Showing 72 results for Efficiency
A. R. Soltani Ghalehjoghi, M. Loghavi,
Volume 11, Issue 40 (7-2007)
Abstract
Tractive efficiency and fuel consumption of Massey Ferguson (MF399) and John Deere (JD 4230) tractors during plowing with moldboard plow were evaluated and compared. The tests were conducted at the Experimental Station, College of Agriculture, Shiraz University, in a field with sandy clay soil at average moisture content of 18% d. b. from zero to 30 cm depth. A randomized complete block design with a 4 3 factorial was used in three replications. The treatments consisted of two types of tractors, MF399 and JD 4230, each at two levels of axle load (standard and liquid ballasted) and three levels of plowing depth, shallow (15-20 cm), medium (20-25 cm) and deep (25-30 cm) using a semi-mounted 4-bottom moldboard plow. In all treatments, the tractor engine speed was set at rated rpm (2000 and 2200 for MF399 and JD 4230, respectively) and forward speed was kept constant at about 4.5±5 km/hr. The measured and calculated parameters included: drawbar pull, rolling resistance, wheel slip, tractive efficiency and fuel consumption. The results indicated that tractive efficiency of MF 399 in deep plowing increased from 36.5% to 53% with ballasting the drive wheels, even though the improved traction was not comparable to that of JD 4230 (64%) at the same plowing depth. However, at ballasted condition it is comparable to JD 4230 at shallow and medium depth plowing due to its lower fuel consumption. Using ballasted JD 4230 for shallow depth plowing is not economically justified due to the excessive fuel consumption and may cause soil compaction due to the lower than optimum wheel slippage. Generally, using MF399 is recommended for lower draft and JD 4230 for higher draft tillage operations. Otherwise, MF399 will encounter severe reduction in tractive efficiency and excessive increase in fuel consumption and JD 4230 will cause soil compaction.
A. Bahrani, Z.tahmasebi Sarvestani,
Volume 11, Issue 40 (7-2007)
Abstract
Understanding the nitrogen remobilization by plant, in order to obtain cultivars with higher quality, has specific importance in plant physiology. In this experiment, a bread and a durum wheat cultivar, were treated with different rates and times of nitrogen application, by using split factorial on the basis of randomized complete block design with three replications at Shiraz region during 2001-2002. Main plots consisted of two levels of cultivars ( Falat and Yavaros) and sub plots included nitrogen (40, 80 and 160 (kg ha-1) and times of nitrogen application (T1= all N fertilizer at planting , T2= 1/2 at planting + 1/2 during stem elongation and T3= 1/3 at planting + 1/3 during stem elongation + 1/3 at heading stage). The results showed that there was a significant difference between cultivars in flag leaf nitrogen content at maturity stage, N remobilization and its efficiency from flag leaf to grains and also grain protein percentage. Durum wheat was more efficient in nitrogen remobilization and therefore, had a higher grain protein percentage. Increase in rates and times of nitrogen application had significant effect on most of the measured traits. There were significant interactions between cultivars, rates and times of N application, indicating that durum wheat was more efficient in N remobilization from flag leaf to the grain. It appeared that N remobilization efficiency was the important factor affecting the grain protein percentage. Also increases in yield are associated with corresponding decreases in wheat protein.
M.rafiy Darani, M. Bakhshoodeh, M. Zibaee,
Volume 11, Issue 40 (7-2007)
Abstract
The main objective of this study was determining the best sprinkler system and ranking total operational sprinkler systems in Isfahan province. The data was collected through 262 questionnaires completed by farmers in Feridan and Semirom cities in Isfahan province. Ranking and comparing the systems were done via criteria matrix and qualitative efficiency of objects and compromise programming. Based on the results of this study, hand-move sprinkler irrigation and then solid-set sprinkler irrigation were found to be the best systems in most of the regions. However, solid-set sprinkler irrigation was the best in some other areas. Results also showed that there were trivial differences between farmer selection in sprinkler irrigation and suitable system in the region. Also, comparison of suitable system and conventional irrigations used by farmers showed that the current systems of farmers are not usually an optimal system.
