مجله پژوهش آب در کشاورزی
سال سی و هفتم شماره 3 (پاییز 1402)

In order to analyze the temporal and spatial changes in the amount of water required for puddling in rice fields of the Sapidroud Network, daily soil moisture data from the SMAP satellite was obtained and used in a seven-year period (2015 to 2021). The puddling stage (from April 20 to June 10) was analyzed after grouping based on different probability of occurrence (1%, 10%, 25%, 50%, 75%, 90% and 99%) and using raster calculations. In addition, in order to validate the calculations, the predicted values were compared with the saturated soil moisture values of 321 soil samples with specific geographic coordinates that had been measured by the Rice Research Institute of Iran. The comparison was conducted by using the mean absolute error (MAE), mean bias error (MBE), and normalized root mean square error (NRMSE). The results showed that in all moisture scenarios (from the wettest to driest), the foothills had less moisture than the plain and, especially, the low lands, and the soil moisture showed a decreasing trend during the growing period. The rate of this reduction increased gradually and in some areas it reached 2% per day at the end of the puddling period (May 22 to 31). The amount of gross water required for puddling increased from the wettest to the driest year and in the middle of the season (May 3 to 5) it was from 1693 to 2983 square meters per hectare and at the end of the season from 2496 to 3602 m3/ha, respectively. The validation results showed that the calculated MAE, MBE, and NRMSE values were 4.26%, 1.59%, and 15%, respectively, indicating that the accuracy is acceptable. The findings showed that the delay in the start of the puddling operation increases the water required for puddling operation (1.34 m3/ha for each day delay in a normal year). Therefore, in the lands of this network, in all circumstances, especially in dry years, to save water, it is better to release/supply water required for puddling from local reservoirs, wells, or from the Sepidroud Dam in early May.

Considering the limited water resources and the high rate of evaporation, water crisis is one of the most important issues in the country. Due to the importance of Flixweed as a medicinal plant, its water requirement and its single and dual plant coefficients were investigated in the lysimeter laboratory of University of Birjand. For this purpose, six lysimeters (of the water balance type) with a diameter of 60 cm and a height of 100 cm were used. Inside all six lysimeters, Flixweed plants were planted with a density of 20 plants/m2, then, evaporation and transpiration were calculated using the water balance equation. Evaporation and transpiration of grass reference was measured directly by three lysimeters and its average was 322 mm. Then, plant coefficients were calculated for four stages of growth (initial, development, middle, and end). In this research, the average values of evaporation and transpiration, evaporation from the soil surface, and transpiration from the target plant were obtained as 202, 23, and 179 mm, respectively. Finally, the individual plant coefficients for the four initial, development, middle and final stages were 0.52, 0.68, 0.96 and 0.57, respectively, and the basic plant coefficients were 0.38, 0.59, 0.94 and 0.52 mm. In general, considering the climate of South Khorasan Province, Flixweed plant is recommended for cultivation due to its low water requirement.

Due to the increasing growth of population and changes in lifestyle, the pressure on water and soil resources has increased, thus, proper management of these resources has vital importance. This research was conducted with the aim of evaluating and comparing the effects of furrow, surface, and subsurface drip irrigation on water productivity, yield, and yield components of spinach in arid and semi-arid climatic conditions of Ahvaz. For this purpose, an experiment in the form of randomized complete blocks with three treatments of irrigation methods including furrow irrigation (FI), surface drip irrigation (SDI) and subsurface drip irrigation (SSDI) was done in three replications in the research farm of the Faculty of Water and Environmental Engineering, Shahid Chamran University, Ahvaz, in 2021. According to the results, the amount of irrigation water used in the FI treatment was 1066 m3/ha and in the SDI and SSDI it was 787 m3/ha, which showed a decrease of 26.17%. In FI, SDI, and SSDI, the average yield of spinach plant (total fresh weight of leaves and stems) was equal to 23.56, 30.17 and 19.28 g and irrigation water productivity was 0.353, 0.613 and 0.392 kg/m3, respectively. In both yield and irrigation water productivity, the SDI treatment had a significant advantage at 5% level compared to the other two treatments. The effects of irrigation treatment on the characteristics of root length, stem length, total length, number of leaves, number of fresh leaves, leaf chlorophyll content and harvest index were not significant. Generally, considering water productivity as criterion, surface drip irrigation is more suitable than furrow irrigation for spinach cultivation.

