Freshwater Irrigation Research Articles

Understanding the Spatial–Temporal Patterns of Floating Islands Impacting the Major Dams of the White Nile

Floating islands in Lake Victoria, the world’s second-largest fresh water lake, disrupt transportation, fisheries, irrigation, and water quality. Despite their impact, the dynamics of these islands remain unexplored. This study investigates island dynamics within the Nalubaale, Kiira, and Bujagali dams in Uganda, exploring the causes of their formation and the subsequent impact on hydropower production. The study collects data of Landsat imagery from 2000 to 2020, CHIRPS precipitation, and Lake Victoria’s water level datasets from 2004, 2010, 2013, 2017, and 2020. The results reveal a strong correlation between precipitation, fluctuating water levels, and floating island formation, with nutrient-rich runoff from municipal waste and agriculture promoting island growth. In addition, rising water levels lead to the dislodging of rocks and soil, contributing to floating island formation, which may manifest with a lag time of up to one month. The analysis shows higher correlations between precipitation, water levels, and floating islands during the long (March–May) and short (September–November) rainy seasons as opposed to drier periods (June–August, December–February). The findings indicate that southeast monsoon winds, which transport floating vegetation, also are essential in influencing island dynamics. Consequently, the major drivers of floating islands in Lake Victoria are identified as precipitation, water level fluctuations and wind variations. Finally, a negative correlation between floating island eutrophication and power production at Kiira and Nalubaale stations suggests that the increased eutrophication caused by the presence of floating islands leads to reduced power output at both Kiira and Nalubaale power stations.

Evaluation of Reproductive Success of the Olive Ridley Turtle Lepidochelys olivacea (Testudinata: Cheloniidae) Using Different Incubation Treatments

In nesting areas with extreme climatic conditions, such as high temperatures, it is advisable to use mitigation strategies that counteract these negative effects on the hatching success of sea turtle nests. We evaluated the effect of incubation treatment on hatching success and incubation period for olive ridley turtles Lepidochelys olivacea during the 2019 nesting season in Guerrero, Mexico. Three incubation treatments (T1 = shade & freshwater irrigation; T2 = shade, seawater pre-irrigation, sand covered & freshwater irrigated; T3 = shade, seawater pre-irrigation, covered with a plastic lid & freshwater irrigated) were trialed at two different times during the nesting season. One of our goals was to compare the reproductive success of hatchery nests versus in situ nests, however, in situ nests hatching success was zero. We found that treatments had no effect on hatching success or incubation period, but there were differences in proportions of dead and crushed hatchlings. Clutches incubated in the second relocation period had longer incubation times. However, nest relocation periods had no effect on hatching success, dead hatchlings, or the proportion of crushed hatchlings. Our results also showed that the amount of seawater applied to the holes and the rate of irrigation were not lethal for the incubating eggs, but prolonged the incubation period. These results could help to increase our understanding of sea turtle reproductive success and may serve as a baseline to adapt the spatio-temporal conditions of the hatcheries in other areas with similar environmental conditions.

Economics of Coconut Cultivation Using Treated Sago Industrial Wastewater and Fresh Water in Salem District of Tamil Nadu

The study attempts to examine the socio- economic profile and economics of coconut cultivation using treated sago industrial wastewater and fresh water in the Salem district of Tamil Nadu. A sample of 180 farmers receiving treated wastewater from nearby industrial units and another 180 farmers receiving fresh water (control farms) were selected through a multistage purposive sampling technique. The major finding of economic analysis of coconut cultivation revealed that the gross income of the sample farm using treated sago industrial wastewater was high at ₹ 1,31,408.00 as a result of the better yield of nuts (12540) as compared to that obtained by irrigation with fresh water (12245). The net income per hectare of coconut was ₹ 46,128.64 and ₹ 34,245.72 for the farm using treated wastewater and control farms, respectively. The study; therefore could establish that using treated industrial wastewater for irrigation will be advantageous in terms of net returns and to an extent substitute use of fresh water for irrigation, besides helping to save on use of and expenditure of organic and inorganic fertilizers.