M. Yasi, M. Mohammadi,
Volume 11, Issue 41 (10-2007)
Abstract
A labyrinth spillway is an overflow spillway to regulate and control flow in canals, rivers and reservoirs. The main hypothesis for the development of such a spillway is to increase the discharge per unit width of structure for a given headwater. This type of structure is often an efficient alternative to a gated-spillway type where either the increase of the flood-passage capacity or the control of the water surface upstream is concerned. This study was aimed to investigate the hydraulic performance of labyrinth spillways of general trapezoidal planform with simple curved apexes. In the experimental work, twelve spillway models with double cycles were considered using three different curved apexes (R/w= 0.15, 0.2, 0.25), each with four different crest heights (w/P= 1.5, 2, 3, 4). Based on the cited recommendations, the length magnification was set to a constant ratio of (l/w= 3) the crest shape was to be of a semi-circular form with simple radius (r= 15 mm) and the spillway walls were vertical with the thickness of T= 2r. An intensive experiment was carried out over a wide range of flows, providing 720 flow data ranging from free flow to submerged flow conditions. 1D flow equation was presented using combined mathematical and dimensional analysis. A coefficient of discharge, Cd, was introduced to represent the influence of the effective geometric and hydraulic parameters on the flow capacity over the spillway. Modular limit was also controlled to see whether the flow over the spillway would be submerged. The results of the study indicate that the modified curved planform of the spillway apexes with consistent divergence in the downstream channel introduces a significant improvement in the flow efficiency over the labyrinth spillways. Spillways with narrower curved apexes (i.e. R/w≤ 0.2), and with the vertical-aspect ratio of (2≤w/P<3) provide more stable and higher hydraulic performance than any other labyrinth planforms over a wide range of flows (i.e. 0.10/P<0.6). In terms of the flow capacity, the proposed spillway model is shown to be more efficient than other zig-zag planforms (i.e. triangular and trapezoidal shapes) with an identical crest length.
S. Akhavan, S. F. Mousavi, B. Mostafazadeh-Fard, A. Ghadami Firoz Abadi,
Volume 11, Issue 41 (10-2007)
Abstract
To investigate yield and water use efficiency (WUE) of potato with tape and furrow irrigations, an experiment was performed at Hamadan Agricultural and Natural Resources Research Center (Ekbatan station) in 2004. The experiment was arranged in a split-plot experimental design based on completely randomized block with 3 replications of irrigation water amount as the main factor (75%, 100%, 125% of cumulative evaporation from class A pan) and sub-factor of irrigation method [including tapes in the middle of furrow ridge on soil surface (TD0), tapes in the middle of furrow ridge at the depth of 5 cm (TD5), tapes on the sides of furrow ridge on soil surface (TS0), and furrow irrigation (F)]. The results indicated that yield of potato increased with increasing water use. Regardless of irrigation method, maximum (32.51 ton/ha) and minimum (19.33 ton/ha) yield of potatoes was achieved with 125% and 75% irrigation water treatments, respectively. The lowest yield (21.35 ton/ha) was obtained in furrow irrigation and the highest yield (28.91 ton/ha) belonged to tape irrigation (TD5 treatment). The highest WUE (4.68 kg/m3) belonged to tape irrigation (TD5 treatment) and the lowest WUE (3.32 kg/m3) belonged to furrow irrigation (F). The difference in WUE between 75% and 100% irrigation water treatments was not significant. The highest WUE (4.49 kg/m3) was achieved in treatment 125%. Also, it is more economical to use irrigation water treatment of 125%, as compared with other irrigation water treatments.
