Iranian Water Research Journal

Abstract Introduction:
Given the increasing population, the decreasing of annual precipitation, and the scarticy of water supply resources, optimal use of existing water resources is one of the best options for achieving sustainable agriculture. Maximizing irrigation water productivity has been a centeral policy of managers and planners of the agricultural sector in recent years. Among the appropriate techniques for improving productivity and efficiency of water use are modern irrigation systems and the application of management scenarios such as deficit irrigation. In the field of modern irrigation, the invention of the subsurface drip irrigation system represents a major advance in the drip irrigation technology. Cotton is one of the most important agricultural products that, in addition to providing raw materials for the textile and oil industries, plays a significant role in jobs creation across the agricultural, industrial, and commercial sectors. Regarding continuous and severe droughts in Kerman province, especially in the Orzoueyeh agricultural region, and the lack of comprehensive studies on this issue—which challenges the economic justification for implementing modern irrigation systems—it is necessary to evaluate both surface and subsurface drip irrigation systems from technical and economic perspectives, particularly for cotton crops in Orzoueyeh County.

Materials and Methods:
The present study was conducted at the Orzoueyeh Research Farm, affiliated with the Kerman Agricultural and Natural Resources Research and Education Center, Orzoueyeh County, Kerman, Iran, during 2024-2025. To evaluate surface and subsurface drip irrigation systems on cotton yield, an experiment was conducted using split strip plots in a randomized complete block design with three replications. This experiment consisted of 12 treatments, three irrigation levels (I₁=125, I₂=100, and I₃=75 percent of water requirement), and two irrigation systems including surface drip irrigation (S₁) and subsurface drip irrigation (S₂), as well as two lateral placement patterns (all rows=L₁ and alternate-row =L₂). The factors I and S were applied in strip and cross arrangements, respectively. In each replication, factor I was arranged vertically, and factor S horizontally. Factor L was assigned to the plots resulting from the intersection of the two factors I and S. To measure and calculate the studied traits after removing the margins, two middle lines of each plot were used. Finally, the yield of the plant per hectare, the number of bolls per plant, and the water use efficiency (WUE) were measured and calculated as the amount of product per volume of water used. The studied traits were subjected to a combined analysis of variance for two years using SAS 9.2 software, and the least significant difference (LSD) test was applied at a probability level of 5% to compare the means. After collecting field data to economically select the best treatment, the results were examined using the partial budgeting method and investment priority analysis. Since determining the investment priority among the treatments under study was essential, an analysis of the final rate of return on investment was conducted.

Results and Discussions:
Based on the results, the crop yield at the irrigation level of 100 percent of water requirement was obtained as 2292 and 2555 kg/ha, and the lateral placement pattern in all rows and alternate rows at this irrigation level yielded 2565 and 2282 kg/ha, in surface and subsurface drip irrigation systems, respectively. The study of various indicators of crop yield, water consumption, water use efficiency, number of bolls per plant, boll weight, and the results of economic analysis of the treatments indicated the superiority of the subsurface drip irrigation over the surface irrigation system, and the superiority of the lateral placement pattern in all rows over the alternate-row, during cotton cultivation for the following reasons. The cotton crop yield in the subsurface drip irrigation system treatment was 234 kg/ha higher than that in the surface drip irrigation system. The number of bolls per plant and boll weight in the subsurface drip irrigation system were 16 and 3 percent higher, respectively, compare with the surface irrigation system. The cotton yield in the all-row irrigation pattern was 254 kg/ha higher than in the alternate-row lateral pattern. Despite the same amount of water consumption, the water use efficiency in the all-row irrigation pattern was about 8 percent higher than in the alternate-row lateral pattern. The number of bolls per plant and boll weight in the all-row irrigation pattern were 12 and 3 percent higher, respectively, than in alternate-row lateral pattern. From an economic point of view, investing in the I₂S₂L₁ treatment (subsurface drip irrigation at 100 percent of water requirement and with planting pattern in all rows) was preferable to investing in other treatments.

