Journal of Water Research in Agriculture
Year:2018 | Volume:32 | Issue:3 |Papers Count:11

Due to drought crisis in recent years, the use of alternative cropping methods that save water without any decrease in yield is increasing. Therefore, in order to evaluate the yield, yield components, and water use of rice under different non-submerged water levels and comparing it with permanently submerged condition, an experiment was conducted at fields of Rice Research Institute of Mazandaran during 2015 and 2016, using a randomized complete block design with three replications. The treatments consisted of two methods, regulated deficit irrigation (RDI) by irrigating all furrows and partial root drying (PRD) by irrigating alternate furrows, with three levels of drought stress: 10, 30, and 60 KPa (RDI10, PRD10, RDI30, PRD30, RDI60, PRD60) and a control treatment with permanently submerged basin irrigation in puddled soil (traditional method). Rice yield, yield components, and water consumption were measured in each treatment. The results showed that yield, plant height, panicle length, number of grains, 1000-grain weight, and water productivity (kg/m3) and water consumption at different levels of irrigation had a statistically significant difference in different treatments. Although the highest yield of rice was obtained in continuous submergence, yield reduction in alternate furrow irrigation treatments with minor stress (RDI10 and PRD10) was negligible and they were in the same statistical group in the two years of study. Also, partial root drying, significantly reduced water consumption, such that PRD10treatment resulted in 32% reduction in water consumption compared to the control treatment, and deficit irrigation, especially partial root drying, increased water productivity. The highest water productivity (kg/m3) was calculated in PRD30 treatment at 0. 724 kg per cubic meter of water. Based on the results, water consumption in the partial root drying was less than regulated deficit irrigation with the same tension, such that water consumption in PRD10 decreased by 15% compared to RDI10. However, average yield of PRD10v in both years was 1. 1% higher. The results related to the yield components were also proportional to yield and partial root drying method compared to regulated deficit irrigation was better.

In this study, yield and evapotranspiration of maize (cv. SC 704) were investigated under salinity stress and nitrogen deficiency. The experiment was carried out in a randomized complete block design. Electrical conductivities of saline water treatments were 0. 5( 15S0"> ), 2. 1( 15S1)">, 3. 5( 15S2) ">, and 5. 7( 15S3) "> dS. 15m-1">. Nitrogen deficiency treatments were 100% ( 15F0"> ), 75% ( 15F1"> ), 50% ( 15F2"> ), and 25% ( 15F3"> ) of nitrogen fertilizer requirement based on soil testing. The treatments were carried out in three replications and in plots with area of 9 m2. In different treatments, evapotranspiration of maize was between 220 to 349 mm and dry matter yield between 9. 4 to 15. 2 ton. ha-1. With increase in the salinity levels in, , , and treatments, the slopes of yield function were estimated as 0. 2, 0. 207, 0. 218, and 0. 231, respectively. Also, with reduction of nitrogen at salinity levels of, , and, the slopes were estimated as 0. 175, 0. 182, 0. 194 and 0. 221, respectively. The results showed that, with increasing stresses, yield of maize decreased more than evapotranspiration. The coefficient of was calculated using the Doorenbos-Kassam relationship. With reduction of nitrogen at salinity levels of, , and, values of coefficient were estimated as 1. 01, 1. 048, 1. 119, and 1. 272, respectively. Also, with increase in the salinity at nitrogen levels of, , and, Ky values were estimated as 1. 15, 1. 19, 1. 258, and 1. 328, respectively. On the average, Ky was calculated as 1. 27. Under the highest stress 15 S3F3">, water and nitrogen use efficiency decreased by: 38% and 34. 5%, respectively, compared to the control treatment (S0F0). The results showed that the water requirement and yield of maize under the mentioned stresses were less than the region’ s potential. Under these conditions, by supplying soil nitrogen and reducing water use, water resources will be used optimally and yield will increase.

