Journal of Water Research in Agriculture
Year:2017 | Volume:31 | Issue:3 |Papers Count:15

The present study was conducted with the aim of investigating the effect of water quality on safflower yield and yield components. The experiment had two factors including water salinity at two levels (S1= 1.8 dS m-1 and S2= 5.8 dS m-1) and landrace genotypes of safflower (G1= Dizaj Hossein Beig- Marand, G2= Koshaksara- Marand, and G3= Agkand- Mianeh). The experiment was laid out as a split plot design with three replications. Results showed that the interaction effects of salinity and landrace genotypes on grain yield, 1000- seeds weights, and the main capitol weight were significant (P<0.05). Landrace genotypes of safflower were different in the harvest index. This result revealed a genetic diversity among safflower genotypes. Water salinity affected biological yield and seeds per capitol. The traits such as leaves and stem numbers, capitol diameter and capitol per plant were not affected by the experimental treatments. With increasing water salinity from 1.8 to 5.8 dSm-1, the seeds per capitol, biological yield, and grain yield decreased by 45%, 56% and 44%, respectively. The highest and lowest 1000-seeds weights were recorded as 38 and 26 g, respectively. The highest grain yield was obtained by Koshaksara-Marand genotype at salinity of 1.8 dS m-1 (1207 kg ha-1) and 5.8 dS m-1 (568 kg ha-1). The lowest yield of 426 kg ha-1 was from Dizaj Hossein Beig-Marand genotype at salinity of 5.8 dS m-1. Therefore, Koshaksara- Marand genotype produced high yield as compared to other genotypes under water salinity treatments.

Application of advance irrigation methods to a proper utilization of water resources is inevitable. The effects of different amounts of irrigation water on yield and quality of two varieties of date palm under asubsurface drip irrigation were studied in Behbahan Agricultural Research Station during two growing seasons (2014-2015). The study was conducted in a randomized complete block design with a split plot design with three replications where three levels of water application based on T1=75%, T2=100% and T3=125% of crop water requirement, were as the main plots and two variety of Khasi and Zahedi were as sub-plots. The results showed that different levels of irrigation have not had no significant effect on the quality and yield of fruit. However, there was a significant difference (p<0.01) between the levels of irrigation in terms of water use efficiency. Accordingly, T1 by 0.88 kg of dates per cubic meter of water showed higher water use efficiency. Comparison of mean interactions between the water application and varieties showed water use efficiency of Khasi and Zahedi varieties were 0.86 and 0.89 kg/m3, respectively. The applied irrigation water of palm trees based on T1 was of 7545 m3/ha which was 2515 m3/ha less compared to that under T2.

It is necessary to determinate of crop water requirement for optimum use of agricultural water resources. This research was carried out for determining water requirement and crop coefficient of Barhee date palm in the first to third year of vegetative growth. A drainage lysimeter was used to measure reference evapotranspiration (ETr) and three drainage lysimeters were used to measure evapotranspiration of date palm (ETc). The amounts of reference evapotranspiration and ETc were calculated using soil water balance. The results showed that ETr values in the first to third year were 2105, 1827, and 2021.8 mm, respectively, while seasonal ETc in vegetative growth were 274.3, 402.7, and 597.2 mm, respectively. ETc increased 46.8% and 48.3%, yearly. The crop coefficient of Barhee date palm was 0.08-0.18 in the first year. In this year, the minimum crop coefficient was recorded in May, while the maximum crop coefficient was in October and January. But, the date palm crop coefficient was 0.10-0.30 in the second year and 0.19-0.43 in the third year of vegetative growth. In second and third years of vegetative growth, the minimun crop coefficient was recorded in March. In the second year, the maximum crop coefficient was observed in August and January, while the maximum crop coefficient in the third year was obtained in November. The increasing plant age and vegetative growth could be the main reasons for the difference in the amounts of water requirement and crop coefficient of date palm in the first to third year.