A. Mohammadi Mohammadabadi, S.j. Hosseinifard, N. Sedaghati,
Volume 12, Issue 43 (4-2008)
Abstract
Effect of change from the conventional (flooding) to subsurface irrigation system was studied on mature pistachio trees (Cultivar Ohadi) in Kerman pistachio research station for four years. This experiment was carried out in a randomized complete block design including 7 treatments and 3 replications. The experiment also used two irrigation intervals (7&14 days) and three water rates according to pan coefficient (20%, 40%& 60% evaporation from surface of class A pan) for subsurface irrigation system with 6 treatments the conventional (flooding) irrigation system was tested as control. The pipes of subsurface irrigation system were installed at 90cm distance from trees trunk at each side of trees, and 50cm from soil surface. Mean of pressure and discharge in the pipes was 0.8 to 1 atmosphere and 5.4 Lh-1m-1, respectively. Different factors of quantity and quality pistachio yield, current vegetative growth, water use efficiency and soil electrical conductivity were measured. The results showed that change of conventional (flooding) to subsurface irrigation system is possible and the best treatment can have water rate of 7174 m3ha-1y-1 with 14 days irrigation interval. In comparison with other treatments, this treatment has better quantity and quality pistachio yield. Water use efficiency (WUE) of this treatment was 164g dry yield per cubic meter. Nevertheless, application of water rate of 4783 m3ha-1y-1 can result in the deficiency of irrigation water. At this water rate, WUE was 177g dry yield per cubic meter. However, it was found that the application of lower water rate (<4783 m3ha-1y-1) produced severe effects on the treated pistachio trees, e.g. decreasing the growth rate, yield and increasing the early splitting in pistachio fruits. Finally, it is concluded that 14-day interval irrigation is the preferred treatment for pistachio trees. Also, soil salinity showed considerable change in subsurface irrigation treatments after irrigation system was changed, especially in the first year.
K. Majd Salimi, S. M Mir Latif,
Volume 12, Issue 44 (7-2008)
Abstract
In tea plantation regions of northern part of the country, application of supplemental irrigation during dry periods (lacking rainfalls) in conjuction with proper nitrogen fertilizer application can significantly improve tea yield per unit of plantation area. In order to quantify the effectiveness of proper irrigation and nitrogen management on tea, the response of tea to various levels of irrigation and nitrogen applications was studied in Fouman suburb of Guilan province. Tea crop production function and its crop coefficient (KC) were determined. A line source sprinkler irrigation was used for creatiating a variable irrigation application and a split-split-plot statistical design was used. Irrigation treatments consisted of full irrigation (I4), deficit irrigation (I3, I2 and I1) and no irrigation(I0). Nitrogen application treatments were N1, N2 and N3 (100, 180 and 360 kg/ha) in three replications randomly arranged as main plots, while irrigation treatments as sub plots were not randomized. During the growing period, soil moisture up to the depth of 90 cm was determined gravimetrically and actual crop water use was calculated from mass balance equation weekly. Reference evapotranspiration (ETo) was estimated by Penman-Montieth equation and was used to estimate tea crop coefficient. During growing period, the actual tea water use of I4 and I0 were computed to be 457 and 256 mm. Tea crop coefficient during dry period (June, July and Augest) ranged from 0.8 to 0.9. Crop resistance factor (Ky) for tea was found to be 1.37. Results indicated that optimum rate of nitrogen (180 kg/ha) along with supplemental irrigation, increased yield and water use efficiency (WUE). Futhermore, supplemental irrigation increased yield and WUE more than nitrogen application. In I0 and I1 treatments, application of 100 kg/ha nitrogen resulted the highest yield and WUE.
M Gorji, H Eshghizadeh, A Khosh Goftarmanesh, A Ashrafi, A Moalem, N Poursakhi, N Pourghasemian, A Miladi,
Volume 12, Issue 46 (1-2009)
Abstract
Iron deficiency is a worldwide nutritional constraint in agricultural lands especially in calcareous soils. Cultivation of crops tolerant to Fe-deficiency is an approach to combat Fe deficiency. The aim of this investigation was to evaluate Fe-efficiency of selected important crops in Iran. A completely randomized block design in triplicates was conducted at IUT research greenhouse in fall 2006. Sweet corn (Hybrid K.S.C. 404), grain corn (Hybrid S.C. 500), safflower (cvs. S3110, S-411), sunflower (Hybrid Hyson) and durum wheat (cv. Shuga) were grown in a nutrient solution at two Fe levels (1 and 10 µM Fe-EDTA). The results showed significant (P < 0.01) variation among the studied crops in Fe-efficiency. Corn hybrids were more sensitive to Fe deficiency (FeE = 26%) as compared to other studied crops, and the greatest reduction was observed in their shoot dry matter at 0.1 mM Fe- EDTA treatment. In contrast, the lowest decrease in root and shoot dry matter weight under Fe-deficient condition was found for durum wheat (FeE=94%). Comparing the calculated Fe-efficiency using different indices showed that Fe concentration and content in the whole plant, shoot and root had no relationship with crop tolerance to Fe deficiency.
