Alternate and Surge Flow Furrow Irrigation Methods for Onion Production. Evaluation in Humbo, Ethiopia

TABLE OF CONTENTS

BIOGRAPHICAL SKETCH

ACKNOWLEDGEMENT

ABBREVIATIONS

LIST OF TABLES

LIST OF FIGURES

LIST OF TABLS IN THE APPENDIX

ABSTRACT

1. INTRODUCTION

2. LITERATURE REVIEW
2.1 Concept of Alternate Furrow and Every Furrow Irrigation System
2.1.1 Alternate furrow irrigation system
2.1.2. Conventional (every) furrow irrigation
2.2. The Concept of Surge Flow
2.3. Irrigation Performance Indicator
2.3.1. Application efficiency
2.3.2. Distribution uniformity
2.3.3. Storage efficiency
2.3.4. Deep percolation loss
2.3.5. Tail water runoff
2.4. Water Use Efficiency

3. MATERIALS AND METHODS
3.1. Description of the Study Area
3.2. Experimental Design and Treatments
3.3. Soil Sampling and Laboratory Analysis
3.4. Irrigation Depth
3.5. Discharge and Tail Water Measurement
3.6. Water Application Duration
3.7. Performance Indicators
3.7.1. Advance rate computation
3.7.2. Distribution uniformity
3.7.3. Application efficiency
3.7.4. Storage efficiency
3.7.5. Deep percolation ratio (DPR)
3.7.6. Tail water runoff ratio (TWR)
3.7.7. Water use efficiency
3.7.7.1. Crop water use efficiency
3.7.7.2. Field water use efficiency
3.8. Statistical Analysis

4. RESULTS AND DISCUSSION
4.1. Soil Physical Characteristics
4.2. Soil Infiltration Rate
4.3. Irrigation Water Requirement of Onion
4.4. Flow Performance Measurement
4.4.1. Flow advance rate
4.4.2. Flow advance time
4.5. Technical Efficiency Evaluation
4.5.1. Application efficiency
4.5.2. Storage efficiency
4.5.3. Distribution uniformity
4.5.4. Tail water runoff ratio (TWR)
4.5.5. Deep percolation ratio (DPR)
4.6. Yield and Water Use Efficiency
4.6.1. Yield
4.6.2. Crop water use efficiency
4.6.3. Irrigation water use efficiency

5. SUMMARY, CONCLUSION AND RECOMMENDATION
5.1. Summary
5.2. Conclusion
5.3. Recommendation

6. REFERENCES

7. APPENDICES
7.1. Appendix I Tables

DEDICATION

This thesis is dedicated to my parents

BIOGRAPHICAL SKETCH

The author was born in Zeret, Gera keya Woreda, Northern Shoa administrative zone of Amhara region in June 1978. He completed his elementary school in 1992, junior secondary school in 1994, and secondary school in 1998 at Zeret Elementary School, Kolako Junior Secondary School, and Mehal Meda Senior Secondary School, respectively. He joined the then Debub University (now Hawassa University) in September 1998 and graduated with Bachelor of Science in Agricultural Engineering and Mechanization in July 2003. After graduation, Wolaita Soddo Agricultural, Technical, Vocational Education, and Training (ATVET) College employed him since October 2003 and worked as an instructor in the Department of Natural Resource until he joined the School of Graduate Studies of Haramaya University in July 2008 to pursue his M.Sc. in Irrigation Engineering.

ACKNOWLEDGEMENT

It is my pleasure to acknowledge my instructor and thesis research major advisor, Dr. Tena Alamirew, for his close friendship, illuminating and inspiring professional guidance, constructive critics, and continuous encouragement from the time the study was conceived right up to its completion.

My heartfelt appreciation goes as well to Wolaita Soddo ATVET College for providing the scholarship and financial support. I also extended my gratitude to Ato Asrat Tera and Ato Yassin Molla, Academic Vice Dean and Administrative and Development Vice Deans of the College respectively for their unreserved support during the study. Very special thanks goes to Abebe Fekadu who helped me a lot and stands beside me on my trouble days when I was in need of assistance in data collection and soil sample collection.

My heartfelt appreciation goes to Soddo Rural Technology Institute staff for their cooperation in constructing the water conveyance system (gutter) and installation of it at the experimental field. I am also happy to acknowledge Humbo Wereda Agricultural Development Office for their comment and guidance in selecting the experimental site at the farmer’s field. I also appreciate the support given by Soddo Soil Laboratory and Debrezite Soil Laboratory for the permission to carry out soil analysis. Provision of meteorological data made by Ethiopian Meteorological Agency Hawassa branch is highly acknowledged. My gratitude also goes to Ato Kaleb Selfak for his willingness, to conduct the experiment on his farmland.

Finally, I take this opportunity to express my deepest appreciation to Ato Abera Moltot and Ato Dereje Assegdew, for their kindness and support. My special thanks extended to Takele Taye, Kaleb Asefa, Elene Assegid, and Solomon Yohannes for their prayers and encouragement. My gratitude also goes to Solomon Asefa, Ashenafi W/Silase, Belete Bala, Eshetue Kassa, Solomon Lukas, Bisrat H/Micheal, Fanuel Lakemaryam, Fistum Yemnu, and Tsehay Bekele, for their worthy advice and encouragement.

Above all, I praise Lord Jesus; he knows all the best and made all things possible for me.

ABBREVIATIONS

Abbildung in dieser Leseprobe nicht enthalten

LIST OF TABLES

1. Treatment combination

2. Physical characteristics of soil at the experimental site

3. Irrigation scheduling

4. Influence of irrigation system and flow regime on flow advance rate

5. The interaction effect of irrigation system and flow regime on application efficiency

6. Influence of irrigation system and flow regime on distribution uniformity

7. Interaction effect of irrigation system and flow regime on tail water ratio (%)

8. Interaction effect of irrigation system and flow regime on deep percolation ratio (%)

9. Interaction effect of irrigation system and flow regime on yield (kg/ha)

10. Effect of irrigation system and flow regime on Crop water use efficiency and irrigation water use efficiency (Kg/m3)

LIST OF FIGURES

1. Location map of the study area (Authors own work)

2. Experimental field layout (Authors own work)

3. Cross sectional view for alternate furrow irrigation

4. Cross sectional view for every furrow irrigation

5. Installation of water conveyance system (Authors own work)

6. Cumulative intake and infiltration rate of soil at experimental the site (Authors own work)

7. Head discharge relationship (Authors own work)

8. Advance time curve of AFS1 for different surges (Authors own work)

9. Advance time curve of EFS1 for different surges (Authors own work)

10. Advance time curve of AFS2 for different surges (Authors own work)

11. Advance time curve of EFS2 for different surges (Authors own work)

12. Advance time curve of AFC and EFC (Authors own work)

13. Yield variability along the furrow length (Authors own work)

LIST OF TABLS IN THE APPENDIX

1. Meteorological data

2. Monthly average meteorological data

3. Determination of ET0 with penman-monteith

4. Irrigation scheduling (CROPWAT-output)

5. Soil data for irrigation scheduling

6. Onion crop data for irrigation scheduling

7. Crop water requirement

8. Cycle time, on time, off time and number of surges at different growth

9. Performance indices at initial growth Stage

10. Performance indices at development growth stage

11. Performance indices at mid season growth stage

12. Average performance indices of the three growth stage

13. Average onion yield along the furrow length

14. Total onion yield (kg/ha)

15. Crop water use efficiency

16. Irrigation water use efficiency

17. Summary of two-way ANOVA table for the performance indices

18. Two-way table for performance indices

19. Infiltration data of the soil at the experimental site

EVALUATION OF ALTERNATE AND SURGE FLOW FURROW IRRIGATION METHODS FOR ONION PRODUCTION AT HUMBO, SOUTHERN ETHIOPIA

ABSTRACT

Surface irrigation has low performance efficiencies due to unavoidable irrigation water loss through excessive runoff and deep percolation. Hence, it is necessary to investigate the water application method that improves the performance of surface irrigation, particularly for furrow irrigation system. This study was carried out from October 2009 to June 2010 at Humbo wereda, wolaita soddo zone, Southern Ethiopia on the farmer’s field with various furrow irrigation treatments to evaluate the conjunctive use of alternate and surge flow irrigation water application methods. The specific objective of study were to evaluate flow characteristics and technical efficiency of alternate and conventional furrow irrigation under the application of surge flow and the water use efficiency for onion production. The experiment had two factors namely furrow irrigation system (EF & AF) and three flow regimes (C, S1, and S2). The discharge and cycle time were 0.6 ls-1 and 11 minutes respectively. The experimental plot had randomized complete block design (RCBD) with six treatment combinations and three replications. The variables collected were advance rate of waterfront and moisture content of the soil. The result shows that, the influence of irrigation system and flow regime on the advance rate of waterfront was significant (p< 0.05). The higher and the lower value of advance rate were 0.14 ms-1 and 0.11 ms-1 for EF & AF irrigation system respectively. From the effect of flow regime, the values of advance rate are 0.167 ms-1, 0.137 ms-1 and 0.062 ms-1 observed for S1, S2 and C flow regime respectively and they are statistically significant. While the effect of their interaction on advance rate of waterfront was not significant (p> 0.05). The influence of irrigation system, flow regime as well as their interaction on performance indices such as EA, ES, TWR & DPR were significant (p< 0.01). The highest values of EA & ES were 64.88% and 85.40%, respectively observed for AFS2 treatment combination. While, the least value of EA & ES is 45.64% and 64.14% respectively observed for EFC treatment combination. The least value of TWR & DPR were 11.38% and 23.74% respectively for AFS2 treatment combination; while the highest value of TWR & DPR were 19.79 and 34.74% observed for EFC treatment combination. The influence of flow regime on DU was significant (p< 0.01). Thus, the highest and the least value of DU are 90.10% and 80.07% observed for S1 and C flow regime respectively. The influence of irrigation system on CWUE and IWUE were significant (p< 0.01). Thus, the highest value of CWUE and IWUE is 8.03 kgm-3 and 5.88 kgm-3 respectively observed for AF irrigation system; but the least value of CWUE and IWUE is 4.06 kgm-3 and 2.97 kgm-3 respectively observed for EF Irrigation system. While the effect of flow regime and their interaction on CWUE and IWUE were not significant (p> 0.05). The influence of irrigation system, flow regime as well as their interaction on the yield was not significant (p> 0.05). As a conclusion the best results in improving efficiency of application, efficiency of storage, CWUE and IWUE by reducing TWR, DPR and advance rate of water were achieved with AF irrigation system combined with S2 flow regime.