Crop Simulation models are used for water management in farms and are widely used for optimization of water use efficiency. AquaCrop model, developed by FAO, is based on yield response to water. Compared to other similar models, AquaCrop requires fewer input parameters. The objective of this study was evaluation of this model for barley under deficit irrigation in Pakdasht region. The experiment was done in 2014-15 growing season and included three irrigation treatments and three sowing dates. The irrigation treatments included full irrigation and two treatments of 80% and 60 percent of full irrigation. Sowing dates included early, normal, and late planting. Comparing the estimated values of AquaCrop model and measured values showed that the model is well capable of simulating the barley biomass production. Average R2, RMSE and MBE for the comparison between measured and estimated values were calculated to be 0.96, 8.4 %, and 2.6 %, respectively.

Evaluation of fruit trees response to water is one of the important strategies in irrigation management. Current study was conducted in order to assess the response of five olive commercial cultivars to three levels of irrigation. The study was conducted in Olive Research Station, in Dallaho Kermanshah province, for three years (2011-13). A split plot experiment based on randomized complete block design with three replications was used to apply the treatments. The main plots included the cultivars Conservalla, Amphisis, Manznilla ,Sivillano and Zard-e- ziton, while different levels of irrigation including 100%, 80% and 60% of water requirement were assigned to sub-plot were assigned to subplots.Potential evapotranspiration was estimated as 1158.8 mm year-1during 2011-13 using ETo calculator software and daily climatic data. Water amount for olive trees in 100% water requirement level was determined as 5828.1 cubic meters per hectare. The results of this study showed that the effects of irrigation levels on some of the reproductive traits such as fruit yield, and fruit and meat weight were significant. Highest yield was obtained in Conservalla with 80% and 100% water demand and amounted to 17745 kg ha-1 and 17106 kg ha-1,respectively. Irrigation levels had no effect on oil content of the olive cultivars. The cultivars were very diverse in terms of traits, such that there was a significant difference in irrigation water productivity, fruit and meat weight, fruit length and diameter, kernel weight, dry matter, and oil content. Interaction between cultivars and irrigation levels was significant only in the case of irrigation water productivity. The results of this research showed that with increasing irrigation levels, productivity of irrigation water decreased. In the cultivar Conservalla at irrigation level of 60%, irrigation water productivity was 4.2 kg/m3 and at irrigation level of 100%, it was 2.9 kg/m3. Conservative cultivar with average water use efficiency of 3.64 kg/m3 had the highest irrigation water productivity among the studied cultivars.

This research was carried out to evaluate the effect of drought on germination, growth, and fruit yield of okra in laboratory and field. Laboratory experiment was conducted as a two-factor factorial in agricultural laboratory of Khuzestan Payame Noor University based on completely randomized design in three replications. The first factor was seed priming (including control and seed priming with water and KNO3) and the second factor was drought stress (matric potentials of -0.3, -0.6, -0.9 and -1.2 MPa). Results indicated that the highest germination percentage was observed under no-stress and hydro priming conditions. Seed germination was decreased with increase in stress, where in control treatment i.e. without hydro priming, increasing drought stress from the first to third level resulted in 72.3 percent reduction in germination percentage. Hydro priming improved seed germination under drought stress and no-stress conditions. The field experiment was carried out during 2015-16 growing season based on RCBD in three replications. The irrigation intervals treatment was based on 70, 100, 130 and 160 mm evaporation from pan. İncreasing irrigation intervals reduced dry matter accumulation, leaf area index, plant height, friut number per plant, and biological and fruit yield of okra. Increasing irrigation interval from the firt level to the second, third, and fourth levels decreased fruit yield up to 9%, 26%, and 31 percent, respectively. Therefore, for optimum yied, okra should experience no drought stress during growth and friut formation. Thus, irrigation after 70 mm evaporation from evaporation pan can be advisable as an irrigation interval for okra. However, since friut yield reduction in the second level of irrigation interval was not considerable and considering economic issues, it may be possible to suggest this irrigation inerval, but it requires more research work.

Detailed estimation of evapotranspiration is required for water balance studies, water utilities, design and management of irrigation conveyance systems and water resources management, and other purposes. In this study, crop coefficients and water requirements of Ajwain, which is one of the most important medicinal herbs, were determined during a growing season in College of Agriculture, University of Birjand, by using lysimeters. For this purpose, three weighing lysimeters were used and water requirement of Ajwain was calculated by water balance method. To calculate the reference evapotranspiration, common grass sown in green spaces was used with a height of 12 cm as the reference plant. Finally, at the end of the growing season, values of Ajwain crop coefficients during different growth stages including early stage, crop development, midseason, and late season were obtained as, respectively, 0.78, 1.06, 1.13 and 0.96. Also, the total evapotranspiration of the plant in lysimeter was 492 mm.

