulted in a significant conservation of irrigation water, with savings of approximately 12.35% compared to the treatment involving irrigation at 100% evapotranspiration under mulched, but without the use of sensors. Across the treatments, the water application efficiency ranged from 94.13 to 91.37%. The highest water use efficiency was observed in the treatment with irrigation at 100% FC under mulched condition on pooled basis (0.20 t ha-1 mm-1). The sensor based drip irrigation system under mulched is an economically viable option to be recommended among farmers in arid and semi-arid climate. Despite the higher initial setup costs, farmers can achieve significant cost savings in the long run due to lower water usage, better yields, and minimised labour requirements.

Seasonal patterns of carbon and water flux responses to precipitation and solar radiation variability in a subtropical evergreen forest, South China

Precipitation and energy are vital factors profoundly affecting carbon and water fluxes in subtropical forest ecosystems. However, knowledge of the seasonality of ecosystem productivity and water fluxes and their dominant controlling factors remains understudied. Based on 12 years (2003–2014) of eddy-covariance measurements, we examined how the seasonal carbon flux components and evapotranspiration respond to climatic variability in a subtropical forest ecosystem. Our results showed that both the magnitude and the percentage of gross ecosystem productivity (GEP) and ecosystem respiration (Reco) in winter increased. The enhanced GEP during winter and dampened Reco in summer and autumn were not sufficient to compensate for the decreased GEP in spring, summer and autumn, and simultaneously increased Reco in spring and winter. Thus, net ecosystem productivity (NEP) slightly diminished during the study period, and the majority of annual net carbon gains occurred in winter and spring with high water use efficiency. In addition, solar radiation predominantly contributed to GEP in spring and winter, while soil moisture is the main contributor in summer. ET greatly determined the GEP in autumn due to both were well-coupled. The vapor pressure deficit (VPD) was a major driver of Reco in summer and autumn inferred that Reco largely depends on substrate availability. However, Reco was mainly attributed to the soil environmental conditions (moisture and temperature) in spring and winter. Our results highlighted that the different extents and asynchronous responses of ecosystem carbon assimilation and respiration to altered energy and moisture availability determined the seasonal patterns of carbon and water fluxes, thus having important implications for assessing or projecting subtropical forest ecosystem responses to current climate change.

Comparative Study of the Impact of Saline Water Irrigation on Tomato Yield, Quality and Growth in Andhra Pradesh, India

Tomato (Lycopersicon esculentum Mill.) belonging to the family Solanaceae, is one of the most important, popular, nutritious, and palatable vegetables grown in Andhra Pradesh. It plays a vital role in providing a remarkable quantity of vitamin-A and vitamin-C in human diet. Tomato is cultivated all over Andhra Pradesh due to its adaptability to wide range of soil and climate. Saline water resources are abundant in the most areas of India. Most of these resources still have not been effectively utilized. The present investigation was conducted on the effects of saline water irrigation on tomato yield, quality and growth at the Research Farm, Department of Agricultural Engineering, Aditya Engineering College, Surampalem, East Godavari district, Andhra Pradesh. Saline water differing in Electrical Conductivity (EC) 6ds/m and 4ds/m was supplied to the plant after the seedlings. The objective of this work is to compare the effect of tomato crop under drip irrigation by three different treatments. First treatment is of fresh water under drip irrigation. Second treatment is of Nacl+water with an EC of 6ds/m under controlled irrigation in the ratio 2.5:7.5. Third treatment is of Nacl+water with an EC of 4ds/m under controlled irrigation in the ratio 1.5:8.5 of the tomato variety Pusa F1 hybrid is used for the experiment. Growth of crop includes plant height, number of fruits, number of leaves, fruit length, fruit diameter and fruit weight. The healthy growth that is 69.4cm plant height, 26 leaves per plant, 34 fruits per plant, 7.8 cm fruit length, 5.4 cm diameter of fruit and 89.4 g of average fruit weight and maximum score (4.86 out of 5) in organoleptic test were obtained in (T-1) i. e. drip irrigation. Although salinized tomato fruits were smaller than non-salinized control fruits, they have increased soluble solids, high sugar content, which all are highly requested qualities by the processing tomato industry. Current research concludes that the fresh water irrigation T-1 recorded the high-water use efficiency and saline water irrigation treatments (T2&T3) having less water use efficiency may be due to the plants suffering with more soil moisture stress due to osmotic pressure build up by the saline water irrigation.

