Article 139 of Iranian Constitution and Foreign Investment Disputes Settlement

With regard to promotion and protection of foreign investment and settlement of disputes arising out of it, Iran has enacted special law titled Foreign Investment Promotion and Protection (FIPPA) and also has signed more than 60 Investment Treaties which refer investment disputes to international arbitration subject to certain conditions. On the other hand, Article 139 of Constitution of the Islamic Republic of Iran has conditioned referral of disputes on public and state properties (including foreign investment) to arbitration to permission and approval of Board of Ministers and the Parliament of Iran. These supposedly conduce to incongruity of rules and legal environment of Iran for foreign investment. Keywords: Foreign Investment, Article of 139 of constitution, Arbitratio

Application of HYDRUS (2D/3D) for Predicting the Influence of Subsurface Drainage on Soil Water Dynamics in a Rainfed-Canola Cropping System

The HYDRUS (2D/3D) model was applied to investigate the probable effects of different subsurface drainage systems on the soil water dynamics under a rainfed-canola cropping system in paddy fields. Field experiments were conducted during two rainfed-canola growing seasons on the subsurface-drained paddy fields of the Sari Agricultural Sciences and Natural Resources University, Mazandaran Province, northern Iran. A drainage pilot consisting of subsurface drainage systems with different drain depths and spacings was designed. Canola was cultivated as the second crop after the rice harvest. Measurements of the groundwater table depth and drain discharge were taken during the growing seasons. The performance of the HYDRUS-2D model during the calibration and validation phases was evaluated using the model efficiency (EF), root mean square error (RMSE), normalized root mean square error (NRMSE) and mean bias error (MBE) measures. Based on the criteria indices (MBE = 0.01–0.17 cm, RMSE = 0.05–1.02 and EF = 0.84–0.96 for drainage fluxes, and MBE = 0.01–0.63, RMSE = 0.34–5.54 and EF = 0.89–0.99 for groundwater table depths), the model was capable of predicting drainage fluxes as well as groundwater table depths. The simulation results demonstrated that HYDRUS (2D/3D) is a powerful tool for proposing optimal scenario to achieve sustainable shallow aquifers in subsurface-drained paddy fields during winter cropping. Copyright © 2017 John Wiley & Sons, Ltd

Integrating Irrigation and Drainage Management to Sustain Agriculture in Northern Iran

In Iran, as in the rest of the world, land and water for agricultural production is under pressure. Integrating irrigation and drainage management may help sustain intensified agriculture in irrigated paddy fields. This study was aimed to investigate the long-term effects of such management strategies in a newly subsurface drained paddy field in a pilot area in Mazandaran Province, northern Iran. Three strategies for managing subsurface drainage systems were tested, i.e., free drainage (FD), midseason drainage (MSD), and alternate wetting and drying (AWD). The pilot area consisted of subsurface drainage systems, with different combinations of drain depth (0.65 and 0.90 m) and spacing (15 and 30 m). The traditional surface drainage of the region’s consolidated paddy fields was the control. From 2011 to 2017, water table depth, subsurface drainage system outflow and nitrate, total phosphorous, and salinity levels of the drainage effluent were monitored during four rice- and five canola-growing seasons. Yield data was also collected. MSD and AWD resulted in significantly lower drainage rates, salt loads, and N losses compared to FD, with MSD having the lowest rates. Phosphorus losses were low for all three practices. However, AWD resulted in 36% higher rice yields than MSD. Subsurface drainage resulted in a steady increase in canola yield, from 0.89 ton ha−1 in 2011–2012 to 2.94 ton ha−1 in 2016–2017. Overall, it can be concluded that managed subsurface drainage can increase both water productivity and crop yield in poorly drained paddy fields, and at the same time reduce or minimize negative environmental effects, especially the reduction of salt and nutrient loads in the drainage effluent. Based on the results, shallow subsurface drainage combined with appropriate irrigation and drainage management can enable sustained agricultural production in northern Iran’s paddy fields

Integrating irrigation and drainage management to sustain agriculture in northern Iran

