Types Of Irrigation Water Research Articles

Drip Irrigation with Sewage Effluent Increased Salt Accumulation in Soil, Depressed Sap Flow, and Increased Yield of Tomato

AbstractSewage application is a cost‐effective method for meeting the challenge of irrigation in water‐short regions. However, there is concern about the accumulation of salt from sewage effluent in soil. Experiments were conducted for 3 years in a greenhouse to investigate the effects of water quality on salt accumulation in soil and on sap flow for drip‐irrigated tomato. The types of irrigation water used in the experiments included secondary sewage effluent, groundwater, and blended water that was obtained by mixing the secondary sewage effluent and the groundwater in equal volumes. The results demonstrated that soil bulk electrical conductivity (ECb) increased with irrigation rates, and sewage application produced a more rapid increase than did blended water and groundwater treatments. Irrigation throughout the growing season could produce a 21–44% increase in salt content from its initial values to values at harvest, and salt accumulation occurred mainly at the 30–45 cm depth of soil. Sewage irrigation was likely to decrease sap flow but increased tomato yield and improved fruit quality parameters excluding ascorbic acid compared with groundwater irrigation. These results suggest that secondary sewage application using drip irrigation increases salt accumulation in the root zone, and depresses crop transpiration to some extent, but does not have a negative influence on tomato yield and fruit quality. Copyright © 2017 John Wiley & Sons, Ltd.

Effects of reclaimed water irrigation and nitrogen fertilization on the chemical properties and microbial community of soil

The ecological effect of reclaimed water irrigation and fertilizer application on the soil environment is receiving more attention. Soil microbial activity and nitrogen (N) levels are important indicators of the effect of reclaimed water irrigation on environment. This study evaluated soil physicochemical properties and microbial community structure in soils irrigated with reclaimed water and receiving varied amounts of N fertilizer. The results indicated that the reclaimed water irrigation increased soil electrical conductivity (EC) and soil water content (SWC). The N treatment has highly significant effect on the ACE, Chao, Shannon (H) and Coverage indices. Based on a 16S ribosomal RNA (16S rRNA) sequence analysis, the Proteobacteria, Gemmatimonadetes and Bacteroidetes were more abundant in soil irrigated with reclaimed water than in soil irrigated with clean water. Stronger clustering of microbial communities using either clean or reclaimed water for irrigation indicated that the type of irrigation water may have a greater influence on the structure of soil microbial community than N fertilizer treatment. Based on a canonical correspondence analysis (CCA) between the species of soil microbes and the chemical properties of the soil, which indicated that nitrate N (NO3−-N) and total phosphorus (TP) had significant impact on abundance of Verrucomicrobia and Gemmatimonadetes, meanwhile the pH and organic matter (OM) had impact on abundance of Firmicutes and Actinobacteria significantly. It was beneficial to the improvement of soil bacterial activity and fertility under 120 mg kg−1N with reclaimed water irrigation.

Evaluation of Alfalfa (Medicago sativa L.) Populations’ Response to Salinity Stress

Alfalfa (Medicago sativa L.) is a moderately salt‐tolerant crop with high economic return and is therefore more suitable for production with lower quality water than most high‐value crops. This study was conducted to examine the effect of water composition types (Cl− or SO42−) of irrigation water and five salinity levels (electrical conductivity of irrigation water [ECiw] = 0.85, 8, 13, 18.3, and 24.5 dS m−1) on biomass production, salt tolerance, and ion concentration of 15 alfalfa populations. The plants were grown in a greenhouse in 60 sand tanks for 347 d under salt treatment. There was no significant effect of water composition type on shoot and root biomass production. Water composition type × EC and water composition type x population interactions were also not significant. Salinity impact was population dependent (EC × population: P < 0.05), except at ECiw 18.3 dS m−1. Across all populations, shoot biomass was significantly reduced with increasing salinity to 77, 50, and 27% of the control at 13, 18.3, and 24.5 dS m−1, respectively. The ‘SISA14’ and ‘SW 8421S’ populations were the most productive under saline conditions with the highest degree of salt tolerance. The results showed that alfalfa biomass response to salinity did not depend on the type of salts (Cl− or SO42−). Shoot Cl− also did not correlate with relative biomass response. Thus, Cl− ion toxicity does not appear to be a factor in alfalfa salt tolerance for these populations. Although there was a correlation between salt tolerance and shoot Na+, the shoot ion concentration provides only a partial explanation of the relative salt tolerance of the alfalfa populations.

