Original Article
Pressurized Irrigation Systems
Nader Naderi; Alireza Mohammadi
Abstract
IntroductionFood security and increasing self-reliance in basic crops are important pillars of the country's economic development plans. One of the most important challenges to this self-reliance is the low water productivity in the strategic crop of wheat. An effective and practical solution is to use ...
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IntroductionFood security and increasing self-reliance in basic crops are important pillars of the country's economic development plans. One of the most important challenges to this self-reliance is the low water productivity in the strategic crop of wheat. An effective and practical solution is to use water optimally and save it. Pressure irrigation increases applied water efficiency by preventing water waste. The advantages of irrigation with the Rainflat system include reduced initial annual irrigation costs compared to the drip tape irrigation method, quick and easy installation without the need for welding, easy and quick assembly and reinstallation, no need for specialized personnel and special tools for installation and assembly, and the ability to use it to irrigate multiple fields. The water productivity index is used to evaluate optimal water consumption in analyses and decision-making. This index is affected by the irrigation schedule. An irrigation schedule is the amount of crop water requirement that is provided to the crop through irrigation intervals. It is believed that if the crop water requirement is used correctly and appropriately in modern irrigation methods, in addition to reducing costs, it is possible to save water consumption by increasing irrigation efficiency and help strengthen groundwater aquifers. Therefore, this study was conducted to investigate the effect of irrigation intervals and different amounts of water in the rain flat sprinkler irrigation method on wheat yield and water productivity.
Methodology This study was conducted in order to investigate the effect of irrigation interval and irrigation water amount on yield and water productivity of wheat in the years 2019 to 2021 in the form of split plots experiment based on randomized complete blocks design in three replications. The experiment was carried out in agriculture research and education center of Semnan (Shahrud). The soil texture was sandy loam. The main plots included 3 irrigation intervals (4, 5 and 6 days) and the sub-plots included three levels of irrigation (100, 80 and 60%). Sprinkler irrigation pipes (laterals) were placed at 4-meter intervals between crop rows. The net irrigation water requirement was calculated using the Penman-Monteith method and at the end, the amount of water consumption, wheat yield, and water productivity were determined and the best treatment was identified.
Results and Discussion Irrigation interval treatments of 4 and 5 days with grain yield of 5410.6 and 5016.1 kg/ha and water productivity of 1.169 and 1.077 kg/m3 were in the superior statistical group. The treatments of 100 and 80 percent irrigation requirement with average yields of 5520.7 and 5218.4 kg/ha had the highest yield, and the treatment of 80 percent irrigation requirement with water productivity of 1.130 kg/m3 had the highest water productivity. The interaction effect of experimental treatments on the studied traits was effective. Thus, the treatments of 4-day irrigation interval with 100% and 80% water requirement and 5-day irrigation interval with 100% water requirement were superior with grain yields of 6352.4, 6172.5, and 6105.5 kg/ha, respectively. The 4-day irrigation interval with 80% water requirement had the highest water productivity of 1.336 kg/m3.
Conclusions The results showed that in the rain flat irrigation method, increasing the irrigation interval to 6 days compared to the irrigation interval of 4 and 5 days reduced the yield by 35.55 and 30.48 percent and water productivity by 35.55 and 29.61 percent. Because the irrigation interval treatments of 4 and 5 days were in the superior statistical group in terms of yield and water productivity, the best irrigation interval is 5 days. By reducing the percentage of irrigation water supply to 60% of the water requirement, compared to 80 and 100% of the water requirement, yield decreased by 39.17 and 42.50%, respectively. However, in terms of water productivity, the treatment of 80% irrigation requirement with an average water productivity of 1.130 kg/m3 had the highest water productivity and was placed in the superior statistical group. Although the treatment with a 4-day irrigation interval with 80% water requirement did not have a statistically significant difference in yield compared to the 4- and 5-day irrigation intervals with 100% water requirement. but it had the highest water productivity among the irrigation treatments. Therefore, with the rain flat irrigation method, the percentage of water requirement can be reduced by 20% in the 4-day irrigation interval.
technical paper
Nader Heydari; Farshid Taran
Abstract
The concept of virtual water has been highlighted in the 21st century as a key indicator to evaluate the optimal use of water in the production of agricultural products, especially in the face of the water shortage crisis. This study analyzed the virtual water of irrigated wheat, known as one of the ...