In Iran, as in the rest of the world, land and water for agricultural production is under pressure. Integrating irrigation and drainage management may help sustain intensified agriculture in irrigated paddy fields. This study was aimed to investigate the long-term effects of such management strategies in a newly subsurface drained paddy field in a pilot area in Mazandaran Province, northern Iran. Three strategies for managing subsurface drainage systems were tested, i.e., free drainage (FD), midseason drainage (MSD), and alternate wetting and drying (AWD). The pilot area consisted of subsurface drainage systems, with different combinations of drain depth (0.65 and 0.90 m) and spacing (15 and 30 m). The traditional surface drainage of the region's consolidated paddy fields was the control. From 2011 to 2017, water table depth, subsurface drainage system outflow and nitrate, total phosphorous, and salinity levels of the drainage effluent were monitored during four rice- and five canola-growing seasons. Yield data was also collected. MSD and AWD resulted in significantly lower drainage rates, salt loads, and N losses compared to FD, with MSD having the lowest rates. Phosphorus losses were low for all three practices. However, AWD resulted in 36% higher rice yields than MSD. Subsurface drainage resulted in a steady increase in canola yield, from 0.89 ton ha-1 in 2011-2012 to 2.94 ton ha-1 in 2016-2017. Overall, it can be concluded that managed subsurface drainage can increase both water productivity and crop yield in poorly drained paddy fields, and at the same time reduce or minimize negative environmental effects, especially the reduction of salt and nutrient loads in the drainage effluent. Based on the results, shallow subsurface drainage combined with appropriate irrigation and drainage management can enable sustained agricultural production in northern Iran's paddy fields.</p

Numerical modeling of soil water dynamics in subsurface drained paddies with midseason drainage or alternate wetting and drying management

As a supplemental practice to land consolidation projects, subsurface drainage systems have been installed in paddy fields to allow for crop diversification and to improve the overall productivity of paddy soils. The HYDRUS (2D/3D) model was applied to investigate the combined effects of different subsurface drainage systems and water management strategies on water balance, groundwater table, transpiration efficiency, and water use efficiency in paddy fields. Field experiments were conducted during four rice growing seasons (2011, 2012, 2014, and 2015) at the subsurface-drained paddies of the Sari Agricultural Sciences and Natural Resources University in northern Iran. Midseason drainage (MSD) management was applied in 2011 and 2012, while alternate wetting and drying (AWD) management was adopted in 2014 and 2015. The model performance was evaluated using the model efficiency (EF), root mean square error (RMSE), normalized root mean square error (NRMSE), and mean bias error (MBE) measures. The model had strong predictive capabilities for simulating the mid-drain water table depth for both water managements. Under MSD and AWD, daily evapotranspiration rates varied from 4.9 to 6.2 mm d−1 and 4.9 to 5.9 mm d−1, respectively. Drainage losses were higher under AWD than MSD, while the reverse order occurred for percolation losses. Compared with MSD, AWD improved the transpiration and water use efficiency of rice in the presence of subsurface drainage. Being capable of describing complex effects of AWD and MSD strategies in subsurface-drained paddy fields, the HYDRUS (2D/3D) model can serve as a practical tool for optimizing water productivity in these fields

Numerical modeling of soil water dynamics in subsurface drained paddies with midseason drainage or alternate wetting and drying management

As a supplemental practice to land consolidation projects, subsurface drainage systems have been installed in paddy fields to allow for crop diversification and to improve the overall productivity of paddy soils. The HYDRUS (2D/3D) model was applied to investigate the combined effects of different subsurface drainage systems and water management strategies on water balance, groundwater table, transpiration efficiency, and water use efficiency in paddy fields. Field experiments were conducted during four rice growing seasons (2011, 2012, 2014, and 2015) at the subsurface-drained paddies of the Sari Agricultural Sciences and Natural Resources University in northern Iran. Midseason drainage (MSD) management was applied in 2011 and 2012, while alternate wetting and drying (AWD) management was adopted in 2014 and 2015. The model performance was evaluated using the model efficiency (EF), root mean square error (RMSE), normalized root mean square error (NRMSE), and mean bias error (MBE) measures. The model had strong predictive capabilities for simulating the mid-drain water table depth for both water managements. Under MSD and AWD, daily evapotranspiration rates varied from 4.9 to 6.2mmd−1 and 4.9 to 5.9mmd−1, respectively. Drainage losses were higher under AWD than MSD, while the reverse order occurred for percolation losses. Compared with MSD, AWD improved the transpiration and water use efficiency of rice in the presence of subsurface drainage. Being capable of describing complex effects of AWD and MSD strategies in subsurface-drained paddy fields, the HYDRUS (2D/3D) model can serve as a practical tool for optimizing water productivity in these fields

Dynamic assessment of the impacts of global warming on nitrate losses from a subsurface-drained rainfed-canola field

