Iranian Journal of Irrigation and Drainage
Year:2012 | Volume:6 | Issue:2|Papers Count:10

Limited water resources, shows the need for efficient use of water in agriculture. In this study to evaluate the impact of water rates based on soil moisture levels on yield of maize. Experiment was conducted in a split plot in randomized complete block design with three replications in Kerman Agriculture and Natural Resources Research Center (Jupar region) during 2008-2010. Four irrigation treatments were conducted including net crop water requirements (control treatment) and 3 treatments, of 1.2 FC, 1.5 FC and 1.8 FC. The FC was measured using installed Tensiometer in each treatment. Irrigation interval in control treatment was calculated by FAOPenman-Montheith model. The product yield, applied irrigation water, irrigation water consumption, water use efficiency, yield components and some measure of economic benefit to cost ratio were evaluated. Results showed the yield of maize was consistent with the reduced volume of irrigation. Accordingly, corn yield in control treatment was 8.5, 29 and 37 percent was higher compared to 1.2 FC, 1.5 FC and 1.8 FC irrigation treatments, respectively. It is while, applied irrigation water increased 8.5, 13.5, and 17 percent compared to the control treatment. As a result, corn water use efficiency was equal in control and 1.2 FC treatments. Irrigation frequency for the control treatment through was 2 days interval and that was obtained for other treatments based on Tensiometer monitoring and ranged from 3 to 8 days. Economic comparison confirmed superior control treatment and treatment 1.2 FC compared to other treatments.

in this study influence of nitrogen and Phosphorous elements of in two irrigation methods of furrow and drip irrigation methods on quantity and quality of sugar beet seed is investigated. The experiment was split plot in completely randomized block design, adopting split factorial on sugar beet seed variety 7233 with three replication. Main factors consist of two irrigation methods includes: furrow and drip irrigation (Tape) systems. Sub plots consist of 4 nitrogen levels (0, 60, 120, 180 kg/ha) and 3 Phosphorous levels (0, 30, 60 kg/ha). Project was conducted in Karaj in the 2004 and 2005 year.Variance combined analysis of different traits of sugar beet seed of research showed that there significant differences between sugar beet seed yield in two irrigation methods, Phosphorous levels and interaction between irrigation and Phosphorous. The effect of Nitrogen levels on seed yield was not significant. The effect of different Nitrogen and Phosphorous levels on seed weigh percentage with less than 3.5 mm and more than 3.5 mm dimension was not significant. The interaction effect of irrigation methods, Nitrogen levels and environment on seed germination percentage was significant. Nitrogen and Phosphorous level increasing in two irrigation methods were not significant effect on seed germination percentage. However, the effect of Phosphorous levels and its interaction with irrigation method had not significant differences on water use efficiency. The effect of Nitrogen increasing on water use efficiency was significant (a=%1). The water use efficiency in drip tape irrigation was significantly more than furrow irrigation. Results show that water use efficiency in drip tape irrigation was 1.7 times respect to furrow irrigation and seed quality was better in drip irrigation compare to furrow irrigation. Drip tape irrigation increase seed yield and decrease water consumption up to %37. So drip tape application for sugar beet seed production in farms is recommended. Nitrogen consumption for accessing potential seed yield and increasing Phosphorous absorption capability is necessary. For accessing the highest seed yield use of 120 kg Nitrogen and 60 kg Phosphorous per hectare base on farm soil analysis is recommended.

In arid and semi-arid areas, significant share of water might be lost due to wind and evaporation. Thus, proper understanding of influential factors affecting on evaporation and drift losses in sprinkler irrigation is important for developing water conservation strategies. The objective of this paper includes proposition of predictive equations by characterizing wind and evaporation losses under different weather conditions and operating pressures (such as 45 and 50 m) for semi-portable hand-move sprinkler system in south western region of Iran (Khouzestan province). The standard ISO 7749/2 has been taken into account to determine evaporation and drift losses. A field test was conducted under single sprinkler. The result shows that sprinkler pressure (45 and 50 m) did not influence evaporation and drift losses. Also, the results showed that evaporation and drift losses were more than 20.8 percent when wind speed exceeded 15 k/hr. Therefore sprinkler irrigation is not recommended in this condition.