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The concept of virtual water has been highlighted in the 21st century as a key indicator to evaluate the optimal use of water in the production of agricultural products, especially in the face of the water shortage crisis. This study analyzed the virtual water of irrigated wheat, known as one of the strategic agricultural products, in Iran and investigated the differences in the amount of virtual water of irrigated wheat in different provinces and climates of the country. The results indicated that the amount of virtual water of irrigated wheat in Iran is in a wide range of 284-3523 m3 ton-1 with an average of 1400 m3 ton-1, being 50% higher than the average values found in a number of other countries (930 m3 ton-1). The highest amount of virtual water (1539-3523 m3 ton-1) is in the provinces of Khuzestan, Kerman, Semnan, Bushehr, Sistan and Baluchestan, Isfahan, Fars, Yazd, some areas of Qom, Kermanshah, South Khorasan, North Khorasan, Chaharmahal and Bakhtiari, and East Azarbaijan with an average of 2610 m3 ton-1. Also, the lowest amount of virtual water (284-586 m3 ton-1) can be seen in the provinces of Mazandaran, Hamedan, Golestan, Kordestan, Kohkiluyeh and Buyer Ahmad, some areas of South Khorasan, Markazi, Hormozgan, and Ilam with an average of 451 m3 ton-1. The study showed that most of the areas under cultivation of wheat in Iran (about 53% of the irrigated wheat lands) are located in areas with water shortage crisis. The advantage of wheat cultivation in terms of water requirement and water use efficiency varies in different provinces. In terms of virtual water content, wheat cultivation is suitable in two provinces of Golestan and Ardabil, which relatively do not have water shortage problems and have low virtual water content of irrigated wheat. Khuzestan province also is preferable for wheat cultivation if the irrigation management is improved, due to the suitable climate and warm weather and the possibility of using winter rains in the growing season and quick ripening of the crop. But, wheat cultivation is not suitable in some regions of Iran, especially in the central and southeastern regions. The results of this study emphasize the necessity of optimal management of agricultural water resources and the strategic selection of areas under wheat cultivation based on the national cropping pattern from the aspect of advantage of production related to water requirements, water resource limitations, improving productivity and reducing virtual water content, reducing of crop wastes, and more attention on virtual water trade of wheat.
Original Article
Maryam Navabian; Mostafa Jamshidi Avanaki
Abstract
Extended AbstractIntroductionKnowledge of soil moisture status can significantly impact irrigation planning and, consequently, water management in the agricultural sector, which is the most expensive recipient of water resource allocation. Soil moisture measurement using the porous block method, based ...
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Extended AbstractIntroductionKnowledge of soil moisture status can significantly impact irrigation planning and, consequently, water management in the agricultural sector, which is the most expensive recipient of water resource allocation. Soil moisture measurement using the porous block method, based on electrical resistance measurement, is one of the techniques for assessing moisture levels. Developing an understanding of its construction can effectively reduce costs, increase accuracy, simplify moisture measurement, and achieve these goals. This study aims to enhance the understanding of soil moisture measurement through the development and assessment of porous blocks constructed with glass mat fibers, specifically P200 and P186 types.Materials and MethodsIn this regard, two types of glass fibers, P200 and P186, were used in the construction of a block with a fibrous structure. The accuracy of moisture measurement was then evaluated in 10 different soil textures. To prepare the soil, it was dried, pounded, and passed through a 2-mm sieve before being placed into a pot. After installing three replicates of each block in the pot, the soil was saturated. At various intervals until the soil dried, the electrical resistance of the block and the soil moisture were measured using the gravimetric method. To assess the accuracy of the blocks, the moisture readings from the blocks were compared with those obtained from the gravimetric method, and statistical indices such as R² (coefficient of determination), RMSE (root mean square error), nRMSE (normalized root mean square error), MAE (mean absolute error), and D-index (index of agreement) were calculated.Results and DiscussionThe results showed that ELE glass fibers absorbed 2.6 and 0.5 times more water than P200 and P186 fibers, respectively, over 180 seconds. A comparison of the fitting curves for the wicking behavior of the two fibers indicates that the quadratic curve provides a better fit than the linear curve. Additionally, the results showed that solution absorption in P186 decreased earlier than in P200. Therefore, it appears that P200 fibers are more effective at absorbing the solution and, subsequently, the water from the soil environment. The results also indicated that ELE and P200 fibers exhibited a similar decreasing trend in moisture over the first 15 minutes; however, after that point, the moisture reduction rate in P200 continued at a lower slope. P200 fibers demonstrated behavior more akin to ELE fibers during both moisture reduction and solution absorption. The findings reveal that the porous blocks constructed with P200 fibers achieved superior accuracy in measuring soil moisture, yielding an error margin of approximately 5%. Notably, the findings indicate that the P186 and P200 fibers exhibit optimal accuracy in medium soil textures, outperforming their performance in other soil types. Specifically, the P186 fibers achieve their highest accuracy in soil textures characterized by a sand content between 50-70% and clay content below 35%. Similarly, the P200 fibers also demonstrate robust accuracy within the same sand and clay content ranges, but they extend their effectiveness to include soils with sand content ranging from 20-50% and clay content around 28%. Conversely, the results suggest that both P200 and P186 fibers struggle with accuracy in soil textures that exhibit either high clay or high sand content. This highlights the importance of soil composition in the performance of these fibers for measuring soil moisture, indicating that they are less reliable in extreme soil conditions. Furthermore, the study highlighted a decline in measurement accuracy at elevated soil moisture levels, indicating that these blocks are most effective within a soil moisture range of 25-40% by weight.ConclusionIn conclusion, this research underscores the potential of utilizing glass mat fibers in the construction of porous blocks to improve soil moisture measurement accuracy. By refining this methodology, the findings contribute valuable insights toward optimizing irrigation practices and advancing water management strategies in agriculture. Enhanced accuracy in moisture readings not only promotes efficient water usage but also supports sustainable agricultural practices, ultimately benefiting food production and environmental conservation efforts.
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