reza saeidi; Hadi Ramezani Etedali; Amir Samadi; Ali Reza Tavakoli
Abstract
Introduction: Rainfed agriculture plays an important role in food production. In Iran, 6 million hectares of cultivated landsare rainfed. Moreover, about10% of raw agricultural products are being produced by rainfed agriculture. Yields of rainfed fields are decreased due to drought in recent years in ...
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Introduction: Rainfed agriculture plays an important role in food production. In Iran, 6 million hectares of cultivated landsare rainfed. Moreover, about10% of raw agricultural products are being produced by rainfed agriculture. Yields of rainfed fields are decreased due to drought in recent years in Iran. Supplementary irrigation is a suitable management to improve and enhance the yield of rainfed agriculture. Determination of appropriate time of supplementary irrigation is necessary in each region. But water allocation for this practice is the main challenge, because water resources are restricted. Therefore, water allocation management between irrigated and rainfedfields could be a viable strategy. Water resources for supplementary irrigation in rainfed fields are saved through deficit irrigation in irrigated lands or from rivers. The purpose of this study is optimum water allocation for supplementary irrigation in wheat and barley farms from rivers to around rainfed fields in Kamyaran region. In this study, supplementary irrigation is considered in three management methods of autumn irrigation, spring irrigation and both of them.
Materials and Methods:Kamyaran is located in Kurdistan province in west of Iran. The area of rainfed field is very vast in this region. Usually, rainfed fields are located in high slop lands and far from water resources in Kamyaran region. Supplementary irrigation is possible in rainfed fields around to water resources and with slope of less than 8%. The area of sub-basins with appropriate situations in Kamyaran region was calculated by geographic information system (GIS). Ratio of wheat to barley in rainfed fields is 3 to 1. Rivers in each sub-basin is the only water resources for supplementary irrigation in Kamyarn region. In this study, the objective function is maximizing net benefit. Also, constraints are total available water volumes in rivers at supplementary irrigations times and rainfed fields with appropriate situation for supplementary irrigation. Decision variable is rainfed area with different irrigation managements (autumn supplementary irrigation, spring supplementary irrigation, autumn+spring supplementary irrigations and rainfed managements). The total costs and income of agricultural production are found in statistical books of agriculture jihad in 2008-2009 growing season.
Results and Discussion: The lands around of rivers with suitable slope are about 30% of rainfed land of Kamyaran. The appropriate rainfed fields in sub-basins of A, B, C, D, E, F and INT were 125.39, 15.52, 18.11, 1111.26, 96.51, 48.13 and 49.55 Km2, respectively. The results of Optimization model showed the supplementary irrigation managements are different in each sub-basin because of different discharge of river in each sub-basin in different months. The optimal supplementary irrigation management for barley rainfed fields is autumnsupplementary irrigation. The yields of barley rainfed fields increase about 90% by autumn supplementary irrigation. The optimal supplementary irrigation managements for wheat are different in each sub-basin, but autumn+spring supplementary irrigations is best managed if water resources will be enough in each sub-basin. Due to restriction of water in rivers at supplementary irrigation time, some of wheat and barley fields remain rainfed in A+B+C and D sub-basin. The results showed minimum and maximum increase of wheat production in D and INT sub-basins are 29 and 134%, respectively. Also production increasing are 87, 112 and 126% in A+B+C, E and F, respectively. Increasing of barley production in the sub-basins of E, F and INT, are 61, 96 and 96%, respectively. Other sub-basins of A+B+C and D remained in rainfed farming. Net benefit increase about 65 and 275% for wheat and barley fields respectively, in 2014. Water productivity in all sub-basins for both wheat and barley is 74.8 and 44.5%, respectively.
Conclusions:This study showed supplementary irrigation management increased the yield and net benefit in rainfed fields of Kamyaran sub-basins. Resultsshowed about 30% of rainfed land of Kamyaran, are suitable for supplementary irrigation. The results of optimization models showed total increase of wheat production in A+B+C,E, F, D and INT sub-basins are 87, 112, 126, 29, 134%, respectively. Also increase of barley production in the sub-basins of E, F and INT, are 61, 96 and 96%, respectively. The result showed production increase about double in Kamayaran region. Also, net benefit increase about 65 and 275% in wheat and barley fields respectively.It has been suggested in A, B, C sub-basin, autumn supplementary irrigation of wheat, in E, F and INT sub-basins, autumn and spring supplementary irrigation for wheat and autumn supplementary irrigation for barley and in D sub-basin, autumn and spring supplementary irrigation for wheat.
kourosh majdsalimi; b. salavatian; e. amiri
Abstract
Introduction: Designing and management of sprinkler irrigation systems depend on the situation and location of its implementation and often rely on professional and long-term tests (9). Having a good irrigation system depends on knowledge of the relationship between soil, water, plants, irrigation scheduling, ...
