نشریه مدیریت آب در کشاورزی
سال پنجم شماره 1 (پیاپی 9، بهار و تابستان 1397)

The importance of using water resources optimally due to the country's climate is not overlooked. For this reason, increasing water use efficiency is one of the main goals in achieving sustainable agriculture. One of the important and effective solutions is to use modern irrigation methods and replace them with traditional methods. In this regard, the discourse on the use of subsurface irrigation systems has grown in the country over the last few years. Perhaps due to reasons such as providing direct fertilizer application, the lowest water losses and higher irrigation efficiency, it has a special place. However, it is important to note that because of the short life operation of the subsurface irrigation system in crops, farmers should be aware of the advantages of the system to the technical and administrative constraints of the underwater irrigation system, and based on a Comprehensive knowledge, decision making. The purpose of this study was to investigate the capabilities and limitations of implementation of subsurface irrigation system in irrigation of crops. In this regard, the advantages and disadvantages of implementing the system have been investigated in the first alfalfa irrigation system of about 8 ha in Qazvin province.

Although thousands of years ago olive was planted in the Mediterranean region, but there is little information about water consumption, crop coefficient and irrigation scheduling of olive trees. With existence limitation of water resources, the need for optimal water use in the agricultural sector is essential. Accordingly, the production of agricultural crops with a minimum water consumption is very important and considered as an important strategy for our country. Increasing demand for olive, either fresh or canned, or in the oil-milling industry, has led the country's agricultural authorities and gardeners to move towards a higher quality and quantity product, but it seems that achieving this goal without proper management in increasingly irrigated olive orchards is not possible. The olive is a resistant tree that produce acceptable yield even under restricted water conditions. Olive needs about 600 to 800 mm of annual precipitation to completely compensate the need for water. In this paper, a review of applied research on irrigation management of olive trees such as water requirement, crop coefficient, irrigation scheduling and its appropriate irrigation systems have been reviewed.

Water constraints and nitrogen deficiency are important factors that can affect rice plant growth. In order to study the optimum nitrogen application under water constraints, a factorial experiment was conducted in Rice Research Institute of Iran in a randomized complete block design with a factorial arrangement. Treatments included four levels of nitrogen fertilizer from source of urea [zero (N0), 60 (N60), 90 (N90) and 120 (N120) kg N ha-1] and three levels of continuous flooding (I0), eight Day (I8) and twelve days (I12) alternate. The results showed that irrigation treatments were not effective on plant height, panicle length and straw yield, while the number of tillers, 100 seed weight and empty seed weight were affected by irrigation practices. Interaction of irrigation and nitrogen treatments showed that increasing nitrogen fertilization in conditions of water deficit could lead to increase of yield, 100 seed weight and number of tillers.

The Agricultural productions in the province of East Azarbaijan and especially in Tasuj plain located on the north of Urmia Lake is completely depends on groundwater resources. It is required to recognize the components of groundwater balance with relative precision for optimal and sustainable application of groundwater resources. Therefore, the present study was conducted with the aim of determining the components of charge and discharge of the groundwater balance for the Tasuj plain for a period of 23 years from 1994-95 to 2016-17. Results showed that average of groundwater charge in this plain was 20×106 m3 which input flow from the groundwater sections (with 39%), infiltration from rainfall (with 27%), infiltration from surface flow (with 12%), infiltration from irrigation water (with 18%) and infiltration from municipal and industries water (with 4%) played a major role in charge of ground water. The average groundwater discharge in this plain was 24×106 m3. Therefore, the average reduction in groundwater storage was 4×106 m3 per year. In other words, discharge from groundwater resources in this plain was higher than that of charge. Basic approaches to sustainable utilization of groundwater resources include increased charge or reduced discharge of ground water resources. Application of procedures for improving irrigation efficiency, land leveling, increasing infiltration from rainfall, surface runoff or irrigation water are some of the executive solutions to balance groundwater.  

