جستجوی مقالات مرتبط با کلیدواژه « برنامه ریزی ریاضی مثبت » در نشریات گروه « اقتصاد کشاورزی »

One of the important economic policies in most countries is to support the producer or consumer by paying subsidies. Most countries in the world implement the targeting of subsidies in a way so that they can reduce their costs and create a great economic benefit for their country. In Iran, subsidies were targeted in 2009 to increase economic welfare and decrease energy consumption. Therefore, this study aims to investigate the role of feed and fuel subsidy policies on the economic performance of poultry farmers in Kerman.

To achieve the economic performance of the poultry farmers of Kerman City, the positive programming method was used for sensitivity analysis. The data of this study was collected through the collection of 200 questionnaires from the operators of Kerman city using the full enumeration method during the years 1400-1401. The policies considered in this study include the policy of gradual elimination of subsidies, including chicken feed and fuel.

The results of the analysis of the positive mathematical program showed that the policy of gradually reducing chicken feed and fuel subsidies has a negative effect on the level of production and profit of poultry farmers in Kerman province.

According to the research results in the target area, both broiler chicken and egg-laying chicken products can enter the production pattern, but the production rate is lower compared to the current pattern. It can also be said that the targeting of subsidies has increased the price of production inputs and reduced the profit of poultry farmers.

In recent decades, the agricultural sector in most developing countries has been influenced by a variety of government interventionist policies aimed at supporting this sector in comparison with other economic sectors. These policies cover a wide range of interventions that directly or indirectly affect the price and market of these products. In Iran, the agricultural sector and its sub-sectors have also been affected by these policies in recent decades. These interventions have been done mainly through controlling the price of goods, imposing quotas or paying subsidies on their production inputs. On the other hand, with increasing pressure for production and cultivation level, the sustainability of the exploitation system has been challenged, so the purpose of this study is to analyze the policy system of the agricultural sector and provide supportive strategies for optimal cultivation and sustainable development. The statistical population of this study in the first part to measure sustainability using the AHP method is experts and experts in the agricultural sector and in the second part secondary information is obtained from the Agricultural Jihad Organization, Regional Water, Statistics Center of Iran and .... Finally, 11 scenarios were developed and implemented in the Hamadan-Bahar plain using GAMS software. The results of the research for each of the studied scenarios showed that in using each scenario, the best scenario should be considered according to the upstream documents and the characteristics of the region,

Water scarcity is a major deterrent to agricultural development. Adopting appropriate policies to sustain this resource has become an important strategic issue in the country. One of the policies implemented in the agricultural sector for sustainable water resources is the policy of changing the pattern of cropping and reducing the level of water crop cultivation based on the pattern and increasing irrigation efficiency. Accordingly, the aim of this study was to determine the effectiveness of gradual reduction of rice cultivation area along with increasing irrigation efficiency on economic and environmental indices in Marvdasht County. For this purpose, a Positive Mathematical Planning Model (PMP) and calibrated based on crop area data for the year 2017-2018 used. The method used for data collection was based on survey, documentary studies and the use of expert opinions and experiences. The results of this study showed that the application of water demand management policies in the context of different scenarios of reducing rice crop area, in spite of the decrease in the economic benefits of the agricultural sector, improves the economic efficiency index of water resources and decreases the water demand. Therefore, in order to stabilize surface and ground water resources in Marvdasht city, it recommend to change the optimum cropping pattern, in order to reduce the cultivation level of water crops and provide farmers with facilities to equip their farms with new irrigation systems.

