جستجوی مقالات مرتبط با کلیدواژه "hot" در نشریات گروه "آب و خاک"

The objective of this research was to save water resources, using nonlinear programming model to optimize the crop pattern under full and deficit irrigation techniques in eight observation fields for eleven predominant irrigated crops, including winter wheat, barley, rapeseed, autumn sugar beet, corn, sorghum, tomato, onion and potatoes, bean and autumn watermelon in the downstream lands of Doyraj Dehloran reservoir located in the southwest of Iran. The yield reduction and net income of each crop were calculated for 50, 60, 70, 80, 90 and 100% of water requirements during the growing season. The objective function for maximizing net profit with different constraints including constant cultivated area was determined for the existing cropping pattern, the policies of the Ministry of Agriculture Jihad and the proposed pattern. In the case of full irrigation, the results showed that the net profit of the Ministry of Agriculture Jihad cropping pattern was increased 1.33, 1.19 and 1.05% for 100, 90 and 80% of water requirement, respectively. Under deficit irrigation conditions (90 and 80%), water resources are saved 18 and 34%, respectively. The proposed cropping pattern, including four crops of wheat, canola, autumn sugar beet and grain corn increased the net profit of 60, 70, 80 and 90% of the crop water requirement treatments by 14.4, 33.6, 54 and 74.7%, respectively, as compared to the existing cropping pattern. In the proposed deficit irrigation treatments, the water resources were saved 60%, 49%, 35% and 19%, respectively. The results of nonlinear programing model showed that the optimization of cropping pattern with deficit irrigation technique, not only increases the net profits, but also it can be effective in conserving surface and ground water resources.

Because of world population growth and limited water resources¡ irrigation should be moved in direction of producing more yield with less water. Therefore researches has concentrated on improvement of water and nitrogen use efficiency¡ which numerical simulation is the effective solutions to optimize the management of water and fertilizer in the field in order to achieve the maximal yield and minimal nitrate pollution of soil in water deficiency crisis condition.This shows the necessity of evaluating of new user friendly models to identify the correct distribution of water and solute in the soil and choosing the best management. The Eu-Rotate-N model has been developed for simulation and optimization of nitrogen use in vegetables rotation and without the need to calibration.This study in 2015 was conducted to evaluate the efficiency of Eu Rate-N model in simulation of moisture and nitrogen distribution and yield under drip and surface irrigation system and for pepper plant in a farm with silty clay loam soil in Isfahan. Four statistical index¡ RMSE¡ NRMSE¡ r2¡ d in order to model validation was calculated. These indexes for soil water content in both treatments and in the complete soil profile were 0.025¡ 13.26¡ 0.65¡ 0.996 respectively. Also NRMSE for soil nitrate content and plant yield in both treatment was less than 20 percent and r2 was more than 90 percent which pointed out to well efficiency and well process of simulation of the model. So the Eu-Rotate-N model efficiency for simulating soil water and nitrate content distribution and yield for pepper was confirmed and we can use Eu Rotate-N model for the simulation and optimization of agricultural water management in the hot and dry climate conditions in heavy soil texture for pepper.