Measuring soil moisture by time domain reflectometry (TDR) is an indirect, safe and fast method, which is on the basis of the dielectric constant of the soil. Applying TDR has an adequate result for most soil conditions, but for atypical conditions such as salinity and high organic matter soils associated with the error. The solution is to perform high-precision calibration to be all situations to estimate the soil moisture. The aim of this study was calibrated burial sensor used in order to increase the accuracy of TDR soil moisture of different textures, which is simulated in the IRAN. In this study, three types of soil texture viz. heavy, medium and light soil were tested in the order of forest lands, crops and rangeland at east Azarbaijan, IRAN. The soil moisture variations were measured by TDR and gravitational methods. Several linear and nonlinear models were developed to model of soil moisture as a function of dielectric constant and measured moisture. Then, a few calibrated appropriate linear and polynomial equations were presented for different soil texture that calculate the actual moisture based on the dielectric constant and the measured moisture measured by the TDR method.

As the population grows, the need for agricultural water also increases, gradually. As a result, in arid and semi-arid regions, attentions have led to the vital sources of groundwater. Drought crisis, the number of unauthorized wells, extraction of groundwater, low efficiency and productivity of water and irrigation without management have been led to fall of ground water and exacerbated water scarcity. Therefore, it is essential to create an optimal management structure in order to be able to handle the amount of water consumption in agriculture. The aim of this research is developing sustainable agriculture in the region, increasing water productivity and saving costs. before, the implementation of the program, more than 23 unauthorized and authorized wells were existed in 32 hectares of groves. But after implementation of the project, the number was reduced to two active wells and a reserve one. Here it is necessary to say that for about half of the wells in the gardens (19 wells) were unauthorized. All unauthorized wells were removed in the range of 32 hectares of gardens. Power distribution to the gardens, implementing of electrical equipment for three wells and equipping three wells with the electric pump are supposed as those that have been done. Then the irrigation system in 32 hectares was changed from the traditional to drip irrigation. A pool of 400 cubic meters was built for water storage. Pruning and trickery implemented at a level of 32 hectares. Besides, Organic fertilizer was prepared by using palm leaf scum and mulching at a level of 32 hectares.by creation of integrated water and land management, 64 small gardens were converted into a 32-hectare unit and managed and handled by a single unit. Due to the integration of all 32 hectares, the current costs such as labor costs reduced and divided between all horticulturalists .By implementing this plan, the amount of extraction of waters decrease gradually and on the other hand, harvesting increases. Generally, it can be said that water consumption will decrease, and agricultural production will increase. This represents an improvement in water productivity and is a major step towards establishing, sustainable agricultural development. By implementing a drip irrigation system, irrigation efficiency has increased by 85%, which has a great impact on reducing irrigation water consumption. Also, by removing terrestrial channels and transferring water through the pipe, the efficiency of transferring water increased more than 90%. The mentioned factors are considered as the solutions of optimal water consumption. The results of the evaluations showed that by implementation of this project, agricultural consumption and annual withdrawal of water from wells decreased to 57%. Also, the amount of agricultural production and harvest increased by 66%, which reflects the effects of integrated water management on improvement of water productivity.besides, it is supposed as a major step towards establishing a sustainable agricultural development. With an increase of 52% in fixed costs of the project, the annually variable cost is reduced by 90% and the annual revenue from sales of products is 3.88 times. Providing variable annual costs for poor farmers is very difficult, which by combination of wells and the integration of gardens,this was reduced to 90% and was mainly due to the reduction of labor costs in 64 small plots. Before the implementation of the project, for each 1/4 hectare of the garden, there was a well.but after the project, this amount is increased to 16 hectares. The average distance between the wells increased from 120 meters to 4000 meters. Therefore, none of the wells are not existed in each other's technical environment and can not negatively affect on each other.

One of the steps in the groundwater balancing plan is to install a metering and volumetric flow meter for water users of ground water resources. Volumetric water delivery is one of the main components of the groundwater balancing plan. The importance of installing metering and volumetric flow meter of water is essential for any proper planning of water resources and this requires, while eliminating the existing defects, it should improve its efficiency. Managing water resources and the groundwater balancing plan without stakeholder and water users of well participations will not be possible. The studies show that in implementing the groundwater balancing plan, there is no executive solution and a specific version to empower farmers to meet the new conditions of water control and delivery. In this research, some examples of the optimization of farmers' cultivation pattern and training for farmer's income in terms of volume delivery are presented. In this research, determining the optimum cropping pattern in 9 wells agriculture in Qazvin plain was considered in terms of volume delivery and linear programming was used for optimization. In the studied wells, the average productivity, net benefit and water use in the optimum crop pattern with water allocation has increased by 93% and 67.7% respectively and water use has reduced by 15% compared to the formal crop pattern.