Climate change and increasing global warming are intensifying droughts, changes in rainfall distribution and depletion of water resources over time. Persisting hot and dry weather has intensified the phenomenon of climate change and posed serious threats to the country's water resources, resulting in the inability to meet the needs like drinking, environmental, industrial and agricultural ones. The fifth report of the Climate Change Board also shows that the phenomenon of climate change in many parts of the world has had a negative impact on agricultural production; but the application of appropriate and timely adaptive scenarios against climate change can reduce the negative effects of this phenomenon on the agricultural crops yield. Bushehr province is mostly exposed to climate change and drought because of its geographical location. According to the National Meteorological Center, the area affected by drought in this province during the ten-year period ending in March 2019, was 83%. Up to 80% of the plains of the province have a negative groundwater level. This problem is more severe in some plains of the province, including Bushkan plain, the water level of this plain has decreased by 1.31 meters annually. This plain is considered as the agricultural hub of province and Dashtestan city. Thus the study of the effects of climate change on the hydrological and agricultural situation of the Bushkan plain and the analysis of the effectiveness of adaptive scenarios to reduce the negative effects of this phenomenon is very important.

In this study, in order to create optimistic and pessimistic scenarios of climate change, the LARS-WG microscale model was used. Then, in order to investigate the effects of climate change on the hydrological status of Bushkan plain, water needs of agricultural crops and crops yield, simulated climate change scenarios and adaptive scenarios include improve irrigation efficiency and deficit irrigation were entered into WEAP model and its agro-agricultural model, MABIA. For the purpose of investigating the adaptation of agricultural production systems to changes in available water and yield as well as to measure the effectiveness of adaptive scenarios, a positive economic planning model was used. For economic model, statistics and information related to the cultivation area, production costs, prices and yields of crops in different areas of Bushkan plain were obtained through the Jihad Agricultural Organization and also completed 100 questionnaires from farmers in the area. Random sampling method was used to calculate the sample size.

By applying two scenarios, optimistic A1B and pessimistic A2, in general, it can be concluded that the most changes in precipitation were in autumn and winter and the most temperature changes were at least in autumn and spring. Also, applying a pessimistic scenario will cause more drastic changes than an optimistic scenario. The results of MABIA model show that by applying both climatic scenarios, the average water requirement of all agricultural products increases during the simulation period compared to the base period.Increasing water demand and decreasing available water have caused water stress and as a result reduced the yield of various agricultural products in Bushkan plain. The results show that the average crop yields decreases, but the highest reduction of yield in both scenarios is related to wheat crop. The results of PMP model indicates that the application of optimistic and pessimistic scenarios will reduce the area under cultivation of this plain by 42% and 55%, respectively. On the other hand, among different crops, the area under cultivation of crops such as wheat, barley and watermelon has declined more sharply. However, the application of adaptive scenarios to improve irrigation efficiency and under-irrigation somewhat offsets the effects of climate change. In optimistic climate change, adaptive scenarios to improve irrigation efficiency and use of deficit irrigation method will improve the area under cultivation of agricultural products by 6 and 4 percent, and in pessimistic climate change by 3.8 and 2.3%.Comparison of the results of applying adaptive scenario shows that despite the less effect of deficit irrigation on improving the area under crops, the increase in profit in this scenario is more than the improvement of irrigation efficiency and the reason is the costs of improving irrigation efficiency compared to the deficit irrigation scenario.

Principles of resource management and low productivity have led to declining groundwater levels and as a result the ban on the exploitation of more groundwater in the plains of Bushehr province, including the Bushkan plain. Accordingly, in this study, the consequences of climate change on the hydrological and agricultural situation in the Bushkan plain of Bushehr province as well as the effectiveness of adaptive scenarios were investigated .Finally, based on the results of the present study, it is suggested that farmers use scenarios such as deficit irrigation methods and improve irrigation efficiency to prevent water loss and reduce the yield of these crops. However, since the results showed that using deficit irrigation method will improve agricultural profits more than improving irrigation efficiency, therefore, using deficit irrigation method has priority over improving irrigation efficiency. Also due to the low impact of climate change on water demand and canola yield, canola is suggested to local farmers as an alternative crop for wheat and barley crops.

