Journal of Water Research in Agriculture
Year:2021 | Volume:34 | Issue:4|Papers Count:9

Measuring the actual evapotranspiration of rice is very important for appropriate and optimal water management in the Northern provinces of Iran. The present study aimed to measure the actual evapotranspiration for two Shiroudi and Hashemi cultivars of rice, in paddy fields of Sari Agricultural and Natural Resources University (SANRU). For this propose, six drainage lysimeters were designed and constructed. After cultivating rice inside the lysimeters, the amount of precipitation, irrigation water, and deep percolation were measured in 5-days intervals. Investigation of the lysimeter results showed differences between water requirement and also deep percolation of the two studied cultivars in growth period (seeding to harvest): water requirement was 351 and 397 mm and the deep percolation was 48 and 97 mm, for cultivars Shiroudi and Hashemi, respectively. Also, the crop coefficients were obtained by comparison of the lysimeter’ s actual evapotranspiration and 14 indirect methods of reference evapotranspiration estimation. Considering the cultivars and the estimating method, the crop coefficients were in the following ranges: 0. 73-1. 12 for the initial stage, 0. 83-1. 41 for the middle stage, and 0. 64-1. 15 for the final stage. Also, the average estimation Error Percentage (PE) of the resulting crop coefficients compared to the recommended coefficients of FAO-Penman-Monteith method, is 11%, 11% and 8% for Hashemi cultivar and 15%, 23%, and 16% for Shiroudi cultivar, in initial, middle and final stages, respectively; which shows the necessity of determining crop coefficients for each cultivar under local conditions. The coefficients obtained in the current study can be useful to calculate the water requirements of Hashemi and Shiroudi cultivars based on indirect estimation methods for designing water projects and water delivery in the irrigation and drainage networks in the research area.

Studying the soil physical characteristics is essential for water productivity in agriculture. Accordingly, this research was conducted in Torogh Agricultural and Natural Resources Research Station in Khorasan-Razavi Province, north-eastern Iran, to investigate the relationships between soil physical characteristics and corn (Zea Maize) yield. Thirty plots (with areas of 15 m2) with different soil textures and organic carbon contents were selected as experimental plots. Corn was cultivated manually and the cultivation operations were done uniformly. Plots were irrigated using a tanker and water meter, and all plots were irrigated equally at the same day in each irrigation. Soil samples were taken from the plots and 35 soil physical characteristics were determined. The statistical relationships between corn water productivity (kg biomass/m-3 water) and soil physical characteristics were analyzed using principal component analysis (PCA), Pearson correlation coefficient, multiple linear regression, and path analysis. The results showed that 78% of the variations in corn water productivity could be explained by three factors of soil PAW100 (Field Capacity at matric head of 100 cm), EI (PAW330) (FC at matric head of 330 cm), and mean equivalent pore diameter. Therefore these three factors could be considered as the most important soil physical characteristics affecting water productivity in silage corn.

One of the strategies to reduce water losses in agriculture is proper irrigation scheduling, which is based on accurate estimation of crop water requirement. In order to determine the evapotranspiration rate of three rose varieties, a one-year study was conducted in a hydroponic greenhouse equipped with drip irrigation system in Arak Plain using drainage type lysimeters. Reference evapotranspiration was also determined using a drained micro-lysimeter with grass. The results showed that the total amount of reference evapotranspiration in the greenhouse was 1608 mm. Also, the total evapotranspiration value of Utopia rose during this growth period was 1423 mm, Dolcevita rose 1480 mm and White rose 1313 mm. The annual average of daily evapotranspiration of rose varieties was 3. 8 mm/day. Due to rose bushes being perennial, the crop coefficients did not have four growth stages and, therefore, the average coefficients varied between 0. 7 and 0. 96 in 10-day intervals. The results also indicated that the average crop coefficient of rose varieties was 0. 81 over a year and the average amount of applied irrigation water was 20573 m3. ha-1. year-1 for approximately 75000 rose plant /ha.

In the new drainage conditions in the center and southwest of Khuzestan Province, by reducing the depth of drainage installation and controlled drainage, studying the dynamics of the mixing zone, understanding the specifications of this region, and its effect on the flow rate of drainage water and salinity is important. In this study, seven groups of piezometers, each consisting of 8 piezometers placed at different soil depths (0. 8 to 5m) and at different distances from the drainage water collector were studied in two research farms, namely, field R9-11 Dabal Khazaei agro-industry (with an average drainage depth of 2 m and distances of 65 m) and field R8-7 in Salman Farsi agro-industry (with an average depth of 1. 4 meters and 42 meters distances). Water level in piezometers, water salinity in different soil layers, and drainage water flow rate and salinity were monitored daily in three periods of heavy irrigation of sugarcane (March to October of 2013, 2014 and 2017). Results indicated that by starting a heavy irrigation, hydraulic head increased and hydraulic head variance between bottom layer (4 and 5 m) relative to the surface layers, established vertical flow and saline inflow upwards. Reducing the installation depth of drains up to 60 cm from in R9-11 compared to farm R8-7 and moving away from the collector up to 400 m in each farm, reduced the installation depth of drains up to 40 cm, and increased the hydraulic load by an average of 8-12 cm. The thickness of the mixing area was up to one meter and the reduction of the average salinity line in the mixing area was 8%. It was found that in addition to irrigation water salinity, drainage water salinity was affected by groundwater salinity and the difference in drainage depth, position of the impermeable layer, and the presence of sand lenses. By decreasing drainage depth, the drainage water discharge decreased sharply, such that the averag drainage water from each lateral in farm R9-11 was 10 mm/day, and in farm R8-7 it was 3. 3 mm/day. The results showed that with increasing the thickness of the salt and fresh water mixing zone due to the optimal reduction of drainage depth, the volume of water consumed in each irrigation cycle decreased due to plant use of this zone, which can be an effective factor in conserving soil and water resources.