1. INTRODUCTION

Irrigation is an essential component of agricultural management where greater production of food and fiber is required under severe constraints of water resources. Specially, effective use of irrigation water is a key issue for agricultural development in regions where water is limiting factor for crop production. The amount of water and land available for agriculture is limited in many developing countries. Although efforts towards increasing crop production have been focused on the field of irrigation, the world is again challenged to increase production using less water. Therefore, the worldwide decline in water resources requires further development of water saving irrigation strategies in order to improve irrigation water use and crop water use efficiency. Thus, increasing water use efficiency has been an urgent issue in such a region where water demand has been an increasing concern. One of the possible approaches is to increase the efficiency and productivity of the existing irrigation systems to optimize water use (less volume of applied water with greater production).

The most frequently used surface irrigation methods in the world are contour irrigation, border irrigation, and furrow irrigation. Among these, furrow irrigation method is the most commonly used and the oldest methods of irrigation in which soil surface is used to convey and infiltrate water. Most recently, it has become important because of the high cost of energy in pressurized irrigation methods and the incorporation of automation in its operation. Therefore, more attention has been given to improve the efficiency of furrow irrigation.

Efficient furrow irrigation requires reducing deep percolation and surface runoff losses. Water that percolates below the root zone (deep percolation) is lost to crop production although deep percolation may be necessary to control salinity. Water loss through deep percolation and runoff, can be minimized by improving the evenness of the applied water and preventing over irrigation.

With proper design, and installation of water control structures, it is possible to improve the efficiency of furrow irrigation. There are different furrow irrigation application systems developed to improve water application efficiency, distribution uniformity and storage efficiency.

One recent development towards optimum utilization of irrigation is to irrigate alternate furrows during each irrigation time (Zhang et al., 2000; Zhang et al., 2001; Kang et al., 2001; Kang and Zhang, 2004). Alternate furrow irrigation is the innovation that involves irrigating only one part of the root of the crop in each irrigation event, leaving another part to dry to certain soil water content before rewetting by shifting irrigation to the dry side. Changing the irrigation sides in AF induces the production of phytohormone known as Abscisic Acid in shoot signaling, which may increase water productivity through regulating crop physiological parameters (Davies et al., 2002; Ahmadi et al., 2010). Abscisic acid regulates the stomata opening in water stress plants. Closure of stomata in leaf is related to the reduction of evaporative water loss.

Alternate furrow irrigation system has been tested for some field crops and fruit trees (Kang and Zhang, 2004). Most recently, it has also been tested in vegetables (Zegbe-Dominguez et al., 2003; Kirda et al., 2004; Leib et al., 2006). In most cases, AF irrigation has shown a great potential to increase irrigation water use efficiency with no significant yield reduction (Davies and Hartung, 2004). It is expected to save irrigation water with a potential to irrigate more land; it also helps to minimize the labor requirement in furrow irrigation technique.

On the other hand, there are indications that AF irrigation system may not be equally applicable for all physiographic Conditions. Alternate furrow irrigation system works well on some soils and crops and does not work on other soils and crops. Hence, its suitability needed to validate for local crop and management condition (Deribew, 2007).

One other very successful alternative approaches of irrigation water management technique that has been applied for about two decades offering a better opportunity for the development of surface irrigation is surge flow irrigation (FAO, 1989). Surge flow irrigation has emerged over the last 20 years as one of the most efficient strategies for use of irrigation water. This water management strategy has considerably revolutionized gravity systems, drastically changing and improving all the parameters involved in this earliest irrigation technique. It is defined as the intermittent application of water to furrows or borders in a series of on time and off time intervals, which vary from a few minutes to hours (Ismail et al., 2004). On the other hand, surge flow irrigation means cycling water on and off while the water advances. This cycling or surging reduces the soil infiltration rate compared to conventional furrow irrigation.

The intermittent application of irrigation water in furrows permits more uniform distribution of infiltrated depth, considerable reduction of the volumes of water required, the possibility of using lighter irrigations, less water loss due to deep percolation and reduced leaching of fertilizers (Mahmood et al., 2003; Horst et al., 2007). All these benefits are associated with a clear reduction in the infiltration rate of the soil. This phenomenon occurs because, between one cycle and the next, the clods break up, particles are reoriented, and there is migration of the sediments that seal the base of the furrow. In addition, while the water supply in each cycle interrupted, air could trap in the soil pores (Walker and Skogerboe, 1987; Jalali-Farahni et al., 1993). Both effects (reduction of infiltration and air interruption) facilitate the rapid advance of the water, solving the old problem of excessive losses of water by deep percolation at the beginning of the furrow. Therefore, many researchers are advocating the promises of surge flow irrigation in maximizing distribution uniformity, application efficiency, and minimizing the advance time, amount of irrigation water to be applied, loss of irrigation water through deep percolation and run off.

Hence, the sustainability of the above-mentioned irrigation systems needs verification for local crop and management condition. Particularly, there are few works on the evaluation of combined use of the two method of water application (Horest et al., 2007). Therefore, this experiment was proposed with the hypothesis that irrigating alternate furrows, with the adoption of surge flow regime i.e., partial wetting of the root zone alternatively with intermittent flow could save water thereby increase water use efficiency (WUE) without causing substantial drop in the yield of irrigated onion crops.

The aim of this experiment was, to evaluate the conjunctive use of alternate and surge flow irrigation water application methods under field conditions. The specific objectives were:

- To evaluate flow characteristics and technical efficiency of alternate and conventional furrow irrigation under the application of surge flow, and
- To evaluate the combined effect of alternate and surge flow irrigations on the water use efficiency for onion production.

2. LITERATURE REVIEW

2.1 Concept of Alternate Furrow and Every Furrow Irrigation System

Alternate furrow continuous (AFC) irrigation meant one of the two neighboring furrows alternately irrigated during consecutive watering. Every furrow continuous (EFC) irrigation or traditional irrigation meant irrigating every furrow during each watering.

2.1.1 Alternate furrow irrigation system

With alternate furrow irrigation system, it is possible to reduce the size of irrigation that does not show a significant yield reduction compared to every furrow irrigation system. This gives an advantage of irrigating more land with less amount of water in areas where the supply of water is limited (Majumdar, 2002). Alternate furrow irrigation system could supply water in manner that greatly reduces the amount of surface wetted leading to less evapotranspiration and less deep percolation. The reduced evapotranspiration in alternate furrow irrigation method is due to reduction in wet soil surface compared to that in conventional furrow irrigation.

Horest et al (2005) conduct a research on field assessment of water saving potential of furrow irrigation. In his experiment, alternate and every furrow irrigation system was compared using several furrow discharge and different furrow length. The best performance in terms of application efficiency, distribution uniformity, and total applied irrigation depth found for alternate furrow adopting the inflow rate of 18 l/s, which produces high application efficiency and distribution uniformity, 80% and 83% respectively and leads to water saving from 200 to 300 mm compared to water use in every furrow irrigation.

The success of alternate furrow irrigation relies upon the fact that when plants expose to water deficit, they save water by limiting leaf area growth and/or closing stomata. Fernandez (1994) carried out three years study designed to measure the response of medium maturity cotton to every furrow irrigation and alternate furrows irrigation. The finding reveals that alternate furrows irrigation is one case-to-apply deficit irrigation practice which leads to substantial water saving and increased irrigation cost efficiency in cotton crops. Alternate furrow irrigation system has been widely used in the USA, to improve irrigation efficiency with good results in potatoes, corn, sorghum, cotton, and peppermint. Large water savings (up to 50%) without a loss in yield or only slight reduction have achieved in the USA with substantial reductions in the labor required to carry out the irrigation (Stone and Nofziger, 1993).

According to ICARDA (2000), alternate furrow irrigation experiment in Arys-Turksitana region of Kazakhstan for two years indicated that the new system of AFI, combined with the use of shallow ground water, is much more effective than traditional methods. Through alternate furrow irrigation less water was applied, less water was lost due to surface runoff, resulting in a net saving of water, and enhanced productivity, with a higher yield of cotton per volume of water applied.

According to Zhang et al. (2000), a comparison was made among different irrigation method and the finding depict that alternate furrow irrigation method uses less irrigation water but can maintain the same grain yield production as that of conventional furrow irrigation with high irrigation amounts. This is because of continuous regulation by root drying signal on stomata opening. When part of the root zone was alternately irrigated, maize plants showed considerable primary root initiation and greater root biomass build up in the soil. Therefore, alternate furrow irrigation treatments were better than fixed furrow irrigation and conventional furrow irrigation treatments in terms of root establishment. Photosynthesis and transpiration measured from 39 to 99 days after sowing of maize, resulted in a more profound restriction on transpiration than on photosynthesis when irrigation amounts were reduced.