M Bakhshoodeh, E Vaseghi,
Volume 13, Issue 48 (7-2009)
Abstract
In this study, marketing situation, problems and services of Dutch Roses was investigated in Isfahan province as a main rose producing region in Iran. In this context, marketing margin, share of marketing agents in marketing margin, marketing cost coefficients and marketing efficiency were calculated and marketing path and marketing services of roses flower including harvesting, transportation, packing, sorting and standardization in major path were investigated. The data used in this study were gathered through completing questionnaires from 38 producers, wholesalers (cut flowers distributors) and retailers (flower sellers) and by interviewing four consulting companies in Dutch Roses production and marketing. The results indicated that 56.5 percent of producers are only engaged with production activities and not exporting flowers to either foreign countries or the other provinces in the country. In the main path, average coefficient of technical efficiency (78.17%) was found to be higher than that of price efficiency (34.67%) and based on the marketing efficiency, 108 Rial value added can be achieved from each 100 Rial marketing services cost..
A Sheinidashtegol, H.a Kashkouli, A.a Naseri, S Boromandnasab,
Volume 13, Issue 49 (10-2009)
Abstract
Sugarcane has been cultivated in an extensive area in Khuzestan and irrigated by hydro-flume or siphon and furrow. In a field experiment during 2005-6 at Amir Kabir Agro-Industry, Khuzestan, the effect of every other-furrow irrigation method was studied on sugarcane in regard to irrigation water volume, water use efficiency and quality and quantity of sugarcane. The experiment was conducted in a completely randomized design with three irrigation treatments, including conventional method (blank), variable every other furrow(alternative furrow) and fixed every other furrow. This experiment was conducted by cv. Cp69-1062 sugarcane. The results showed that water use efficiency rates were 0.41, 0.58 and 0.7 kg/m3 for conventional, fixing furrow and alternative, respectively. However, water use efficiency rates were not significantly different in treatments. It had minimum amount of water use efficiency in every other furrow treatments. Maximum water use efficiency, quality and quantity of sugarcane were obtained every other irrigation. Maximum irrigation water was used in conventional treatment and resulted in minimum irrigation, quality sugarcane and water use efficiency. It produced 14.5 ton/ha sugar for 20604 m3/ha application of irrigation. Sugarcane quality and quantity characteristics in variable treatments, except for length number per hectare, were not significant.
M. Karimi Kakhaki , A. Sepehri,
Volume 13, Issue 50 (1-2010)
Abstract
In order to study the effect of deficit irrigation at reproductive growth stages on water use efficiency and drought tolerance of four sunflower cultivars, including Azargol, Allstar, Alison and Euroflor, an experiment was conducted during 2007 growing season at experimental field of Agricultural Faculty of Bu-Ali Sina University, Hamadan, Iran. The experiment was a split plot based on randomized complete block design with three replications. The irrigation levels included full irrigation, deficit irrigation at heading, deficit irrigation at flowering, deficit irrigation at seed filling, deficit irrigation at heading and seed filling and deficit irrigation at flowering and seed filling stages. The biological and economic yield (BY and EY), harvest index (HI), water used, water use efficiency (WUE) and water stress indexes were measured. The results indicated that the highest BY (11681.7 kg.ha-1), EY (4854.0 kg.ha-1) and HI (42%) were obtained from full irrigation treatment. The lowest negative effects in cultivars belonged to deficit irrigation at seed filling stage. Euroflor obtained the highest of these parameters with 10127.1 Kg.ha-1, 4081.5 Kg.ha-1 and 40% respectively. Highest WUE was related to twice cutoff of irrigation in flowering and seed formation stages and then without irrigation in seed formation stage by 1.09 and 0.96 Kg.m-3. Allstar and then Euroflor had highest WUE among sunflower cultivars by 1.01 and 0.94 Kg.m-3 respectively. Results also indicated that Euroflor was a tolerant cultivar and STI (Stress Tolerant Index) and GMP (Geometric Mean Productivity) were acceptable indexes for selection. Finally, deficit irrigation at seed formation stage had the lowest negative effect on yield and HI with suitable WUE. In addition, Euroflor showed the highest yield, drought tolerance and HI with suitable WUE.
