جستجوی مقالات مرتبط با کلیدواژه « نیاز خالص آبیاری » در نشریات گروه « آب و خاک »

Irrigation planning is one of the management strategies, which is based on determining the exact water requirement. The lysimetric method is the most accurate method of determining the water requirement of the plant, but due to the high cost and the need for high technical knowledge, it cannot be used anywhere. The basis for determining the water requirement in the Ardabil Plain is the use of NETWAT software output information, which is known as the National Water Document of Iran. This software calculates the water requirement using the Penman-Monteith FAO model. The output of this software due to the need to update climate information, not introducing the exact range of plains, ignoring sub-climates in some plains and catchments (including Ardabil Plain), and not considering some important crops in the plain (lack of potato water requirement in Ardabil Plain) and the creation of new databases in recent years, should be reconsidered. 

This study in Ardabil Plain and water requirement of the dominant crop pattern including wheat, barley, potato, alfalfa, and bean crops was calculated by the Penman-Monteith method and CROPWAT software. To calculate the net irrigation requirement, first, the evapotranspiration potential of the plain was obtained using climatic information from three stations Ardabil, Abi Biglou, and Namin. Then, the effective rainfall of the plain was extracted by the information from Ardabil, Abybeigloo, Namin, Koozeh Topraghi, Gilande, and Samian rain gauge stations. Required information on plain soil was prepared using 22 points in the plain. In the last step of the information preparation phase, the characteristics of the cropping pattern plants were defined using field measurements, local experiments, and FAO publication No. 56. The cropping pattern (91.4% of the cultivated area of Ardabil Plain) included wheat, barley, potatoes, alfalfa, and beans, which according to the five-year statistics ending in 2021, the cultivated area of these crops was 18,300 (32.6%), 10300 (19.4%), 15700 (28%), 5200 (9.2%) and 1200 (2.2%) hectares. After preparing the case information, the water requirement was calculated for each of the wheat, barley, potato, alfalfa and bean products in each of the soil sampling points in 10-day periods during the growing season. Based on the point information obtained, a zoning map of net irrigation needs in the Ardabil Plain was prepared.

Based on the obtained point information, a zoning map of net irrigation needs in the Ardabil Plain was prepared. The results showed that the zoning of the net need for irrigation divides the Ardabil Plain into three separate parts in this regard. The northern part and the southern part are divided into high consumption, the eastern and southeastern parts are low consumption, and the western part and parts of the center are divided into medium consumption. In addition, according to the zoning results, the average, minimum, and maximum net irrigation needs of the crops were calculated. For the wheat crop, the average, minimum, and maximum net irrigation requirements were 164, 314, and 259 mm, respectively. For the barley crop, the average, minimum, and maximum net irrigation requirements were 110, 255, and 205 mm, respectively. For the potato crop, the average, minimum, and maximum net irrigation requirements were calculated as 325, 613, and 484 mm, respectively. In addition, for alfalfa and bean crops, the mean, minimum, and maximum net irrigation requirements were estimated at 425, 872, and 670 mm and 337, 637, and 497 mm, respectively.

The results showed that if the average of the whole plain is used for wheat, barley, potato, alfalfa, and bean crops, instead of point or regional information, about 18, 20, 21, 23, and 22% deficit irrigation, respectively, and in Low consumption sector accounts for about 58, 86, 49, 58, and 48% of excess irrigation. Also, the results showed that using the output numbers of NETWAT software will cause wrong water management in Ardabil Plain. Therefore, using the results of the National Water Document (NETWAT) will lead to incorrect water management due to the problems mentioned. That is if the results of the national document are used as the basis for determining the water requirement in the Ardabil Plain, compared to the minimum and maximum numbers obtained from this research, about 32 and 38 MCM will occur in the exceeding irrigated and deficit irrigated plains, respectively (without considering the impact potato crop due to not calculating its water requirement in the national water document for Ardabil Plain). Considering climate change and also the development of different databases, it is suggested to use up-to-date information for water requirement calculations. Also, considering that the Ardabil Plain is divided into three separate parts in terms of the net need for irrigation, therefore it is recommended that instead of using one number as the consumption in the whole plain, from point or regional information obtained from this research for wheat, barley, Use potatoes, alfalfa and beans.