Subsurface drainage, as a structural modification to improve the productivity of paddy fields, changes the hydrology of the fields. In this research, the response of water balance and drainage water salinity to free and controlled subsurface drainage systems during winter cropping in paddy fields was investigated by using the DRAINMOD-S model. The data were collected during two canola growing seasons (2015-2017) from a paddy field with a subsurface drainage system (drain depth of 0. 65 m and drain spacing of 30 m). The calibrated and validated model was applied to explore effects of conventional and controlled (by controlling water table depth at 40 cm)-subsurface drainage on water balance and soil and drainage water salinity. The model showed acceptable capability for simulating water table depth and drainage water salinity during calibration and validation processes. Based on the simulations, for drain depth of 1. 5 m, increase in drain spacing from 30 to 70 m resulted in 805. 3 and 741. 6 kg ha-1decrease in total salt load under free and controlled drainage systems, respectively. For drain spacing of 30 m, increase in drain depth from 0. 5 to 1. 8 m, caused 2. 7-9 mm and 5. 1-14. 3 mm increase in drainage water in controlled and free drainage systems, respectively. Simulation results indicated that, to decrease salt load, a drainage system with 30 m drain spacing and 0. 5 m drain depth is suitable for both free and controlled drainage conditions. Based on the results, controlled drainage can be used as a management tool to diminish environmental problems in heavy paddy soils from the viewpoint of salt load and drainage water volume.

The purpose of this research was to analyze the mechanisms affecting conservation agriculture in order to optimize the management of agricultural water in irrigated wheat fields of Kermanshah province. A qualitative and quantitative research method was applied in order to identify the mechanisms affecting conservation agriculture. In the qualitative section, 45 influencing mechanisms were identified by using content analysis method. In the quantitative part, factor analysis was used and the identified mechanisms in the qualitative section were categorized. Target population of this research consisted of 2000 wheat farmers in Kermanshah province, among whom 322 people were selected by simple random sampling method. The data were collected and analyzed by using a questionnaire, whose face and constant validity was evaluated by the faculty members and experts; and its validity was obtained as 0. 89. The results of the analysis of the mechanisms led to the identification of eight effective factors in conservation agriculture and water resources management. The factors were supportive factors, educational and extension factors, provision of infrastructure, national and local culture, policy and planning, institutional factors, research and development, and monitoring and evaluation, respectively. These factors were able to explain about 84% of the variance of the total mechanisms of conservation agriculture for optimal agricultural water management.

Water demand is one of the most effective factors in irrigation scheduling. In evapotranspiration formulas, crop coefficient (Kc), as a representative of different plants characteristics, is of great importance. Calculating this coefficient using the existing methods and formulas is costly and time-consuming, and results are point-specific. However, nowadays, calculation methods that provide large-scale Kc values are of interest. The methods based on remote sensing have been welcomed by many researchers. The objective of the present study was calculating crop coefficient (Kc) and leaf area index (LAI) of rice in different growing stages, using OLI sensor. In this regard, data LAI of two rice fields (areas of 15 and 65 hectares) located in north part of Sari, Iran, were used in two growing seasons (2014-2015 and 2015-2016). The average Kc at transplantation, tillering, heading, and maturity stages was, respectively, 0. 92, 1. 24, 1. 19, and 1. 12, showing that Kc had a good correlation with NDVI at different stages (r>0. 97). According to the results, NDVI is a good estimator for rice Kc. In addition, Rice Growth Vegetation Index (RGVI) in all growing stages had a correlation coefficient r>0. 93. RGVI is considered as a good estimator of LAI. Approximately at all growing stages, except heading, more than 93% of LAI changes were predicted by RGVI. Generally, it can be concluded that the most suitable indices for estimating Kc and LAI of rice are NDVI and RGVI, respectively.