M Sarai Tabrizi, H Babazadeh, M Parsinejad, S.a.m Modares Sanavi,
Volume 14, Issue 52 (7-2010)
Abstract
Deficit irrigation is one of the irrigation management methods that is used to increase Water Use Efficiency. Considering the internal plant adaptability characteristic to water shortage, Partial Root Drying method has been introduced in recent years. In this field research improvement of Water Use Efficiency for Soybean was determined. This experiment which was conducted at four furrow irrigation treatments at the Research Field of Tehran University in Karaj in 2008, consists of full irrigation (100% soil moisture deficit compensation), conventional deficit irrigation at 50 and 75 percent soil moisture deficit compensation and Partial Root Drying at 50 percent soil moisture deficit compensation with three replications. The amounts of irrigation used were exactly compensation level (negligible loss). Results indicated that Water Use Efficiency according to Duncan's Multiple Range Test at the five percent level of probability there was a significant difference between partial root drying treatment (PRD50%) and conventional deficit irrigation treatment at fifty percent soil moisture deficit compensation (DI50%),. Water Use Efficiency in PRD50% compared with DI50%, DI75% and full irrigation increased by 48.3%, 61.9% and 70.1% respectively.
A. Faryabi , E. Maroufpoor , H.ghamarnia ,
Volume 14, Issue 54 (1-2011)
Abstract
Precision in design of sprinkler irrigation systems and their proper management are very important for both development and also improvement of those systems. Therefore, the main objective of this study was to evaluate the design and management of the solid-set sprinkler systems in Dehgolan plain located in Kurdistan province. For this purpose, 10 solid-set sprinkler systems were selected randomly and a few performance parameters such as: Christiansen’s uniformity coefficient (CU), distribution uniformity (DU), potential application efficiency of low-quarter (PELQ) and application efficiency of low-quarter (AELQ) were estimated. The results of investigation showed the mean values of 66, 50.6, 44.8 and 43. 8%, for the above mentioned parameters, respectively. Also, the results of investigation showed both low PELQ values and water distribution uniformity of those evaluated systems compared to the recommended values by Merriam and Keller (1978). Moreover, due to deficit irrigation, except for one evaluated system, in all other systems, AELQ values were equal to PELQ. The results of our investigation also showed that non-suitable design and implementation of the evaluated systems were among the most important reasons for low values of PELQ, because of non-suitable operating pressure. The most important reasons for low water distribution uniformity were the simultaneous use of many sprinklers and also performance of different sprinklers models in a system. Finally, the results of our investigation showed poor operation for the evaluated systems in many cases.
M. Farzamnia, F. Abbasi,
Volume 15, Issue 55 (4-2011)
Abstract
Qanat is a traditional structure that provides water without spending much energy and expense. Therefore, in eastern regions where there are no big rivers available qanat can play an important role in public economy and should be taken into consideration. The regions around Kerman such as Joupar, Mahan, Bam, Narmashir and Fahraj have many qanats with high discharges. Therefore, protection of this water resource is essential in view of either our cultural heritage or water resources. For this reason, in the present research exploitation problems, water distribution, planting pattern, and variation of water quality and quantity in 15 qanats of Kerman province were studied. Results showed that qanats’ discharges have changed in long run and had a noticeable decrease in the recent decade, and as a result planting pattern and areas in downstream fields have been changed. In the above mentioned fields, average water conveyance efficiency and roughness coefficient in water canals and mean application efficiency were 83.6 percent, 0.024 and 59.3 percent, respectively. Mean water productivity for cultivated crops such as wheat, alfalfa, sugar beet, grain corn, forage corn, watermelon was 0.43, 0.51, 0.31, 0.65, 4.75, 8, and for horticultural crops such as pistachio, almond, date palm, citrus, and stone and pome fruit was 0.52, 0.3, 0.66, 1.1, and 0.54 kg/m3, respectively. Based on the results, the main problems of qanats are the lack of necessary budget allocation by agricultural organizations, digging deep wells on qanats border, technical issues, exploitation, and maintenance management problems.