Effects of partial root-zone drying irrigation and water quality on soil physical and chemical properties

Using recycled wastewater (RW) is considered to be a strategic choice for overcoming water scarcity worldwide, so there is a pressing need to improve irrigation and nutrient uptake to sustain crop yields and at the same time to reduce the negative impacts of RW. In the present study, tomato plants (Lycopersicon esculentum Mill. var. “Azmier”) were exposed to three different water qualities: recycled wastewater (RW); fresh municipal tap water (FW); and a blend of RW and stormwater (BW), in combination with five irrigation scenarios: full irrigation (FI) full plant water requirement; deficit irrigation (DI), with 75% and 50% of FI as DI75 and DI50, respectively; and partial root-zone drying (PRD), with 75% and 50% as PRD75 and PRD50, respectively. The effects of these treatments on soil hydraulic conductivity (Ks), soil pH, root growth, leaf area (LA) as well as the residual phosphorus (P), potassium (K+), calcium (Ca2+) and magnesium (Mg2+) in the soil were investigated. The results showed that there was no significant difference in the soil Ks. However, different types of irrigation waters significantly affected the soil pH, while irrigation scenarios had no effect on soil pH. Also, irrigation scenarios influenced root growth and LA, while PRD scenarios lowered soil P, K+, and Mg2+ concentration compared to DI. The results also showed that water quality influenced canopy coverage 107days after planting (DAP). It is clear that PRD is a promising scenario for sustaining agriculture in areas with high water scarcity.

Water Scarcity and Irrigation Efficiency in Egypt

This study provides quantitative assessments of the impacts of efficiency enhancement for different types of irrigation water under water scarcity conditions. It employs a single country CGE (STAGE 2) model calibrated to an extended version of a recently constructed SAM for Egypt 2008/09. The SAM segments the agricultural accounts by season and by irrigation scheme, including Nile- and groundwater-dependent as well as rain-fed agricultural activities. The simulations show that Egypt should manage potential reductions in the supply of Nile water with more efficient irrigation practices which increase the productivity of Nile water, groundwater and irrigated land. The results suggest a more ambitious plan to boost irrigation efficiency for summer rice would be desirable in order to outweigh any potential shrinkage in output and exports. Furthermore, even doubling all non-conventional water resources is not sufficient to compensate the potential adverse impacts of Nile water losses. This highlights the importance of irrigation efficiency for the Egyptian economy.

English

The objective was to evaluate the effect of tannery sludge vermicompost in the chemical properties of soil cultivated with tomato and irrigated with wastewater. The experimental design was completely randomized in a factorial 6 × 2, totaling twelve treatments with three replications. The treatments were: four tannery sludge vermicompost (25% Sludge tannery(LC) + manure - T1, 25% Sludge tannery(LC) + rice husk - T2; 50% Sludge tannery(LC) + manure - T3 and 50% Sludge tannery(LC) + cane gray - T4), conventional fertilization (T5) and control (without fertilization - T6) and two types of irrigation water (domestic sewage and class 2 water). The physico-chemical characteristics and chemical soil and vermicompost (fertilizers) were determined before the culture of the installation vessels and after ninety days of driving the tomato crop. The data were submitted to analysis of variance by F test and comparisons between treatment means were performed by 5% Tukey test. In general, concentrations of chemical parameters in the soil after addition of vermicompost have increased, particularly in the addition of T2 = 25% LC + 75% of rice husk and T4 = 50% LC + 50% cane gray. The treated soil demonstrated pH, CEC, organic matter and saturation enhanced base increased, sodium and potential acidity decreased. Thus it can be concluded that vermicompost used can be added to soil conditioners changing the soil chemical attributes positively. Key words: vermicomposting, chemical attributes, reuse.