In this research, the effect of irrigation water salinity and salicylic acid spraying were investigated on the yield of shallot (Qazvin local variety). Water salinity treatments at four levels of 2(S1), 4(S2), 6(S3), and 8(S4) dS.m-1 and salicylic acid at four concentrations of 0(A1), 0.5(A2), 1(A3) and 2(A4) mM were applied in the greenhouse. The experiment was performed as factorial and in a completely randomized design, with three replications. Soil moisture was measured daily, and irrigation scheduling was done based on it. Results showed that salinity stress reduced crop water uptake and shallot tuber weight. Salicylic acid application improved crop water status and increased tubers weight under salinity stress. A4 treatment was the ideal concentration for maximum yield. Application of 2 mM salicylic acid at salinity levels of S1, S2, S3, and S4 increased tubers yield by 11.6%, 32%, 40% and 91%, respectively, compared to the control (A1). The response of dry yield to evapotranspiration showed that by increasing salinity stress, percentage of yield decreased more than the percentage of evapotranspiration. Use of salicylic acid decreased dry yield sensitivity to salinity stress, such that from treatment S1 to S4 yield response coefficients (Ky) were between 1.01- 1.62 (in A1 treatment), 0.93- 1.3 (A2), 0.48- 1.09 (A3) and 0.31- 0.97 (A4). The effect of salicylic acid on water productivity were calculated between 2.13- 1.14 (in A1), 2.15- 1.68 (A2), 2.26- 2 (A3), and 2.38- 2.19 kg.m-3 (A4). In conditions of using saline water for crop irrigation, application of salicylic acid will increase water productivity. Based on the experiment results and in conditions of lack of high-quality water for irrigation, salicylic acid spraying on crops will be a suitable method to reduce the harmful effects of salinity stress.

Drought and flood are the consequences of climate change. However, establishing public participation through water cooperatives is one of the most important recent measures in the face of climate change. The purpose of this research was to analyze some mechanisms affecting the sustainable development of water cooperatives thru a case study of Dehestan-e Satar, Songhor and Kolyayi County. This quantitative applied research was a survey in terms of method. The research tool was a researcher-made questionnaire based on the theoretical framework and a review of the related literature. The reliability of the questionnaire was checked and confirmed by Cronbach's alpha coefficient, after using the opinions of the experts of the Kermanshah Province Jihad-e Agriculture Organization plus the board members of water users cooperatives to secure its validity. Structural Equation Modeling was used to test the hypotheses and analyze the data. For this purpose, Smart PLS3 and SPSS23 software were used. The statistical population of the research were all the members of the water users cooperatives in Satar Plain whose total population was 472 people. The sample participants (n=211) were selected through stratified sampling method and using the Cochran's formula. According to the results of the path analysis and research hypothesis testing, legal mechanisms with the path coefficient of (β=0.257) had a positive and significant effect on the sustainable development of the cooperatives. Also, the results showed that educational mechanisms (β=0.233), support mechanisms (β=0.214), relational mechanisms (β=0.203), and policy-making mechanisms (β = 0.147) had a positive and significant effect on the sustainable development of Dehestan-e Satar Water Users Cooperative.

This research was conducted in order to investigate the quality of groundwater for agricultural use in the northern and central parts of Kerman Province. In this study, there were 534 water samples from 8 counties (Kerman, Zarand, Bam, Bardsir, Jiroft, Baft, Faryab, and Rafsanjan), which were collected from different sources, and concentration of Na+, Ca+2, Mg+2, Cl-, SO4-2, and HCO3-2 was determined. Also, indicators such as Total Dissolved Solids (TDS), Sodium Absorption Ratio (SAR), Permeability Index (PI), Residual Sodium Bicarbonate (RSBC), Electrical Conductivity (EC), Salinity Potential (PS), Magnesium Hazard (MH), Water Hardness (TH), percentage of sodium soluble in water (SSP) were determined and evaluated. After determining the quality characteristics of water, the results were compared and interpreted with water standards for agriculture. AqQA software was used to draw graphs to investigate and compare water characteristics. Based on the results, more than 37% of the studied resources were classified as unsuitable (salinity above 2 dS/m) in terms of salinity. Zarand and Rafsanjan counties had unfavorable conditions in terms of groundwater quality indicators, with EC, SAR, PS, TH, SSP and MH in critical conditions in one or both counties, but, in terms of agricultural water standards, the other sites had good quality water. The combined type of underground water in all areas was Ca-Mg-SO4-Cl: while in the northern parts of the province, such as Rafsanjan, Zarand, Bardsir, as well as Bam and Kerman, the predominant anion of water was chlorine, in Faryab, Baft and Jiroft, the status of the predominant anions was slightly sulfate. In most of the counties, Na+>Mg+2>Ca+2 were the dominant anions of chlorine-waters, and little bicarbonate was observed. Also, the dominant water in all areas were Na-Cl and Mg-Cl . Therefore, it is necessary to manage water properly and plant crops suitable for the chemical conditions of waters.