Kang et al. (2000), investigation showed that alternate furrow irrigation maintained high grain yield with up to 50% reduction in irrigation amount, while FFI and CFI all showed a substantial decrease in yield with reduced irrigation. As a result, water use efficiency for irrigated water was substantially increased, and concluded that alternate furrow irrigation is an effective water saving irrigation method in arid areas where maize production relies heavily on repeated irrigation .

Webber et al. (2006) conducted an experiment to evaluate the WUE of two water saving technologies (AF and DI) on two crops (green gram and common bean) in Fergana Valley of Uzbekistan. Conventional and alternate furrow irrigation with three irrigation schedules (recommended, moderate and severe depletions) were used to irrigate the crop. The result of the study indicates that both alternate furrow irrigation and deficit irrigation practices can reduce irrigation water requirements and increase water use efficiency. Consistent water savings, of close to 25%, had been realized with alternate furrow irrigation over conventional furrow irrigation. Moreover, when it was used in combination with deficit irrigation scheduling, water savings can be as large as 50% with no significant yield reductions, as compared to the recommended irrigation volumes.

Field study carried out by Graterol et al. (1993) demonstrated that alternate furrow irrigation system led to lesser water input without soil water depletion yet was still able to generate soybean yields comparable to the conventional system of irrigating every furrow. Adoption of the alternate furrow irrigation system would lead to more efficient water use and water saving. Based on this study CWUE was 6.12 and 5.52 kg ha -1 mm -1 for the AFI and CFI respectively across the two years. Bakker, et al. (1997) investigated alternate furrow irrigation has been successfully used in a variety of cropping systems and climatic conditions to save water without loss in production.

2.1.2. Conventional (every) furrow irrigation

Karajeh et al. (2000) investigated that under conventional furrow irrigation (CFI), out of the total irrigation water, 51- 54 % used to moisten soil (saturation), 20-25% for infiltration and in the fields, 5-6 % for the evaporation from water surface, and 18-21% for surface runoff. Significant quantities of irrigation water losses by infiltration and surface runoff (about 40% of total water supply) reduced water supply to the irrigated lands and decreased the efficiency of agricultural production as well as the reliability of drainage systems. This irrigation system has speed up the processes of decomposition and removal of organic elements and mobile forms of nutrients in the root zone that eventually, brought to soil fertility losses.

Mintesinot et al. (2004), made a comparative study that has been undertaken over two irrigation seasons (1998/1999 and 1999/2000) between the traditional irrigation management (every furrow-traditional scheduling) and alternative water management options (alternate furrows-scientific scheduling and every furrow-scientific scheduling) on maize plots in northern Ethiopia. Yield-based comparison has shown that every furrow-scientific scheduling generates the highest yield levels followed by alternate furrows-scientific scheduling. The yield increase by every furrow-scientific scheduling over the traditional management had found 54%. Water productivity-based comparison has shown that alternate furrows-scientific scheduling generates the highest water productivity values followed by every furrow-scientific scheduling. The increase (by alternate furrow irrigation, scientific scheduling) over the traditional irrigation management was 58%.

2.2. The Concept of Surge Flow

Surge flow irrigation is the intermittent application of water to furrows or borders in a series of relatively short on- and off-time periods, which usually vary from about 5 minutes to several hours. With this technique, water is applied intermittently and not continuously as in conventional surface irrigation. The main objective of surge flow irrigation is to improve the efficiency by reducing deep percolation and runoff losses and to obtain a uniform wetting of the root zone. When water is admitted to the furrow for a given period of time, and then shut off to allow the furrow to de-water, the intake rate of the furrow is reduced. Thus, when the second surge of water is admitted, less water infiltrates into the soil than would otherwise occur, hence more water is available in the dry parts of the furrow, and the advance is more rapid. The combined effects of reduced infiltration during the advance phase plus a more rapid advance lead to more uniform distribution of water along the furrow. Thus, the uniformity of application is significantly improved.

Irrigating fields using surge flow is accomplished by alternating periods of constant or expanding, non-zero inflow (on time) with rest periods of zero inflow (off time). According to James (1988), each surge is defined as a complete cycle of on off time and it is commonly characterized by a cycle time and cycle ratio. The duration of time between successive inflows (between the beginning of one surge and the beginning of the next) is a cycle time and the ratio of on time to cycle time is cycle ratio. The summation of advancing surge cycle on time is advance inflow time (Yonts et al., 1996).

Kanber et al (2001) made field comparison among surge and continuous flow irrigation under different inflow rate and several cycles time to analyze the potential of former for reducing deep percolation and tail water runoff. The finding showed a 21-38% decrease in tail water runoff and 19-70% decrease in calculated deep percolation for surge flow irrigation depending on the inflow rate and cycle ratio compared to continuous flow irrigation.

El-Hassas et al. (2006) carried out a two season field experiment to investigate the performance and limitation of surge irrigation on the basis of advance rate, distribution efficiency, application efficiency, grain yield, and crop water use efficiency using two discharge rate (2.4 and 3.2 ls-1) and four cycle ratio(continuous, 0.33, 0.50, 0.67 and 0.75). The result of the finding showed that the fastest advance rate was observed for surge flow with 0.75 cycle ratio treatment. Therefore, surge flow treatments save water due to faster advance rate and low infiltration. Similarly, the highest value on distribution uniformity, application efficiency, grain yield, and water use efficiency was found for surge flow irrigation than continuous flow irrigation.

2.3. Irrigation Performance Indicator

To evaluate the performance of irrigation systems a set of recognized and accepted parameters are required. According to FAO (1989), among the factors used to judge the performance of an irrigation system or its management, the most common are application efficiency and distribution uniformity. These parameters can be subdivided and defined in a multitude of ways, as well as named in different manners. There is not a single parameter, which is sufficient for defining irrigation performance. Conceptually, the adequacy of irrigation depends on how much water is stored within the crop root zone, losses percolating below the root zone, losses occurring as surface runoff or flow as tail water, the uniformity of the applied water, and the remaining deficit or under irrigation within the soil profile following irrigation.

2.3.1. Application efficiency

Application efficiency, is defined as the amount of water beneficially used by the crop divided by the total amount of water applied (FAO, 1989). Hansen et al. (1980) noted that the concept of water application efficiency can be applied to a farm can vary from extremely low to values approaching 100%. The depth of water applied is a dominant factor influencing efficiency of application. Even if water spread uniformly over the land surface, excessive depths of application would result in low efficiencies. Many variable factors such as land uniformity, irrigation method, size of irrigation stream, length of run, soil texture, permeability, and time the irrigator keeps water running on his farm and hence the depth he applies can influence the application efficiency.

According to Kenneth (1988), application efficiency is an irrigation concept that is very important both in system selection and design and in irrigation management. The ability of an irrigation system to apply water uniformly and efficiently to the irrigated area is a major factor influencing the agronomic and economic viability of farming enterprise. Application efficiency is also an index, which is a measure of how effective an irrigation event is in minimizing unavoidable losses.

According to Solomon (1988), attainable water application efficiencies vary greatly with irrigation system type and management, and the attainable water application efficiency of furrow irrigation system ranges from 60 to 75% that might be achieve with reasonable design management. According to Morries and Vicki (2006), the attainable water application efficiency of furrow irrigation system ranges from 60 to 80 % and efficiency of surge flow irrigation system ranges from 65 up to 80 %. According to Kassa (2001), evaluation of the performance of surface irrigation methods at Melka-Werer, Middle Awash Valley, indicated that the maximum possible application efficiency (EA) for furrow irrigation computed was 64.5% for inlet flow rate 2.5 l / s and 0.8 m furrow spacing. Whereas the total irrigation- water losses (due to deep percolation and runoff) was 56-62%. Other reported ranges of application efficiency is from 50 to 70% by Rogers et al. (1997)

Mulubrehan (2007) observed application efficiencies of 57.6%, 55.0% and 47.2% for the cycle ratios of 1/3 (CR1), ½ (CR2) and 1 (C) respectively. The value of cycle ratio had significant effect on application efficiency. His study shows that surge flow treatment combinations had better application efficiency than the continuous flow treatments. Kanber et al. (2001) in Turky and Ismail et al. (2004) in Egypt concluded that surge flow treatments had better application efficiency than the continuous flow treatments. Similarly, Mahmood et al. (2003) findings on wheat, surge flow border irrigation in Pakistan showed that surge flow irrigation had appreciably higher application efficiency than the continuous one. Derbew (2007) found significantly different application efficiency of alternate furrow irrigation system and conventional furrow i.e. result of his investigation shows that application efficiency for alternate furrow irrigation is better than for conventional furrow irrigation.

2.3.2. Distribution uniformity

When a field is with uniform slope, soil and crop density receives steady flow at its upper end the waterfront will advance at a monotonically decreasing rate until it reaches the end of the field (FAO, 1989). Roger et al. (1997) explained that water lost to percolation below the root zone due to non-uniform application or over application water runoff from the field, all reduces irrigation efficiencies. To express the efficiency of an irrigation system, the uniformity of the water applied should be determined.

Mulubrihan (2007) noted that distribution uniformity was significantly affected by surge cycle ratio. In his study, the highest distribution uniformity was observed for the small cycle ratio 1/3 (CR1) with the mean value of distribution uniformity 87.1% and the least was recorded for the large cycle ratio of continuous 1(C) with the mean value of 68.0%. Therefore, according to his study, the highest distribution uniformity observed for surge flow treatments than for the continuous treatments. This may be because of the fact that surge flow irrigation reduced the infiltration rate and can lead to the faster water advance. In line with this, Horst et al. (2007) indicated that better distribution uniformity for surge flow irrigation than for the continuous flow irrigation.