Pre-sowing soil carbon dioxide emissions of the following year from the silage maize field irrigated with different levels of wastewater in conventional and direct sowing practices

Abstract While knowing CO2 emissions during the seasonal period are important, determining residual effect before sowing in the following year can be an available practice in improving wastewater irrigation strategies. Therefore, this study investigated CO2 emission from the silage maize field plots irrigated with wastewater at different levels under conventional and direct sowing in the pre-sowing period after two experimental years by comparing freshwater with full irrigation, and correlated with H2O emission and, soil moisture and temperatures. The results showed that irrigation with wastewater and conventional tillage in the previous two years resulted in higher CO2 emissions in the following period also, and 27 and 11% higher emissions were determined in irrigation with wastewater at 100 and 67% levels than full freshwater irrigation. In irrigation with wastewater at 100% level and direct sowing, soil moisture was found higher, while reduced H2O emission and the soil temperatures at 5 and 10 cm depths. Considering moisture conservation effect of direct sowing, it could be concluded that to reduce on the residual CO2 emission effect of irrigation with wastewater from previous years, deficit irrigation in direct sowing can be recommended practice.

Strategy to Minimize Plant Accumulation of Contaminants of Emerging Concern: Alternation between Treated Wastewater and Freshwater Irrigation

Treated wastewater (TWW) is increasingly used for agricultural irrigation in arid and semiarid areas, but it can introduce contaminants of emerging concern (CECs) into the food chain, posing a potential risk to human health. While many studies have shown that plants can accumulate some CECs, so far little effort has been made to explore mitigation strategies. This study tested the concept of alternating between TWW with conventional freshwater for irrigation to minimize CEC accumulation in plants. Tomato and lettuce seedlings were first cultivated in CEC-containing hydroponic solutions for 3 weeks, and then in CEC-free media for another 3 weeks. The plant tissues contained elevated concentrations of perfluorobutanesulfonate, perfluorobutanoic acid, perfluorohexanoic acid, carbamazepine, and fluoxetine ranging from 42.1 to 2724.2 ng/g (dry weight). However, after being transferred to CEC-free media, most CEC levels decreased by over 75%, attributed to plant metabolism, growth dilution and back release to culture media. This proof-of-concept study suggested that using TWW during the early part of the growing season may effectively minimize CEC accumulation. Such hybrid irrigation schemes have a great prospect for expanding the safe reuse of TWW and other lower-quality water sources in agriculture and should be further evaluated under field conditions.

Accumulation of Na+ in Cotton Field under Mulched Drip Irrigation of Brackish Water in Arid Areas

In arid areas, the disordered accumulation of Na+ in cotton fields under mulched drip irrigation seriously affects the normal growth and development of cotton. To reveal the process and mechanism of Na+ accumulation, in situ field tests were conducted in typical cotton planting bases in the south of Xinjiang, China. Eight experimental scenarios were set up to use brackish and fresh water for drip irrigation under mulch during the whole growth period of cotton according to the drip irrigation system. By monitoring the weather, groundwater level, and soil moisture before and after irrigation, and testing the soil salinity and Na+ concentration, the temporal and spatial distribution and transport characteristics of Na+ were compared and studied. The results showed that: (1) owing to the strong spatial variation of soil permeability, soil water and salt dynamics exhibited significant differences after irrigation in all experimental scenarios in the study area, especially at a depth of 0–60 cm. (2) The Na+ profile exhibited a “thin waist”, whose depth depended on the climate and lithology of the soil; however, this phenomenon was not observed in the salt profile. (3) The accumulation of Na+ in cotton fields is an extremely complex dynamic process that is influenced by both natural and human activities. This process is controlled by the dynamic characteristics of soil water and salt, but it is different from the distribution of soil salt in time and space. This study provides necessary technical support for the formulation of drip irrigation systems under brackish water film, and provides a scientific basis for fine agricultural planting and water resources management in arid areas.