Nitrate is one of the worldwide pollutants of groundwater and surface water, which affects human and livestock health at high concentration levels in water resources. Among the different techniques of nitrate removal, adsorption method has attracted attention, due to simplicity, cost-effectiveness, and efficiency. In this research, the effect of variables pH (4, 6, and 8), flow rate (8, 11, and 16 mL/min), bed height (40, 50, and 60 cm), and column diameter (45, 57, and 67 mm) were investigated on nitrate removal from aqueous solutions by modified zeolites column. The BET analysis was used to determine the specific surface and diameter of the pores. Structure and morphology of zeolite was determined using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). For modification of zeolite levels, the hexadecyltrimethylammonium bromide solution with concentration of 25 mM was used. The agricultural drainage water with concentration of 80 mg L-1 nitrate was artificially prepared by dissolving potassium nitrate salt in distilled water in the laboratory. The result of the analysis showed that the zeolite sample was from the clinoptilolite type, with specific surface area and mean pore diameter of 11. 984 m2g-1 and 15. 295 nm, respectively. The results also showed that changes in pH, flow rate, bed height, and column diameter on different indexes of breakthrough curve were significant at 5% level. The maximum adsorption rate occurred at pH=6, while the maximum adsorption efficiency (65. 24%) occurred at pH= 8. The reduction of the flow rate caused increase in nitrate removal efficiency, but the highest amount of adsorption (0. 2 mg g-1) occurred at a flow rate of 11 mL/min. The highest amount of absorption and removal efficiency occurred at the bed height and column diameter of 60 cm and 67 mm, respectively.

Evaluation of drip irrigation systems is performed to improve systems performance. In order to investigate the performance of drip irrigation system in pistachio orchards of Mahvalat region in Khorasan Razavi province, the drip irrigation systems in operation was evaluated during 2014-2015. At first, the general specifications of the selected irrigation systems were recorded and then emitters discharge and pressure were measured in the operating parts. In each system, one manifold was randomly selected and four lateral pipes located at the beginning, one-third, two thirds, and end of each manifold were selected. Emitters discharges at the beginning, one-third, two thirds and end of each lateral pipes and pressure at the beginning and at the end of the lateral pipes were measured in the all selected manifold pipes. Also, the minimum lateral inlet pressure at each manifold was identified by measuring the flow pressure of the all lateral inlets. Results showed that the water Emission Uniformities of the systems (EU) were within the range of 84. 89 to 97. 10 percent and the systems performances based on this index were classified as good to excellent. Potential application efficiencies of the low quarter of the systems (PELQs) varied from 63. 09 to 77. 78 percent. Application efficiencies of low quarter of the systems (AELQs) were in the range of 70. 10 to 86. 42 percent. Based on PELQs and AELQs indexes, the performance of drip irrigation systems in the studied pistachio orchards were good.

Semnan province faces water and soil limitations due to its geographical location, desert and semi-desert climate. Pressurized irrigation methods are used as one of the options for improving water use efficiency in this province. In this study, sprinkler irrigation systems were evaluated in Semnan province. For this purpose, 6 sprinkler irrigation systems including wheel move, classic with portable sprinkler, and center pivot systems were evaluated in different farms. Potential and actual application efficiency (PELQ and AELQ), uniformity, and distribution coefficients (CU and DU) for wheel move systems were 40. 7%, 29. 6%, 57. 2% and 52. 7%, respectively, and for classic systems with portable sprinkler they were 54. 8%, 54. 8%, 75% and 65%. For center pivot system, these parameters were 83%, 79. 6%, 5/94%, and 91%, respectively. In center pivot system, these parameters were the best. Good designing, new and appropriate sprinklers, and low height of sprinklers were the factors causing better operation of this system. Next to center pivot, the classic system with portable sprinkler had better performance. New and appropriate sprinklers, low height of sprinklers, and appropriate pressure in this system increased the efficiency in farm No. 4, while in farm No. 5, inappropriate sprinklers distance decreased efficiency of the classic system with portable sprinkler. In other farms, low pressure of sprinklers, decreasing the discharge and spray radius of sprinklers relative to nominal values and high pressure difference in the system caused low efficiency of wheel move system.