Development of modern irrigation systems has been one of the main programs in developing agricultural sector in the past few decades. Assessing the role of these systems in increasing indicators of irrigation water management can play an important role in future national policies and planning. Therefore, this study was conducted with the aim of appraising water consumption management indicators in tomato production in different regions of Iran and evaluating the role of surface drip irrigation systems in increasing these indicators.

In this study, a field survey was conducted to measure yield and applied irrigation water of tomato under the farmers’ management in tomato production hubs. Volume of applied water by farmers in 176 farms in Fars, South Kerman, Hormozgan, Bushehr, Khorasan Razavi, Qazvin, Khuzestan, Golestan, Zanjan, Hamedan and Semnan provinces with different conditions of climates, irrigation methods (furrows and drip), salinity of irrigation water and soil; and different tomato cultivars were measured during growing season 2018-2019. The measured applied irrigation water values were compared with the net irrigation requirements estimated by the FAO Penman-Monteith method using meteorological data from the last 10 years, as well as the values of the national water document. Then, the effect of modern irrigation methods (surface drip irrigation) on applied water, application efficiency and physical water productivity was investigated in the study areas. Crop yield was recorded at the end of the growing season and water productivity (WP) was calcucated as the ratio of yield to total applied water (irrigation water and effective rainfall). Analysis of variance was used to investigate the possible difference between yield, applied water and WP among the hubs. Data adequacy was assessed by using the method provided by Sarmad et al. (2001).

The results showed that yield, applied irrigation water and WP in tomato production hubs were significantly different at the P ≤ 0.01. The average volume of applied irrigation water by the farmers was 7729 m3/ha. Water productivity in production areas varied from 4.33 to 9.52 kg/m3 and its average was 7.10 kg/m3. The average net irrigation requirement and irrigation application efficiency were 674 mm and 78%, respectively. Irrigation application efficiency obtained from the studied tomato farms was slightly higher than the average irrigation efficiency in Iran reported by Abbasi et al. (2016). Deficit irrigation was occurred in the fields of some areas such as Bushehr, Golestan and Semnan. Tomato planting time (spring or autumn) affected applied irrigation water, yield and WP. The volume of water used in autumn planted farms (5356 m3/ha) was less than spring planted farms (9831 m3/ha). The average yield of tomatoes in spring planted farms (74.3 t/ha) was significantly higher than the yield of fields planted in autumn (46.1 t/ha). However, the average of WP in spring planting farms (7.7 kg/m3) was higher than the productivity of farms planted in autumn (6.6 kg/m3). The application of surface drip irrigation systems in comparison with furrow irrigation resulted in 25% reducing in applied water, 10% increasing the application efficiency and 16% improving in water productivity.

In general, the results of this study provide useful information on applied irrigation water management indicators in tomato production to managers and water decision makers within Iran. Proper development and management of drip irrigation systems for row crops such as tomatoes and autumn planting of tomatoes in warm tomato production hubs is recommended for effective use of autumn rainfall. Also, training and application of methods to improve the performance of surface irrigation (using methods to reduce evaporation and the use of low pressure systems) is recommended to increase irrigation efficiency and reduce applied irrigation water.

Grapes is one of the most important horticultural products in terms of cultivation area, economic and high nutritional values. Iran with an annual production of 2.8 million tons, is among the top countries in the production of grape product in the world. However, there are not accurate information on the volume of irrigation applied water and water productivity of this product in Iran. Therefore, this study was conducted with the aim of measurement of applied water at field scale and evaluation of water productivity of grape in vineyards farms at different hubs of this crop production in Iran.

The volume of irrigation water provided by gardeners in 164 vineyards were measured in the provinces of Qazvin, Fars, Khorasan-Razavi, Zanjan, West Azarbaijan, East Azarbaijan, Hamedan, Markazi, Northern Khorasan, and Semnan as hubs of this product. These hubs covered about 80 percent of the irrigated vineyard cultivated areas. In each hub, 1-4 cities with the highest area under vineyard cultivation were selected for evaluation. The measurements were carried out in different irrigation and planting methods, various soils, different salinity of irrigation water and soil and different grape varieties during the growing season of 2018-2019 without interfering with the farmer's irrigation program. The measured values were compared with the net irrigation water requirement estimated by the Penman-Monteith method using the last 10 years meteorological data and also with the national water document values. Crop yield was recorded at the end of the growing season and water productivity was calucated as the ratio of yield to total water (irrigation applied water and effective rainfall). Analysis of variance was used to investigate the possible difference between applied water and water efficiency among the hubs. Data adequacy was assessed by using the method prposed by Sarmad et al. (2001).