Zeolite amendment reduces lead accumulation and improves growth and yield in tomato plants irrigated with sewage water.

Although sewage water (SW) is a source of nutrients, it also causes heavy metal accumulation in soil; especially, lead (Pb+) contamination of soil is a serious concern in agriculture. Soil contaminants limit the bioavailability of nutrients to plants. So, they affect plant growth and produce quality. Therefore, a pot experiment was conducted to investigate the effect of zeolite soil amendment on the accumulation of Pb+ in tomato crop grown with SW irrigation. The pot media of SW-irrigated plants was amended with different concentrations of zeolite, viz., 0.75%, 1.50%, and 2.25%. The results showed that the application of 0.75% zeolite increased leaf area, plant height, fruit number, and plant fresh and dry biomasses by 37%, 17%, 14%, 24%, and 7% compared to freshwater irrigation. Moreover, the lowest zeolite dose also led to higher chlorophyll content (68.02 SPAD) compared to SW-irrigated plants (55.13 SPAD). Similarly physiological traits, such as A, gs, and E, were higher (17.68µmolm-2s-1, gs 0.28mmolm-2s-1, and 7.88mmolm-2s-1, respectively) in 0.75% zeolite-treated plants than in SW-irrigated plants (12.99µmolm-2s -1, 0.19mmolm-2s-1, and 7.00mmolm-2s -1, respectively). On the contrary, a reduced level of hydrogen peroxide and malondialdehyde and decreased activity of antioxidant enzymes were observed in low-dose zeolite applied plants. Zeolite reduced Pb+ accumulation in tomato plants as compared to SW-irrigated plants, whereby Pb accumulation in the fruits of SW-irrigated plants was 80% more than those of zeolite + SW-treated plants. Conclusively, this study has revealed the improvement in morphological and physiological growth attributes of the SW-irrigated tomato plant in response to zeolite application.

Effects of biochar addition and deficit irrigation with brackish water on yield-scaled N2O emissions under drip irrigation with mulching

Biochar has been proven to have great potential for mitigating greenhouse gas emissions and improving crop growth. However, the effects of biochar addition on yield-scaled N2O emissions in a mulched and drip-irrigated maize field using different irrigation water qualities and quantities remain unclear. A two-year field experiment was conducted to examine the effects of biochar addition, irrigation level and water salinity on soil N2O emissions, maize yield and grain N uptake in Northwest China. Eight treatments in total included the combination of two biochar addition rates of 0 t/ha (B0) and 60 t/ha (B1), two irrigation levels of full (W1) and deficit irrigation (W2, W2 = 1/2 W1) and two water salinity levels of freshwater (S0, 0.71 g/L) and brackish water (S1, 4 g/L). The soil properties, N2O emission fluxes, maize yield and grain N uptake, along with the abundances of N-cycle functional marker genes were measured during the two growing seasons. Soil water-filled pore space (WFPS), soil NH4+-N and NO3--N contents accounted for the majority of the variation in the dynamic changes of N2O fluxes. Deficit irrigation had lower N2O emissions compared with full irrigation, which was more pronounced in the second year. Relative to freshwater irrigation, brackish water irrigation increased N2O emissions under W1, but freshwater and brackish water irrigation had similar N2O emissions under W2 in both years. Biochar addition effectively mitigated N2O emissions by 29.4–31.0% and 17.9–29.2% under different irrigation treatments in 2020 and 2021, respectively. The continuous drought induced by deficit irrigation weakened the effectiveness of biochar in reducing N2O emissions. The differences in N-cycle functional marker genes could not reflect the variation in cumulative N2O emissions among treatments. Under all irrigation treatments excluding W2S1, biochar addition improved the total maize yield and grain N uptake over the two-year period by 4.06–10.74% and 5.57–8.63%, respectively. Brackish water and deficit irrigation increased grain and grain N yield-scaled N2O emissions, whereas biochar addition reduced both of them. Overall, these findings suggest that biochar addition can effectively reduce N2O emissions and increase yield and grain N uptake under brackish water and deficit drip irrigation with mulching in a maize field system, and thus adding biochar can help with achieving the sustainability of agricultural production in areas with limited freshwater resources.