Genetic variability for root, shoot and water use efficiency traits in castor (Ricinus communis L.)

A study was conducted to identify castor (Ricinus communis L.) genotypes with good root growth for water mining, high total drymatter(TDM) and high water use efficiency (WUE). Sixty four genotypes including germplasm lines and advanced varietal/hybrid trial(AVT/AVHT) entries were sown during rainy season of 2008 in two specially constructed rootstructures(32 in each structure)replicating twice with four plants/replication after attaining the bulk density of the structure asthat offield . Data on root (length, volume, dry weight),shoot (leaf area index, TDM,stem girth) and WUE traits (SPAD chlorophyll meter reading, specific leaf area, 13C, 18O) were recorded at 90 DAS. Efficient genotypes were selected based on a composite index using principal component analysis (PCA) and top 10 genotypes were selected for root and shoot growth traits. These genotypesinclude RG 1437, RG 1463, RG 1494, RG 1614, RG 1645, RG 1941, RG 2058, RG 2113, RG 2127 and RG 2139.

Far-Red Light Affects Stomatal Opening and Evapotranspiration of Sweet Basil

Far-red light (FR; wavelength: 700–800 nm) is known for its effects on plant morphology and photosynthesis. However, its effects on stomatal responses and transpiration are not well understood. This study investigated the effects of FR on stomatal development and evapotranspiration in sweet basil grown under red, blue, and green (RGB) light-emitting diodes (LED). FR was provided for 10 days at 0, 30, 100, and 130 μmol·m−2·s−1 with the same base light (RGB ratio of 6:2:2; a photosynthetic photon flux density of 200 μmol·m−2·s−1). Evapotranspiration was measured using a load cell, and stomatal development was monitored microscopically. FR increased the height of sweet basil mostly due to the shade avoidance syndrome. The photosynthetic rate was not improved with FR, probably due to insufficient base light intensity. Despite similar leaf area and root growth, daily evapotranspiration increased with FR, resulting in higher water use. Although the stomatal density and guard cell area were similar across treatments, the stomatal aperture area was larger in plants with FR, thus increasing evapotranspiration. In conclusion, FR with the base RGB light intensity of 200 μmol·m−2·s−1 enhanced the evapotranspiration of sweet basil by regulating stomatal opening, but it did not enhance photosynthesis.

Quantifying Household Water Use and Its Determinants in Low-Income, Water-Scarce Households in Karachi

Water system investments in megacities in South Asia are driven by a perceived ‘shortage’ of water supply compared to water demand. However, water demand estimates for such cities often do not reflect local socioeconomic and demographic characteristics nor account for seasonal variability. In this study, using a mixed-methods approach, we quantify household water use and its determinants and assess the seasonality of access to piped water in the low-income, water-scarce township of Lyari in Karachi. Results from over 600 household surveys show that the reported per capita water usage at the household level is lower than the assumed water demand by the city’s water utility. Water use is found to differ by gender, season, and economic status. More affluent households are able to “purchase” water security and sustain higher water use even in situations of extreme water scarcity. The perceived sufficiency of water supply improves markedly in the winter despite no increase in supply, indicating reduced demand. These findings can inform more accurate water demand projections for Karachi and highlight the importance of accounting for local socioeconomic and environmental contexts in water demand projections.

Effects of Different Water and Nitrogen Supply Modes on Peanut Growth and Water and Nitrogen Use Efficiency under Mulched Drip Irrigation in Xinjiang.