Similarly, Yonts et al. (1995) reported that surge flow irrigation helps to obtain a uniform wetting of the root zone, with minor differences in the infiltration depth at the beginning and end of a furrow. Thus, the difference in intake opportunity time between the upper and lower ends of the furrow was less and resulted in a uniform distribution of water intake over the length of the furrow. Besides, Ismail (2006) in his research carried out in Egypt indicated that in continuous flow, the water allowed to run long enough to fill the root zone area. Therefore, the water stayed longer on the soil at the beginning than at the end; as a result, more water infiltrates at the beginning and less infiltrates at the end of furrows, and this leads to low distribution uniformity along the furrows. According to Mahmood (2004), under the water application during surge irrigation, the computed distribution uniformity at different experimental site ranges from 63.5 to 92.5% but for continuous irrigation, it ranges from 59.5 to 83.5%.

2.3.3. Storage efficiency

The storage efficiency is the ratio of the stored water depth to the required depth. The storage efficiency is an indicator of how well the irrigation meets its objective of refilling the root zone. The value of storage efficiency is important either when the irrigations tend to leave major portions of the field under-irrigated or where under-irrigation purposely practiced to use precipitation as it occurs. This parameter is the most directly related to the crop yield since it will reflect the degree of soil moisture stress. Usually, under-irrigation in high probability rainfall area is a good practice to conserve water but the degree of under-irrigation is a difficult question to answer at the farm level (FAO, 1989).

Jurreins et al. (2001) expresses adequacy of irrigation turn in terms of storage efficiency and the purpose of an irrigation turn is to meet at least the required water depth over the entire length of the field. Conceptually, the storage efficiency depends on how much water is stored within the crop root zone, losses percolating below the root zone, losses occurring as surface runoff or tail water, the uniformity of applied water and the remaining under irrigation. The water storage efficiency refers to how completely the water needed prior to irrigation has been stored in the root zone during irrigation.

Mulubrihan (2007) carried out field studies during 2006 season to test the characteristics of surge irrigation for the furrow stream 2 l/s and 1 l/s with cycle ratio of for 1/3 (CR1), ½ (CR2) and 1 (C). In evaluating the field observed data, the cycle ratio had statistically significant effect on the storage efficiency. Storage efficiency with respect to cycle ratio was found to be 81.2 %, 77.7% and 86.25% for 1/3 (CR1), ½ (CR2) and 1 (C). Here, the highest storage efficiency obtained for the continuous cycle ratio (C) with the mean value of 86.25% and the least observed with the mean value of 77.7% for the large cycle ratio (CR2). He concluded that continuous flow treatments had better storage efficiency than surge flow treatments. This might be because of continuous flow treatments obtained higher amount of water applied than the surge flow treatments.

Derbew (2007) was evaluating storage efficiency in his experiment for the AFI, CFI systems. The result shows that there were no significant differences among irrigation systems in terms of their storage efficiency. The result obtained was 78.73% and 75.83% for AFI and CFI respectively.

2.3.4. Deep percolation loss

High deep percolation losses aggravate water logging and salinity problems, and leach valuable crop nutrients from the root zone. Depending on the chemical nature of the groundwater basin, deep percolation can cause a major water quality problem of a regional nature. These losses can return to receiving streams heavily loaded with salts and other toxic elements and thereby degrade the quality of water (FAO, 1989).

According to Mulubrihan (2007), cycle ratio affects the deep percolation significantly. In his study, the highest deep percolation losses were observed for the cycle ratio of continuous (C) flow with the mean value of 35.42% and the least deep percolation losses were for the small cycle ratio 1/3 (CR2) with average value of 28.8%. Based on his research work, the average deep percolation losses for continuous flow treatments ranged from 34.50% to 36.33%. Here, there was no significant difference between continuous flow treatments, whereas for surge flow, it ranged from 27.62% to 32.53% and the treatments were significantly different. Kanber et al. (2001) also concluded that surge flow treatments reduce deep percolation losses by 19-70% over the continuous flow treatments for Harran clay soils. In Horst et al. (2007) reported that deep percolation was very high for continuous flow treatment but small for surge flow irrigations.

2.3.5. Tail water runoff

Runoff losses cause additional pressure to irrigation systems and regional water resources. Erosion of the topsoil on a field is generally the major problem associated with runoff. The sediments can then obstruct conveyance and control structures downstream, including dams and regulation structures (FAO, 1989).

Mulubrihan (2007) reported that the highest runoff losses were observed for continuous flow cycle ratio 1(C) with the mean value of 17.4% and the least runoff losses were recorded for the large cycle ratio ½ (CR2) with the mean value of 13.25%. In his experiment, the runoff losses in continuous flow treatments were higher than that of all surge flow treatments, which had the same discharge with the continuous flows. The results reveal that the highest tail water loss was measured for treatments of continuous flow with the mean value of 19.37% and 15.43%, and the least tail water was observed for surge flow treatments with the mean value 12.67%. Kanber et al. (2001), Minwiyelet (2004), Abebaw (2009) also reported that surge flow was found to be promising in minimizing the tail water runoff loss. Besides, Horst et al. (2007) was states that surge flow has the ability to reduce tail water runoff.

2.4. Water Use Efficiency

Water use efficiency is a term to describe the relationship between water (input) and agriculture product (output). When used in this way the term is, strictly speaking, a water use index. Water use efficiency can express the effectiveness of irrigation water delivery and use (Stephens and Hess, 1999).

To maximize crop water-use efficiency, it is necessary both to conserve water and to promote maximal growth. The former requires minimizing losses through runoff, seepage, evaporation and transpiration by weeds. The latter task includes planting high-yielding crops well adapted to the local soil and climate. It also includes optimizing growing conditions by proper timing and performance of planting and harvesting, tillage, fertilization and pest control. In short, raising water-use efficiency requires good farming practices from start to finish (FAO, 1997).

3. MATERIALS AND METHODS

In this section, a brief description of the study site is made, methods followed in making physical and chemical characterization of the soil are outlined, and procedures followed to estimate technical and water use efficiencies are presented.

3.1. Description of the Study Area

The study was conducted at Ela kebela irrigation project in Humbo district found in Southern Nation, Nationalities People’s Regional State (SNNPR) in Wolaita zone located 452 km on the main road from Addis Ababa to Arbaminch, and 177 km from regional capital city Hawassa. It is located at 6o7’33”N latitude, 3707’5”E longitude, and has 1360 m a.s.l elevation. The mean annual rainfall of the area ranges between 1000 mm –1500 mm, and average maximum and minimum temperature of 25.6OC and 14.3OC respectively. Agroecology of the district is 70% Kolla (500-1500 m a.s.l) and 30% Woinadega (1500-2000 m a.s.l) having two major cropping season belg and meher (WZFEDD, 2005). The major crop grown in the area are maize (Zea may. L.), teff (Eragrostis teff), banana (Musa spp), sweet potato (Ipomoea batatas L.). Tomato, carrot, and onion are also grown in the area using irrigation. The type of soil in the area is sandy clay loam.

Abbildung in dieser Leseprobe nicht enthalten

Figure 1. Location map of the study area (Authors own work)

3.2. Experimental Design and Treatments

The experiment had two factors; namely, irrigation system (EF and AF) and three surge flow regimes (C, S1, and S2). The flow rate and cycle time were constant for the treatments. The experimental plot had randomized complete block design (RCBD) with six treatment combinations and three replications, which give 18 plots (Figure 2). Each plot had three ridges and four furrows so that data was taken from the middle furrow. The two-side furrow serves as a buffer. The total area required for the experiment was 34.4 m by 65 m i.e. 2236 m2 or 0.2236 ha. The treatments are formulated and presented in Table 1.

Table 1.Treatment combination

Abbildung in dieser Leseprobe nicht enthalten

3.3. Soil Sampling and Laboratory Analysis

The soil was characterized in terms of its physical properties. The soil properties analyzed include, texture, pH, bulk density, FC and PWP. Three pits having a volume of one cubic meter located on the diagonal line along the length of the experimental field were prepared to collect soil sample. FC and PWP were determined at Debrezeit Agricultural Research Center Soil and Water Laboratory while othes like texture, bulk density, pH, and EC, were measured at Wolaita Soddo Soil Laboratory.

Texture and bulk density

Soil texture was determined using Pipette method. Following the procedure recommended by Staney and Bernard (1992), the percentage of clay, loam and sand were determined, and the textural class of the soil profile was decided using USDA textural triangle. Bulk density of the soil was determined from undisturbed soil samples, which was taken at two depths from 0-30 cm and 30-60 cm using core sampler of known volume. The cylinder of the core sampler was driven into the soil and un-compacted core obtained within the tube. The sample was dried in an oven at 1050C for 24 hrs until all the moisture was driven off and the sample weighed. The soil bulk density was measured using equation (1) described by Walker (2003)

Abbildung in dieser Leseprobe nicht enthalten

Field capacity and permanent wilting point

Soil moisture contents at field capacity and permanent wilting points were determined using pressure plate apparatus by applying pressures of 1/3 and 15 bars, respectively. Then from the moisture content of the soil at field capacity and permanent wilting point, total available water in the experimental field was determined by using equation (2) (Allen et al., 1998):

Abbildung in dieser Leseprobe nicht enthalten

Soil moisture content determination

For soil moisture determination, soil samples from each treatment plot were taken before irrigating the plot and two days after irrigating the plot with augers from the three depths 0-20 cm, 20-40 cm and 40 cm-60 cm, at 5(five) locations such as 0 m, 16.25 m, 32.5 m, 48.75m and 65 m along the length the furrow. The moisture content was measured gravimetrically using equation (Michael, 2008).