Seawater irrigation on nests can increase male marine turtle production

Global warming is increasing marine turtle nesting beach sand temperatures throughout the world. All marine turtles have temperature-dependent sex determination, with female hatchlings produced at warmer incubation temperatures. These warmer sand temperatures are causing a scarcity of male hatchlings at many nesting beaches. A range of mitigation strategies including shading and freshwater irrigation are being trialled at marine turtle nesting beaches around the world to address this issue. Because seawater is always abundant at marine turtle nesting beaches, we trialled a number of intense, one-off seawater irrigation experiments (equivalent to 100 and 200 mm rainfall) to test if male green turtle Chelonia mydas hatchling production could be increased without decreasing overall hatching success at Heron Island, southern Great Barrier Reef, Australia. We found that different combinations of seawater volume and temperature could produce a short-term drop in nest temperature by 2°C. When applied during the middle of embryonic development, these irrigation treatments could increase the proportion of male hatchlings compared to non-irrigated control nests, with less than a 10% decrease in hatching success. Hence, seawater irrigation has the potential to be a viable management strategy to increase the proportion of male marine turtle hatchlings at beaches that produce all, or nearly all, female hatchlings.

ДИНАМИКА ИРРИГАЦИОННОГО КАЧЕСТВА ОРОСИТЕЛЬНОЙ И ДРЕНАЖНО-СБРОСНЫХ ВОД НИЖНЕ-ДОНСКОЙ ОРОСИТЕЛЬНОЙ СИСТЕМЫ В 1972 И 2019–2021 ГОДАХ

Purpose: to assess the dynamics of the irrigation quality of irrigation water from the main canal and drainage wastewater (DWW) from the outlet collectors using the example of the Nizhne-Don irrigation system (NDIS) to justify the sustainability of their environmental safety. Materials and methods. The objects of the study were DWW from the TsS, K-3, LS-2 and MKL-7 collectors, water from the Tsimlyansk reservoir supplied to the Nizhne-Don main canal (NDMC). The subject of the study was the hydrochemical indicators of the DWW in 1972 and 2019–2021, and the comparative irrigation characteristics of the waters. Results. Comparison of water irrigation characteristics from NDMC in 1972 and 2019 showed an increase in sulfate salinity by about 35 %. The irrigation coefficient according to H. Stebler (Ka) has decreased from 43.24 to 28.15 since 1972, while the irrigation water quality from NDMC remains good (Ka > 18). In 1972, the average value of the irrigation coefficient (Ka) of DWW during the irrigation period in the K-3 collector was 2.98, in LS-2 – 4.14, in TsS – 5.54, in MKL-7 – 22.96. In 2019–2021 – 10.44; 14.85; 12.62; 11.61 respectively. Conclusions. The irrigation quality of the Don irrigation water from the NDMC has now deteriorated compared to 1972 by 1.54 times. Over the fifty-year period of operation of the NDIS, the irrigation quality of the DWW in the collectors K-3, LS-2 and TsS increased by 2–3.5 times. Irrigation water quality in the MKL-7 collector decreased by 2 times. It has been proven that the use of fresh irrigation water for irrigation contributes to a sustainable increase in the environmental safety of DWW. The need to reuse DWW for irrigation should be decided at the regional level based on the economic feasibility of the cost of cleaning and transporting water to the irrigation system.