Bushkan is one of the most important plains of Bushehr province which is considered as the agricultural pole of this province. The aim of this study was to evaluate the effects of climate change on the cropping patterns in different areas of Bushkan plain. Accordingly, in this study, the WEAP model and its agro-economic model, MABIA, have been used to study the hydrological status of the plain. Finally, using the positive mathematical programming (PMP), the effects of climate change on the cropping patterns in different areas of the Bushkan plain has been studied. The results show that by applying RCP 2.6 and RCP 8.5 scenarios, the water availability of different regions of Bushkan Plain during the 2018-2050 period is reduced by an average of 6 and 12 percent. By applying these changes to the positive mathematical programming, it was found that the total area under the cultivation of six areas is greatly reduced. According to this fallow agricultural lands is suggested as an appropriate solution to prevent long-term damage to agricultural production in the region.

Relatively good income, short period of cultivation and limited water requirement of saffron, farmers of Qazvin Plain made intend to cultivation of this product in their fertile lands in recent years. For this purpose, in present study the effects of increase acreage of saffron on cropping pattern, farmers' gross profit and the consumption of inputs were investigated. To achieve this goal, from Positive Mathematical Programming (PMP) model and product function with Constant Elasticity of Substitution (CES) were used. The required data are related to years 2012-2013 that by completing the questionnaires from 127 sample farmers were collected. The results showed that with the arrival of saffron to the current pattern of representative farms, cropping pattern changes in site reducing the acreage of products with more cost and higher water requirement such as corn, sugar beet and canola in small farms (from -1/78 to-13/9 percent), medium farms (from -4/92 to-14/1 percent) and large farms (from -7/05 to-16/4 percent). In this regard the farmers with large farms experiences the most changes in the current cropping pattern.

The purpose of this study was to investigate the role of efficiency in the transmission of climate and price shocks on farmers' behavior. The hypothesis of this study is that efficient farmers in the agricultural sector are more resilient and less vulnerable to climate and price shocks. In order to test this hypothesis, data envelopment analysis approach and positive math planning model were used. Data needed for this purpose were collected from the Agricultural Jihad questionnaires in Razan township, north of Hamedan province. The findings indicate that, due to the effects of climate change, farmers' groups are less effective than inefficient farmers and have more resistance. Also, farmers are less effective than price changes, which reflect the stable situation of this group of farmers in relation to these shocks. Therefore, it can be inferred that moving towards a productive boundary can be a means to reduce the impact of climatic hazards, markets and fluctuations in agricultural production in the studied area.

As for the key role of the agricultural sector in providing food to the human being, the proper utilization of soil and water resources is necessary. To maintain sustainability in the growth rate of agricultural production and saving vital environmental elements from damages done by excess use of chemical inputs, an appropriate price policy of chemical inputs is essential. Therefore, in this research, an attempt is made to quantify the effects of chemical inputs price policy on cropping patterns and consumption of these inputs. For this research 4, price scenarios including 50%, 100%, 200%, and 500% increase in prices of chemical inputs are used. Both primary and secondary data were utilized. in this research Results showed that the gross margin of farmers under all 4, scenario decreases, the area under crops that used more fertilizers and pesticides reduced and that of those consume lesser amounts of chemicals and fertilizers increased. Suggestion: As the gross margin of farmers decreases by the implementation of these scenarios to encourage them to implement price policies especially policies of increasing prices of chemical inputs by 200% and 500% providing fiscal as well as the technical incentive to the farmers is essential.

Creating water market as an economic solution on one hand, and simultaneously using modern irrigation techniques as a technical solution, in addition to adapting to the existing dehydration conditions, can optimize the pattern of farming and sale of water saved in the market and ultimately lead to increased farm income Gets The results showed that due to the launch of the water market in the region and the increase in the price of irrigation water from 10 to 100 percent, the level of all of the Hashtgerd plain is lower than the base year, and the changes in the pattern of cultivation after the simulation The acceptance of Hashtgerd plain farmers is different in applying the water price increase scenarios for different products. Also, despite the water market and the increase in the price of irrigation water from 10 to 100 percent, it reduces water consumption in the fields of selected products of Hashtgerd plain. By increasing the price of irrigation water, the volume of water consumed for all products of the pattern decreases. The results showed that, following the launch of the water market and rising water prices, at levels of this increase, farmers are moving toward improving irrigation technology and reducing their yields and incomes. However, to some extent, rising water prices, improving irrigation technology with considering the high cost of investing in such systems, they will not justify them, and in this area they resist the change in irrigation system and do the traditional irrigation, but in the range of rising water prices, the tendency towards changing the irrigation method is more modern and the traditional irrigation decreases. The limited water resources will not increase. Overall, the results showed that the effect of the increase in water prices in the conditions of the launch of the water market in 7 scenarios(10,20,30,40,60,80 and 100%), as well as the effect of improving the technology of irrigation method in two scenarios (20% of new methods And 80% of the traditional irrigation method (40% of the new methods and 60% of the traditional irrigation method), and after a combined assessment in 56 states, at best, an increase of revenue of 194.14 million rials will be achieved in the region.