The optimization of irrigation and fertilization indexes for peanuts with drip irrigation is urgently needed in Xinjiang. A field experiment was conducted during the 2021 peanut growing season at Urumqi, Xinjiang, in Northwestern China, to evaluate the effects of different water and nitrogen treatments on the growth, yield, and water and nitrogen utilization of peanuts. In field experiments, we set up three irrigation levels (irrigation water quotas of 22.5, 30, and 37.5 mm, respectively, for W1, W2, and W3), two nitrogen application levels (77.5 and 110 kg·ha-1, recorded as N1 and N2), and a control treatment (W2N0) that did not include the application of nitrogen. The results showed that nitrogen application enhanced the growth, physiological indexes, yield, and water use efficiency of the W1, W2, and W3 treatments when the irrigation volume remained the same. In comparison with no nitrogen application (W2N0), the peanut growth, physiological indexes, yield, and water use efficiency improved with increasing irrigation amounts in the N1 and N2 treatments. With an increase in the irrigation volume, the water use efficiency grew; the W3N2 treatment had the highest water use efficiency, which was 1.32 kg·m-3. The total water consumption and reproductive-stage water consumption of the peanuts in all treatments increased with the irrigation volume, and a high yield was achieved at 402.57 mm, which was 5.2974 Mg·ha-1. In the W1, W2, and W3 treatments, the nitrogen partial factor productivity significantly decreased as the nitrogen application increased, with the nitrogen partial factor productivity in the W3N1 treatment being the highest, at 60.61 kg·kg-1. A comprehensive evaluation based on principal component analysis assigned W3N2 the higher score. These findings suggest that irrigation water quotas of 37.5 mm should be coupled with 110 kg·ha-1 nitrogen applications for peanuts using drip irrigation in mulch film in Xinjiang.

The interplay of drought and hurricanes on tree recovery: insights from dynamic and weak functional responses.

Identifying the functional traits that enable recovery after extreme events is necessary for assessing forest persistence and functioning. However, the variability of traits mediating responses to disturbances presents a significant limitation, as these relationships may be contingent on the type of disturbance and change over time. This study investigates the effects of traits on tree growth-for short and longer terms-in response to two vastly different extreme climatic events (droughts and hurricanes) in a Puerto Rican forest. I found that trees display a dynamic functional response to extreme climatic events. Leaf traits associated with efficient photosynthesis mediated faster tree growth after hurricanes, while trees with low wood density and high water use efficiency displayed faster growth after drought. In the longer term, over both drought and hurricanes, tree size was the only significant predictor of growth, with faster growth for smaller trees. However, despite finding significant trait-growth relationships, the predictive power of traits was overall low. As the frequency of extreme events increases due to climate change, understanding the dynamic relationships between traits and tree growth is necessary for identifying strategies for recovery.

Impact of fixture purging on water age and excess water usage, considering stochastic water demands

Higher water ages are linked with water quality decline as chlorine dissipates, temperatures become more favorable for microbial growth, and metals and organic matter leach from the pipes. Water fixtures with automated purging devices can limit water age in premise plumbing systems, but also increase water use. To develop purging strategies that lower age while also minimizing water use, the stochastic nature of water demands must be considered. In this research, a hydraulic plumbing network model, with stochastic demands at fixtures, was used to compare water age and water use for five purging conditions: purging at regular intervals, “smart” purging (considering the time of last use), purging with different volumes of water, purging at different fixtures, and the purging with different levels of home occupancy. Higher purging frequency and volume resulted in lower water ages, but higher water use. Purging greatly reduced the variability in water ages, avoiding extreme ages entirely. Water age was minimized by scheduling the purging around occupancy behavior, such as before the occupants wake up or return from work. Scheduled purging used more water than smart purging. Purging after 12 h of nonuse used only 55% of the additional water required for purging every 12 h. Purging after 24 h of nonuse at the kitchen tap and shower used only 38% of the additional water required for purging every 24 h, while maintaining lower water ages and removing the variability in water ages. While larger purging volumes had a greater impact on water age, there were diminishing returns. Purging has a larger impact on low-occupancy homes because fixtures have less frequent use. Overall, this research provides a methodology to compare purging strategies that minimize both water age and water use. While the numerical results presented here are only valid for the specific layout and usage habits, they provide insights and trends applicable to other cases.