The results showed that the average of applied water and water productivity among the hubs were significant at 1% probability level. The applied irrigation water used in the vineyards and water productivity were 6669 m3/ha and 2.63 kg/m3, respectively. Drip irrigation was about 20% effective compared with surface irrigation in reducing the applied irrigation water in the studied vineyards. Water productivity in drip irrigation orchards was essentially the same as surface irrigation and was not statistically significant. The reason was the lack of proper use and utilization of modern irrigation methods.The average net irrigation water requirement in the study areas estimated by the Penman-Monteith method using meteorological data for the last 10 years as well as the national water document were 6645 and 6456 m3/ha, respectively. The range of irrigation application efficiency in the studied vineyards was from 68 to 100 and its average was 89%. Comparison of applied water and net irrigation requirement indicated deficit irrigation due to water shortage in vineyards of most hubs. In total, 31% deficit irrigation occurred in the studied vineyards, which is a threat to soil salinity and destruction of soil structure in long-term. Grape planting method had a significant effect on reducing the applied water, increasing grape yield and consequently water productivity. Scaffolding method had a positive and significant effect on all studied indices in comparison with the crawling/reptile planting method. It caused a decrease of about 15% in applied water, an increase of 41% in yield and 37% in crop water productivity.

Due to the fact that vineyards are faced with deficit irrigation and water stress, training the farmers about the accurate and scientific methods of deficit irrigation in the vineyards can be effective to reduce the destructive side effects of water stress. Due to the widespread use of surface irrigation in the vineyards, training and application of methods to improve surface irrigation performance (evaporation reduction methods, using low pressure methods such as gated pipes, mulching, etc.), to increase irrigation efficiency and to reduce irrigation water applied is recommended. Changing traditional planting methods from crawling/reptile to scaffolding and surface irrigation (qana) to furrow, in addition to reducing evaporation, are the effective ways to increase the yield of vineyards and water productivity.

"Water accounting" is an approach to organise the information on water supply and analyse its socio-economic values in different sectors of the country. The estimation of the volume of water required for the national agricultural productions in the framework of product-based water accounting can be investigated. The key question is: what is the share of water consumption for the production of main crops in the country? In this study, using the net crop water requirement database of 2014-2015, and assuming an irrigation application efficiency of 44.7%, the water consumption of the selected crops in the country was estimated. Results show the maximum volume of water consumption by main crops is 78.6 billion m3, where 16.9 m3 is allocated to wheat production including 18.3% of the total water consumption for crops in the country. Comparing the net water consumption of wheat with other crops over 620 plains indicates that wheat, after barley, has the lowest net water consumption equal to 3562 m3/ha. Therefore, the volume of water consumption for wheat production is mainly affected by the cultivation area of irrigated wheat in the country (2.4 million hectares). Improving water productivity reduces the volume of water consumption in main crop production. The socio-economic values of main crop production could take precedence over its costs.

Climate change is a challenging topic for irrigation researchers as it has affected crop water demand. In the present study, the effects of climate change on minimum temperature, maximum temperature, precipitation, and the water demand of 12 crops including wheat, alfalfa, potato, barley, garlic, cucumber, watermelon, pumpkin, sugar beet, rapeseed, grain maize, and bean were investigated and also a trend analysis was carried out up to the year 2050. The impacts of implementing and not implementing the irrigation efficiency enhancement, the cropping pattern changes and the development of the early-maturing cultivars as the adaptation strategies in combination with climate change scenarios were investigated between the water years 1399–1428 (2020–2050). The results showed that without implementing the adaptation strategies, the net irrigation water requirement would increase by 3.98% to 8.38% compared with the recorded data. Growth in the irrigation efficiency up to the potential efficiency would cause a 19.23% reduction in the gross irrigation requirement on the average. By implementing the cropping pattern changes strategy through stopping the cultivation of some water-intensive crops such as alfalfa and developing the cultivation of rapeseed, net irrigation water requirement would decrease by 10.9%. By replacing late-maturing potatoes by the early and medium-maturing cultivars and developing of early-maturing grain maze cultivation, net irrigation requirement decreased by 8.86%. Furthermore, the results revealed that implementing all the above-mentioned adaption strategies would reduce the gross irrigation requirement by 34.0%. Hence, the three above-mentioned strategies can be used as the measures that executive managers and farmers choose to implement in order to adapt to climate change.