According to debates and concerns about environmental changes, land use coverage changes have been taken seriously in recent decades. One of the most popular approaches to the simulation is Agent-Based Modelling (ABM). ABM is a set of computational models for simulating the actions and reactions of autonomous agents. The purpose of this research in 2016, is to simulate the status of agricultural land use cover changes in Babolsar over the next 30 years using the mathematical programming based-multi agent system (MP-MAS). The results showed that rain fed products would eliminate from the cultivation pattern of the region, and the development of mechanized Rice cultivation will occur. The area under cultivation of the horticultural products of the region will grow from 3,959 hectares to over 5585 hectares. The results will help managers with a strategic insight at the future of agricultural land use cover changes as they can simulate feedback on their policies and economic decisions.

Considering that the agricultural sector is strongly dependent on climate parameters of temperature and precipitation, it reacts rapidly related to climate change. Farmers are not able to control the climatic conditions, but management and optimization of the cropping pattern according to the region's climate can reduce the effects of climate change on the yield of agricultural products.
In this research, the effects of climate change on the yield, gross margin and Cropping Pattern of Gorgan County were investigated. For this purpose, at first, by using the regression analysis, the effects of climate variables on temperature and annual precipitation on the yield of selected products during the period of 1367-1396 were investigated. Then, the climate change of the study area was predicted for the upcoming periods (2021-2040), the near future (2051-2070) and the far future (2081-2100) by General Circulation Model HadGEM2. in the end, the region's cultivated area was stimulated by the application of Positive Mathematical Programming (PMP) and the effects of climate change on the cultivated area in the mentioned periods were investigated.
The results showed that climate parameters such as temperature and precipitation have a significant effect on the yield of selected products. Also, by applying predictions of climate change in the cropping pattern model, Potato with 0.27 and 71.7 percent increase, the highest increase in yield and cultivated area respectively, and High-quality long-grain rice with 0.17 percent reduction have the highest decrease in yield and barley with 89.1 percent reduction have the highest decrease in the cultivated area. and the gross margins of farmers were increased in all three periods.
Suggestion: As a result, it could be mentioned that consideration of the effects of climate change and improving the productivity of agricultural products, can decrease the negative effects of this event.
 JEL Classification: C22, C02, Q25, Q54

Water market as a significant economic means plays an important role in the optimal allocation of water resources in agriculture and also has significant effects in determining the cropping pattern and improving the welfare of farmers. With this approach, this study aimed at investigating the role of the water market on the use of water resources in Mashhad plain of Iran (Mashhad, Chenaran, and Torghabeh-Shandiz Counties) in farming year of 2013-14. For this purpose, the model of positive mathematical programming (PMP) and functions of regional production of agricultural products (SWAP) were used. The data were collected by Morgan sampling and Krejcie from 350 questionnaires completed randomly with farmers by referring to the organizations concerned. The results showed that following the formation of water market in the region, cropping patterns were directed towards products with higher profitability; also, substantial water-saving was achieved in the region, so that after the formation of the water market, water consumption decreased in the above-mentioned Counties by 37, 23.85 and 29.09 percent, respectively, indicating the usefulness of the formation of water market in order to reduce the use of water resources in the region.