Surface paving more important than species in determining the physiology, growth and cooling effects of urban trees

Urban trees provide numerous ecosystem services including the mitigation of urban heat. However, this cooling effect is often restricted due to poor tree growth and health caused by harsh growing conditions. The aim of this study is to analyse the influence of surface paving on the physiology, growth and cooling benefits of street trees of three common species with contrasting drought tolerance (Aesculus hippocastanum, Tilia × europaea and Quercus palustris) in Gothenburg, Sweden. Tree structural parameters, leaf water potentials, gas exchange, leaf area density and chlorophyll content were measured in three summertime periods in 2017 and 2018. Moreover, based on the measured data, the cooling effects of studied trees due to shading and transpiration were modelled.For all species, trees at highly paved sites were found to have significantly reduced growth, physiological performance and cooling effects compared to sites with a higher degree of permeable surfaces. This negative effect of surface paving was stronger than the effect of species, despite differences in drought tolerance and water use strategy between studied species. Based on the sensitivity of species to surface paving, we recommend Q. palustris and T. europaea for sites with good growing conditions due to their potential to maintain high water use and growth rates, and A. hippocastanum for highly paved sites where shading is not the primary ecosystem service sought. Our findings emphasise the importance of tree planting design in supporting urban tree growth and the continuous provision of ecosystem services, particularly in the context of the changing climate.

Targeted sequencing of the Panicum miliaceum gene space and genotyping of variant sites from population genetics studies, combined in a single assay, as a tool for broomcorn millet assisted breeding

Broomcorn millet (Panicum miliaceum L.) is a prehistorical cereal, today cultivated as a minor crop with low yields but with a renewed interest for its high water use efficiency and gluten-free grains. To reverse the downward trend in broomcorn millet cultivation, the crop needs genetic improvement and creation of novel genetic variation to increase productivity. In order to facilitate genomics-assisted breeding, we designed a reduced representation genome-sequencing assay that investigates 1.8% of the nuclear DNA in a targeted and reproducible way, with an intensity of genomic sampling that is a direct function of local recombination rate. We used this tool and set up bioinformatics analyses tailored to the polyploid genome of P. miliaceum for maternity and paternity testing, quantification and genomic distribution of homozygous regions and estimation of parental genome contribution for individual seedlings in advanced inbred lines from a breeding program and compared their genomic composition with registered varieties. We found several clues that suggest that the genetic purification process to ensure genetic uniformity is incomplete in varieties of this species. Residual heterozygosity was detected in the genome of three registered varieties ranging from 4.4 to 6.25% of their haploid genome length. Other registered varieties show genome-wide homozygosity. We found, however, evidence of intravarietal genetic variation in three cases that suggest that the breeder seed or commercial seed production had fixed by self-pollination multiple inbred lines with very similar, though not identical, genotypes within each variety.

Effects of Douglas fir cultivation in German forests on soil seepage water quantity and quality

Norway spruce (Picea abies L.) has been a key tree species and timber source in European forests the last centuries and is increasingly suffering from drought and bark beetle infestations due to climate warming. Current management options include replacing of Norway spruce monocultures with pure and mixed stands of European beech (Fagus sylvatica) that is the naturally dominating tree species in Central Europe. Additionally, Douglas fir (Psudotsuga menziesii), a tree species with high water use efficiency and drought tolerance, is being increasingly cultivated to increase the resilience of European forests and meet the future demand of conifer timber in a warming climate. We studied the seepage water quantity and quality with a particular focus on the nitrate (NO3–) concentration and N leaching under pure and mixed stands of Douglas fir, Norway spruce, and European beech at seven sites in Germany. Additionally, we investigated seepage water concentrations of SO4-S, Ca, Mg, K, Al and hydrological variables (interception, canopy throughfall, transpiration). Looking at the seepage water quantity and quality, the best management option is the cultivation of pure beech stands. However, this is associated with the well-known risk of monocultures concerning ecosystem disturbance. Beech stands showed the highest seepage water quantities and the lowest seepage water concentrations of major cations and anions, including NO3–. Seepage water quantity was the smallest under pure Douglas fir compared to spruce and beech stands. The composition effects of stand tree species on seepage water quality and nutrient leaching were site-dependent. At N-rich sites, pure Douglas fir stands showed higher seepage water NO3– concentrations than spruce and beech stands, whereas the tree species effects were small at N-poor sites. With respect to seepage water quantity and quality, cultivation of mixed Douglas fir–beech stands is a promising option for producing conifer timber and at the same time avoiding increased disturbance risks of mono-species forests under a warmer climate. Our results support the recommendation of mixed Douglas fir–beech stands based on soil quality, ecosystem resilience, and forest economic studies.

