Irrigation In Region Research Articles

Assessing Surface Water Quality for Irrigation Purposes in Some Dams of Asir Region, Saudi Arabia Using Multi-Statistical Modeling Approaches

The dam is a crucial water source for both consumption and irrigation in the Asir region of the Kingdom of Saudi Arabia. The current study evaluates surface water quality at the dam and examines the effects of some physicochemical and trace metals on irrigation using multiple statistical approaches. The physicochemical parameters and trace metals of the dam water were measured at 27 sites in the Asir region. Three sites were generated using the K-mean clustering technique; the first group included five sites, the second group contained 20 sites, and the third group added 2 sites. The chemical facies of the surface water were Na-K-SO42−. The surface water had low levels of Zn (0.19 mg/L), Cd (0.10 mg/L) and Pb (0.22 mg/L) except for B (38.50 mg/L), excessive concentrations of Na (2090.65 mg/L), K (535.72 mg/L), SO42− (208.11 mg/L) and Cl− (105.96 mg/L), while pH varied between 6.0 and 8.5 except at a few sites. The EC (electrical conductivity) values were within the standard for irrigation purposes. The results of irrigation water indices such as magnesium absorption ratio (MAR), magnesium hazard (MH), Kelly’s ratio (KR), and soluble sodium percentage (SSP) indicate that dam water is mostly fit for irrigation except for sodium percentage (Na%) and sodium adsorption ratio (SAR). The irrigation water quality index (IWQI) values revealed that 51.85% of samples had a high suitability class and 11.11% of samples had moderate suitability, whereas the rest were low suitability for irrigation use. The redundancy analysis (RDA) biplot revealed that water pH, DO, TH, and SO42− were increased with decreased EC and salt level. The generalized linear model (GLM) model found that salt had a negative effect on the amount of Fe, Ni, Se, and Al concentrations. The study recommends that proper protective measures, including acceptable criteria for different water parameters, are required to reduce the potential influence of physicochemical parameters and metals on irrigation water in agricultural fields.

Soil moisture estimation in South Asia via assimilation of SMAP retrievals

Abstract. A soil moisture retrieval assimilation framework is implemented across South Asia in an attempt to improve regional soil moisture estimation as well as to provide a consistent regional soil moisture dataset. This study aims to improve the spatiotemporal variability of soil moisture estimates by assimilating Soil Moisture Active Passive (SMAP) near-surface soil moisture retrievals into a land surface model. The Noah-MP (v4.0.1) land surface model is run within the NASA Land Information System software framework to model regional land surface processes. NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA2) and Global Precipitation Measurement (GPM) Integrated Multi-satellitE Retrievals (IMERG) provide the meteorological boundary conditions to the land surface model. Assimilation is carried out using both cumulative distribution function (CDF)-corrected (DA-CDF) and uncorrected SMAP retrievals (DA-NoCDF). CDF matching is applied to correct the statistical moments of the SMAP soil moisture retrieval relative to the land surface model. Comparison of assimilated and model-only soil moisture estimates with publicly available in situ measurements highlights the relative improvement in soil moisture estimates by assimilating SMAP retrievals. Across the Tibetan Plateau, DA-NoCDF reduced the mean bias and RMSE by 8.4 % and 9.4 %, even though assimilation only occurred during less than 10 % of the study period due to frozen (or partially frozen) soil conditions. The best goodness-of-fit statistics were achieved for the IMERG DA-NoCDF soil moisture experiment. The general lack of publicly available in situ measurements across irrigated areas limited a domain-wide direct model validation. However, comparison with regional irrigation patterns suggested correction of biases associated with an unmodeled hydrologic phenomenon (i.e., anthropogenic influence via irrigation) as a result of SMAP soil moisture retrieval assimilation. The greatest sensitivity to assimilation was observed in cropland areas. Improvements in soil moisture potentially translate into improved spatiotemporal patterns of modeled evapotranspiration, although limited influence from soil moisture assimilation was observed on modeled processes within the carbon cycle such as gross primary production. Improvement in fine-scale modeled estimates by assimilating coarse-scale retrievals highlights the potential of this approach for soil moisture estimation over data-scarce regions.

Analysis of 22-year Drought Characteristics in Heilongjiang Province Based on Temperature Vegetation Drought Index.