Effect of Irrigation Water Types and Spraying With Seaweeds on Vegetative Growth, Biochemical Attributes and Minerals Contents of Ziziphus mauritiana and Citrus sinensis Seedlings

Effect of Irrigation Water Types and Spraying With Seaweeds on Vegetative Growth, Biochemical Attributes and Minerals Contents of Ziziphus mauritiana and Citrus sinensis Seedlings

The impacts of magnetic treatment of irrigation water on plant, water and soil characteristics

Magnetic treatment has remained a controversial process for antiscale treatment of industrial and domestic water treatment over the past many years. Hence a study was initiated to evaluate the magnetic treatment of irrigation water on growth and yield parameters of cow pea and brinjal using pot and field experiments. Also, the impact of magnetic treatment on water properties and soil moisture were also evaluated. Under pot experiment, the treatments tried are normal water, hard water 150 and 300ppm, saline water 500, 1000 and 2000ppm of both control and magnetic treated solutions, respectively. Two permanent magnets with the strength of 1800–2000G was used. The results showed that magnetic treatment of irrigation water types led to an improvement in crop growth and yield parameters of cow pea. Magnetic treatments tend to reduce electrical conductivity, total dissolved solids and salinity levels of all solutions except normal irrigation water, whereas a definite trend of increase in pH was noticed for all the treatments. Soil moisture study results showed that the differences in soil moisture for days 1–3 after irrigation with magnetized irrigation water were lesser than those for the control solutions. Irrigation with magnetized irrigation water caused higher soil moisture compared with the control for different solution of saline and hard water respectively. In the field experiment with brinjal also the magnetic treatment of normal and saline water improved the yield by 25.8 and 17.0% over control. Scanning electron microscope image analysis results confirmed that under magnetic treated hard water, there was variation in the crystal structure of calcium carbonate. The length of these crystals is more when compared to control solutions. These results indicated the beneficial effect of magnetically treated irrigation water on growth and yield of crops, the properties of water and confirmed the possibility of using low quality water for agriculture.

GAS EXCHANGE OF COWPEA VARIETIES SUBJECTED TO SALT STRESS

Salt stress influences growth and development of the plants. In order to survive under these conditions, response mechanisms are developed and might be differently expressed by varieties of the same crop. This study aimed to evaluate physiological changes in the two cowpea varieties, subjected to salt stress conditions. The experiment was carried out in a greenhouse. A completely randomized design was adopted, with a 2 x 2 factorial considering 2 varieties (BRS Tapaihum and BRS Pujante) and two types of irrigation water (saline and non-saline). The water supply with saline solution of 10 dS m-1, prepared with NaCl, started at 41 days after sowing and was applied daily for seven days. Chlorophyll and gas exchange indices were measured during the application of the treatments. At the end, shoot fresh and dry weight (leaves and stem), relative water content and leaf Na+ and Clconcentrations were measured. The results showed that the varieties BRS Tapaihum and BRS Pujante resisted to salinity levels of 10 dS m-1 for seven days. BRS Pujante accumulated more Cl- compared to BRS Tapaihum, which caused the reduction in chlorophyll contents and the greater drop in photosynthetic activity

Halotolerant Plant Growth Promoting Bacteria Mediated Salinity Stress Amelioration in Plants

Soil salinization refers to the buildup of salts in soil to a level toxic to plants. The major factors that contribute to soil salinity are the quality, the amount and the type of irrigation water used. The presented review discusses the different sources and causes of soil salinity. The effect of soil salinity on biological processes of plants is also discussed in detail. This is followed by a debate on the influence of salt on the nutrient uptake and growth of plants. Salinity decreases the soil osmotic potential and hinders water uptake by the plants. Soil salinity affects the plants K uptake, which plays a critical role in plant metabolism due to the high concentration of soluble sodium (Na + ) ions. Visual symptoms that appear in the plants as a result of salinity include stunted plant growth, marginal leaf necrosis and fruit distortions. Different strategies to ameliorate salt stress globally include breeding of salt tolerant cultivars, irrigation to leach excessive salt to improve soil physical and chemical properties. As part of an ecofriendly means to alleviate salt stress and an increasing considerable attention on this area, the review then focuses on the different plant growth promoting bacteria (PGPB) mediated mechanisms with a special emphasis on ACC deaminase producing bacteria. The various strategies adopted by PGPB to alleviate various stresses in plants include the production of different osmolytes, stress related phytohormones and production of molecules related to stress signaling such as bacterial 1-aminocyclopropane-1-carboxylate(ACC) derivatives. The use of PGPB with ACC deaminase producing trait could be effective in promoting plant growth in agricultural areas affected by different stresses including salt stress. Finally, the review ends with a discussion on the various PGPB activities and the potentiality of facultative halophilic/halotolerant PGPB in alleviating salt stress.