In the last decade the use of chemical fertilizers have been followed environmental consequences adverse such as water and soil pollution and health problems for humans and other living things. As the use of chemical fertilizers could create serious risks for the environment and public health, the aim of this study is to determine the optimal combination of fertilizers for crops in the Goharbaran region of Sari using Goal Programming model and the Game Theory, and finally, cropping pattern in the current and optimal fertilizer consumption for crops is discussed using Positive Mathematical Programming. Required data for this study has collected with interview of 250 farmers during the years 2014-2015. The results of this study showed that the consumption of fertilizers for all crops have not been optimal by representative farmers. Therefore, current fertilizer consumption for all crops is more than optimal value. Based on results of positive mathematical programming, despite of constantan the total cultivation level, profits increased 3% in optimum fertilizer consumption rather than current fertilizer consumption.

In recent decades Climate and its changes have become one of the world major issues and as one of the major environmental problems. Agricultural sector is one of the first areas affected by these changes because farmers are not able to control climatic conditions; however, management and change in factors such as crop cultivar and optimization of the cultivation pattern according to area climate can reduce the adverse effects on growth and yield of agricultural products and play a significant role in the sustainable production of foods. Therefore, in this research, the effects of climate change on cropping pattern in Mashhad have been investigated. The statistics and data needed for the research were collected through Mashhad Agriculture Jihad Organization, meteorology Organization, as well as in-person interviews with agriculture specialists and farmers in Mashhad. The results of this study show that rainfall level, maximum and minimum seasonal temperatures have increasing trend and these changes have a significant effect on the yield of crops in the region. Also, considering the climate change scenarios (to 2031) during the planting period of each studied product, their crop area values have been changed and farmers' gross margin increased by 1.6 percent compared to the base year (2014). Finally, the results of this study indicate that the greatest changes in yield due to climatic conditions are related to wheat and barley; therefore, it is necessary for policy makers to pay attention to this issue in order to reduce the risk of these products production and prevent from reduced production of these strategic crops.

Due to problems such as high risk, water resources constraints, environmental problems and low technology levels in the agricultural sector, policy-making in this sector requires major revision. according to this, accordingly the main purpose of this research is to analyze the impact of policies and factors such as reducing water resources, reducing the use of fertilizer and developing mechanization on the farming model of Hamedan province, taking into account risk conditions and using a positive math planning approach. Based on the coefficient of variation of the cities, Nahavand and Bahar were selected as the Low risk and riskiest city. According to the results, with decreasing of water resources, barley cultivation in Nahavand and alfalfa remained constant in the Bahar city and wheat and corn in Bahar city and alfalfa in Nahavand were eliminated from the crop pattern. Water sensitivity analysis showed that by saving 55 percent of water consumption, the production level, and current profit could be reached. Due to the policy of reducing fertilizer use in the Bahar city, the level of fixed hay and wheat, maize and barley are eliminated from the cultivar model, but in Nahvand it does not change the cultivar pattern, which showed that the sensitivity analysis of fertilizer limits showed a decrease of 40% The use of fertilizer, the pattern of cultivation will not change. In the Bahar, with the policy of mechanization development, the level of cultivation of wheat and maize, the increase in barley and alfalfa and potatoes is constant, but in Nahavand, alfalfa, wheat, and barley, maize is increasing, and potatoes remain constant like Bahar city. Also, by applying this scenario, the total profit in the Bahar city has increased and declined in the city of Nahavand. Therefore, the Nahavand area needs less mechanization development. The results of this study showed that the high risk of production in each region leads to risk of policy implementation. This means that significant changes in yield and, consequently, greater risk will make farmers more sensitive to changing the current situation and imposing constraints and implementing the policies expressed.

The appearance of water scarcity problems in current decades at most pf countries leads to take new policies regarding water demand management instead of water demand supply. Therefore, the current study attempted to investigate the effects of irrigation water quota on cultivation pattern and gross margin in Qorveh–Dehgolan aquifer. The positive mathematical programming (PMP) and production function with constant elasticity of substitution (CES) was used to analyze data. The necessary data was collected through a stratified random sampling and fill questionnaires for the agricultural year 2015-16. The results showed that, applying the policy of irrigation water quota (under scenarios of 10 to 40 per cent respect to base year) would lead to reduce the level of cropland of products with high water requirement such as alfa-alfa and potato crops and it would lead to increase the level of cropland of products with lower water requirement such as wheat and barley crops and thus reducing the level of cropland as a whole. And again the results showed that, application of the policy cause of increase of water productivity but decrease of gross revenue.