Water resources shortage and continuous growth of the water demand of different sectors have resulted in critical water resources conditions in Qezelozan-Sefidrood River Basin. The situation has been exacerbated by different management strategies of eight riparian provinces with numerous development projects which affect the river flows in different provincial territories. Furthermore, climate change as an external driver can have significant negative impacts on the hydrologic conditions of the basin. This paper evaluates the effects of climate change and the development projects on water resources management in the Qezelozan-Sefidrood River Basin, using four different scenarios which the future climatic and development conditions. The climate change variables are based on the outputs of the HADCM3 model under the A2 and B2 emission scenarios. Results suggest a high sensitivity of Gilan Province to the upstream developing scenarios, resulting in reduction of Sefidrood Reservoir inflows by %35. When climate change is also considered, this reduction can be up to %43.Based on the results, finalization of the new reservoir projects in the basin can decrease the Temporal Reliability Index of the basin by %10 and %14 in the 2010-39 and 2070-99 periods, respectively.

One of the main consequences of climate change is its impact on agricultural water use that could face the water resources management with serious challenges. In this research, to examine climate change influence on sugar beet and wheat water use in selected plains of Khorasan Razavi province, minimum temperature, maximum temperature, precipitation and sunshine hours for 2 coming decades were simulated using LARSWG5 model according A1B, A2 and B1 scenarios confirmed by IPCC. Then potential and actual evapotranspiration and effective rainfall calculated using Hargreaves-Samani and FAO methods respectively and were determinate water requirements of these plants on the next 20 years compared with the base period (1991-2010). The results showed that the minimum and maximum temperatures will increase at all selected plains and the highest increase in minimum temperature in wheat growing period under all three scenarios A1B, A2 and B1 respectively equal 30.9, 45.77 and 29.13 percent will be seen in Sabzevar and during growth period of sugar beet respectively above scenarios will be seen in Golmakan with 5.23, Neyshabur with 6.62 and Neyshabur with 4.77. Also precipitation will increase in all stations except Torbat jam and the highest rate of increase in wheat growing period under these scenarios, respectively 35.24, 35.56 and 42.49 percent will be seen in Gonabad and in sugar beet growing period, respectively 69.21, 80.95 and 70.19 will occur in Sabzevar, Gonabad and Sarakhs. The results also showed that the water requirement of these plants in most plains of province will not noticeably change except of Torbat jam-Fariman that will increase equal 17, 14 and 18 percent in the growth period of wheat and 19, 18 and 18 percent in growth period of sugar beet and Sarakhs that will faced with reducing equal 14, 15 and 15 percent in the growth period of wheat and 6 percent in the growth period of sugar beet according the above scenarios.

Many hydrological models require high resolution rainfall data. The aim of this paper was to interpolate annual and monthly rainfall in Golestan province from sparse point data. To do this the methods, which make use of secondary variables (e.g. a digital elevation model, DEM) for rainfall estimation were compared with those, which do not make use of such information in estimation. The methods applied included univariate interpolation algorithms such as inverse square distance and ordinary kiriging and multivariate geostatistical algorithms such as cokriging, kriging with an external drift and simple kriging with varying local means. The performance of each interpolator was assessed through examination of mapped estimates of rainfall and crossvalidation. It was concluded that cokriging provides the most accurate estimates of rainfall for May to October except June which was best estimated using kiriging with an external drift judging by the cross-validation estimation error summary statistics. For other periods ordinary kriging yielded more accurate rainfall predictions than other interpolators. The worst algorithm was inverse square distance that ignores both the elevation and rainfall records at neighboring stations. Relative nugget effect of semivariograms and correlation between rainfall and elevation affected the performance of different methods. For instance, ordinary kriging outperformed other technique when the correlation between rainfall and elevation was less than 0.5.

Salinity and water scarcity are tow main limitations on crop production in arid and semi-arid regions. This paper used sample field experimental yield data of cotton with three levels of irrigation water salinity, 2.2, 5.5 and 8.3 dS/m and four levels of irrigation amounts, 50, 75, 100 and 125 percents of cotton water requirements in Birjand. The best fitted production function was transcendental model with R2 equal 0.94. The purpose of this paper was to determine maximum salinity of irrigation water for Cotton. Results showed that maximum salinity of irrigation water is 8.6 dS/m on the condition that the price of saline water being equals to base price of fresh water in Birjand region.