Conclusion:
Investment in the I₂S₂L₁ treatment (subsurface drip irrigation at 100 percent water requirement and in the in all rows lateral palcement) was preferable to investment in other treatments. The results of the technical analysis of the project also showed that the I₂S₂L₁ treatment had the best statistical position. Considering that cotton is a water-intensive crop and the amount of irrigation has a great impact on yield, all the studied traits showed better results in the 100 percent water requirement treatment compared with the other two treatments. Therefore, it can be conducted that this treatment is more economically justifiable. In addition, the full irrigation treatment was made based on economic evaluation and profitability for the farmer. Although deficit irrigation is beneficial for water conservation in the field, it is seldom adopted by farmers who primarily prioritize maximizing financial returns.

Abstract Water scarcity is a global and regional concern and requires a global and regional perspective. The water shortage crisis that the world and consequently Iran is experiencing shows the importance of water resources and the optimal use of those resources. Therefore, water supply is of special importance for the people of the world and different economic sectors, and any disruption in its process can lead to social and economic problems. Most policymakers and researchers believe that water scarcity and its effects on developing and developed countries as a global threat. It is clear that the issue of water has become an area of international cooperation. Concerns about water scarcity and water management problems in different parts of the world have made water issues the focus of many international and non-governmental organizations (NGO). According to studies, the formation of regional water markets is one of the methods of water resources management. To reach regional water markets, one of the effective tools is to create a suitable platform for economic convergence. Convergence is generally centered on gravity models. In the structure of these models, the basic condition for achieving economic convergence is convergence in production and productivity. This study has dealt with the most important variables affecting economic convergence through the productivity channel. Because distance is important in the formation of regional water markets, Iran has been selected and studied for convergence analysis with neighboring countries (Pakistan, Turkey, Russia, Kazakhstan, UAE, Armenia, Azerbaijan, Bahrain, Kuwait, Oman, Qatar, Saudi Arabia). Also, in order to see the effect of productivity shocks in the best possible way, a dynamic computable general equilibrium model has been used. The data required to simulate the scenario presented in this study are taken from the ninth version of the GTAP database. This version includes the world with 140 regions or countries, including Iran and 57 economic sectors. 57 parts of the model have been changed to 13 parts and 5 production factors to 8 production factors, which are as follows. Sectors include: Agriculture, Other Agriculture, Livestock, Forestry, Fisheries, Coal, Oil, Gas, Industry, Petrochemicals, Electricity, Water and Services. Production factors include: water, land, rain fed land, pasture land, skilled labor, unskilled labor, capital and natural resources. The characteristic of computable general equilibrium models is that it different scenarios can be evaluated and examined in the context of general equilibrium. For the productivity variable, the concept of total productivity of production factors is used, which is one of the factors affecting production and convergence. The results showed that positive productivity shocks have led to the expansion of foreign trade between Iran and neighboring countries. In practice, the expansion of trade can be considered as a factor for economic convergence between Iran and neighboring countries. Also, the productivity shock, in addition to slowly increasing economic prosperity, has also led to a kind of stability and stability in economic growth. Therefore, if productivity is an inevitable movement in the economic use of water resources, it can lead to economic convergence with an emphasis on water trade. Also, the result of the dynamic model shows a positive outlook for Iran and neighboring countries. Since economic convergence is a precondition for reaching regional water markets, Therefore, convergence with border countries is a suitable strategy for the Iranian economy to form regional water markets. It is natural that the formation of regional water markets can provide a good opportunity to deal with the crisis in water resources and also increase prosperity and stability in economic growth. So that the effect of the welfare change scenario shows that this index in Iran will increase from 31952.9 in 2023 to 2793848 in 2030 and this shows the positive effect of the regional water market on welfare. So that the effect of the welfare change scenario shows that this index in Iran will increase from 31952.9 in 2023 to 2793848 in 2030 and this shows the positive effect of the regional water market on welfare. According to the literature on gravity models, total value added, which constitutes GDP, is the most important variable affecting the convergence. Therefore, the effect of productivity shock on GDP indicates the necessary potential for economic convergence. The result of the dynamic model showed that the effect of positive productivity momentum on the change in the value of GDP is positive. It should be noted that, in the long run, by 2030, Iran and neighboring countries will reach a relative stability in terms of GDP value. Thus, the flow of productivity in the long run can provide stable conditions for GDP. Accordingly, the appropriate strategy for the Iranian economy in the formation of regional water markets can be considered as convergence with neighboring countries, which will also provide a good opportunity to deal with the crisis in water resources.