Impact of Different Irrigation Systems on Water Quality in Peri-Urban Areas of Gujarat, India

The ever-growing population of India, along with the increasing competition for water for productive uses in different sectors – especially irrigated agriculture and related local water systems and drainage – poses a challenge in an effort to improve water quality and sanitation. In rural and peri-urban settings, where agriculture is one of the main sources of livelihood, the type of water use in irrigated agriculture has complex interactions with drinking water and sanitation. In particular, the multi-purpose character of irrigation and drainage infrastructure creates several interlinks between water, sanitation (WATSAN) and agriculture and there is a competition for water quantity between domestic water use and irrigated agriculture. This study looks at the determinants of the microbiological quality of stored drinking water among households residing in areas where communities use different types of irrigation water. The study used multiple tube fermentation method 'Most Probable Number' (MPN) technique, a WHO recommended technique, to identify thermotolerant fecal coliforms and E. coli in water in the laboratory (WHO 1993). Overall, we found that the microbiological water quality was poor. The stored water generally had very high levels of Escherichia coli (E. coli) contamination, 80% of the households had water in storage that could not be considered potable as per the World Health Organization (WHO) standards, and 73% of the households were using a contaminated water source. The quality of household storage water was largely unaffected by the major household socioeconomic characteristics, such as wealth, education level or social status. Households using surface water for irrigation had poor drinking water quality, even after controlling for hygiene, behavioral and community variables. Drinking water quality was positively impacted by proper storage and water treatment practices, such as reverse osmosis. Hygiene and sanitation indicators had mixed impacts on the quality of drinking water, and the impacts were largely driven by hygiene behavior rather than infrastructures. Community open defaecation and high village-household density deteriorates household storage water quality.

Effects of Different Irrigation Water Types, N Fertilizer Types, and Soil Moisture Contents on N2O Emissions and N Fertilizer Transformations in Soils

The use of reclaimed water (RW) for irrigation alleviates agricultural water shortages. However, N2O emissions and N fertilizer transformations in soils irrigated with RW under different N fertilizer types and soil moisture contents are poorly understood. A 216-h laboratory incubation experiment was conducted to evaluate the effects of irrigation water types (RW and fresh water, FW), N fertilizer types (15N-labeled KNO3 and (NH4)2SO4), and soil moisture contents at 40, 60, and 90 % water-filled pore space (WFPS) on N2O emissions and N fertilizer transformations in intact soil cores. The results showed that cumulative N2O emissions ranged from 3.78 to 36.30 mg N m−2, and fertilizer-derived N2O losses accounted for 0.14–2.44 % of N fertilizers, while fertilizer-derived N residues (NO3 −-N + NH4 +-N) accounted for 10.16–26.95 % of N fertilizers. The N2O emissions at 40 % WFPS and fertilizer-derived N residues at 60 % WFPS in soils irrigated with RW were significantly (10.98 and 20.95 %, respectively) higher than those irrigated with FW, while fertilizer-derived N2O losses at 60 % WFPS in soils irrigated with RW were 10.26 % higher than those irrigated with FW. The N2O emissions and fertilizer-derived N2O losses in soils amended with (NH4)2SO4 at 40 and 60 % WFPS were significantly (26.61–178.84 %) larger than those amended with KNO3, while fertilizer-derived N residues in soils amended with KNO3 were significantly (41.47 %) higher than those amended with (NH4)2SO4. The N2O emissions significantly increased with increasing soil moisture content. Our results indicate that N fertilizer types and soil moisture contents are the two important factors regulating N2O emissions and N fertilizer transformations. When RW irrigation is used, controlling soil moisture contents within 41 and 60 % WFPS (the optimum is 46 % WFPS) and application of KNO3 can reduce N2O emissions and fertilizer-derived N2O losses, and correspondingly increase fertilizer-derived N residues, which can contribute to climate change mitigation.