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Introduction: Designing and management of sprinkler irrigation systems depend on the situation and location of its implementation and often rely on professional and long-term tests (9). Having a good irrigation system depends on knowledge of the relationship between soil, water, plants, irrigation scheduling, the required amount of irrigation water to the water-holding capacity of soil, climate and plant growth (6).The less use of sprinkler irrigation systems and less performed research projects in the Guilan province, lack of correct design parameters due to shortage of the required parameters for local and regional planning, has led to reliance on charts and tables. Therefore, planning water resources cannot be performed well and with accurate details. According to many researchers (8), the technical evaluation should be a regular and short-term process to review the problems and possible performance of irrigation systems. Merriam and Keller (10) defined the assessment of an irrigation system analysis, based on field measurements in real terms during the normal work of the system. Therefore, to develop these systems over the next few years, it is essential to evaluate the use of irrigation systems and review the performance of existing problems and utilizing the results to improve it. The aim of this study was to assess the current status of implemented irrigation systems in the tea plantations of Guilan and evaluate their performance.
Materials and Methods: In this study, six classic sprinkler irrigation systems in tea fields of Guilan province were evaluated during two years. Sprinkler irrigation systems of semi-portable, solid-set and solid-set (hand-move sprinkler) were selected randomly. To evaluate this irrigation systems, Christiansen’s uniformity coefficient (CU), distribution uniformity (DU), potential application efficiency of low-quarter (PELQ) and application efficiency of low-quarter (AELQ) in the form of trial blocks were estimated by measuring pressure fluctuations which were applied to the entire system. Using irrigated area and irrigation water depth, adequacy of irrigation curve, deep percolation losses and spray losses were determined on the basis of existing relationships.
Results and Discussion: Average values of CU, DU, PELQ and AELQ for 6 tea fields were 65, 52, 44 and 44 percent, respectively. Application efficiency in all irrigation systems, Christiansen’s uniformity coefficient and distribution uniformity were lower than recommended values in the references. Merriam and Keller (11) reported the allowable range for potential application efficiency of low-quarter between 65 to 85 percent. With respect to irrigation less than the actual water requirement of the plant in tea fields, AELQ was equal with PELQ. Untechnical design and implementation of irrigation systems, particularly poor operating pressure and economic problems were detected as the main reasons for the low PELQ. Simultaneous use of sprinklers with different specifications and models, old irrigation systems, water leakage from valves and other equipment, practically change the pressure and flow rate, which were the main reasons for the decrease in uniformity of water distribution and application efficiency of low-quarter. According to Cobban (4) uniformity coefficient of sprinkler irrigation systems were reported between 31 to 55 percent in Tanzania tea fields and in other reports were between 58 to 72 percent (7), which was due to poor design, long spacing of sprinklers and high speed wind. Christiansen’s uniformity coefficient and distribution uniformity of low-quarter in ED, WB & EP systems were lower than recommended values by Merriam and Keller (%81≥CU≥87% & %67≥DU≥80%)(10). In spite of the little losses in deep percolation, irrigation adequacy of these systems was relatively low and unacceptable. In such circumstances, only about 20 to 38% of irrigated area in WA and CK systems, respectively received the required water or more, according to lack of soil moisture (required irrigation depth). The main reason was low uniformity of water distribution in irrigation systems which was described previously. Evaluated spray losses in irrigation systems was variable between 4.8 to 13 percent. The losses obtained in irrigation systems in tea fields in comparison with the values 2.6 to 42.4 which were obtained in other regions of the country were less by (1, 3, 5 and 12) due to low wind speed and high relative humidity (2) as the main reasons.
Conclusion: Average values of CU, DU, PELQ and AELQ for 6 tea fields were 65, 52, 44 and 44 percent, respectively that were lower than recommended values in the references. The results showed that old irrigation systems in tea fields are not in good functional status due to untechnical design and implementation, operation, exploitation and inappropriate maintenance (due to economic problems and lack of farmer’s knowledge on irrigation). To improve the performance and efficiency of irrigation systems in the tea fields, detailed information are recommended, to design and implement with detailed information accomplished by regional companies. Moreover, the use of solid-set (hand-move sprinkler) sprinkler irrigation instead of semi-portable with manual handling (aluminum pipes), operation of irrigation groups and promoting farmers' knowledge about the principles of proper the scheduling and management, operation and maintenance of irrigation systems are very effective to improve the performance indices.
A.R. Tavakoli
Abstract
The main purpose of rainfed farming is increasing the water productivity by applying suitable agricultural management including single irrigation (SI) and panting time for wheat varieties. In order to study the SI optimization and determination its optimal program, a field experiment was conducted as ...
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The main purpose of rainfed farming is increasing the water productivity by applying suitable agricultural management including single irrigation (SI) and panting time for wheat varieties. In order to study the SI optimization and determination its optimal program, a field experiment was conducted as split-split plot based on a randomized complete block design with three replications for different wheat varieties at main station of Dryland Agricultural Research Institute (DARI), Maragheh, Iran, during two crop seasons of 2000-2004. The treatments included three panting time, three SI and five wheat varieties (V1=72YRRGP, V2=Fenkang 15/Sefid (seed white), V3=Turkey, 13//F9.10/Maya”S”, V4=Azar2, V5=double cross shahi). On based of water productivity indices, rain water productivity (RWP), irrigation water productivity (IWP), and total water productivity (TWP) optimal program of single irrigation scenarios was 100mm at early, 75mm at normal and 50mm at late sowing date. V3 wheat variety was better than other varieties. At this single irrigation program, maximum single irrigation water productivity (11.3 – 21.3 kg.mm-1) in producing grain yield and stabilized wheat production were obtained
