Irrigation
A.R. Kiani; M.R. Yazdani; M.T. Feyzbakhsh
Abstract
Introduction: In Golestan province, despite the lack of water resources, traditional rice cultivation, a crop with high water consumption, is increasing due to economic justification. This issue has become one of the main problems of the province's agricultural sector in recent years. In order to prepare ...
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Introduction: In Golestan province, despite the lack of water resources, traditional rice cultivation, a crop with high water consumption, is increasing due to economic justification. This issue has become one of the main problems of the province's agricultural sector in recent years. In order to prepare the planting bed (puddled transplanting) in the traditional method of rice production, a significant amount of irrigation water is used before planting the seedlings in the main land. Moreover, the plant is in the water during the growing season, which causes high water losses by surface water evaporation and deep penetration. Rice direct seeding cultivation is a method that has been considered in the world for various reasons, including higher water productivity. Currently, reports indicate that more than 50% of groundwater resources are extracted and allocated annually for rice cultivation in the region investigated. In general, field information and observations indicate that the level of paddy cultivation is increasing in the province. In the past few decades, agricultural policymakers have sought to restrict and ban rice cultivation in the country, except in Gilan and Mazandaran provinces. The rationale behind this decision is high water consumption, declining groundwater aquifers and long-term instability of water resources. The developed strategy did not work effectively, as it did not consider the benefits of the farmers in the short run. The increasing trend in the area under paddy fields from 1995 to 1500 hectares per year shows the unsuccessfulness of this up-to-down strategy.Materials and Methods: A field experiment was conducted to investigate the effect of rice cultivation and irrigation methods on yield, water consumption and water productivity over two rice cropping seasons (2019–2020) in northern Iran (Gorgan Agricultural Research Station). Irrigation method as the main factor in four levels (permanent flooding, intermittent as wet and dry, sprinkler, tape) and cultivation method in three levels (direct seed in dry bed, non-puddled transplanting and traditional transplanting) in the form of a strip design. The plot was based on a randomized complete block design with three replications. The applied water, yield and some yield components and water productivity were measured and calculated during the growing seasons.Results and Discussion: The results showed that in all irrigation methods, yield was significantly reduced by changing the traditional seeding transplanting to dry seed. The amount of water applied in sprinkler and drip irrigation methods from traditional seedlings was significantly reduced as compared to direct seed seeding. Dry seed cultivation, however, consumed more water than traditional transplanting in the flood irrigation treatments (wet and dry and permanent). The highest yield (8206 kg/ha) was obtained for traditional seedling cultivation by flood irrigation, and no significant difference was observed between the yields for the other irrigation methods. In general, changing the irrigation systems had a greater effect on water consumption than changing the rice cultivation method. In addition, changing the cultivation method had a greater effect on changing the type of irrigation systems. In traditional transplanting cultivation, the yield decreased by about 14, 9 and 11%, respectively, by changing the irrigation systems from permanent flood irrigation to sprinkler, wet and dry, and drip irrigation. The highest water use was observed for flood irrigation method in direct seeding (12490 m3/ha) and direct transplanting (11967 m3/ha).Conclusion: Currently, farmers cultivate rice by transplanting in padded land irrigated by flooding techniques in Golestan province, which results in high water consumption (about 13,000 m3/ha). By changing the irrigation method from flood irrigation to drip for traditional transplanting cultivation, water consumption decreased by about 39% and as a result water productivity increased by about 22%, albeit a 11% reduction in yield occurred. With the conversion of traditional transplanting seedling by flood irrigation to non-puddled transplanting by drip irrigation, the yield decreased by about 24% and the amount of water by about 45%, and water productivity in this case reached 0.9 kg/m3. This can be considered as the best alternative for conserving both water resources and production. If only reducing water consumption is the main priority (regardless of yield reduction), the best treatments are drip irrigation with direct seeding, non-puddled transplanting and then traditional seedling, respectively. If there is a sprinkler irrigation system in the field, this option is given priority in the direct seeding and non-puddled transplanting. If changing the irrigation system is not considered, the use of intermittent irrigation (as a wet and dry) with non-puddled transplanting, traditional methods and direct seeding are preferred, respectively.