Design and Performance Evaluation of a Low-Cost Domestic Level Filter to Treat Kitchen Wastewater

The aspects of water security mainly govern by the availability and the quality of the water. As foreseen, use of portable fresh water for landscape irrigation can be a problem in the future. This research study was carried out with objectives of characterizing the raw kitchen wastewater (KWW), designing a domestic level filter for treating KWW and evaluating the removal efficiency of newly designed filter for reuse purpose. Four combinations of treatment systems were used namely in an order, sand and gravel layer, sand and bricks, sand and bricks with a coco peat layer and sand, bricks, coco peat and activated charcoal units for filtering. Raw kitchen wastewater samples were collected three times per day and made a composite sample by mixing equal proportion of each. Water quality parameters were measured before and after treatment of the KWW and compared with the Central Environmental Authority, Sri Lanka (CEA) standards. The average pH, Chemical Oxygen Demand (COD) and oil content in raw KWW was significantly higher than CEA standards. Based on results, raw KWW cannot be reuse for irrigation and it requires adequate treatment prior irrigation. The quality of filtrate from treatment system four resulted with the mean values of pH, electrical conductivity, temperature, total dissolved solids, COD and oil content and respectively quantitative figures were 7.2 ,0.65 mS cm-1, 29.5°C, 230.1 mg L-1, 365 mg L-1 and 2.8 g L-1 .The combination of sand, bricks, coco peat and activated charcoal filter filtrated effluent was within the CEA standards, which can be reuse for irrigation.

Improvement of water and crop productivity of silage maize by irrigation with different levels of recycled wastewater under conventional and zero tillage conditions

Although wastewater irrigation has a long history involving different stages of development, the future expectation to improve crop yield and water productivity in wastewater irrigation practices is still relevant. Therefore, the aim of this study is to evaluate water productivity, yield and crop quality of silage maize irrigated with different application levels (100%, 67%, and 33% of irrigation need) of recycled wastewater with three replicates in conventional tillage and zero tillage practices and comparing them with full fresh water irrigation. The results of two-year field studies showed that zero tillage resulted in saving 10.1% of irrigation water on average compared to conventional tillage and actual evapotranspiration in silage maize with zero tillage was 7.4% less. Biomass yield was the highest in full irrigation with wastewater under zero tillage. Zero tillage practice provided 12.0% and 13.2% higher water productivity(WP) and irrigation water productivity(WPirrig), respectively compared to conventional tillage. The WP was higher in treatments with wastewater with 100% and 67% irrigation levels, while the WPirrig was higher in treatment with wastewater with 67% irrigation level. While the crop total soluble solids, nutrients, crude protein, chlorophyll(SPAD), leaf area index and leaf relative water content (LRWC) values were higher in full irrigation with wastewater, acid and neutral detergent fibers and membrane damage was lower. Crude protein in zero tillage was lower than in conventional tillage, while SPAD and LRWC were higher. It could be concluded that wastewater can increase silage maize biomass yield and crop quality. This result may be more valuable in terms of both protecting scarce fresh water resources and contributing to the environment with waste disposal. Moreover, 67% irrigation treatment with wastewater can be preferred for the higher WP and WPirrig values, and zero tillage can be used as a practical treatment that contributes to the yield and water saving.

Effects of aerated brackish water irrigation on growth of Lycium barbarum seedlings

The management of Lycium barbarum seedling has an important influence on its fruit yield and quality at mature stage. Pot experiments were conducted to investigate the effects of four water salinity levels (0.6 (fresh water), 1.5, 3.0 and 4.5 g/L) under non-aeration (O2 content of 8.5 mg/L) and aeration (15.0 mg/L) irrigation on soil enzyme activity and the physiological parameters and growth status of Lycium barbarum seedlings. The results showed that brackish water irrigation increased soil electrical conductivity by 1.8 – 5.8 times, inhibited soil enzyme activities by 12.1% – 52.0%, and decreased the net photosynthetic rate by 10.7% – 24.8%, transpiration rate by 24.3% – 27.3%, and plant water consumption by 0.9% – 18.0% compared with fresh water irrigation. Brackish water irrigation also significantly inhibited the growth of leaves, base stem, roots and biomass of Lycium barbarum seedlings. Compared with non-aeration irrigation, the micro-nano bubble aerated brackish water irrigation promoted the activities of urease and alkaline phosphatase by 0.5% – 33.0% and 4.4% – 9.0%, respectively, and increased net photosynthetic rate by 3.3% – 8.0%, plant transpiration rate by 0.1% – 25.3%, and water consumption by 0.7% – 5.0% under brackish water irrigation. It also promoted the growth of leaves, branches, base stem and roots, and increased the biomass accumulation of Lycium barbarum seedlings by 7.4% – 9.3%. The aerated water irrigation with micro-nano bubbles can alleviate the negative effects of salt stress on the growth of Lycium barbarum seedlings to varying degrees, so the salinity of irrigation water less than 3.0 g/L combining with the aerated disposal is suggested to be as an optional solution to the planting of Lycium barbarum seedlings in arid oasis regions.