Heilongjiang Province is the main grain producing region in China and an important part of Northeast China Plain, which is one of the three black soil belts in the world. The cultivated region of black soil accounts for 50.6% of the black soil region in Northeast China. Due to the obvious rise of temperature and uneven distribution of precipitation in the 20th century, it has been considered to be one of the important reasons for agricultural drought and aridity. Under the background of climate change, understanding the multiyear changes and occurrence characteristics of cultivated land drought in different agricultural regions in Heilongjiang Province is of great significance for the establishment of agricultural drought prediction and early warning system in the future, guiding agricultural high-standard farmland irrigation in different regions, promoting black soil protection, and then improving grain yield. This paper calculates the temperature vegetation drought index (TVDI) based on the normalized difference vegetation index (NDVI) and surface temperature (TS) product data of MODIS from 2000 to 2021. Taking TVDI as the drought evaluation index, this paper studies the temporal and spatial variation distribution characteristics and occurrence frequency of drought in the whole region and four agricultural regions of Heilongjiang Province: Daxing an Mountain and Xiaoxing an Mountain (region I), Sanjiang Plain (region II), Zhangguangcai Mountains (region III), and Songnen Plain (region IV). The results show that medium drought generally occurred in Heilongjiang Province from 2000 to 2021, accounting for about 70% of the total cultivated land. The drought was severe from 2000 to 2009 and weakened from 2010 to 2021. In the 110 months of the crop growing season from 2000 to 2021, about 63.84% of the region suffered more than 60 droughts. It is found that the frequency of drought varies from region to region. More than 80 droughts occurred in the west of region IV and the middle of region II. The characteristics of region IV are large sandstorm, less precipitation, and lack of water conservancy facilities, resulting in frequent and strong drought. It is also found that the occurrence frequency, degree grade and regional distribution of drought are closely related to seasonal changes. In spring, the occurrence grade and frequency of drought in region IV are the strongest and the drought phenomenon is serious. In autumn, drought is frequent and distributed in all regions, but the grade is not strong (mainly medium drought), and the drought phenomenon is medium. It is humid in summer. Crops in Heilongjiang Province are one crop per annual. Spring drought seriously restricts the water content of crops. Long-term drought will lead to poor crop development and reduce yield. Therefore, only by clarifying the characteristics of regional time drought, monitoring accurate drought events and accurately predicting the occurrence of drought, can we guide high-standard farmland precision irrigation, improve crop yield and ensure national food security. At the same time, severe drought will affect the terrestrial ecosystem, resulting in the distribution of crops and microorganisms, and the transformation between carbon sink and carbon source.

Environmental risk of multi-year polythene film mulching and its green solution in arid irrigation region

Environmental risk of multi-year polythene film mulching (PM) was evaluated and investigated. The location observation following 19-year (2000–2018) PM in irrigated region indicated that the cumulative accumulation of soil microplastics was as high as 2900 ± 19.5 n kg−1. Microplastic accumulation was tightly associated with soil plasticizer concentration (Pearson’s r = 0.728, p <0.05), and the concentration of dominant phthalic acid esters (PAEs) was up to 117.5–705 μg kg−1. As such, we conducted organic mulching substitute experiment (2019–2020) with non-mulching (CK), maize straw mulching (SM), living clover mulching (CM), PM, PM+SM and PM+CM respectively. The data showed that organic mulching (SM, CM) achieved similar productivity benefit as PM-involved treatments (p > 0.05). Critically, total concentration of PAEs decreased by 6.43% in SM relative to CK, and by 9.61% in PM+SM relative to PM respectively. High throughput sequencing indicated that the proportions of predominant bacteria and fungi were totally lower in PM than those of organic mulching, particularly Sphingomonadaceae and Stachybotryaceae. KEGG analyses indicated that organic mulching promoted the metabolisms of polycyclic aromatic hydrocarbons, benzoic acid (probability>75%) and heterologous organism metabolism (p<0.001), due to improved microbial community assembly. Therefore, organic mulching efficiently accelerated microbial mineralization of PM pollutants, and may act as a green solution to displace PM.

