It is the correct cropping structure that achieves the compatibility between more than one goal to reach the most efficient cropping structure in achieving and rationalizing water consumption and low use in the context of a set of constraints and determinants of productivity. In order to increase farm income and provide a large amount of irrigation water to benefit from the surplus In horizontal expansion. The model of the analysis of the agricultural structure in Dakahlia governorate included 18 crops through five different models. The first model (alternative) achieved this total yield of  6.780 billion pounds, more than the equivalent of 116 million pounds. Of the proposed model is less than its equivalent in the prevailing crop structure of 81 million m3 as a result of the increase in the area of some of the crops grown from their counterparts in the dominant structure. In accordance with Ministerial Decision No. 28 of 2018 issued by the Minister of Irrigation published in Al-Ahram newspaper on 8/3/2018, the year 142 - No. 47939, reducing the area of rice in Dakahlia governorate by 45%, four other models were reached.

The issue of  water resources using which make the best using  stayed one of the most important issue  which Egyptian society suffer from on the two levels  individual  and national .  The research depended for a achieving his goals on the discriptive and statistical method which representative on linear programmar method and the researcher depended on the data which be published by research associations such as the central agency for the general mobilization and statistics and ministry of agriculture and  reclaimation the lands.  The research showed that the limitations of crops combination are (the agricultural land – the water resources) and the constraints which be used in linear programmar model are (crops area- feddan return net) and by the looking for the   actual crops combination we can observe that it consist of (42 crops divided into (17 winter crops – 13 summer crops- 6 nile  crops- 6 fruits) and from the research results showed that the gross water amount was (46271.5) million m3 and the water amount for the winter crops was (14870.7) million m3 and the water amount for the summer crops was (23552.6) million m3 whereas the nile crops was (1041) million m3 and the fruits was (6807.2) million m3 and which related to the crops area the results showed that the gross area was (13678254.7) feddan and the winter crops was (6613977.2) feddan whereas the summer crops was (5325536.7) feddan and the nile crops was (392740.8) and which related to the fruits was (1246000) feddan

The research aimed to study the effect of reducing water voracious crop areas, such as (rice, sugar cane, bananas, alfalfa) on the available water quantity in the agricultural sector, where the data analysis showed that the most of the voracious crops especially rice and sugar cane are concentrated at the old lands within the valley as it explained in the research later, therefore, the research focused on inventory and analysis of the old land data within the valley to determine the best alternatives of the cropping pattern which achieves the state's goal of saving water and maximizing the return of the water unit, and is compatible with the current local, regional and environmental water conditions and the future developments that may occur in the future, that by using linear programming, through three models that have been formulated: the first is minimizing water requirement, the second model maximizes the net of acre return, while the third model maximizes the return of the water unit, using available data published and unpublished issued by the concerned authorities. The research focused mainly on the possibility of reducing the water needs of cropping pattern as a main objective, in addition to increasing the self-sufficiency ratios of strategic crops through the first scenario, and increasing the areas of export crops to increase the export proceeds through the second scenario, as far as possible within the available water and land area in the study area, using different statistical models.  The results of the analysis of the statistical models in the first scenario showed that the total quantity of irrigation water available for the cropping pattern of the study crops reached 41.483 billion m3, while 38,604, 38.726, 38.683 billion m3 were used for the statistical models respectively, this indicates that the required water quantities decreased by 2.879, 2.758, 2.800 billion m3, with a change rate of about 6.94, 6.65, 6.75% for the statistical models, respectively.    The net return of the water unit for the actual cropping pattern reached about 1.634 LE/m3, while it reached about 1.755, 1.767, 1.765 LE/m3 for the statistical models respectively, which shows the increase in net return of water unit by 0.122, 0.133, 0.131 LE/m3, with a change rate of about 7.46, 8.17, 8.05%, for statistical models respectively.  The second scenario aims beside minimizing the water needs of cropping pattern, increasing export crop areas such as onions, peanuts, potatoes, tomatoes and other vegetables as much as possible, assuming situation stability of foreign trade.  The results of the analysis of the statistical models in the second scenario showed that the total quantity of irrigation water available for the cropping pattern was about 41.483 billion m3, while 38,471, 38.912, 38.803 billion m3 were used for the statistical models respectively, indicating that the required water quantities decreased by 3.013, 2.572, 2.681 billion m3, with a change rate of about 7.26, 6.20, 6.46%, for statistical models, respectively. The net return of the water unit for the actual cropping pattern was about 1.634 LE/m3, while it reached about 1.773, 1.830, 1.833 LE/m3 for the statistical models respectively, which shows the increase in the net return of water unit by 0.139, 0.197, 0.199 LE/m3, with a change rate of about 8.53, 12.04, 12.21%, for statistical models respectively.  Crop rotations can be applied to the new lands using water savings including (wheat and maize), with an area ranging from 2048 to 2399 thousand feddans, and including (wheat and summer and nili vegetables), with an area ranging from 2941 to 3444 thousand acres, also including (maize, winter and nili vegetables), with an area ranging from 3432 to 4021 thousand feddans. With regard to the impact of reducing the area of water crops to water gap which reached about 20.9 billion m3, it decreased by about 2.879, 2.758, 2.800 billion m3, which make water gap decreased to about 18.02, 18.14, 18.10 billion m3, with change rate of about 3.77, 3.61, 3.66%, for statistical models respectively, while the results of the second scenario show decreased of about 3.013, 2.572, 2.681 billion m3, which make water gap decreased to about 17.89, 18.33, 18.22 billion m3, with change rate of about 3.94, 3.37 and 3.51% for statistical models respectively. The research recommends the following points: 1. Reduce the areas of rice, sugar cane and alfalfa to save a quantity of water ranging between 2.572 - 3.013 billion m3 of land within the valley. 2. Using of water savings resulting from reducing the areas of water crops to expand the cultivation of new land with strategic and monetary crops. 3. Sugar beet area can be expanded at least to the extent that it covers the shortage of sugar production caused by reducing the sugar cane area, then taking into account and study the effects resulting from that. 4. Modification of cropping patern structure to be in accordance with the local, regional, environmental situations that may affect current and future water availability.

The study amid to investigate the stability of production and Egyptian exports of onion and analysis of production policy of the crop. This is to show the economic effects of taxation and the support of the crop on the production and the comparative advantage of the crop to redistribute the Egyptian exports of onions so as to increase the value of exports of the crop. The results of the analysis indicate that values of nominal protection coefficient of Tradable output, nominal protection coefficient of Tradable input were, 0.90, 0.93 and 0.90 in 2010 year, respectively indicating that producers did not obtain the real prices of their production  which turned to the form of support to the consumer. On the other side, theDomestic Resource cost was 0.20 in the year of 2010 indicating the comparative advantage in the onion production. Results of stepwise multiple regression of the factors affecting the Egyptian exports showed that feddan productivity, the farm price and export price of U.S onion have statistical significant effect on the quantity of exports with F value being 17.82 the above factors contribute at 86% of the total factors affecting the onion exports during the study period (1995-2010). The results of linear programming showed that a minimum limit of Egyptian exports of onion to the importing countries, is necessary so as to the Egyptian exports of onion do not lose any foreign markets which, in turn, increase the value of onion exports by 44.64% compared to the current value in order to take advantage of importing the promising markets of onion crop, such as Saudi Arabia, Iraq, Jordan, the Netherlands and Italy.