Long-term saline water drip irrigation alters soil physicochemical properties, bacterial community structure, and nitrogen transformations in cotton

Saline water irrigation has become important in alleviating shortages of freshwater resources in arid areas. However, long-term saline irrigation increases soil salinity with resulting effects on soil nutrient transformations. Although soil nitrogen (N) transformations are key processes in terrestrial ecosystems, how irrigation with saline water affects N transformations is not fully understood. Therefore, we used metagenomics to investigate effects of 11 years saline water drip irrigation on soil bacterial community structure and N transformations in a cotton field. In a field experiment, there were two irrigation water salinity (ECw) treatments, 0.35 dS·m−1 [freshwater (FW)] and 8.04 dS·m−1 [saline water (SW)], and two N application rates, 0 (N0) and 360 kg N ha−1 (N360). Compared with FW irrigation, SW irrigation significantly increased soil water content, salinity, organic carbon, total N, and ammonium N, but significantly decreased pH, nitrate N, and potential nitrification rate (PNR). PNR was significantly positively correlated with soil nitrate N and total N but negatively correlated with soil water content. In the bacterial community, SW irrigation significantly increased relative abundances of the phyla Actinobacteria, Chloroflexi, and Gemmatimonadetes but decreased those of Proteobacteria and Acidobacteria. Saline water irrigation increased relative abundance of genes associated with N fixation (M00175), denitrification (M00529), and dissimilated nitrate reduction (M00530) but decreased that of Nitrate/nitrite transport system (M00438). Saline water irrigation significantly increased relative abundances of nirK, nirS, norC, nifD, nifK, nifH, gdhA, GDH2, GLUD1_2, nasB, narI, narG, narH, nxrA, and nxrB genes but decreased those of amoC nirA, nirB, nirD, narB, norB, gudB, GLU, napA, and nasA. Saline water irrigation also affected enzymes associated with N transformations, with increases in relative abundance of enzyme genes associated with nitrite reductase (NO formation), N fixation enzymes, and glutamate dehydrogenase and decreases in that of glutamate synthase. According to redundancy analysis, soil water content, electrical conductivity, and bulk density were the main soil physicochemical drivers of functional genes affecting N transformations. Thus, SW irrigation changes bacterial community composition by affecting soil physicochemical properties and therefore affects N cycling by promoting denitrification and N fixation and inhibiting nitrification.

Plant Physiological Responses After Fresh and Sewage Water Irrigation: Plant Health Perspectives

Plant Physiological Responses After Fresh and Sewage Water Irrigation: Plant Health Perspectives

Study for Recycling Water Treatment Membranes and Compnents towards a Circular Economy-Case of Macaronesia Area.