Abbildung in dieser Leseprobe nicht enthalten

Then the volumetric water content was calculated from the gravimetric water content using equation 4.

Abbildung in dieser Leseprobe nicht enthalten

The depth of water required to bring the specific depth of soil to field capacity at every irrigation event was computed using soil moisture deficit (SMD) as proposed by Michael, (2008) using equation 5.

Abbildung in dieser Leseprobe nicht enthalten

The depth of water retained in root zone of the soil was computed based on the moisture contents of the soil samples before and after irrigation. The depth of water retained in root zone was calculated using equation 6 (Michael, 2008)

Abbildung in dieser Leseprobe nicht enthalten

Where, d = depth of water retained into root zone of the soil (cm)

Mafi = moisture content in the ith layer of the soil after irrigation (% weight basis)

Mbi = moisture content in the ith layer of the soil before irrigation (% weight basis)

Asi = bulk density of the soil in the ith layer

Di = depth of the soil ith soil layer within the root zone (cm)

n = number of layers in the root zone

3.4 . Irrigation Depth

The designed depth of application and irrigation interval, which are function of intake characteristics and water storage capacities of the soil, determined using CROPWAT. Before starting the actual experiment, full information of meteorological data were collected from Hawassa Meteorological Agency. Soil infiltration rate was measured using double ring infiltrometer and the basic infiltration rate was used as an input to the CROPWAT model for making irrigation scheduling.

3.5. Discharge and Tail Water Measurement

A gutter from sheet of metal was constructed and installed across the upper stream of the experimental furrows, from which water was diverted through gated PVC pipes / spiles fixed to the side of the gutter faced to the experimental furrow (see Figure 5). A constant head was created to obtain a fixed discharge. Before starting the actual experimental work, the maximum non-erosive discharge was estimated with the help of USDA – SCS’s empirical equation 7 (Cuenca, 1989).

Abbildung in dieser Leseprobe nicht enthalten

Where, C = 0.6 and S = longitudinal slope in percent

Abbildung in dieser Leseprobe nicht enthalten

Figure 5. Installation of water conveyance system (Authors own work)

For measuring tail water runoff, the pits were excavated at the end of each test furrow. The upper surface between the pits and end of test furrow covered with plastic sheet and the tail water was collected in the inside of pit using graduated plastic buckets.

3.6. Water Application Duration

The time required to deliver the desired depth of irrigation water which was calculated previously using CROPWAT model into each furrow was calculated using equation (8) (Michael, 2008):

Abbildung in dieser Leseprobe nicht enthalten

The gross irrigation water requirement was computed with the assumption of 70 % as average application efficiency for well managed surface irrigation system (Morries and Vicki, 2006; Solomon, 1988, Allen et al., 1998)

3.7. Performance Indicator s

Evaluation of the two irrigation system (EF and AF), the three flow regime(C, S1 and S2) as well as their interaction was carried out in terms of technical performance indices such as advance rate, application efficiency, storage efficiency, distribution uniformity, tail water ratio and deep percolation ratio.

3.7.1. Advance rate computation

In order to measure the advance time in furrow at which water move, wooden peg were installed at equal interval along the length of the furrow. Five timing points were fixed along the individual furrow corresponding to specific treatment at an interval of 16.25 m. The advance time was recorded as the advancing water reaches each stake. From the recorded advance time and distance covered by the waterfront at five points i.e. at 0 m, 16.25 m, 32.5 m, 48.75 m, and 65 m along the furrow, the advance rate computation was done using equation (9) (Israelsen, 1980).

Abbildung in dieser Leseprobe nicht enthalten

3.7.2. Distribution uniformity

Distribution uniformity was measured using the distribution uniformity index (equation 10) as proposed by James (1988):

Abbildung in dieser Leseprobe nicht enthalten

3.7.3. Application efficiency

For each of treatment combination, the corresponding application efficiency was measured using equation (12) (FAO, 1989; Michael 2008):

Abbildung in dieser Leseprobe nicht enthalten

3.7.4. Storage efficiency

Storage efficiency was measured using equation (13) as recommended by (FAO, 1989; Michael, 2008):

Abbildung in dieser Leseprobe nicht enthalten

3.7.5. Deep percolation ratio (DPR)

The loss of water through drainage beyond the root zone was measured as the deep percolation ratio, DPR, using equation (14) (FAO, 1989):

Abbildung in dieser Leseprobe nicht enthalten

3.7.6. Tail water runoff ratio (TWR)

Losses of water from the irrigation system via runoff from the end of the field indicated in the tail water ratio, TWR, defined as (15) (FAO, 1989):

Abbildung in dieser Leseprobe nicht enthalten

3.7.7. Water use efficiency

The water use efficiency was determined by dividing harvested yield in kg per unit volume of water (kg/m3). The two kinds of water use efficiencies used in this experiment were:

3.7.7.1. Crop water use efficiency

It was measured by dividing the crop yield to the total amount of water depleted in the process of evapotranspiration using equation (16) (Michael, 2008):

Abbildung in dieser Leseprobe nicht enthalten

3.7.7.2. Field water use efficiency

It is the ratio of crop yield to the total amount of water applied in the field and calculated as (Michael, 2008):

Abbildung in dieser Leseprobe nicht enthalten

3.8. Statistical Analysis

The variability among treatment effect in terms of performance parameter was analyzed using the analysis of variance technique. When the variability among the treatments on a particular variable is significant, the least significant difference (LSD) technique was used to separate the means.

4. RESULTS AND DISCUSSION

In this section, results obtained on soil characterization, technical efficiency evaluations and water use efficiencies are presented, described, and discussed.

4.1. Soil Physical Characteristics

The laboratory result of the soil physical characteristics for 0-30 cm and 30-60 cm depths are presented in Table 2.

Table 2. Physical characteristics of soil at the experimental site

Abbildung in dieser Leseprobe nicht enthalten

*FC= field capacity, PWP=permanent wilting point, EC= electrical conductivity, TAW= total available water

The average sand, silt and clay percentage of the soil in the experimental area were 65.7, 11.3 and 23.0, respectively. Thus, according to the USDA soil textural classification, the soil is sandy clay loam with pH ranges of 6.6 to 6.8. Onion can grow in any type of soil but for higher yield best suited soil ranges from sand to clay loam and favorable pH is between 6.5 to 8.0 (Curah and Rabinowith, 2002). Hence, the physical characteristics of the soil on proposed area is suitable for onion production. The average field capacity and permanent wilting point of the soil were found to be 33.01% and 22.14% on volume basis, respectively. Abdur et al. (2010) reported that the typical FC and PWP value for sandy clay loam soil are in the range (31-34) % and (18-22.5) %. Hence the value obtained are within the range of reported.

4.2. Soil Infiltration Rate

The infiltration test results of the study site is presented in Appendix Table 19. The average infiltration rate, and cumulative intake, curves are shown in Figure 6. The basic infiltration rate was about 11 mm/hr. Rbinson (1990) and WDNR (2004) reported that the basic infiltration rate of sandy clay loam soil is in the range of 10 to 20 mm/hr. Hence, the result obtained is within the range expected for the sandy clay loam textural classes.

Abbildung in dieser Leseprobe nicht enthalten

Figure 6. Cumulative intake and infiltration rate of soil at experimental the site (Authors own work).

4.3. Irrigation Water Requirement of Onion

The mean daily evapotranspiration of the area was found to be 3.11 mm (Appendix Table 3). Accordingly, the value for KC, root depth, and length of growing stage are adopted from (Allen et al., 1998) and presented in Appendix Table 6. The total available water of the soil was 142 mm/m, calculated from the water content of the soil at FC and PWP (Table 2). Then the net and gross irrigation requirement of the onion crop computed using the CROPWAT model is presented in Table 3.

Table 3.Irrigation scheduling

Abbildung in dieser Leseprobe nicht enthalten

4.4. Flow Performance Measurement

The calibration curve generated to decide water level in the gutter is presented in Figure 7. The effective head set to obtain 0.6 l/s discharge was found to be 3 cm.

Abbildung in dieser Leseprobe nicht enthalten

Figure 7. Head discharge relationship (Authors own work)

4.4.1. Flow advance rate

The flow advance rate monitored against the different irrigation system and flow regime is presented in Table 4.

Table 4. Influence of irrigation system and flow regime on flow advance rate

Abbildung in dieser Leseprobe nicht enthalten

Key: means followed by the same letter for the same factor are not significantly different, EF=every furrow, AF=alternate furrow, C=continuous flow regime, S1 = one third cycle ratio surge flow regime, S2= half cycle ratio surge flow regime, LSD= least significant difference, CV = coefficient of variance

The analysis of variance in Appendix Table 17 and summary Table 4 showed that the influence due to irrigation system and flow regime was significant (P< 0.01), while the influence due to their interaction were not significant. The highest flow advance rate (0.14 ms-1) and the lower flow advance rate (0.11 ms-1) were observed for application of every furrow and alternate furrow irrigation system respectively. This indicates that the flow of water in every furrow irrigation system was 1.273 times faster than the flow of water in alternate furrow irrigation system. The probable reason for this could be the additional infiltration in alternate furrow irrigation to the adjacent furrow reduces the volume of water in the furrow. This is consistent with the results of slower advance rate that have been associated with alternate furrow irrigation (Hodges et al., 1989; Deribew, 2007).