High water use plants influence green roof substrate temperatures and their insulative benefits

Green roofs are amongst the solutions employed to deliver sustainable buildings in cities. Their vegetation and substrate layers can reduce the heat transfer through the roof, thus potentially reducing energy used for building cooling and heating. However, little research has investigated the insulative properties of drought-tolerant plants which also have high water use. These plants have been found to improve runoff retention by removing larger volumes of water from the substrate through higher transpiration rates than succulents. This planting strategy may also enhance green roof cooling performance due to their greater evapotranspiration rates.In this study, the thermal performance of three drought-tolerant species with high water use — Lomandra longifolia, Dianella admixta, and Stypandra glauca — was evaluated and compared with a commonly used succulent species (Sedum pachyphyllum) and a bare unplanted module.L. longifolia had the best insulative performance during the entire investigated period, reducing green roof substrate surface temperature up to 1.86 °C compared to succulent S. pachyphyllum. In summer, the mixture reduced heat gain to a greater extent than monoculture plantings of all species except L. longifolia. Summer measurements also suggest that plants with high leaf area index (LAI) and higher albedo should be selected to reduce surface temperatures. High evapotranspiration rates of high water use L. longifolia led to greatest reduction of bottom surface temperatures during a heatwave when decreasing its water content from 18.5% to 2.9%. Results obtained using an analytical hierarchical partitioning technique indicated air temperature had the most significant impact on temperatures at both the surface of the planting substrate and the bottom of each green roof unit, accounting for 48% to 58% of the variation.

An Overview of Smart Irrigation Management for Improving Water Productivity under Climate Change in Drylands

Global drylands, covering about 41% of Earth’s surface and inhabited by 38% of the world’s population, are facing the stark challenges of water scarcity, low water productivity, and food insecurity. This paper highlights the major constraints to agricultural productivity, traditional irrigation scheduling methods, and associated challenges, efforts, and progress to enhance water use efficiency (WUE), conserve water, and guarantee food security by overviewing different smart irrigation approaches. Widely used traditional irrigation scheduling methods (based on weather, plant, and soil moisture conditions) usually lack important information needed for precise irrigation, which leads to over- or under-irrigation of fields. On the other hand, by using several factors, including soil and climate variation, soil properties, plant responses to water deficits, and changes in weather factors, smart irrigation can drive better irrigation decisions that can help save water and increase yields. Various smart irrigation approaches, such as artificial intelligence and deep learning (artificial neural network, fuzzy logic, expert system, hybrid intelligent system, and deep learning), model predictive irrigation systems, variable rate irrigation (VRI) technology, and unmanned aerial vehicles (UAVs) could ensure high water use efficiency in water-scarce regions. These smart irrigation technologies can improve water management and accelerate the progress in achieving multiple Sustainable Development Goals (SDGs), where no one gets left behind.

Optimization of Water Use Efficiency of Hydroponic Maize Fodder Production System under Different Microclimatic Conditions

Aims: Hydroponic method of producing fodder is an advanced technique which helps to achieve very high-water use efficiency (WUE). The main objective of the study was to optimize WUE by controlling the system and reducing the stress on the crops to give higher yield.
 Study Design: The experiment employed a statistical design known as Completely Randomized Design Place and duration of the study: The experiment was carried out in the Precision Farming Development Centre (PFDC) building, Kelappaji College of Agricultural Engineering and Technology (KCAET), Tavanur during May and June 2021.
 Methodology: Three different water application methods namely, mist (I1), micro sprinkler (I2), fogger (I3) was selected. Artificial light source of LED red (L1), LED blue (L2), LED red + blue (L3) and sunlight (L4) were considered for the study. Statistical analysis was conducted to understand the significance of different treatments used in the experiment in optimizing yield and WUE of the system.
 Results: Highest yield was observed in treatment involving fogger irrigation and LED red + blue (2.11 kg/tray) with highest WUE (515.43 kg/m3) compared to other treatments. Seed to fodder ratio obtained was 1:6. Chemical analysis showed higher percentage of crude protein (13.56%) and crude fibre (12.59%) in this treatment. Higher growth of green fodder under artificial light source can be attributed to the continuous supply of energy compared to highly varying sunlight and also the uniform distribution of water by fogger irrigation which maintained favourable condition for fodder growth.
 Conclusion: Results clearly indicated that growing green fodder with artificial light source (LED red + blue) and water supply with fogger can be recommended to farmers for achieving better growth of green fodder for domestic animals.