Multi-parametric analysis of groundwater quality to assess human health risk and hydrogeochemical processes in an agriculturally intensive alluvial aquifer of Northwest India

ABSTRACT Groundwater is one of the most vital sources of irrigation in semi-arid regions of India, and in Punjab, India this resource is being highly exploited due to intensive agricultural practices. In the present study, groundwater quality in Bathinda district of Punjab, India was evaluated to know its suitability for drinking and human health risk associated with direct use of groundwater. To examine the suitability of groundwater for drinking purposes, drinking water quality index (DWQI) approach was used. Non-carcinogenic human health risk associated with the presence of fluoride and nitrate in groundwater was evaluated for the adults and children, through dermal and oral ingestion exposure pathways. Further, to know the processes governing the aquifer geochemistry, Gibbs plot, interionic relationships and principal component analysis were carried out. The results of the present investigation revealed that quality in 73% groundwater samples was not suitable for direct consumption. The results of hazard index (HI) indicated that 91% samples in case of men and 95% samples in case of women and children have HI value more than 1. There is a high non carcinogenic human health risk potential due to direct use of groundwater, and children and women are more prone to this risk. The inter-ionic relationships exhibited that evaporation processes due to semi-arid hot type climate, silicate weathering, shallow groundwater level, interaction of canal and ground water along with the agricultural return flow mainly controlled the groundwater chemistry in the area under investigation.

Remote Sensing—Based Assessment of the Water-Use Efficiency of Maize over a Large, Arid, Regional Irrigation District

Quantitative assessment of crop water-use efficiency (WUE) is an important basis for high-efficiency use of agricultural water. Here we assess the WUE of maize in the Hetao Irrigation District, which is a representative irrigation district in the arid region of Northwest China. Specifically, we firstly mapped the location of the maize field by using a remote sensing/phenological–based vegetation classifier and then quantified the maize water use and yield by using a dual-source remote-sensing evapotranspiration (ET) model and a crop water production function, respectively. Validation results show that the adopted phenological-based vegetation classifier performed well in mapping the spatial distributions and inter-annual variations of maize planting, with a kappa coefficient of 0.86. In addition, the ET model based on the hybrid dual-source scheme and trapezoid framework also obtained high accuracy in spatiotemporal ET mapping, with an RMSE of 0.52 mm/day at the site scale and 26.21 mm/year during the maize growing season (April–October) at the regional scale. Further, the adopted crop water production function showed high accuracy in estimating the maize yield, with a mean relative error of only 4.3%. Using the estimated ET, transpiration, and yield of maize, the mean maize WUE based on ET and transpiration in the study region were1.94 kg/m3 and 3.06 kg/m3, respectively. Our results demonstrate the usefulness and validity of remote sensing information in mapping regional crop WUE.

A Water Balancing Act: Water Balances Highlight the Benefits of Community-Based Adaptive Management in Northern New Mexico, USA

Quantifying groundwater recharge from irrigation in water-scarce regions is critical for sustainable water management in an era of decreasing surface water deliveries and increasing reliance on groundwater pumping. Through a water balance approach, our study estimated deep percolation (DP) and characterized surface water and groundwater interactions of two flood-irrigated fields in northern New Mexico to evaluate the regional importance of irrigation-related recharge in the context of climate change. DP was estimated for each irrigation event from precipitation, irrigation input, runoff, change in soil water storage, and evapotranspiration data for both fields. Both fields exhibited positive, statistically significant relationships between DP and total water applied (TWA), where one field exhibited positive, statistically significant relationships between DP and groundwater level fluctuation (GWLF) and between GWLF and total water applied. In 2021, total DP on Field 1 was 739 mm, where 68% of irrigation water applied contributed to DP. Field 2′s total DP was 1249 mm, where 81% of irrigation water applied contributed to DP. Results from this study combined with long-term research indicate that the groundwater recharge and flexible management associated with traditional, community-based irrigation systems are the exact benefits needed for appropriate climate change adaptation.

Significant differences in agro-hydrological processes and water productivity between canal- and well-irrigated areas in an arid region

Understanding the agro-hydrological processes and water productivity of canal- and well-irrigated systems is vital for agricultural water management in arid regions. In this study, the Agro-Hydrological & chemical and Crop systems simulator (AHC) was used in a distributed manner to evaluate the agro-hydrological processes and to assess water productivity under the conditions of canal- and well-irrigated systems. With the Heji irrigation system (Heji) located in the arid upper Yellow River basin, Northwest China as the case study area, the AHC was calibrated and validated by the field observation data of 2018 and 2019. Then the model was used in a distributed manner for the entire Heji. Results showed that there were significant differences in the agro-hydrological processes and water productivity between canal- and well-irrigated areas. The spatially averaged actual evapotranspiration was larger in canal-irrigated areas, and the cumulative net bottom water and salt fluxes were mainly downward in well-irrigated areas. The applied water was used more efficiently with higher equivalent water productivity of water applied (EWPIP) in canal-irrigated areas. However, the total water consumption (evapotranspiration) was in higher efficient utilization with higher equivalent water productivity of water consumption (EWPET) in well-irrigated areas. These findings can provide implications for regional irrigation water management and salinity control in the arid areas.