Economic Impacts of Water Scarcity Under Diverse Water Salinities

Exploitation of alternative water sources is expected to grow in the decades to come in water-stressed countries with fast population growth, especially in regions where a further decline of natural freshwater availability is expected due to climate change. Increasing utilization of non-freshwater usually leads to salinity build-up in fields and water sources as well as accumulation of various pollutants — both having a considerable impact on the suitability of non-freshwater for irrigation due to constraints associated with crop salinity tolerance and food safety regulations. We developed a linked Computable General Equilibrium (CGE) — farm-level model of a water economy with representation for multiple water types characterized by different qualities. We employ the model to assess the impact of water shortage on the Israeli economy, where steadily growing water scarcity leads to an increasing utilization of alternative water sources. We simulate water shortage scenarios based on the Long Term National Master Plan for The Water Economy developed by the Israeli Water Authority (IWA). The linked CGE — farm-level model provides a mechanism for estimating the Constant Elasticity of Substitution (CES) rates between different irrigation water types used in agriculture. This mechanism accounts for the effects of salinity on yields and takes into consideration food safety regulations for irrigating crops with treated wastewater. We demonstrate that, in contrast to previous studies, CES rates between different water types are not identical. The CES rates obtained in our study have relatively low values, which can be attributed to the constraints associated with crop salinity tolerance and food safety regulations. Our results reveal that water shortage can lead to a significant decline of Israel’s GDP, where a considerable part of the decline is attributed to the decrease in agricultural outputs. The magnitude of the impact depends on the underlying assumptions regarding future desalination capacity. To further study the effect of desalination, we run simulations under various desalination levels and examine its impact on the GDP. We also examine the extent to which the impact of water shortage is sensitive to CES rates between different irrigation water types.

Responses of grafted tomato (Solanum lycopersiocon L.) to abiotic stresses in Saudi Arabia.

Quantity and quality of irrigation water are considered the most imperative limiting factors for plant production in arid environment. Adoptions of strategies can minimize crop water consumption while nonexistent yield reduction is considered challenge for scholars especially in arid environment. Grafting is regarded as a promising tool to avoid or reduce yield loss caused by abiotic stresses. Tomato (Solanum lycopersium Mill.), commercial cultivar Faridah was grafted on Unifort rootstock and grown under regulated deficit irrigation (RDI) (100%, 80% and 60% ETc), using two types of irrigation water, fresh (EC = 0.86 dS/m) and brackish (EC = 3.52 dS/m). The effects of grafting and RDI on water use efficiency, vegetative growth, yield, fruit quality were investigated. Plant vegetative growth was reduced under water and salinity stresses. Grafting the plant significantly improves the vegetative growth under both conditions. The results showed that crop yield, Ca+2 and K+ were considerably increased in grafted tomato compared to non-grafted plants under water and salinity stresses. Grafted tomato plants accumulated less Na+ and Cl−, especially under high levels of salinity compared to non-grafted plants. Grafting tomato plants showed a slight decrease on the fruit quality traits such as vitamin C, titratable acidity (TA) and total soluble solids (TSS). This study confirmed that grafted tomato plants can mitigate undesirable impact of salt stress on growth and fruit quality.

Impacts of Climate and Management Variables on the Contamination of Preharvest Leafy Greens with Escherichia coli

The observed seasonality of foodborne disease suggests that climatic conditions play a role and that changes in the climate may affect the presence of pathogens. However, it is hard to determine whether this effect is direct or whether it works indirectly through other factors, such as farm management. This study aimed to identify the climate and management variables that are associated with the contamination (presence and concentration) of leafy green vegetables with E. coli. This study used data about E. coli contamination from 562 leafy green vegetables (lettuce and spinach) samples taken between 2011 and 2013 from 23 open-field farms in Belgium, Brazil, Egypt, Norway, and Spain. Mixed-effect logistic and linear regression models were used to study the statistical relationship between the dependent and independent variables. Climate variables and agricultural management practices together had a systematic influence on E. coli presence and concentration. The variables important for E. coli presence included the minimum temperature of the sampling day (odds ratio = 1.47), region, and application of inorganic fertilizer. The variables important for concentration (R(2) = 0.75) were the maximum temperature during the 3 days before sampling and the region. Temperature had a stronger influence (had a significant parameter estimate and the highest R(2)) than did management practices on E. coli presence and concentration. Region was a variable that masked many management variables, including rainwater, surface water, manure, inorganic fertilizer, and spray irrigation. Climate variables had a positive relationship with E. coli presence and concentration. Temperature, irrigation water type, fertilizer type, and irrigation method should be systematically considered in future studies of fresh produce safety.