Desalination is an opportunity to get fresh water for irrigation and for drinking. Reverse Osmosis (RO) for sea water desalination is a solution for the high demand for water in Atlantic islands. The most efficient process to get desalinated water is RO; however, it is necessary to study what to do with the RO membranes used at the end of their life. This paper confirms the possibility to recycle them. The main categories of recycling by thermal processing commonly used in the industry include incineration and pyrolysis to produce energy, gas and fuel. These processes can be applied to mixed plastic waste, such as the combination of materials used in the manufacture of RO membranes. Recycling RO elements from desalination plants is shown to be an opportunity and pioneering initiatives are already underway in Europe. Energy recovery, via incineration, is feasible nowadays and it is a possibility to recycle RO membranes. On the other hand, the recycling of RO elements, via the pyrolytic industry, for fuel production could be centralized in a new industry already planned in the Macaronesia area and all obsolete osmosis membranes could be sent there for recycling. Recycling RO membranes is a very important opportunity for the environment and economy of the zone. This is a new business in water treatments with membranes, very interesting for decreasing the residues and the carbon footprint. The importance of this work is applied to sea water membranes, brackish water ones, and also wastewater tertiaries RO elements at the end of their life.

Evaluating soil water and salt transport in response to varied rainfall events and hydrological years under brackish water irrigation in the North China Plain

• Responses of soil water and salt dynamics to varied rainfall events and hydrological years were evaluated. • Salt leaching and deep drainage occurred mainly due to summer-concentrated rainfall during wet year. • Salt decrease percentage in the CL was greater than that in the GL in all hydrological years. • One brackish water irrigation application is avail salt leaching both in cropland and grassland. Soil salination challenges sustainable agricultural production and management in the lowland area of the North China Plain (NCP). This study investigated the effect of varied rainfall events and hydrological years on deep drainage and salt leaching in Nanpi County in the NCP. Field experiments were conducted to measure soil matric potential (SMP) and soil water electrical conductivity (EC w ) in 300 cm profiles of an irrigated cropland (CL) and unirrigated grassland (GL). The HYDRUS-1D model was calibrated and validated to optimize soil water and salt transport parameters using the SMP and EC w data obtained in 2015 and 2016, respectively. The results showed that the HYDRUS-1D model was reliable to simulate soil water and salt migration in 300 cm profiles at both sites. The salt leaching depths and degrees were positively correlated with precipitation amount. The heavy rain (45 mm) and rainstorm (68 mm) favored salt leaching within 100 cm, and severe and extreme rainstorms resulted in salt leaching within 150–200 cm both in the CL and GL. The SDP in the CL was greater than that in the GL in all hydrological years owing to agricultural cultivation and irrigation. Salt leaching in the 300 cm profiles mainly occurred in the rainy seasons of wet year, with the salt decrease percentage (SDP) being 61% in the CL and 42% in the GL. Salt leaching due to precipitation was sufficient in the irrigated CL in all hydrological years, and precipitation in normal rainfall years could remove 70–80% of soil salts within 50–63 cm soil depth. Grass growth without irrigation led to water deficits and salt accumulation when the annual precipitation amount was less than that in wet years. The results demonstrated that precipitation, combined with irrigation using of brackish and freshwater, could be usefully for soil salt leaching. A recommended irrigation scheme for water saving and salt control in CL and GL is one brackish water irrigation application and three freshwater irrigation applications each year in the NCP.

Assessing the ecological and health implications of soil heavy metals in vegetable irrigated with wastewater in calcareous environments

The introduction of heavy metals from wastewater irrigation to the soil-crop-human biological domain has become a vital environmental and human health challenge. We evaluated the impact of wastewater irrigation (WW) on the severity of heavy metal pollution and health risk potential in different vegetables under WW versus fresh water (FW) irrigation. A multifaceted assessment was conducted using the pollution index (PI), ecological risk (ER), bio-concentration factor (BCF), hazard quotient (HQ), overall hazard index (HI), carcinogenic risk (CR), the bio-concentration factor (BCF), and total carcinogenic risk (TCR). The findings revealed that WW irrigation increased metal concentrations across all soil samples and vegetables in the order of Cd > Zn > Pb > Cu and Zn > Cu > Pb > Cd, respectively., The PI and ER indices indicated a significant increase of 27–330% and 260–310%, respectively in the WW-irrigated soils compared to the FW-irrigated soils. The heavy metals concentrations in the edible tissues of vegetables and their associated BCF values under WW irrigation exhibited the orders, Zn > Cu > Pb > Cd and Zn > Cu > Cd > Pb >, respectively Cabbage had the greatest potential to take up heavy metals compared with other crops. The mean HQ and HI were in the low risk category (0.1 ≤ HQ and HI < 1). Likewise, CR and TCR values were within acceptable limits (1.00E-06–1.00E-04) by consuming veggies produced with WW to children and adults, implying that there are no significant health risks to local inhabitants. However, the levels of HQ, HI, CR, and TCR were significantly higher in vegetables grown with WW than in those irrigated with FW, suggesting that wastewater irrigation may have a detrimental impact on human health.