Performance of forage cactus submitted to different levels of irrigation and organic fertilization in the semi-arid region of Paraiba

The forage cactus represents one of the main sources of fodder for livestock in the semi-arid region. However, although it is cultivated on a large scale in several regions, there are still few studies addressing issues of improved management, especially about irrigation and fertilization of recently used varieties, such as those resistant to false carmine cochineal. Thus, this research aimed to evaluate the effect of different levels of irrigation and sources of organic fertilizer on the productive performance of forage cactus variety Mexican Elephant’s Ear (Opuntia stricta). The experiment was set up at Fazenda Riachão, municipality of Boa Vista, Paraíba. Two types of manure (bovine and caprine) and the control were used, associated with the absence of irrigation and five different depths, which varied from 1.5 to 5.5 L of water per week per plant. A 3x6 factorial design with five repetitions was used in a randomized block design. The depths of water applied promoted a significant increase in the variables analyzed. The goat manure was the most effective in obtaining better values of the number of cladodes per plant and productivity.

Planting trees in saline soil using ridge cultivation with drip irrigation in an arid region of China

AbstractLand degradation due to soil salinization is a widespread problem in arid and semiarid areas. In the Hetao Irrigation District in the upper reaches of the Yellow River in China, nearly one‐third of the land is salinized. To improve the environment in these salt‐affected regions, we conducted a field experiment in the Hetao Irrigation District from 2018 to 2020 that involved planting poplar and willow trees in saline soil using ridge cultivation with drip irrigation. After 3 years of water–salt regulation by drip irrigation, soil salinity at 0–40 and 0–120 cm with initial values of 12.22 and 8.27 dS m−1 was reduced by 85.19% and 68.56%, respectively. The survival rates of the seedlings were 99.3% (poplar) and 99.4% (willow) in the first year, and 90.6% (poplar) and 95.8% (willow) in the third year. Moreover, drip irrigation used 42.19% less water for salt leaching than other common methods. In addition, understory vegetation gradually established, and its species, coverage, and density increased year by year. A plant community structure gradually developed that comprised Poaceae and Asteraceae. In general, we found that ridge cultivation with drip irrigation led to an improved the soil environment which affected the development of the ecosystem shifting it in a stable, healthy, and sustainable direction. Taken together, our results indicate that ridge cultivation with drip irrigation can decrease soil salinity and produce ecological benefits.

The development of a competency framework for transanal irrigation

Transanal irrigation (TAI) is an established treatment in the management of all types of bowel dysfunction. The National Institute for Health Care and Excellence (NICE) recommends that TAI is initiated by a suitably trained health professional; however, it must then be established how that health professional becomes suitably trained. Much has been published about how TAI works, including its benefits and risks and the types of equipment available. However, no definitive competencies have been agreed among experts in this area. The Northern Region Irrigation Professional Group have recently developed a framework of evidence-based competencies for transanal irrigation. This article discusses the process of development and describes the evidence base and benefits behind the competencies.

Application of water-saving technologies for cotton irrigation in the Lower Volga region

The article presents the results of research in 2019-2020 in the south of Russia. There were 4 options for irrigation and 4 doses of fertilization to obtain a yield of 2 to 5 t/ha of raw cotton with different irrigation methods. It was found that a maintenance of the Soil Pre-Irrigation Moisture (SPIM) 75-75-70 % of Full Moisture Capacity (FMC) together with the doses of fertilizer N140P60K45 made it possible to achieve the minimum Irrigation Water Expenses (IWE) of 463 and 269 m3 and the Total Water Consumption (Water Total Consumption Coefficient – WTCC) of 664 and 456 m3 to obtain 1 ton of raw cotton, achieving the yield of 4.32 and 4.49 t/ha, respectively, with sprinkling and drip irrigation. An increase of the fertilizer doses to N175P75K56 contributed to rise of yield to 5.28 and 5.41 t/ha, simultaneously reducing IWE the to 378 and 224, and WTCC - to 543 and 379 m3/t. Compared to furrow irrigation, the use of sprinkling and drip irrigation made it possible to reduce IWE by 37.0 and 73.7 %, WTCC - by 47.4 and 63.7 %, increasing the yield of raw cotton to 38.0 and 43.5 %.