Effects of Different Fertilizer and Irrigation Water Types, and Dissolved Organic Matter on Soil C and N Mineralization in Crop Rotation Farmland

Inorganic N fertilizer and irrigation water types on the C and N dynamics are poorly understood. This work aimed to evaluate the effect of different N fertilizer and irrigation water types on soil C and N mineralization. The farmland experiment was conducted with three types of N fertilizer (urea, ammonium sulfate, and slow-release urea) and drip irrigation with two types of water (groundwater and reclaimed water) for a summer maize-winter wheat crop rotation. Soil samples were collected from the experimental farmland for incubation experiments. The results showed that the average cumulative mineralization of soil C (incubation 20 days) and N (incubation 14 weeks) in different treatments ranged from 73.50 to 91.37 mg kg−1 and 52.65 to 64.04 mg kg−1, respectively. N fertilization significantly increased dissolved organic carbon (DOC), dissolved organic nitrogen (DON), soil organic carbon (SOC), and soil organic nitrogen (SON) contents in the soils, but N fertilizer and irrigation water types had no significant influence on them. Correspondingly, N fertilization significantly enhanced the mineralization of C by 14.14–21.22 % and N by 15.81–22.16 % in soils but no significant difference among different N fertilizer types. Compared with groundwater, reclaimed water irrigation enhanced the mineralization of C by 3.33 % and N by 1.01 %, but the difference was not statistically significant. The cumulative mineralization of C and N in soils after DOM removal average significantly decreased 9.83 and 14.83 %, respectively, which indicates that DOM plays an important role in soil C and N mineralization. Our results indicate that inorganic N fertilization promotes soil C and N mineralization, which may inevitably aggravate global warning. Reclaimed water irrigation had similar influence on soil C and N mineralization as groundwater irrigation; thus, we recommend irrigation with reclaimed water in water shortage areas.

Impact of biosolids and wastewater effluent application to agricultural land on corticosterone content in lettuce plants

We studied corticosterone occurrence in lettuce plants grown on three biosolids amended soils under irrigation with either tap water or secondary wastewater effluent. Corticosterone was examined as it has possible implications for human health. It is a major glucocorticoid, and as such has an effect on regulation of metabolism, immune functions and stress response.The plants were grown in 220-L lysimeters packed with 3 soils which represent a wide range of physicochemical properties. Lettuce was grown in cycles (two in summer and two in winter) during 3years, and in every spring season the sludges were re-applied. Corticosterone was quantified using ELISA and LCMS, and was found in the biosolids, tap water, wastewater effluent and lettuce plants. The respective ranges of concentrations were: 11–92ngg−1, 0.5–1.6ngL−1, 4.2–4.7ngL−1; and 1–900ngg−1 dry weight.A positive relationship was found between corticosterone concentrations in winter-grown lettuces and the plants fresh weight. The corticosterone content of the plants did not correspond with either the type of irrigation water or the biosolids type and rate of application or the soil properties.

Impact of cultivation year, nitrogen fertilization rate and irrigation water quality on soil salinity and soil nitrogen in saline-sodic paddy fields in Northeast China