As it is indicated in Table 4, from application of different flow regime, the highest advance rate (0.167 ms-1) and the least advance rate (0.062 ms-1) were observed for one third cycle ratio regime and continuous flow regime respectively. The influence of each flow regime on advance rate of water flow was significantly varied. This means the advance rate of water flow with one-third cycle ratio surge is 1.22 and 2.70 times faster than the advance rate of water flow with half cycle ratio surge and continuous flow respectively. In other words, water front in surge flow application complete a given advance distance in shorter time compared to waterfront in continuous flow application. This improves the distribution uniformity and application efficiency. The reported result agrees with the conclusion made by El- Hassan et al. (2006).

4.4.2. Flow advance time

Figures 8-12, indicates the advance time of surge and continuous treatments at the development growth stage. Generally, surge flow advanced faster than the respective continuous flow treatments. Among the surge flow treatments, surge flow treatment EFS1 (i.e. the treatment combination of EF and S1) advanced faster than the others. It was observed that the advance time used to complete the advance distance with surge flow treatment EFS1 was about 43% less than the respective continuous flow (EFC). Similarly, EFS2 reached at the end of the furrow by a 24% less time than every furrow continuous flow (EFC). On the other hand, AFS1 and AFS2 arrived at the tail end of the furrow by 46% and 34% less advance time, respectively, compared to respected alternate furrow continuous flow, AFC. The result obtained here agrees with what has been reported by Mahmood (2004) in which he found that on average reduction of 26.20%, 33.92% and 39.48% advance time in surge flow compared to continuous flow at the three sites.

A faster advance rate provides uniform distribution of water along the furrow length of run by reducing the difference between opportunity times in the upper and the lower end of the field. The main surging benefit observed so far by many researchers is the faster advance during multiple surges that has increased its importance. The observed data indicates that the advance phase during the first phase behaves like the continuous advance curve in all treatment combination (Figure 8-12). Further, the movement of water was found to be faster during later surges due to surging effects.

It is also be seen from the Figure 8-12 that the curve is flatter and parallel to each other up to the point where the furrows were wetted by the previous surges and the water speed slowed down in dry sections of the furrows and later due to the inflow cutoff. However, it moves faster during the next wetting phase. According to Mohammed (2004), and Minwyelet (2004), the reason for this response is the infiltration phenomena. Their finding shows a significant decline of infiltration rate after the first surging. The possible reason for reducing infiltration rate during multiple surging and increasing the advance rate associated with consolidation of a thin layer of fine material at the bottom of the furrow, moisture redistribution and surface seal formation.

Abbildung in dieser Leseprobe nicht enthalten

Figure 8. Advance time curve of AFS1 for different surges (Authors own work)

Abbildung in dieser Leseprobe nicht enthalten

Figure 9. Advance time curve of EFS1 for different surges (Authors own work)

Abbildung in dieser Leseprobe nicht enthalten

Figure 10. Advance time curve of AFS2 for different surges (Authors own work)

Abbildung in dieser Leseprobe nicht enthalten

Figure 11. Advance time curve of EFS2 for different surges (Authors own work)

Abbildung in dieser Leseprobe nicht enthalten

Figure 12. Advance time curve of AFC and EFC (Authors own work)

4.5. Technical Efficiency Evaluation

4.5.1. Application efficiency

In order to investigate the influence of irrigation system (Irr.sys), flow regime (FR) and their interaction, on application efficiency, analysis of variance was made (Appendix Table 17.) and the result was summarized in Table 5.

Table 5. The interaction effect of irrigation system and flow regime on application efficiency

Abbildung in dieser Leseprobe nicht enthalten

Key: means followed by the same letter of same LSD0.5 are not significantly different, EF=every furrow, AF=alternate furrow, Ir. Sys. = irrigation system, FR= flow regime, C=continuous flow, S1 = surge flow one, S2= surge flow two, LSD= least significant difference, CV = coefficient of variance In Table 5, the outcome of statistical analysis showed that the effect due to irrigation system, flow regime, and their interaction were significant (P< 0.01). Looking into the interaction effect, the lowest value is 45.64% for EF irrigation system at a level of continuous flow regime and the highest value is 64.88% for AF irrigation system at a level of half CR surge flow regime. The mean of EF irrigation system at a level of continuous flow regime is significantly varied from the mean of other treatment combination. EF irrigation system at a level of surge flow regime gives better application efficiency value compared to EF irrigation system at a level of continuous flow regime.

The highest value obtained is related with the improvement of application efficiency that has been associated with surge flow regime and AF irrigation system. There are findings that indicates AF irrigation system improves application efficiency compared to EF irrigation system. (Woldesenbet, 2005; Derbew, 2007; Mitslal, 2008). According to their finding, there is a significant difference between the application efficiency of AF irrigation system and EF irrigation system. That is application efficiency of alternate furrow irrigation system is greater than application efficiency of every furrow irrigation system. The improvement of application efficiency with alternate furrow irrigation might have resulted from encouragement of lateral movement of water across the ridge, which reduces the forward movement of water along the furrow compared to every furrow irrigation system. In addition to this alternate furrow reduces the vertical infiltrated amount of water. Therefore, it minimizes the loss of irrigation water due to deep percolation below the effective root zone of the crop.

Again, the highest value of application efficiency is related with the application of irrigation water using surge flow regime. This is indicated by the mean of EF irrigation system at a level both surge flow regime and mean of AF irrigation system at any level of flow regime, are significantly, vary from the mean of EF irrigation system at a level of continuous flow regime. In line with this Mulubrehan (2007) showed that surge flow treatment combinations had better application efficiency (59.7%) than the continuous flow treatments (46.13%). In similar studies, Ismail et al. (2004) in Egypt concluded that surge flow treatments had better application efficiency (95%) than the continuous flow treatments (63%). Similarly, Mahmood et al. (2003) findings on wheat, surge flow border irrigation in Pakistan showed that surge flow irrigation had appreciably higher application efficiency than the continuous flow irrigation.

4.5.2. Storage efficiency

The analysis of variance in Appendix Table 17 demonstrates that the influence due to irrigation systems, flow regime and their interaction on storage efficiency were significantly (p< 0.01) varied and the interaction effect is summarized in Table 5.

Table 5. indicates that in the interaction effect, the least storage efficiency value (60.14%) was observed for EF irrigation system at a level of continuous flow regime and the highest value of storage efficiency (85.40%) was observed for AF irrigation system at a level of half CR surge flow regime. The mean of EF irrigation system at a level of continuous flow regime was significantly varied with mean of other five-treatment combination. The mean of five treatments were not significantly varying each other. However, the best combination of the two factors that shows better performance in storage efficiency was alternate furrow irrigation system at a level of half CR surge flow regime.

This result does not agree with the finding of Abebaw (2009), Mulubrihan (2007). According to their finding, continuous flow performs better than surge flow treatment in terms of storage efficiency because continuous treatment receives higher amount of irrigation water than surge flow. This may be due to the fact that in this study, both continuous and surge flow have received equal amount of irrigation water.

4.5.3. Distribution uniformity

Distribution uniformity result calculated from field data presented form Appendix Table 9-12 used for analysis of variance. The outcome of analysis is summarized in Table 6 below.

Table 6. Influence of irrigation system and flow regime on distribution uniformity

Abbildung in dieser Leseprobe nicht enthalten

Key: means followed by the same letter for the same factor are not significantly different, EF=every furrow, AF=alternate furrow, C=continuous flow regime, S1 = one third cycle ratio surge flow regime, S2= half cycle ratio surge flow, LSD= least significant difference, CV = coefficient of variance

Table 6 showed that flow regime variability was statistically significant (P< 0.01). The highest value (90.1%) was observed for one-third cycle ratio surge flow and the least value (80.1%) was for continuous flow. Similarly, Mulubrihan (2007) and Abebaw (2009) noted that distribution uniformity significantly affected by surge flow regime; i.e. the highest values of distribution uniformity were observed for surge flow treatments compared to continuous flow treatments. This might be because of the fact that surge flow irrigation reduced the infiltration rate and can lead to faster water advance rate resulting in more uniform distribution of irrigation water along the length of furrow. In line with this, Horst et al. (2007) indicated that better distribution uniformity for surge flow irrigation was observed compared to continuous flow irrigation.

Similarly, Yonts et al. (1995) reported that surge flow irrigation helps to obtain a uniform wetting of the root zone, with minor differences in the infiltration depth at the beginning and end of a furrow. Thus, the difference in intake opportunity time between the upper and lower ends of the furrow was less and resulted in a uniform distribution of water intake over the length of the furrow. Besides, Ismail (2006) in Egypt indicated that in continuous flow, the water allowed to run long enough to fill the root zone area. Therefore, the water stayed longer on the soil at the beginning than at the end. As a result, more water infiltrates at beginning and less infiltrates at the end of furrows, which leads to low distribution uniformity along the furrows.

According to Mahmood (2004), the computed distribution uniformity at different experimental site range from 63.5 to 92.5% for surge irrigation, but 59.5 to 83.5% for continuous irrigation. This indicates that range of distribution uniformity for surge flow is better than continuous flow treatment. In similar studies, Ismail et al. (2004) investigated that the distribution uniformity value 68 to 78% for continuous flow treatment and 82 to 98% for surge flow treatment combination.

4.5.4. Tail water runoff ratio (TWR)

The tail water runoff ratio calculated for different treatment combination is presented in Appendix Table 9-12 and the outcome of statistical analysis summarized in Table 7.

