Ali Pahlevani; Hamed Ebrahimian; Fariborz Abbasi
Abstract
Surface irrigation systems have been widely used in in arid and semi-arid regions of the world, but inappropriate design and management has led to high water losses and reduced water productivity. The objective of this research was to investigate the effect of plastic mulch placements in furrow irrigation ...
Read More
Surface irrigation systems have been widely used in in arid and semi-arid regions of the world, but inappropriate design and management has led to high water losses and reduced water productivity. The objective of this research was to investigate the effect of plastic mulch placements in furrow irrigation on soil water distribution and water productivity under fodder corn production. Field experiments were carried out in Karaj in 2018. Four different treatments were considered in terms of plastic mulch placements including mulch on the ridge (R), mulch on the furrow bed (F), mulch on the ridges and the furrow bed (FR), and a treatment without mulch or control treatment (C). In order to measure water content, soil samples were taken one day before and three days after each specific irrigation event with 5 days intervals from four points (at 0-25 cm and 25-50 cm under the ridges and furrows) for all treatments. The mean values of volumetric water content during the growing season for the FR, F, R and C treatments were 24.8, 23.8, 18.0 and 17.1 percent, respectively. The results indicated that plastic mulch had substantial impact on retaining the soil moisture by reducing evaporation from the soil surface and the treatments with plastic mulch on the bed of the furrow (FR, F) had the highest soil moisture in comparison to the other treatments. Water productivity for dry matter of the FR, F, R and C treatments was 4.5, 4.4, 3.6, and 3.0 kg/m3, and for fresh matter of the FR, F, R and C treatments was 7.6, 7.4, 5.7, and 4.7 kg/m3, respectively. Based on the results, using plastic mulch on the furrow bed is recommended in order to reduce water loss and increase water productivity in furrow irrigation. Considering the effect of plastic mulch in maintaining soil water content, it is also recommended to utilize this method with the deficit irrigation method. Economic aspects should be taken into consideration in the future research on this topic.
Mahdi Kalanaki; Fatemeh Karandish; Seyed Farhad Saberali
Abstract
In this research, after calibrating and validating the DSSAT-CERES Maize model, the integrated effects of modifying planting date and irrigation water depth on maize water use efficiency was investigated for four stations of Gharakheil, Babolsar, Ramsar and Noshahr in Mazandaran Province. In this regard, ...
Read More
In this research, after calibrating and validating the DSSAT-CERES Maize model, the integrated effects of modifying planting date and irrigation water depth on maize water use efficiency was investigated for four stations of Gharakheil, Babolsar, Ramsar and Noshahr in Mazandaran Province. In this regard, the model was first calibrated and validated based on data collected in a two-year maize cropping system in Sari county under three irrigation treatments i.e. full irrigation and deficit irrigation at two levels of 55% and 75%, during 2010 and 2011 growing seasons. Then, the water-yield functions were determined for the selected cropping calendars over the period 10 April till 29 June, and for the four selected stations. Thereafter, the optimal irrigation depth, aimed at preventing significant reduction in crop yield, was determined. Based on the selected criteria and indices, the model was accurate enough for simulating leaf area index, the important morphological calendars, total dried biomass, maize grain yield and total crop N uptake. Except for Gharakheil station and regardless of the irrigation treatment, delaying planting date may reduce the optimal irrigation water depth by 14-75% due to the decreased length of the cropping cycle. Based on the 30-year average weather data, the lowest optimal irrigation water depth in Babolsar, Noshahr, and Ramsar was 366, 200 and 122 mm, respectively, which will be obtained under the cropping calendars of June 9, June 29 and June 29, respectively. Nevertheless, the difference in the optimal irrigation water depth between the full irrigation treatment and the deficit irrigation treatment will be higher under early planting date. Based on the results, irrigation water depth management and modifying the cropping calendars may result in a 1.6-22.8% water saving under maize cropping systems in Mazandaran Province. Nevertheless, validating the given results of this research requires carrying out the other field investigations in the selected sites and under the proposed cropping calendars.