Groundwater recharge assessment and long-term simulation for managing the threat of salinization of irrigated lands

The advancement of irrigated agriculture is indispensable to satisfy the growing food demands of the world's prospering population. It is also essential for accomplishing many UN SDGs (United Nations' Sustainable Development Goals) such as SDG1 (No Poverty), SDG2 (Zero Hunger), and SDG15 (Life on Land). Without proper management, however, irrigation advancement can cause twin hydrological problems, i.e., rising aquifer levels and salinization in irrigated areas. Currently, more than a fifth of the total worldwide irrigated region is adversely affected by these problems. Furthermore, whenever left unaddressed, these problems could spread to more than half of the irrigated lands worldwide by 2050. To evaluate the aforesaid issues in an irrigated region of India, this study first developed a water balance model to assess the long-term groundwater recharge which would help to understand the system dynamics of the problems. Then, after analyzing the results, a simulation model was set up for the study region considering local agro-hydro-climatic and soil conditions. The approach used is the first of its kind in the selected study region and it will offer a better comprehension of the dynamics of the processes that guide the system imbalances. The presented approach is novel and easy to follow and it can also be replicated in other parts of the world dealing with comparative issues. The model’s performance was evaluated statistically before being applied. The models performed very well as evidenced by high R-squared values and model efficiency, and low ME and RMSE values. The groundwater recharge analysis revealed that the aquifer levels have been rising for the last two decades and they will continue to rise if no preventive measures are implemented. The simulated scenarios showed that under the base case alternative the aquifer levels will increase at a mean yearly rate of 0.08 m. Hence, apt management plans such as altered cropping pattern, conjunctive water use, and canal lining are recommended. The most favorable scenario divulged that even a little alteration of two to six percent in different inputs would contain the region safe from the problems mentioned above.

Study on the Spatial and Temporal Distribution of Irrigation Water Requirements for Major Crops in Shandong Province

Understanding the spatial and temporal distribution of irrigation water requirements is significant to realize the rational allocation of water resources and also serves as the basis for analyzing agricultural water-saving potential. This study refers to the standard irrigation regions in southwestern, northern, central, southern, and eastern Shandong province. The irrigation water requirements at 20 weather stations in Shandong Province from 1968 to 2016 were calculated, and the spatial and temporal distribution characteristics were analyzed. The results indicated the following: (a) The trend of the annual irrigation water requirements for summer maize and winter wheat showed an insignificant increase in the eastern Shandong irrigation region, a significant decline in northern and southwestern Shandong irrigation regions, and an insignificant decrease in the other irrigation regions. (b) The multi-year average irrigation water requirement for summer maize generally presents a spatial distribution characteristic which is less in the southwest, more in the northeast, less in the south, and more in the north, while the spatial distribution characteristic for winter wheat is less in the southeast, more in the northwest, less in the south, and more in the north. (c) The main meteorological factors affecting the irrigation water requirements for summer maize are precipitation and sunshine duration, while relative humidity is the main factor affecting winter wheat in Shandong Province.

Effects of irrigation water quality and NPK-fertigation levels on plant growth, yield and tuber size of potatoes in a sandy loam alluvial soil of semi-arid region of Indian Punjab

Management of saline water through desalination or blending with low salinity canal water may be a viable strategy for potato irrigation in semi-arid regions having saline ground water and scarce canal water. A 4-year study was conducted to investigate the effects of four water qualities [canal water (CW), desalinated water (DSW), saline ground water (GW) and mixed water (MW) (CW + GW)], three N-P-K-fertigation levels [F100 = 100% NPK (190, 28.4 and 53.9 kg ha−1 of N, P and K, respectively), F80 = 80% NPK and F60 = 60% NPK] and their interaction on the performance of two potato varieties grown in a sandy loam alluvial soil of semi-arid region. The electrical conductivity (EC) of CW, DSW, GW and MW ranged from 0.3 to 0.4, 0.2–0.3, 3.2–4.2 and 1.8–2.2 dS m−1, respectively. Drip irrigation with GW resulted in 21–44% reduction in total tuber yield compared with CW, however, the maximum reduction (54%) was observed in grade-A tuber yield that was accompanied by a considerable increase in grade-C tuber yield. Irrigation with MW increased total tuber yield by 9–37% compared with GW. Irrigation with DSW manifested a 41% and 14% increase in total tuber yield as compared with GW and MW, respectively. The tuber yield obtained with MW was comparable with DSW up to soil EC1:2 of 0.65 dS m−1, and beyond that level, DSW was observed to be superior. The variety ‘Kufri Surya’ had slight yield advantage over ‘Kufri Pukhraj’ when CW, DSW and MW were used, however, yields of both varieties were statistically at par under GW irrigation. The variety ‘Kufri Jyoti’ exhibited a 13–22% yield advantage over ‘Kufri Surya’ for all irrigation water qualities. Plant growth and yield attributing parameters were the highest at F100 which declined progressively with a decrease in fertigation level for all water qualities. However, these differences were narrow between GW and MW and moderate between CW and DSW. Therefore, in drip fertigated potatoes using saline or mixed water in a sandy loam soil, it is advocated to use 80% of recommended NPK without any loss in tuber yield and to reduce cost of cultivation & environmental pollution.