A field experiment was conducted which focused on the effects of walnut wood biochar and chemical fertilizers on quality characteristics of Black Seed (Nigella sativa) under water deficit conditions. The experiment was carried out in a split plots factorial layout based on a randomized complete block design with three factors and three replications. Three levels of irrigation (I1: 100%, I2: 70% and I3: 40% of crop water requirement) were assigned as the main plots and the combination of three levels of biochar (B1: 0, B2: 10 and B3: 20 t. ha-1) and two levels of chemical fertilizers (F1: without and F2: with chemical fertilizer) were allocated to sub plots. Recommended dose for nitrogen, phosphorus, and potassium was 150 kg N. ha-1, 75 kg P2O5. ha-1 and 100 kg K2SO4. ha-1, respectively. Results showed that irrigation had no effect on soil properties, but application of 20 t ha-1 of biochar improved soil saturation percentage, soil organic carbon, and total nitrogen. Irrigation significantly influenced the seed yield, oil yield, oil percentage, and fatty acids, except oleic acid. The 70% water requirement treatment increased the amount of fatty acids, except stearic acid. Plant quality characteristics significantly increased by 10 t ha-1 biochar application. Application of 10 t ha-1 biochar plus 70% irrigation water requirement and using chemical fertilizer (I2B2F2) produced the highest seed yield (1158. 4 kg ha-1). Based on the results, it seems that application of 10 t ha-1 biochar is suitable for black seed production under water deficit condition.

After installing subsurface drainage system, quality of drainage water in saline lands continuously changes, starting from the beginning of irrigation and drainage network operation, until reaching a more or less equilibrium state. Reaching a state of equilibrium in areas with saline groundwater may take several years. In this regard, field experiments are useful but they also have significant limitations. As an alternative, simulation models are among the methods that greatly eliminate these limitations. Therefore, in this research, the performance of DRAINMOD-S model was evaluated in simulation of drainage volume, drainage water salinity, and water table fluctuations. To validate the results of the model, data collected in the 2007-2008 cropping year from ARC18-18 farm was used in the research site of Sugarcane Research Center (Amir Kabir Agro Industrial Development Unit of Sugarcane Development Company, Khuzestan Province). This information included meteorological and soil data, drainage outflow, irrigation water salinity, water salinity within piezometers, and drainage water salinity. After statistical analysis and calculating the root mean square error (RMSE) and standard error (SE), the fits between the measured and simulated values of drainage water salinity, groundwater salinity, water table fluctuations and drainage discharge were investigated. The RMSE statistical index was 4. 76 dS /m for drainage water salinity, 0. 82 dS/m for groundwater salinity, 21. 2 cm for groundwater surface and 2. 1 L/s for the drain discharge, which indicated a fairly good accuracy compared with actual conditions. The results showed that the model was capable of simulating the water level fluctuations, drainage outflow and its salinity in Khuzestan region with saline and shallow groundwater table.

This study was conducted to investigate accumulation of Cu, Fe, Zn, Cd, and Mn in different vegetables such as spinach (Spinacia oleracea), fenugreek (Trigonella foenum-graceum) and dill (Anethum graveolens) under irrigation with contaminated water of Ghareso River and well water (control), as two treatments. This study was carried out on root and shoot of three vegetables with three replications as split-plot in a randomized complete block design. The results showed that contaminated water significantly increased the concentration of Cu, Fe, Zn, and Mn in spinach (P Mn > Zn > Cu > Cd. Fe had the highest and Cd had the lowest accumulation in plants. The concentration of Cu and Fe in the shoot and root of spinach, fenugreek, and dill was higher than the WHO standard. The contents of Zn and Mn in the shoot and root of spinach, fenugreek, and dill were below the permissible limit of some standards, but more than the other standards. The amount of Cd in the shoot and root of the examined vegetables was higher than the permissible limit of all standards.