In order to compare the effect of water pricing policy with increasing irrigation efficiency and investment in water and sewage technology, on reducing the deficit of groundwater reservoirs "DGR", production, net imports, net social benefits and income of farmers in Khorasan Razavi province, Five cities including Mashhad, Sabzevar, Neyshabour, Torbat Jam and Torbat Heydarieh were selected and the impact of these policies was studied using a positive mathematical programming model (PMP_GME). The analysis of the effect of rising water prices showed that although this policy has different results in different regions, making it impossible to implement, farmers' income is reduced from 19 to 98 and an average of 63 percent and increases social costs by 50 percent. So that the cost per cubic meter of saved water will be 5750 Rials. By increasing the efficiency of water transmission and distribution and without increasing the area under cultivation, the DGR is reduced by an average of 83%. The farmer's cost will be 300 Rials and the social costs will be 700 Rials per cubic meter. If the total irrigation efficiency is corrected to its potential, the DGR is reduced by 106%. If the increase in efficiency is accompanied by lack of control over the level of crops, although the production increases, but in conditions, the DGR are rising, but on average they fall by 53%. Replacing new systems instead of old and increasing the irrigation efficiency until to potential level without increasing the level of cultivation, reduces the DGR by 94%. But without increasing water application efficiency, only 63% of the DGE is corrected. It is therefore suggested, in place that the efficiency of transmission and distribution of water has increased, government reduce the extraction of ground water, proportional of increase in irrigation efficiency. Also, in critical areas, providing facilities for new irrigation systems be conditional on reducing water harvesting.

In fifth development plan, some suitable scientific and managerial policies have been expressed in order to optimizing the use of inputs and producing compatible crops with the conditions of each area. In this study with applying positive mathematical programming method, we evaluated the impacts of possible changes in consumption of inputs on cropping pattern of agricultural crops in Amol Township. These possible changes are propounded in the form of some scenarios like 1% reduction in water usage (PMP1), 7% reduction in fertilizers usage (PMP2), 1% reduction in pesticides usage (PMP3), 0.64% increase in employment (PMP4) and simultaneously mix these scenarios (PMP5). So that in 1392-1393, 124 farmers of this Township were interviewed through simple random sampling method. The results show that with running scenarios 1, 3 & 4 separately, any changes don’t occur in cultivated area of crops; so the least reduction that models reaction to it was calculated by sensitivity analysis. Also the results show that with running scenario 5 (PMP5), observe respectively 5 and 0.2 percent decrease in cultivated area of crops and current gross margin of this Township in compare with current model. So that the greatest reduction in cultivated area, respectively with 40 and 30 percent are related to irrigated barley and Rainfed soybean. Also, all of these scenarios lead to reduction in gross margin, which will reduce the welfare of the farmers in this area; therefore, it is suggested to take the necessary actions for improving their livelihoods.