Assimilating remote sensing data into a crop model improves winter wheat yield estimation based on regional irrigation data

Irrigation plays an important role in crop yield production in arid and semi-arid regions. However, irrigation effects have not been well addressed in the application of crop models at a regional scale due to limited data availability, which constrains the reliability and accuracy of simulation results. Assimilating remote sensing information into crop models can provide a viable approach to reduce associated uncertainties. In this study, regional irrigation data for winter wheat (Triticum aestivum L.) grown on the Loess Plateau was used to calibrate and validate the ChinaAgrosys (China Agricultural System) crop model at site and regional scales. Remote sensing data was then assimilated into the ChinaAgrosys crop model under four assimilation schemes. Two remotely sensed assimilation state variables (i.e., LAI and NDVI) and two assimilation algorithms (i.e., PSO (Partical swarm optimization) and SCE-UA (Shuffled complex evolution)) were considered. During the winter wheat growing season on the Loess Plateau, 30.6% of the wheat production area was irrigated once, 6.7% was irrigated two times, 3.7% was irrigated three times, and the remaining wheat area was rainfed. The R2 values between maturity date, LAI, and yield simulated by the ChinaAgrosys crop model and observations at 21 agrometeorological stations on the Loess Plateau were greater than 0.73, 0.44, and 0.60, respectively, during 2010–2015. The accuracy and spatial heterogeneity of winter wheat yield estimation were effectively improved by assimilating remote sensing data into the ChinaAgrosys crop model based on regional irrigation data. Under the four assimilation schemes, the combination of PSO+NDVI produced the highest accuracy for yield estimation in Hongtong county (92.8%), followed by SCE-UA+NDVI (92.0%). Our results demonstrated the importance of accounting for the spatial heterogeneity of water availability when applying a crop model in arid and semi-arid regions. Additionally, our analysis regarding different assimilation state variables and algorithms indicated that both simulation accuracy and calculation efficiency should be considered when assimilating remote sensing data into a crop model for simulating crop growth at regional scales.

Boron Removal from Desalinated Seawater for Irrigation with an On-Farm Reverse Osmosis System in Southeastern Spain

Seawater desalination can provide water for irrigation in coastal regions where freshwater resources are scarce. Reverse osmosis (RO) is the most common technique to obtain desalinated seawater (DSW) worldwide. However, using DSW for irrigation may pose an agronomic risk as RO permeates have a boron concentration above the phytotoxicity thresholds of some sensitive crops, such as woody crops (0.5 to 1.0 mg/L). In this study, an on-farm RO system designed to reduce the boron concentration of DSW was evaluated from a technical and economic perspective. The impact of variations in the operating parameters feed water temperature, pressure, and pH, on the boron reduction process was assessed. The results showed that boron rejections close to 99% can be obtained by increasing the feed water pH to 11 with an operating pressure of 10 bar. Looking at the affordability of the system, a total production cost of 1.076 EUR/m3 was estimated for the 1.1 m3/h on-farm system used in the trial. However, this cost is expected to decrease to 0.307 EUR/m3 for a commercial RO plant (42 m3/h), highlighting the importance of the scale factor. Our results provide novel guidance on the feasibility of implementing on-farm boron removal RO systems, when DSW is provided by coastal plants with boron concentrations above the crop tolerance.