F. Aghababaei, F. Raiesi,
Volume 15, Issue 56 (7-2011)
Abstract
The positive and beneficial effects of mycorrhizal symbiosis on the growth of various plants have already been documented. Most arable crops can mutually establish symbiosis with endo-mycorrhizal fungi, however, mycorrhizal associations with almond (prunus amygdalus), particularly in calcareous soils of arid and semi-arid regions, have not been studied. Thus, to realize the symbiotic association between mycorrhiza fungi and economically important native almond genotypes in Chaharmahal va Bakhtiary province, an experiment consisting of a randomized complete factorial design with three factors: almond genotypes (Mamaei, Rabee, Talkh, Sefid), soil phosphorus levels (0 and 150 kg P ha-1) and mycorrhizal treatments (almond inoculated with Glomus intraradices, Glomus mosseae and without inoculation) with three replications was conducted under greenhouse conditions by 4 months. Results showed that physiological traits including chlorophyll concentration, net photosynthetic rate and water use efficiency, were significantly increased for 20%, 300% and 300%, respectively in mycorrhizal almond plants, while transpiration rate was decreased
(8-10%). Although the genotype of almond and soil P were dependent on these factors, mycorrhiza species had the same effects. Increased available P in the soil enhanced the growth in all treatments and photosynthesis of nonmycorrhizal almonds.
R. Taghizadeh, R. Seyed Sharifi,
Volume 15, Issue 57 (10-2011)
Abstract
In order to evaluate the effects of nitrogen fertilizer levels on grain yield and nitrogen use efficiency in corn cultivars, a split plot experiment based on randomized complete block design with three replications was conducted at the Research Farm of Islamic Azad University of Ardabil during 2006-2007 cropping seasons. Factors consisted of nitrogen fertilizer at four levels (0, 80, 160 and 240 kg/ha) and corn cultivars at three levels (SC-310, SC-404 and DC-370). The results showed that grain yield was significantly affected by nitrogen levels, corn cultivar and nitrogen level × corn cultivars. The highest grain yield was related to application of 240 kg/ha nitrogen with SC-404 cultivar. Nitrogen levels of 160 and 240 kg/ha had similar yields, but more yield than 80 kg/ha. With increasing of nitrogen levels, plant height, the number of grains per ear rows significantly increased. Comparisons of means showed that increasing the application of nitrogen fertilizer decreased nitrogen use efficiency. Nitrogen use efficiency decreased from 17.13 kg/kg with application of 80 kg/ha nitrogen fertilizer to 12.4 kg/kg in application of 240 kg/ha nitrogen fertilizer. Nitrogen use efficiency was affected by corn cultivar. Nitrogen use efficiency in SC-404 was higher than SC-301. In conclusion, in order to increase grain yield and nitrogen use efficiency, SC-404 hybrid should be applied with 160 kg N/ha in climatic conditions of Ardabil Plain.
R. Bagheri, Gh. Akbari, M. H. Kianmehr, Z. Tahmasebie Sarvestani,
Volume 16, Issue 59 (4-2012)
Abstract
To evaluate the effect of nitrogen slowly released from pellet, composed of manure and urea fertilizer on the Nitrogen efficiency and morphological Characteristics and grain yield of corn hybrid (S.C704), a field experiment was carried out in Aboureihan research farm of Tehran University in 2009. The factorial design of the study comprised a randomized complete block with three replications. The application rates of N at four levels (46, 92, 138 and 184 kg N. ha-1) and two levels by methods of N distribution (pellet and mixed with soil) were applied. In this research, a Screw Extruder setup was designed and manufactured. Statistical analysis indicated that NUE, as well as agronomic efficiency (AE) was reduced while physiological efficiency (PE) increased with increasing N rates. Also, most plant length and stem diagonal and cob diagonal pellet belonged to the treatment. But, the number of leaves per plant did not affect the distribution method of fertilizer.The results showed significant differences among various rates of nitrogen and methods of N distribution considering grain yield and grain protein. The higher rates of N increased grain protein, grain yield and yield components (except for number of rows per ear). Maximum grain yield (11.1 t. ha-1) was obtained with 184 kg N. Ha-1 treatment.