Salinity of irrigation water selects distinct bacterial communities associated with date palm (Phoenix dactylifera L.) root

Saline water irrigation has been used in date palm (Phoenix dactylifera L.) agriculture as an alternative to non-saline water due to water scarcity in hyper-arid environments. However, the knowledge pertaining to saline water irrigation impact on the root-associated bacterial communities of arid agroecosystems is scarce. In this study, we investigated the effect of irrigation sources (non-saline freshwater vs saline groundwater) on date palm root-associated bacterial communities using 16S rDNA metabarcoding. The bacterial richness, Shannon diversity and evenness didn’t differ significantly between the irrigation sources. Soil electrical conductivity (EC) and irrigation water pH were negatively related to Shannon diversity and evenness respectively, while soil organic matter displayed a positive correlation with Shannon diversity. 40.5% of total Operational Taxonomic Units were unique to non-saline freshwater irrigation, while 26% were unique to saline groundwater irrigation. The multivariate analyses displayed strong structuring of bacterial communities according to irrigation sources, and both soil EC and irrigation water pH were the major factors affecting bacterial communities. The genera Bacillus, Micromonospora and Mycobacterium were dominated while saline water irrigation whereas contrasting pattern was observed for Rhizobium, Streptomyces and Acidibacter. Taken together, we suggest that date-palm roots select specific bacterial taxa under saline groundwater irrigation, which possibly help in alleviating salinity stress and promote growth of the host plant.

An economic analysis of impact of climate change in irrigation ecosystem of Tiruchirappalli district of Tamil Nadu, India

Climate change refers to long-term changes in the weather pattern and temperature trend. Due to drastic climate change and global warming, the availability of fresh water for irrigation became a major concern. Hence the present study was conducted to study the impact of climate change in canal, ground water and both canal and ground water irrigation ecosystems of Tiruchirappalli district of Tamil Nadu, India. For the present study, three blocks were purposively selected from the Tiruchirappalli district. 150 sample farmers were selected from 15 villages. Percentage analysis showed that there was an increase in irrigation intensity in all three-irrigation ecosystems and there was an increased number of irrigation for Sesame and Groundnut in the study area. All three irrigation ecosystems showed a decline in water availability. The irrigated area of major crops in the Tiruchirappalli district declined significantly along with an increase in the area of specific crops namely Sugarcane, Green Gram and Sorghum. The Ricardian model was employed to quantify the impact of climate change on the net income of farmers in all the three irrigation ecosystems. The Ricardian model revealed that both the Kharif season rainfall and the Rabi season rainfall had a positive impact on the net income of farmers in all three-irrigation ecosystems while the Kharif season maximum temperature had a detrimental effect on the net income in both canal and groundwater irrigation ecosystem. Tobit model was used to analyse the factors influencing the adoption of climate-smart technologies in the irrigation ecosystem. Tobit model results revealed that farm size, education and extension contact were the factors influencing the adoption of climate-smart technologies in all the three-irrigation ecosystems. The major constraint in all the three irrigation ecosystems was the labour shortage to adopt climate-smart technologies followed by the consequent yield reduction. Government should plan for climate strategies to enhance the beneficial effects and to mitigate the harmful effects of climate change in the district.