Determination of crop water requirement is of great importance in irrigation planning and effective management of water in agriculture. In this regard, lysimeters are used to measure water input and output and water balance method. Therefore, this research was carried out to determine the water requirement of Cannabis sativa L. in 2017 at the Faculty of Agriculture of Birjand University. For this purpose, six weighing lysimeters were used and cannabis water requirement was calculated using the water balance equation. Three lysimeters were planted to grass (12 cm height) as the reference crop, and in the other three lysimeters the cannabis plant was cultivated. Based on the results of the water balance equation, the evapotranspiration potentials of the reference plant and cannabis were 899. 6 and 688. 89 mm, respectively. The length of different stages of plant growth, including the initial, development, middle and end stages, was 30, 55, 75, and 20 days, respectively. Also, the cannabis crop coefficient values in the four stages of plant growth were 0. 28, 0. 68, 1. 01 and 0. 54, respectively. These values are recommended for estimating the water requirement and irrigation management of cannabis.

The purpose of the present study was to determine the effect of fertigation with different levels of nutrient solutions and different irrigation regimes on water productivity (ratio of yield to water containing nutrients) in greenhouse lily cultivation. The experiment was conducted in two years at the University of Guilan. In the first year, the best treatment was determined among four different concentrations of nutrient solution according to Coic solution including S1, S2, S3, and S4. The results of mean comparison showed that S1 treatment (treatment with the highest concentration of nutrients) had a positive effect on most vegetative, reproductive, and postharvest characteristics of lily. In the second year, with appropriate nutrient solution and three different levels including S11, S12, and S13, different irrigation regimes according to field capacity percent (%FC) were considered. Four different irrigation regimes including 70%, 80%, 90%, and 100% FC were applied. The results of the second experiment showed that application of deficit irrigation treatments including 90%, 80%, and 70% of FC increased water productivity without any significant effects on the vegetative and reproductive characteristics. The results also showed that irrigation treatments had significant effects on traits such as vase life, which was increased by decreasing water consumption and increasing nutrient concentration. Regarding the vegetative characteristics of lily plants, the data showed that traits such as fresh and dry weights of roots, leaves, and flowers were positively affected by decreasing irrigation levels and increasing concentration of nutrient solution, while plant height and both number and weight of daughter bulbs were not affected by these treatments. The highest water productivity (nutrients solutions) was obtained in the S3 and 80% FC, being 21. 57 kg/m3.

Crop coefficient is one of the most important factors in irrigation planning and optimal allocation of water resources to plants. The crop coefficient is obtained through the ratio of actual evapotranspiration to reference crop evapotranspiration. In this research, in order to determine the crop coefficients of Narcissus flower, which is an important ornamental plant, an experiment was conducted during 2018 growing season using lysimeters, in Birjand. Three lysimeter was used in this project and water requirement of Narcissus flower was calculated by water balance method. Turf grass with a height of 12 cm was used to determine reference crop evapotranspiration. The base crop coefficients were obtained as 0. 42, 0. 85, 0. 86, and 0. 74, and the coefficients of the soil surface evaporation were 0. 49, 0. 28, 0. 25 and 0. 22 at, respectively, primary, developmental, middle, and end stages. Finally, the values of Narcissus flower’ s crop coefficients at different stages of growth including primary, developmental, middle, and end stages were calculated as 0. 91, 1. 13, 1. 11, and 0. 96. The estimation of water requirement and irrigation management of Narcissus flower will be possible using the obtained Kc values.

Agriculture in arid and semiarid areas is dependent on groundwater extraction. Utilization of groundwater resources in Zaveh-Torbath Haydarieh plain is more than the aquifer's renewable potential, therefore, these resources have a reservoir deficit. To this end, in this study, using the information obtained from interviews with farmers in this plain, who were selected through cluster sampling in the year 2015-2016, and the use of the Tobit Model and the two-stage method of Hackman, factors influencing the extraction of groundwater resources were studied. The results of the two-stage Hackman model showed that, in the first stage, the explanatory variables including the dominant cultivation and personal and share ownership of water wells had a positive final effect of 0. 35, 0. 43 and 0. 41, respectively, while variables of well depth, type of water transfer channel, and low yielding crops had a negative effect on overdraft of groundwater resources. In the second stage, the results showed that farm-to-well distance, farmer's annual income, and type of the dominant cultivation had a positive and significant effect at 5 percent on overdraft. Accordingly, paying more attention to the technical factors effective in water management, as well as raising farmers' awareness of their participation in improving cropping pattern, is an effective step in reducing overdraft of groundwater resources.

In order to evaluate the effect of the duration of water in the magnetic field on the qualitative and quantitative characteristics of radish plant, a research was conducted in the research greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad, in a completely randomized design with three treatments and three replications. Treatments included distilled water (control), distilled water magnetized with a duration of 30 minutes, and distilled water magnetized in one hour with a field intensity of 0. 6 Tesla. The results showed that magnetized water with duration of one hour caused an increase of 29%, 46%, 46%, 43%, 19%, and 82% in leaf area, tuber circumference, chlorophyll a, and carotenoid, fresh weight of shoot and dry weight of the tuber, respectively. Also, this treatment increased tuber mass and fresh weight by about 100%. In general, the treatment of the magnetized water with the duration of one hour was the best treatment. According to the results, the duration of irrigation water magnetization in the magnetic field can affect radish plant characteristics.