P. Shahinrokhsar, M. E Asadi,
Volume 16, Issue 61 (10-2012)
Abstract
Modification of irrigation scheduling and management improvement of irrigation systems are two essential factors that have significant impact on agricultural water use efficiency. Therefore, a field experiment was conducted to evaluate the effect of tape drip irrigation (T) and furrow irrigation systems (S) under different irrigation regimes on yield and yield components of soybean in growing season of 2006-2007 at Gorgan Agricultural Research Station in north part of Iran. The experiment was laid out in a split plot design in a randomized complete form where each treatment was replicated three times. The main plots were irrigation systems of tape and furrow, and three irrigation regimes 100 (I100) , 75 (I75) and 50 (I50) percent of total irrigation requirement were chosen as secondary plots. Results showed that thousandgrain weight (gr) and plant height (cm) in furrow irrigation were significantly more than the tape drip irrigation method. Also significant differences between different irrigation regimes in terms of plant height, node numbers and yield were observed. So, I100 and I50 had highest and lowest values, respectively. In terms of irrigation system, 63 percent of water consumption was reduced in tape drip irrigation method. Also, the results indicated that higher and lower water use efficiencies were obtained from tape drip irrigation method with I50 treatment (1.09 kg m-3) and furrow irrigation with I100 treatment (0.50 kg m3), respectively.
A. Vaezi, M. Abbasi,
Volume 16, Issue 61 (10-2012)
Abstract
The Soil Conservation Service Curve Number (SCS-CN) method is widely used for predicting direct runoff from rainfall events. The ratio of initial abstraction (λ=Ia/S) to maximum potential retention (S) was assumed in its original development to be equal to 0.2 (λ=Ia/S=0.2) in SCS-CN method. Application of the initial abstraction ratio equal to 0.2 out of the area where it has been developed may lead to a non logical estimation of runoff. Thus, the study was conducted to determine the initial abstraction ratio (λ=Ia/S) by analyzing measured rainfall-runoff events. The dataset consisted of 58 rainfall-runoff events during 15 years (1987-2001) of rainfall and runoff measurements from Taham-Chay watershed, northwest of Zanjan, Iran. Based on the results, the estimated runoff value on the basis of Ia= 0.2S was 26.7 times higher than the measured value, on average. There was a very low relationship between the measured and estimated runoff values (R2=0.09) and mean model error was 0.13. The Ia/S values varied from 0.004 to 0.008 with an average of 0.006. When Ia/S value was modified to 0.08, ratio of the measured to estimate runoff value was 1.4 and the determination coefficient (R2) of the relationship between the two was 0.41. When seven rainfall events that had the low rainfall intensity values (lower than 0.14 mm/h) and two events that had the high rainfall depth (bigger than 10.47 mm) during the past five days were removed from the data analysis process, ratio of the measured to estimated runoff value decreased to 1.3 and the determination coefficient (R2) of the relationship between the two enhanced to 0.90. The mean model error for the modified Ia/S value also decreased to 0.007. It also improved model efficiency coefficient (EF) to -0.089 compared with 0.91 for traditional Ia/S value (0.2).
R. Asadi, F. Hassanpor, M. Tabatabaei, N. Koohi,
Volume 17, Issue 63 (6-2013)
Abstract
Application of the modern irrigation systems such as T-Tape irrigation system is one of the ways to achieve aptimal irrigation The present study deals with the effect of surface and subsurface drip irrigation systems on the cotton yield For this purpose, a field experiment was conducted in the Agricultural and Natural Resource Research Institute of Orzoueyeh, located in the Kerman province. The experiments were conducted in a split plot design based on the Randomized Complete Block Design (RCBD) with three replications. The treatments were comprised of three levels of the crop water requirements (i.e. irrigation based on 100, 80 and 60 percent of crop water requirement) in main plot and with the two irrigation systems, surface one and subsurface one. The results showed that the yield resulting from treatments with 60 and 80 percent crop water requirement was respectively 981 and 413 kg/ha lower than that of treatment with 100 percent crop water requirement. In addition, the obtained yield due to subsurface system was 248 kg/ha greater than that of the surface pattern. The interaction of treatments on the yield of the crop also indicates that the treatment with subsurface system and 100 percent crop water requirement produces the maximum yield. Despite equal water consumption in each sub plots, the WUE in subsurface system was 14 percent higher than that of surface system. From the economical point of view, benefit to cost ratio in the subsurface system is 8 percent less than surface system. Considering the results obtained in this study in the light of water saving as the main objective in deficit irrigation and water use efficiency (WUE) for cotton cultivation in Orzoueyeh, the 80% of crop water requirement is preferred