In order to investigate the effects of different irrigation regimes on yield quantity and quality of flue-cured tobacco cv. K 326, an experiment was carried out based on a randomized complete blocks design (RCBD) with three replications, at Tirtash Tobacco Research Center, in 2011. Treatments were combination of W 1=40%, W 2=60%, W 3=80%, and W 4=100 percent crop water requirement with D 1=5, D 2=10, D 3=15 days irrigation interval with two control treatments (without irrigation (R) and furrow irrigation (I)). The results showed that treatment W 4 D 1, W 4 D 2, W 4 D 3, W 3 D 1, W 3 D 2, W 3 D 3, W 2 D 1, and W 1 D 1 had statistically significant difference with the other treatments and had more dry leaf yield. Also, the minimum leaf chlorine content was observedin W 4 D 2, W 3 D 1, W 2 D 1, W 2 D 2, W 1 D 3, and Rtreatments. Under W 4 D 2, W 3 D 1, W 3 D 3, W 2 D 1, W 1 D 1, W 1 D 2, and W 1 D 3 treatments, tobacco had statistically significant difference with other treatments and had higherprice. Also, the minimum gross income was obtained under W 2 D 2, W 2 D 3, W 1 D 3, I, and R Treatments.

Qanat is one of the most surprising structures that is used for extraction of underground water in arid and semi-arid regions. There are 607 qanats in Semnan province, providing a total discharge of 93.5 million m3 of water per year. In this research, existing conditions and irrigation in agricultural fields of 15 qanats of Semnan province were studied and some executive strategies were recommended to improve qanats’ performance. , quantity and quality changes of qanat water, application efficiency and water productivity downstream the studied qanats were evaluated. Results showed that insufficient credit, tunnel and wells collapsing due to lack of necessary construction and resistant covering, entrance of flood into qanats, numerous owners and rural migration were the most important reasons of discharge reduction and qanats destruction. Variations of EC and pH in qanats water were relatively low for a long period of time. Average of application efficiency in cultivated lands downstream the studied qanats was about 51.6%. Whereas it was 45.5% downstream the studied wells in the same regions. Average water productivity for various crops was 0.63 kg/m3. Establishment of strong groups to better partnership of owners in operation and maintenance of qanats, regular dredging, tunnel staining, well covering, tunnel tubing and fixing valve in qanat outlet, construction of qanat water reservoir and establishment of proportion between crops water requirement and amount of irrigation water in downstream lands of qanats are the most important practical strategies for improving qanats conditions.

Increasing conveyance efficiency and reducing water loss in distribution canals are very important. The current study aimed at investigating and comparing empirical equations and SEEP/W model for estimating seepage of earth channels. For this study, the earth canal of Boldaji, constructed in loamy soil and located downstream of modern irrigation and drainage network of Gandoman and Boldaji, Chaharmahal and Bakhtiari province, was chosen. Using dimensional similitude equations and considering 0.13 as scale ratio, the dimensions and discharges of the mentioned channel were applied to the laboratory model. In this study, 9 discharges (40-161 L/s) were converted to the applicable discharges of the model. Experiments carried out for 4 different water table depths and trapezoidal and triangular cross sections with 3 replications. Furthermore, by employing modified empirical models of Moritz, Ingham, India, Molesworth and Yennidumia, Offengenden, and Davis-Wilson, besides SEEP/W model, the amounts of seepage in the lab model were estimated. The results showed that for all investigated conditions and considering R2, r, RMSE, and MAE, Moritz presented the closest and the most accurate estimates of seepage (R2=0.992, r=0.996, RMSE=0.48 and MAE=0.44 lit/m2/min). Moreover, due to poor results of Molesworth and Yennidumia and Indian equations, they are not suggested for the study area.Although SEEP/W demonstrated appropriate performance for trapezoidal cross section, it did not show promising results for the triangular one. Considering the lower costs and shorter time as the results of utilizing dimensional analysis, it is recommended for controlled laboratory conditions in other similar regions.