Irrigation
E. Asadi Oskouei; S. Kouzegaran; M.R. Yazdani; A. Rahmani
Abstract
Introduction: Correct assessment of evapotranspiration fluctuations in different meteorological scenarios plays an important role in the optimal management of water resources. Probability analyzes with different probabilities of occurrence can increase flexibility in decision making and increase the ...
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Introduction: Correct assessment of evapotranspiration fluctuations in different meteorological scenarios plays an important role in the optimal management of water resources. Probability analyzes with different probabilities of occurrence can increase flexibility in decision making and increase the reliability of decisions. Rice (Oryza sativa L.) is one of the most important agricultural products in the world. Although rice is cultivated in a wide range of climatic and geographical conditions, it is vulnerable to changes in environmental conditions. Planting management, design of irrigation systems, and suitable irrigation cycle for optimal production are important issues for sustainable production.
Materials and Methods: The study area includes the northern region of Iran, i.e. the provinces of Gilan, Mazandaran and Golestan, which is the main rice-growing area in Iran. Changes in rice evapotranspiration in three different cultivation dates with four different occurrence probabilities of 75, 50, 25 and 10%, was calculated using the FAO Penman-Monteith equation and meteorological data with a statistical period of 30 years (2020- 1990). Also, the average rice crop coefficient at different stages of growth in 10-day periods was estimated based on the Weibull model. These probabilities represent the probable limits of the expected values of evapotranspiration in different scenarios of low, normal, high, and very high evapotranspiration years.
Results and Discussion: The results showed a relatively constant difference of 1 to 2 mm between different rice cultivation histories in the major rice cultivation areas of Gilan and Mazandaran in normal to very high evapotranspiration years. In the years of low evapotranspiration, the water requirement was significantly different from the normal, high and very high evapotranspiration years, which decreased from east to west. This difference was approximately 30% higher in Golestan province as compared with other areas. In the early planting situation relative to the late planting situation in the major western and central coastal areas, there was a 10% decrease in water consumption. At the scale of the whole growing season in Gorgan, evapotranspiration in different conditions of planting date was on average 20% (1300 cubic meters) more than the main regions of Gilan and Mazandaran. In case of timely planting, the net irrigation requirement in very high evapotranspiration years was about 2000 cubic meters per hectare more than the normal years. In years with high evapotranspiration, late planting increased the net irrigation requirement by more than 210 mm compared to different planting dates in Gorgan. According to the obtained results, the largest difference between evapotranspiration values during normal and very high evapotranspiration years was in the late planting situation. Therefore, it seems that late planting causes a significant increase in water consumption in the high evapotranspiration years. Consequently, it is better to avoid rice cultivation when the rice growing season is anticipated to be warm.
Conclusion: Evapotranspiration, as one of the main components of the hydrological cycle, had a significant role in proper irrigation planning and water resources management. The results underline the importance of estimating the rice evapotranspiration to avoid appreciable yield loss under extreme conditions.
M. Alizadeh; F. Mirzaei; T. Sohrabi; M. Kavoosi; M.R. Yazdani
Abstract
Water management in cracked paddy soils is an important issue in rice cultivation. In order to investigate the effect of rice straw and zeolite and their interaction effect on the physical condition of soils of paddy fields and prevention of crack, rice straw factor at four levels (0, 0.5, 1 and 1.5 ...
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Water management in cracked paddy soils is an important issue in rice cultivation. In order to investigate the effect of rice straw and zeolite and their interaction effect on the physical condition of soils of paddy fields and prevention of crack, rice straw factor at four levels (0, 0.5, 1 and 1.5 percent) zeolite factor at four levels (0, 8, 16 and 24 tons per hectare) and also moisture stages of soil which are wet and dry stages at 5 levels which have been studied in three replication as factorial based on the complete randomized block design in Rice Research Institute of Iran. Soil distance from the wall of the container, the width of cracks, a few days to reach the crack with a certain width, bulk density and surface cracks were measured. Results showed that adding high levels of residue to delay the occurrence of cracks. However, the addition of zeolite has no significant effect in delaying the cracks. The relationship between bulk density and surface cracks that follow the linear equation, With increasing cracks surface, bulk density is increased. Finally, Can be concluded that the addition of plant residues, causing disappearance of existing cracks and returned to the soil to be the initial state.