Climate change and its impacts on water recourses is known as one of the most important challenges which human would be faced with it in the future century. Although different studies are performed to consider the effects of climate change on the metrological and hydrological variables using climatic scenarios and General Circulation Models, but its effects on agricultural sectors such as water requirement are less investigated. The main objective of this study is to asses the effect of climate change on the net irrigation requirement changes of main crops in Hamadan-Bahar plain (winter wheat, barley, potato, sugar beet, maize (grain), maize (grass), peas and onion) in three next decades according to different scenarios using LARS-WG5 model compared with baseline period.
In this study daily metrological variables including precipitation, minimum and maximum temperature and relative humidity were collected from the Islamic Republic of Iran Meteorological Organization for 1981-2010. For main purpose, first of all, the capability of LARS-WG5 model was investigated and verified to simulate meteorological variables including minimum and maximum temperature, solar radiation and precipitation at Hamadan synoptic station in the baseline period (1981-2010). In the next step, meteorological variable values were stimulated by HadCM3 model based on A1B, A2 and B1 emission scenarios in the period of 2011-2040. Finally, the net irrigation requirement values of main crops were estimated for baseline and three future decades.
Based on the simulated results of LARS-WG5 model, the average values of air temperature and precipitation will increase by 0.77, 0.88 and 0.78 oC and 2.1, 5.9 and 10.2% for A1B, A2 and B1 scenarios, respectively.The results showed that average monthly precipitation will increase in October, December and February for three scenarios and decrease in March, April and May for A2 and B1 scenarios. Also, the total amount of net irrigation requirement of examined crops will increase between 2.6 to 28.2 mm for three future decades compared with baseline period. According to A2 scenario, the net irrigation requirements of wheat and barley have the lowest values of increasing change and sugar beet and potato have the highest increasing changes.
According to the A2 as a plausible scenario, the total net irrigation requirement of sugar beet, wheat, barley, potato, maize (grain), maize (grass), peas and onion in 30 next years will increase 267, 75, 57, 275, 250, 153, 145 and 224 cubic meters per hectares, respectively compared with baseline period. In general, considering increasing changes of the net irrigation requirements of different examined crops, the selection of appropriate cropping patterns consistent with climate change is required.

Iran is one of dry region in the world. Except the Caspian sea borders and the range and the elevations of Alborz and Zagros, this country often have a dry climate with a little precipitation. The collect rainwater method for different purposes has been used for the long time in Iran. This research has been done for Kalat basin, and conduct to check the appropriate way to determine the location for collecting rainwater. At the first step, the basin was divided to smaller sub basins by GIS software. Then for a period of 18 years (1991-2010) the need of water plant was calculated by Cropwat software. The assumption was that the cropping pattern of all of sub basin was the same pattern with basin area. Then due to lack of rain station, to calculate runoff in the spring, the curve number method was used (SCS). After estimating the runoff created in upstream of any sub basin, by comparing the net irrigation needs in downstream lands with the runoff created in upstream, a convenient location to collect rainwater, was suggested. Eventually, it became clear that it is possible to add 46 percent to irrigation lands.

In this study, impact of climate change on net irrigation requirement (In) and yield of wheat using CGCM3 climate projection model, one of the AOGCM models, in Behshahr area is evaluated. changes in temperature and precipitation were simulated run under the IPCC scenario A2 for 2011-2040, 2041-2070 and 2071-2100 periods. This work was done by using statistical and proportional downscaling techniques. For In estimating, Potential evapotranspiration (ETo) and effective rainfall (Pe) were calculated using Hargreaves – Samani equation and USDA method, respectively. Impact of water deficit on crop yield was estimated using the linear crop-water production function developed by FAO. Results showed that Net irrigation requirement (In) will increase when sowing date is moved toward winter season which would be of further limitations under climate change conditions. For the specific proposed sowing dates, the relative crop yield reduction (YD) was not significantly changed in the future compared to base period. If the sowing date is moved forward to winter season, YD will increase due to a higher evapotraspiration and lower available effective rainfall.