To address farmers’ as well as water resources and environment managers’ opinions, it is necessary to develop the optimal cropping pattern models for maximizing farmers’ benefits, reducing nitrogen leaching, and improving the rate of aquifer recharge by applying quantitative-qualitative conjunctive use of unconventional surface water (reclaimed wastewater) and groundwater. In this research, the developed models (nonlinear programming (NLP) and particle swarm optimization (PSO)) were run in Varamin Irrigation Network for water year 2012-2013. The results of solving 3-objective nonlinear programming (NLP)  model showed that by improving the net benefit of cropping pattern optimization, water productivity and aquifer recharge by about 6%, 22% and 29% led to reduction of conjunctive withdrawals of wastewater and groundwater and fertilizer consumption by about 13% and 85%. Also, the results of solving 3-objective model by Particle Swarm Optimization (PSO) algorithm showed that by improving the net benefit of cropping pattern optimization, water productivity and aquifer recharge by about 7%, 49% and 30%, conjunctive withdrawals of wastewater and groundwater summation and fertilizer consumption decreased by about 35%, 88%, respectively. Comparison of the results of the values of objective functions in different scenarios by NLP and PSO methods showed a difference of about 0.002% to 0.01%. So, heuristic algorithm (PSO) has very little difference with NLP and has great ability in providing optimal results. The results of this research could be applied to the optimum use of water resources, increasing farmers’ benefits and decreasing nitrogen leaching in other irrigation network projects. However, it is to be emphasized that use of wastewater for irrigation of food crops for human and domestic animals is not recommended and full compliance with standards and regulations in applying reclaimed waste water in agriculture, is necessary and binding.

Shortage of water is one of the main factors limiting development of agricultural activities. This has led to the fact that farm management and productivity of agricultural water need full participation of farmers. Therefore, the purpose of this study was to analyze the factors affecting barriers and facilitators in adoption/development of new irrigation systems by farmers. The statistical population of this study included 70 experts of the departments of Agriculture Jihad whose viewpoints were collected and analyzed. Data was collected by using a questionnaire as research tool and SPSS and Lisrel software were used for analysis. To determine the reliability of the questionnaire, alpha coefficient was used by R software, which amounted to 91 percent, reflecting the reliability of data in similar conditions. In order to identify the factors affecting barriers and facilitators in development of new irrigation systems, factor analysis was used. The results of analysis in development barriers section led to identification of five barriers that included farmers awareness, technical problems, administrative costs, government policy, and technical knowledge. These barriers could explain about 69 percent of variations of adopting new irrigation systems. Identified facilitators included satisfaction of progressive farmers, clear comparative advantages, and monitoring and institutional partners. These facilitators could explain about 40 percent of variations about adoption of new irrigation systems. Also, in order to identify direct and indirect relationships between identified barriers and facilitators, Structural Equation Modeling (SEMs) was used. Results of this section showed that farmer awareness (b= 0.87), administrative costs (b= 0.67), clear benefits (b = 0.54) barriers had a direct impact on the development of new irrigation systems. Also, other results of this study showed that there was an indirect and weak relationship between administrative costs, farmers’ interests, and farmers’ awareness in development of new irrigation systems. According to the results, none of the identified facilitators had any significant effect on the adoption of new irrigation systems by farmers.