SUMMARYSaline-sodic soils are widely distributed in the western Songnen Plain of Northeast China and planting rice has been found to be an effective and feasible approach for improving saline-sodic soil and increasing food production. Assessment of the effectiveness and sustainability of this method requires monitoring of the changes in soil salinity and nutrient content. The objective of the current study was to investigate the changes of soil salinity and nitrogen (N) contents over 1, 3, 6 and 9 years of cultivation, four application rates of N (N0: no N, N1: 100 kg N/ha, N2: 200 kg N/ha and N3: 300 kg N/ha) and two irrigation water types: ground water irrigation (GWI) and river water irrigation (RWI). Salinity and N contents of soil and water samples were analysed before planting and after harvest throughout the experiments. Soil pH and electrical conductivity (EC), especially in the surface layer of 0–40 cm depth, decreased with years of cultivation with both GWI and RWI, while soil inorganic N and total N contents increased. Moreover, with increasing N application rates, soil inorganic N and total N contents increased significantly in the 0–20 cm soil layer. Increasing N application had little effect on soil pH and EC. Reclaiming and planting rice promoted desalination of the surface and formation of a fertile tillage layer in saline-sodic paddy fields. In terms of irrigation and drainage in saline-sodic paddy fields, both soil salinity and N contents increased. Soil total salinity increased annually by 34 and 12·8 kg/ha, and inorganic N contents increased annually by 9 and 13·5 kg/ha with GWI and RWI, respectively. Therefore, comprehensive agricultural practices should be adopted for improving and cropping rice in saline-sodic paddy fields.

INFLUENCE OF IRRIGATION WATER TYPES AND ORGANIC MANURES ON RICE PRODUCTION

A field experiment was conducted at Research Farm of Agronomy Dept., Fac. Agric., Mansoura Univ., Mansoura, Egypt for a period of one year (2014) to find out the effect of irrigation water types and organic manures on some soil chemical properties and yield of rice crop (Var., 104). A strip plot design was used with three replications, the irrigation water types (I) were industrial wastewater, agricultural drainage water and normal irrigation water. The organic manures (T) consisted of FYM, compost, and FYM + compost, These treatments were given in rate of 5 and 2 t fed-1. The plants without treatments were served as a control. The results illustrate that, the soil pH was decreased while soil EC was increased significantly due to using industrial and agricultural drainage water in combination with organic manure treatments. The highest soil pH was recorded by the treatments I1T2 (7.62), I3T4 (7.66) and I2T4 (7.35) at vegetative, tillering and harvest stages, respectively. The treatments I1T4, I2T4 and I1T2 recorded the highest soil EC (ppm) at vegetative (522), tillering (291) and harvest (394) stages, respectively. The obtained data illustrate that, using of normal irrigation water (I3) combined with addition of FYM + Compost @ recommended doses (T4) recorded the highest (5416 kg fed-1) grain yield of rice crop followed by I3T3 (4415 kg fed-1), I2T4 (4292 kg fed-1), I3T2 (4195 kg fed-1) and I3T1 (4050 kg fed-1). Also, under use of different irrigation water, the addition of compost @ 2 t fed-1 (T3) was found to be superior than application of FYM @ 5 t fed-1 (T2) in registering the highest grain and straw yield of rice crop.

Economic Impacts of Water Scarcity under Diverse Water Salinities

Exploitation of alternative water sources is expected to grow in the decades to come in water-stressed countries with fast population growth, especially in regions where a further decline of natural freshwater availability is expected due to climate change. Increasing utilization of non-freshwater usually leads to salinity build-up in fields and water sources as well as accumulation of various pollutants - both having a considerable impact on the suitability of non-freshwater for irrigation due to constraints associated with crop salinity tolerance and food safety regulations. We developed a linked CGE - farm-level model of a water economy with representation for multiple water types characterized by different qualities. We employ the model to assess the impact of water shortage on the Israeli economy, where a steadily growing water scarcity is leading to an increasing utilization of alternative water sources. We simulate water shortage scenarios based on the Long Term National Master Plan for The Water Economy developed by the Israeli Water Authority (IWA). The linked CGE - farm-level model provides a mechanism for estimating the Constant Elasticity of Substitution (CES) rates between different irrigation water types used in agriculture. This mechanism accounts for the effects of salinity on yields and takes into consideration food safety regulations for irrigating crops with treated wastewater. We demonstrate that, in contrast to previous studies, CES rates between different water types are not identical and generally lower than previously assumed – differences that can be attributed to the constraints associated with crop salinity tolerance and food safety regulations. Our results reveal that water shortage can lead to a significant decline of Israel’s GDP, where a considerable part of the decline is attributed to the decrease in agricultural outputs. The magnitude of the impact depends on the underlying assumptions regarding future desalination capacity. To further study the effect of desalination, we run simulations under various desalination levels and examine its impact on the GDP. We also examine the extent to which the impact of water shortage is sensitive to CES rates between different irrigation water types.