The impact of global warming on water and nitrate losses from a rainfed-canola cropping system under various artificial drainage systems was assessed using an integrated field-modeling approach. Four subsurface drainage systems with different drain depths (Dx) and spacings (Ly), including D0.90L30, D0.65L30, D0.65L15, and Bilevel (with a drain spacing of 15 m and alternate drain depths of 0.65 and 0.90 m), were considered. The HYDRUS (2D/3D) model was first calibrated and validated using data collected for all drainage systems during the 2015–2016 and 2016–2017 canola cropping cycles, respectively, and then applied to simulate water/nitrate losses for different drainage systems under meteorological conditions predicted assuming expected future global warming. Future weather data were downscaled from 20 general circulation models and four RCP scenarios for the mid 21st century (for 2041–2070). The model capability of representing experimental field data was evaluated using the mean bias error (MBE), the normalized root mean square error (nRMSE), and the model efficiency (EF). The HYDRUS (2D/3D) model provided reliable description of soil water contents (MBE=-0.5 % to 0.2 %, nRMSE = 0.005−0.034%, and EF = 0.73−0.99), drainage fluxes (MBE= -21.7 × 10−3 to 24.9 × 10−3 mm d-1, nRMSE = 0.23−0.37%, and EF = 0.69−0.85), soil nitrate concentrations (MBE= -0.002 to 1.00 mg cm−3, nRMSE = 0.08−0.18%, and EF = 0.51−0.88), and nitrate fluxes (MBE= -0.97 to 0.72 mg cm-1 d-1, nRMSE = 0.35−0.57%, and EF = 0.77−0.87). The modeling results indicate that climate change will cause an increase of up to 148 % in average daily drainage fluxes and up to 125 % in average daily nitrate fluxes compared to the base case. This will result in an increase of 4–125 % in seasonal nitrate losses from various drainage systems, with the lowest and highest projections for the D0.65L15 and D0.65L30 systems, respectively. The HYDRUS-simulated results indicate that the D0.65L15 system is environmentally safer than the other evaluated drainage systems for predicted global warming conditions concerning water/nitrate losses

Subsurface drainage to enable the cultivation of winter crops in consolidated paddy fields in Northern Iran

Subsurface drainage is a prerequisite to grow winter crops in the consolidated paddy fields in Northern Iran. A four-year study (2011-2015) was conducted to quantify the effects of subsurface drainage on the saturated hydraulic conductivity, water table, drain discharge and winter crop yields. Subsurface drainage systems with two drain depths of 0.65 and 0.90 m and two drain spacings of 15 and 30 m were installed at the consolidated paddy fields of Sari Agricultural Sciences and Natural Resources University, Iran. During four successive winter seasons, the water table depth and drain discharge were measured daily. Soil saturated hydraulic conductivity was measured twice; before drainage system installation and four years following the installation. Canola grain yields were determined at harvest of each cultivation season. During the study period, the soil saturated hydraulic conductivity increased with the highest increase in the top 0-30 cm. The deeper drains were more effective in controlling the water table compared to the shallow, and the daily drain discharge of the deeper drains in the fourth year were higher than those of shallow drains. The canola grain yield of all drainage systems increased significantly by the seasons, and the largest difference in canola grain yield between first and fourth seasons was 2191 kg· ha-1 (318% increase) in the fields with 0.90 m drain depth and 30 m drain spacing. Totally, it became clear that installation of subsurface drainage systems with 0.90 m depth and 30 m spacing in the paddy fields of Northern Iran can be recommended to achieve high yield of winter crop, soil condition improvement, and multi-purpose land use.</p

Alternate wetting and drying for different subsurface drainage systems to improve paddy yield and water productivity in Iran

Alternate wetting and drying (AWD) irrigation for different subsurface drainage systems was tested in an experimental paddy field in Sari, Mazandaran Province, Iran. During two growing seasons in 2014 and 2015, two local rice cultivars (Daylamani and Hashemi) were tested for four combinations of subsurface drainage systems with 15 and 30 m drain spacing, and 0.65 and 0.90 m drain depths and compared to a control plot with only surface drains with a depth of 1.2 m. Subsurface drainage improved water use efficiency of the Hashemi (17.9–1.8%) and Daylamani (1.4–15.4%) cultivars compared with the surface drainage in the control plot. Under subsurface drainage conditions, Hashemi, with an overall crop yield of 5392 kg ha−1, performed better than Daylamani, with an overall crop yield of 5010 kg ha−1. These yields were considerably higher than the corresponding yields in the control plot, 4405 kg ha−1 for Hashemi and 4972 kg ha−1 for Daylamani. Of the subsurface drainage systems, the drain depth/spacing combination D0.90/L30 m performed better than the others. No significant difference in the irrigation application efficiency was found between subsurface and surface drained plots. The results showed that subsurface drainage practices in combination with AWD can be an effective strategy to improve land and water productivity in paddy fields if an appropriate drying period is selected by considering drought tolerance of different cultivars.</p