In order to design or evaluate an irrigation system, the infiltration phenomenon and its variations should be determined accurately. In saline and sodic soil and water conditions, the importance of this issue will become greater. The main objective of this study was to estimate the coefficients of different infiltration equations (Kostiakov, Kostiakov-Lewis, Horton, Philip, and U. S. Soil Conservation) and to evaluate the performance of these equations under different qualities of irrigation water, initial soil moistures, and constant water head. Using a laboratory method, infiltrations were measured in soil columns for constant water head. Then, by applying the cumulative infiltration and drainage outflow data to HYDRUS-1D model, soil hydraulic parameters were determined by the inverse solution. To determine the coefficients of infiltration equations, the outputs of the HYDRUS-1D model including cumulative infiltration verses time were corrolated. The values of root mean square error (RMSE), standard deviation root mean square error (SDRMSE), normalized root mean square error (NRMSE), percent relative absolute error (AE) and percent relative error (RE), were used to evaluate the performance of each infiltration equation and to rank the equations. The equation that had the highest rank was considered as the best and more stable equation. The Horton equation with RMSE, SDRMSE, NRMSE and AE of 0.043, 0.018, 0.006 and 1 and the Kostiakov equation with the values of 0.234, 0.175, 0.025 and 4, were the most and the least suitable eqations, respectively. The evaluation of the performance of infiltration equations using statistical indicators showed that the Kostiakov-Lewis and the Kostiakov infiltration equations were the best and the worst equations, respectively. Comparison of NRMSE values showed that in most cases, under deficit irrigation, infiltration equations estimate infiltration more accurately. For a given treatment, the errors of Kostiakov-Lewis and Philip infiltration equations increased as the amount of irrigation water increased, and as the end of the season approached. The rest of the equations did not show any especial trends. To measure infiltration, it is necessary to consider the effects of irrigation water quality, initial soil moisture, and water heads, because these parameters influence the coefficients of infiltration equations and, consequently, the irrigation efficiency.

Crop growth models facilitate management of irrigation water and fertilizer because less on-site (filed) visits and direct measurements are required. On the other hand, these models are complex and difficult to be understood and require input data that is not available, thus, using them in management decisions, which should be done before cultivating season, will be difficult. The objective of this study was to develop a model for grain yield prediction of Corn (Zea maize) based on simulated leaf area index (LAI) under water stress conditions. In this study, corn LAI was simulated based on cumulative degree-days and water stress index. The model used crop and soil as well as meteorological data including daily maximum and minimum air temperature (oC), precipitation (mm), and solar radiation (MJ.m-2d-1). The model was developed based on the 2013 growing season data for single cross 704 cultivar under full irrigation and water stress conditions, and was validated with 2014 growing season data. The highest values of simulated LAI in the 100% water requirement (WR) treatment were between 6.14 and 5.78, in the 80% WR between 5.63 and 5.4, and in the 60% WR was between 4.11 and 3.47, which varied by 0.13 (2%), 0.14 (2.5%) and 0.29 (6.6%), respectively. In the mid- stage of growth, the estimated LAI was more consistent with measured values (2%). In treatments under stress (except for the fourth stage of sampling), the LAI estimated by the model was 6.6% higher than the values observed. In all treatments, the high correlations (R2) between the values of the simulated LAI and observed LAI in both years of the experiment were between 0.9 and 0.99.

Crisis of renewable water resources and rising demand for access to fresh water in arid and semi-arid countries is increasing. Therefore, it is indispensable to conserve water resources with high quality for urban purposes and drinking and use water resources with lower quality (such as treated wastewater) for other purposes such as agriculture and industry. In these conditions, having adequate information and local data in different parts of the world is essential. Thus, the main purpose of this study was to investigate the effects of two-year long-term irrigation with treated municipal wastewater in comparison with well water (as the control treatment) on the physical properties of soil. The soil physical properties were measured in three layers, each with three replications, and included saturation hydraulic conductivity (Ks), soil moisture characteristic curve, moisture content at field capacity ( qFC) and permanent wilting point (qPWP) as well as “available water”, bulk and practical density, and porosity of the surface soil to depth of 90 cm. The study was conducted using a two-year split plot design. The results of statistical analysis showed that there was no uniform trend between various parameters and the influence of irrigation treatments at different depths of soil parameters were different. Results showed that the soil Ks in treatments irrigated with wastewater increased, compared to the control treatments, by 109%, 25%, and 75% in depths of 0-30, 30-60, and 60-90 cm, respectively. In addition, application of treated wastewater caused increase in the soil moisture content at qFC and qPWP point, but reduced the amount of total available water content. The effect of irrigation with treated wastewater decreased surface soil bulk density and increased its practical density. Also, the soil porosity in the 0-30 and 30-60 cm layers was lower compared to the control treatment, but was higher in 60-90 cm layer. Generally, it can be concluded that the use of treated wastewater improves soil physical conditions, but the application of untreated sewage water and TWW for irrigation is not recommended for edible crops.