Table 7. Interaction effect of irrigation system and flow regime on tail water ratio (%)

Abbildung in dieser Leseprobe nicht enthalten

Key: means followed by the same letter are not significantly different, EF=every furrow, AF=alternate furrow, C=continuous flow regime, S1 = one third cycle ratio surge flow regime, S2= half cycle ratio surge flow regime, LSD= least significant difference, CV = coefficient of variance The variability between the treatments and factors were significant. Observing influence of interaction, the highest value (19.79%) and least value (11.38%) of tail water ratio were observed for EF irrigation system at a level of continuous flow regime and AF irrigation system at a level of half CR surge flow respectively. The mean for EF irrigation system at a level of continuous flow regime (19.79%) was significantly differ from the mean of other treatment combination. That is, the amount of irrigation water loss in EFC treatment combination is higher than the loss in EFS1, EFS2, AFC, AFS1, and AFS2 by 47.2%, 66.5%, 70.8%, and 73.8% respectively. It is clear that the best treatment combination in minimizing irrigation water loss due to runoff was AF irrigation system at a level of half CR Surge flow regime. This reveals the advantage of alternate furrow irrigation combined with surge flow regime in minimizing tail water losses.

This experiment showed that 32% - 42% reduction in tail water runoff ratio for the different treatment combination compared to EF irrigation system at a level continuous flow regime. Similarly, according to kanber et al (2001), there was 21% -38% reductions in tail water runoff in surge flow compared to continuous flow irrigation system. The possible reason for this, the lateral movement of water to the ridge of furrow reduces the forward motion of waterfront particularly for alternate furrow with surge flow treatment combination.

Similarly, according to Mulubrihan (2007) and Abebaw (2009), runoff losses for continuous flow were higher than that of all surge flow treatments. Kanber et al. (2001), Minwiyelet (2004) also reported that surge flow was found promising in minimizing the tail water runoff loss. Besides, Horst et al. (2007) was states that surge flow has the ability to reduce tail water runoff.

4.5.5. Deep percolation ratio (DPR)

The analysis of variance in Appendix Table 17 showed that the influence due to irrigation systems, flow regime and their interaction were significant (p< 0.01).

Table 8. Interaction effect of irrigation system and flow regime on deep percolation ratio (%)

Abbildung in dieser Leseprobe nicht enthalten

Key: means followed by the same letter are not significantly different, EF=every furrow, AF=alternate furrow, C=continuous flow regime, S1 = one third cycle ratio surge flow regime, S2= half cycle ratio surge flow regime, LSD= least significant difference, CV = coefficient of variance

Looking into the interaction effect in Table 8, the highest value of deep percolation ratio (34.34%) was observed for EF irrigation system at a level of continuous flow regime and the least value (23.74%) was observed for AF irrigation system at a level of half CR surge flow treatment combination. Surge flow treatment shows 31% reduction in loss of irrigation water as deep percolation compared to EF irrigation system at a level of continuous flow regime. Similarly, Kanber et al (2001) was conducted an experiment of comparison among surge flow and continuous flow treatment. He has investigated that 19%-70% reduction in deep percolation of water below the effective root zone for surge flow treatment compared to continuous flow treatments.

The mean for EFC (34.34%) was significantly (p<0.05) different from the mean of the EFS1 (24.24%), EFS2 (25.21%), AFC (24.90%), AFS1 (23.85%) and AFS2 (23.74%). The influence of other five treatment combination on deep percolation ratio was not significantly (p > 0.05) varied each other. The study illustrates the advantage of surge flow regime in minimizing irrigation water loss through deep percolation.

In line to Horst et al. (2007) reported that deep percolation was very high for continuous flow treatment but small for surge flow irrigations. According to Mulubrihan (2007) and Abebaw (2009), cycle ratio affects the deep percolation ratio significantly.

4.6. Yield and Water Use Efficiency

4.6.1. Yield

The mean of yield obtained (converted into kg/ha) is presented as shown in Table 9. The highest yield obtained was 13243.59 kg/ha for EFC treatment combination and the lowest yield was 12858.97 kg/ha observed for AFS1 treatment combination. This indicates that yield of EFC treatment combination had shown 384.6 kg (2.9%), 264.1 kg (2%), 233 kg (1.8%), 154 kg (1.2%) and 141 kg (1.2%), increment compared to yield of AFS1, AFS2, FES2, AFC, and EFS1 respectively. However, the analysis of variance (Appendix Table 17) showed that irrigation system, flow regime and their interaction do not significantly (p > 0.05) influence the onion bulb yield.

Table 9. Interaction effect of irrigation system and flow regime on yield (kg/ha)

Abbildung in dieser Leseprobe nicht enthalten

Key: means followed by the same letter are not significantly different, EF=every furrow, AF=alternate furrow, C=continuous flow regime, S1 = one third cycle ratio surge flow regime, S2= half cycle ratio surge flow regime, LSD= least significant difference, CV = coefficient of variance

The yield difference along the length of furrow for each treatment was observed (Figure 13). This was done by dividing the furrow length at four equal interval and yield was collected two meter of each partition and weighed.

Abbildung in dieser Leseprobe nicht enthalten

Figure 13. Yield variability along the furrow length (Authors own work)

From Figure 13, one can see that yield was uniform for treatment AFS2 and highly variable for treatment combination EFC along the length of furrow. Almost for all treatments, the yield was higher at the upper end than the tail end of the furrow. This may be associated with the distribution uniformity of irrigation water. Similarly, Ismail et al. (2004) reported that yield reduction increased along the furrow length. According to his explanation, the highest and the lowest yields were observed at the beginning and tail end of the furrow respectively for both surge and continuous flow treatments. This behavior is due to the water distribution along the furrow not uniform practically, which is caused by the contact time of water with the soil.

4.6.2. Crop water use efficiency

The result of variance analysis for the crop water use efficiency is shown in (Table 10) showed that AF perform better than EF irrigation system (p<0.01). However, the reduction of yield by alternate furrow irrigation system is only 142.73 kg/ha which is not statistically significant. In addition, there was a significant reduction (50%) in the volume of water applied to the AF treatments combination. The reason probably is due to better application efficiency obtained with AF irrigation system compared to EF irrigation system. This is consistent with the significant improvements in CWUE that have been associated with AF (Bakker, et al., 1997, Zhang et al., 2000, Derbew, 2007, Mitsilal, 2008).

Table 10. Effect of irrigation system and flow regime on Crop water use efficiency and irrigation water use efficiency (Kg/m3)

Abbildung in dieser Leseprobe nicht enthalten

Key: means followed by the same letter for the same factor are not significantly different, EF=every furrow, AF=alternate furrow, C=continuous flow regime, S1 = one third cycle ratio surge flow regime, S2= half cycle ratio surge flow regime, LSD= least significant difference, CV = coefficient of variance

From the result of statistical analysis (Appendix Table 17) and Table 10, statistically (p<0.05) there is no significant difference between the influence of flow regime as well as main factor interaction on crop water use efficiency.

4.6.3. Irrigation water use efficiency

The average value of irrigation water use efficiency was determined for each of the treatment (Appendix Table 17) and used for analysis of variance. The result of analysis was summarized and presented as Table 10. From the result of analysis, it is clear that irrigation system significantly (p<0.01) affects the irrigation water use efficiency. The highest irrigation water use efficiency (5.876 kgm-3) for alternative irrigation system and the least irrigation water use efficiency (2.97 kgm-3) were observed for every furrow irrigation system. This is consistent with the significant improvements in FWUE that have been associated with AFI (Zhang et al., 2000, Derbew, 2007 and Mitsilal, 2008).

As it is indicated in Appendix Table 17 and in the above Table 10, there was no significance (p > 0.05) difference between the influence of flow regime and main factor interaction on irrigation water use efficiency.

5. SUMMARY, CONCLUSION AND RECOMMENDATION

5.1. Summary

Furrow irrigation is one of the oldest methods of irrigation in which soil surface is used to convey and infiltrate water. This method of irrigation is inexpensive compared with sprinkler or trickle methods. Because of this, it is the most commonly used irrigation system in the world as well as in the county. However, surface irrigation systems including furrow irrigation are associated with lower irrigation efficiency. Therefore, more attention has to be given to improve the efficiency of furrow irrigation with the implementation of different water management techniques. Nowadays, there are different furrow irrigation application systems developed to improve water application efficiency, distribution uniformity and storage efficiency.

Hence, the suitability of different irrigation technique needs verification for local crop and management condition. Therefore, the experiment was carried out with the general objective of evaluating the conjunctive use of alternate and surge flow irrigation water application methods under field conditions. The evaluation was made using performance indices such as flow characteristics, technical efficiency, and water use efficiency with growing onion as an indicator crop.

The experiment was conducted on 65 m furrow length, 0.6 m furrow spacing, and 1% general average slope of the furrow on sandy clay loam soil. The experiment has two factors namely furrow irrigation system (every furrow and alternative furrow irrigation) and flow regime (continuous flow, surge flow with one third cycle ratio, and surge flow with half cycle ratio). Therefore, it was designed as two factor factorials in randomized complete block design (RCBD) with six treatment combinations and three replications. The analysis of data was made with statistical analysis software (SAS) and mean separation was made using least significant difference (LSD). The primary data on advance time of waterfront, moisture content of soil sample before/after irrigation and tail water runoff had collected and recorded for the selected irrigation

The influence of irrigation system (every furrow and alternate furrow) and flow regime (continuous flow, surge flow with one-third cycle ratio and surge flow with half cycle ratio) as well as their interaction on different performance indices was evaluated. The performance indices were application efficiency, storage efficiency, distribution uniformity, tail water ratio, deep percolation ratio and water use efficiency (crop water use and irrigation water use).