Irregular consumption of groundwater resources in the northern Mahyar plain that is located in Zayande Rood basin river has considerably decreased the water’s level of aquifer of this plain and groundwater resources as important resources of water supply for agriculture of this region have been faced with a negative balance. On this basis, Aquifer management in terms of preserving and sustainability of water resources is very important. The regional economic dependence on irrigated agriculture and the decline of the Mahyar Aquifer due to agricultural pumping have been much of the basis for the relatively recent governmental interest in developing policy alternatives for conserving water in the aquifer. Especially, for the area's economy is based on agricultural production. Although governments supportive payments to agricultural activities are fulfilled for the purpose of increasing of social benefits, it will cause some economic and environmental externalities. The objectives of this study were to analyze and evaluate the outcomes of water price increment as specified water conservation policy alternatives on groundwater consumption and cropping patterns on the aquifer of northern Mahyar plain in Isfahan province, using non-linear optimization models.
The objective of this study is to analyze the effects of irrigation water pricing scenarios on groundwater balance and the modification in farmer's cropping patterns in the northern Mahyar plain. The objective function in this study is to maximize net present value to land, management, groundwater, and irrigation systems over a twenty years planning horizon. For these purposes, A Positive Mathematical Programming (PMP) model is considered in a dynamic framework and was calibrated to land use data for a base period of 2004-2005. The effects of the eight pricing scenarios of water in the range of zero to 1800 (IRR) on parameters over a period of twenty years were simulated by the model. PMP approach produces a constrained non-linear optimization model that mimics the land and water allocation decision facing producers each year The choice variables in the model are the acreages planted to each of the major crops and the water use by crop. This method is a useful approach in the determination of planning strategies and policies for groundwater systems. This method was intended to collect data and survey-based study of 250 questionnaires, documents, and use of views and experiences of experts.
The results derived from the model employed in this work showed that water pricing alone can potentially reduce considerably the consumption of aquifer groundwater, and adjust the trend of overexploitation of groundwater by irrigated agriculture. This effect is generated mainly as a result of water pricing providing incentives to the modification of farmer's cropping patterns through the substitution of crops with higher water requirements by others which use less water. Therefore, another modification in farmer's cropping patterns is substitution of crops with traditional irrigation by modern irrigation system. In fact, it has been analyzed that under certain structural and economic conditions, the effect of pricing policies can generate significant levels of water savings. The chief generalization is that the high water price scenarios significantly decreased the rate of decline in saturated thickness. Regardless of the price scheme, the saturated thickness will increase so long as the rate of recharge exceeds the irrigation rate. Therefore, it stands to reason that we should observe an increase in the saturated thickness than a base price scenario. A limitation of this proposed model regards the assumption of constant technology for both irrigation systems and pumping engines, which is significant in affecting the results.
Water pricing policies can affect water saving, at least in some situations, depending on water tariff rates, external conditions, and type of consumer behavior. Given the initial volume of groundwater in the northern Mahyar plain, it is imaginable that critical conditions will be reached in the near future by continuing the base scenario. A non-linear dynamic programming model in the framework of PMP techniques has been built to analyze the effects of water pricing scenarios on groundwater conservation of northern Mahyar plain. The Positive Mathematical Programming (PMP) method proved to be very effective. As seen in the data section there was not a plethora of information (data) on this subject. Therefore, it was important that the method chosen for this study could use a minimal amount of data while still maintaining accuracy. The PMP method was able to take the minimal data, calibrate to it, and then effectively reproduce the observed results. Additionally, the production function was able to be incorporated into this process seamlessly while maintaining accuracy. The result shows that under the high price scenarios, water application per acre decreased significantly during the early years of the simulated period. This suggests that high water prices have a significant effect on the rate of increment of the northern Mahyar aquifer stability. This is one of the first times that the PMP method has been incorporated into an applied groundwater management problem such as this, while also incorporating hydrological and agronomic information over time.

Paddy yields in Alamout region have been declined due to Chilo Suppressalis Walker pest. Slybyt scheme has been launched by government to overcome this problem. Since the success of the project mainly depends on farmers, participation, this study aims modeling farmer participation to the rice Slybyt scheme in the region and its effects on the cropping pattern and farmers’ gross profit. To this end, Positive Mathematical Programming (PMP) and the Maximum Entropy (ML) approach were used. Data collected from a sample of 136 farmers in 2012- 2013 by questionnaires using the Stratified Random Sampling method. The results showed that in both Eastern and Western part of the region, farmer's participation in the Slybyt scheme increases the rice yield relative to the base year while the rate of increase was different in relation to farm size. The result showed that the acreage of irrigated wheat, irrigated barley and beans decreased while the acreage of rice ,grass pea ,vetch and garlic increased. Also increase in farmers, gross margin from 4.78 to 13.09 percent relative to the base year was other consequence of farmer's participation in the Slybyt rice project.