Optimal Annual Allocation Model of Large Storage Based Irrigation Project by Multi Level Approach

The effective management of water available for irrigation in arid and semi-arid regions has increased in importance due to limited water supply. The need for allocation of water resources optimally in a water limiting condition has already been recognized, and much research has been carried out. In the present study, an annual irrigation planning model is formulated for Nagarjuna Sagar Project command in the semi-arid region of South India dealing with optimal allocation of annual available water among command areas of each main canal taking off from the reservoir and reallocating the available land and water of each command area to different seasons of a year and finally allocating the available land and water of each season among crops grown in that season, maximizing the total annual benefit of the project. The problem is solved in three stages. In the first stage, fortnightly crop water requirements are calculated from the evapotranspiration model by Penman – Monteith method. In the second stage, seasonal crop water production functions are developed using the single crop intraseasonal allocation model for each crop of all seasons. In the third stage, allocations of area and water are made at seasonal, interseasonal and at reservoir levels by deterministic dynamic programming, maximizing the net annual benefit from the project. Optimal cropping pattern and irrigation water allocations are made with full and deficit irrigation strategies for various levels of probability of exceedences of expected annual water available and results obtained are discussed.

THE MODERN RESEARCHS ON GROUNDWATER RESOURCES OF MOIST SUBTROPICAL SOILS OF AZERBAIJAN

One of the leading areas of modern soil science is the study of groundwater for use in agriculture. The importance of this direction is determined by the development of methods for studying soil processes. In uncultivated soils formed under natural vegetation, the approach of the groundwater level to the surface leads to soil salinization and waterlogging. Long-term and systematic irrigation in the Lerik region creates a completely new water and soil process. The reserves of humus, carbon, nitrogen and the C:N ratio were determined in pseudo-podzolized clayey mountain-forest yellow earth soils (Aric, Staqnic Cleyic Acrisols - Loamic) common in the zone of humid subtropics in the Lerik region located in the southern part of Azerbaijan. In order to turn uncultivated soils into arable land, it is necessary to create a mathematical model of groundwater level fluctuations, to determine the functional relationship between the amount of nutrients and the final product. The application of the results of mathematical calculations ensures the involvement of lands in agriculture and obtaining high productivity from these lands. The results of analyzes of the river waters chosen as the object of study show that there were no serious mineralization processes in the rivers. The mineralization of river waters in the Lerik region varied within 0.439-0.678 g/l. The content of magnesium in water taken from the Lerik region ranges from 0.021-0.037 g/l. The content of sodium and potassium ions in the salinity of water ranges from 0.061-0.083 g/l. According to the results of analyzes, it can be seen that the mineral composition of the Lerik River is useful for drinking and suitable for agriculture, as irrigation water.

Interaction between soil water and fertilizer utilization on maize under plastic mulching in an arid irrigation region of China

Plastic film mulching (PM) has become a widely used cropping method in arid and semiarid areas. However, it is unknown how different PMs affect crop water and N utilization and their interaction under different N supplies. A two-year field experiment was conducted in the Hetao Irrigation District (HID), in northwest China. Following local irrigation practices, 500 mm border irrigation was used to grow spring maize over two growing seasons (2019 and 2020) with two N levels: high-N (225 kg N ha–1) and low-N (150 kg N ha–1). Combined with three mulching methods, the experiment had five treatments: (i) no mulching with high-N (control, CK), (ii) black plastic film with high-N (HB), (iii) transparent plastic film with high-N (HT), (iv) black plastic film with low-N (LB), and (v) transparent plastic film with low-N (LT). The 4 PM treatments had higher average soil water storage (0–120 cm) than CK. The PM treatments had the highest water consumption coefficients (Kwcn) at 6–leaf to 12–leaf stage (Kwc2) and milking to maturity (Kwc5) stage. The HP treatments (HB and HT) had higher soil nitrogen storage than CK during the growth period. Averaged across two seasons, HB and HT had 23.9%, 29.2% respectively, higher grain yields than CK. Averaged across two seasons, the transparent PM treatments had 7.49%, 5.31%, and 1.72% higher water use efficiency (WUE), partial factor productivity of nitrogen (PFPN), and harvest index, respectively, than the black PM treatments. The PM treatments showed the relationship between water use efficiency of biomass (WUEb) and nitrogen use efficiency of biomass (NUEb), with WUEb increased, NUEb also increased. Given these results, we recommend the high-N level and transparent PM for maize cropping to increase yield and resource utilization efficiency in the HID.