Hosein Zahedpour; Vahid Rezaverdinejad; hossin dehghani sanich
Abstract
Improving water productivity and irrigation efficiency is important in Iran due to limitations in water quality and quantity. This study was conducted to investigate and analyze application efficiency and water productivity at field scale in Nazloo-Chay plain, located in Urmia province, during 2015-2016. ...
Read More
Improving water productivity and irrigation efficiency is important in Iran due to limitations in water quality and quantity. This study was conducted to investigate and analyze application efficiency and water productivity at field scale in Nazloo-Chay plain, located in Urmia province, during 2015-2016. For this purpose, five wheat fields, as fall planting, and five fields for spring crops i.e. maize and pumpkin (two fields of each) and sunflower (one farm), were studied. Irrigation system in wheat fields was border, while spring crops were furrow irrigated with closed end condition. To evaluate and measure the water productivity and irrigation efficiency in each irrigation event, some parameters were measured including irrigation depth, system geometry, soil water depletion in the root zone before irrigation (SMD) and the plant parameters. In the five wheat fields, a total of 21 irrigation events were performed and all of which were monitored and evaluated. The average of irrigation efficiency and standard deviation in the 21 irrigation events at these five wheat fields was about 30.9% and 19.5 percent, respectively. For the three spring crops, 27 irrigation events were evaluated and the overall average irrigating efficiencies for sunflower, pumpkin (cucurbita) and maize were about 69.3%, 51.5% and 52.5%, respectively. The average of standard deviation in spring plantings was calculated at about 13.9 percent, which indicates that the scattering of application efficiency was less in spring plantings than fall planting. Based on the results, the average of physical water productivity in wheat fields was 1.1 kg/m3. This index for sunflower, pumpkin (Cucurbita) seed and maize was calculated at about 0.27, 0.17 and 7.02 kg/m3, respectively. Average economic water productivity in wheat was 14512.4 Rial/ m3 and for sunflower, maize and cucurbita seed were 20252.6, 13463.9, and 23305.3 Rial/ m3, respectively, which indicated high economic water productivity for sunflower and Cucurbita seed. Generally, the crop management practices in all fall and spring plantings including fertilizer and pesticides applications were based on scientific recommendations, but irrigation management was poor in all farms. One of the main reasons for low application efficiency in these farms (in particular the fall plantings) was the poor field leveling that required high water depths for irrigation of the fields.
m y; Mohsen Ahmadee; s b; a h
Abstract
Climate change has important impacts on most of the natural processes, including hydrological cycle. Evapotranspiration, as a part of hydrological cycle, will also undergo these changes. Due to the importance of evapotranspiration in water resources and agricultural management, this research was ...
Read More
Climate change has important impacts on most of the natural processes, including hydrological cycle. Evapotranspiration, as a part of hydrological cycle, will also undergo these changes. Due to the importance of evapotranspiration in water resources and agricultural management, this research was conducted to study climate change effect on evapotranspiration in Neyshabour plain. Evapotranspiration was calculated for five farms in Neyshabour plain using SWAP software and meteorological and agronomic data. In irrigated farms, the HADCM3, ECHAM5OM and CGCM3T47models were used to calculate crop actual evapotranspiration for 2020-2039 and 2080-2099 periods based on A2, B1 and A1B scenarios and the climate model used in rainfed farms was the HADCM3 based on A2 and B1 scenarios. The greatest calculated difference in evapotranspiration was found between the period 2080-2099 and base period (1992-2011) in the A2 scenario. Also, evapotranspiration values for the period 2080-2099 will increase compared to the period 2020-2039 in all three scenarios. Among the crops of investigate, wheat will have the greatest changes (12%) in evapotranspiration in the future periods compared to the base period, while changes of maize will be only 3%. However, the average daily evapotranspiration of maize during the growing season (about 12 mm/day) will be more than the other crops.