From the result, the influence due to irrigation system and flow regime on advance rate were highly significant (p<0.01). The flow of water in every furrow was 1.273 times faster than the flow of water in alternate furrow irrigation system. Also, statistically, the influence of each flow regime on flow advance rate of water was significantly different. This means the advance rate of surge flow with one third cycle ratios is 1.22 and 2.70 times faster than the advance rate of surge flow with half cycle ratio and continuous flow respectively.

In terms of advance time, it was observed that the advance time used to complete the advance distance with surge flow treatment EFS1 was about 43% and with surge flow treatment EFS2 was 24% less than the respective every furrow continuous flow (EFC). On the other hand, AFS1 and AFS2 arrived at the tail end of the furrow by 46% and 34% less advance time, respectively, compared to respected AFC. It is also be seen from the Figure 9-13 that the curve are flatter and parallel to each other up to the point where the furrows were wetted by the previous surges and the water speed slowed down in dry sections of the furrows and later due to the inflow cutoff. However, it moves faster during the next wetting phase.

The interaction influence of the two main factors was highly significant (p<0.01) on application efficiency, storage efficiency, tail water ratio and deep percolation ratio. Among the six-treatment combination, EFC shows least performance on improving the application efficiency and storage efficiency. In addition to this, the highest water loss though deep percolation and runoff was observed for this treatment combination. AFS2 was found to be more effective in improving application efficiency and storage efficiency as well as in minimizing irrigation water loss as tail water and deep percolation.

Crop water use efficiency and irrigation water use efficiency are highly (p<0.01) influenced by irrigation system. The highest value of crop water use efficiency and irrigation water use efficiency 8.0 kgm-3 and 5.8 kgm-3 were respectively observed for alternate furrow irrigation system. Thus, alternate furrow irrigation system has shown better performance than every furrow irrigation system on these indices.

Distribution uniformity was influenced by only flow regime. The highest value (90.1%) on distribution uniformity and the least value (80.0%) on distribution uniformity were observed for surge flow with one-third cycle ratio and for continuous flow respectively. Thus, surge flow is better in distributing irrigation water uniformity along the length of furrow.

5.2. Conclusion

The conclusions drawn from this research are:

- Alternate furrow irrigation system shows double increment in crop water use efficiency and irrigation water use efficiency compared to every furrow irrigation system.
- Alternate furrow irrigation system shows a significant improvement on some of the performance indices such as application efficiency and storage efficiency. It also has a pronounced effect to minimize irrigation water loss through deep percolation and runoff.
- Application of water using surge flow irrigation shows remarkable improvement on advance rate, application efficiency, storage efficiency, distribution uniformity, and also it minimizes loss of water as deep percolation and runoff.
- Alternate or every furrow with surge flow application improves the advance rate of waterfront.
- The results of this study indicate that better performance in the improvement of application efficiency and storage efficiency with the reduction of tail water and deep percolation loss resulted from using surge flow regime with adoption of any the irrigation system. Particularly surge flow regime plus alternate furrow irrigation system shows better performance than any of other treatment combination.

5.3. Recommendation

Based on the scope of the study and findings the following recommendations have been made.

i. The experiment is a one-season one-place experiment. Hence repeating the experiment in space and time shall improve the validity of the finding.
ii. Soil water sampling was done gravimetrically. This made frequent monitoring difficult, and the number of observations collected could have increased, using either neutron probe or other in-situ moisture profiles.
iii. The test crop considered here is onion. However, other crops like tomato, cabbage, paper are common in the area.
iv. Even though, alternate furrow or every furrow with surge flow application are a solution for poor performance of furrow irrigation, it`s management may be difficult at the farmer’s level in the absence of automation.
v. Then, it may be better to focus on training, adoption, and implementation of hydro flume, which is undergoing by Oromia water works for the effective use of the different water management technique at the farmer’s level.

6. REFERENCES

Abebaw Kebede, 2009. A Comparative performance evaluation of surge and continuous flow irrigation in short furrows. M.Sc. Thesis, Haramaya University, Haramaya,

Abdur R., P. Fisher, N. Robinson, M. Kitching, C. Aumann, M. Imhof, and S. Chandra, 2010. Plant available water capacity of dry land cropping soils in the south-eastern Australia. 19th World Congress of Soil Science, Soil Solutions for a Changing World. Brisbane, Australia.

Ahmadi, S.H., M.N. Andersen, F. Plauborg, R.T. Poulsen, C.R. Jensen, A.R. Sepaskhah, S. Hansen, 2010. Effects of irrigation strategies and soils on field grown potatoes: Yield and water productivity. Agricultural Water Management 97: 1486–1494.

Allen, R.G., L.S. Pereira, D. Raes and M. Smith, 1998. Crop evapotranspiration. Guidelines for computing crop water requirements. FAO Irrig. Drain. Paper No. 56. FAO, Rome, Italy.

Bakker, D.M., S.R. Raine, and M.J. Robertson, 1997. A preliminary investigation of alternate furrow irrigation for sugar cane production. Egan Ferguson and Company Queensland.

Cuenca, R.H., 1989. Irrigation System Design. An engineering approach. Oregon state University, New Jersey.

Currah L. and H.D. Rabinowith, 2002. Allium Crop Science. Recent Advance. CABL Publishing. pp 199-214.

Davies, W.J. and W. Hartung, 2004. Has extrapolation from biochemistry to crop functioning worked to sustain plant production under water scarcity? In Proceedings of the Fourth International Crop Science Congress. Australia, September 26–October 1, 2004.

Davies, W.J., S. Wilkinson, B. Loveys, 2002. Stomata control by chemical signaling and the exploitation of this mechanism to increase water use efficiency in agriculture. New Phytologist 153: 449-460.

Deribew Shanko, 2007. Performance evaluation of alternate, fixed and conventional furrow irrigation systems for onion production at Shalled Ziway Dugda District, Arsi Zone. M.Sc. Thesis, Haramaya University, Haramaya,

El-Hassan, W.H, Y. Kitamura, F.S. Gamal and A.E. Eneji, 2006. Assessment of surge irrigation technique under furrow irrigation system in the Nile Delta. Acadamic JurnalInc.,USA. International Journal of Agricultural Research 1 (5): 462- 470.

Fernandez, C.J., 1994. Alternate furrow irrigation may decrease cotton profits in southwest Texas. Row Crop Publications. http://www.uvalde.tamu.edu/pubs/row.htm (On line 9/15/09).

Food and Agricultural Organization (FAO), 1997. Small-scale irrigation for arid zones: Principles and options. (http://www.fao.org/docrep/W3094E/W3094E00.htm (11/14/2010 )

Food and Agricultural Organization (FAO), 1989. Guidelines for Designing and Evaluating Surface Irrigation Systems. Irrigation and Drainage paper No. 45. Rome, Italy: FAO.

Graterol, Y.E., D.E. Eisenhauer and R.W. Elmore, 1993. Alternate furrow irrigation for soybean production. Agricultural Water Management, 24: 133-145

Hansen, V.E., O.W. Israelsen, and G.E. Stringham, 1980. Irrigation Principles and Practices. John Willey and Sons, Inc. New York.

Hodges, M.E, J.F Stone, J.E. Garton and D.L. Weeks., 1989. Varience of water advance in wide spaced furrow irrigation. Agricultural Water Management 16: 5-13

Horst, M.G., S.S. Shamutalov, J.M. Gonçalves and L.S. Pereira, 2007. Assessing impacts of surge flow irrigation on water saving and productivity of cotton. Agricultural Water Management, 87 (2): 115-127.

Horst, M.G., S.S. Shamutalov, L.S. Pereira, J.M. Goncalves, 2005. Field assessment of the water saving potential with furrow irrigation in Fergana, Aral Sea Basin. Agric. Water Manage. 77: 210–231.

ICARDA (International Center for Agricultural Research in the Dry Areas), 2000. Annual Report. CAD’s Research portfolio. http://www.icarda.org/publications/Anual. Report /2000/project3.1html (online 5 /10/ 2010)

Ismail, S.M., H. Depewege and B. Schultz, 2004. Surge flow irrigation under short field conditions in Egypt. Irrigation and Drainage 53: 461 – 475 (2004).

Ismail, S.M., 2006. Effect of tillage on water advance and distribution under surge and continuous furrows irrigation methods for cotton in Egypt, Irrig. and Drain. 55: 191–199.

Israelsen, O.W., and V. E. Hansen, 1980. Irrigation Principles and Practices. Jonsen Wiley and Sons, Inc. New York, London.

Jalali–Farahani, H.R. Duke and D.F. Heermann, 1993. Physics of surge irrigation: Relationship between soil physical and hydraulic parameters. Transaction of ASAE, 36 (1): 45-50.

James, L.G., 1988. Principles of Farm Irrigation System Design. John Wiley & Sons, Inc. New York.

Jurreins, M., D. Zeriun, J. Boonstra, and J. Feyen, 2001. SURDEV: Surface irrigation software: Design operation and evaluation of Basin, Border and Furrow irrigation. ILR Publication 59, Wageningen, the Netherlands.

Kanber, R., H. Koksal, S. Onder, S. Kapur and S. Sahan, 2001. Comparison of surge and continuous furrow methods for cotton in the Harran plain. Agr. Water Management 47:119-135.

Kang, S., J. Zhang., 2004. Controlled alternate partial root-zone irrigation: its physiological consequences and impact on water use efficiency. J. Exp. Bot.55 (407): 2437–2446.

Kang, S., L. Zhang, H. Xiaotao, Z. Li, and P. Jerie, 2001. An improved water use efficiency for hot pepper grown under controlled alternate drip irrigation onpartial roots. Sci. Horti. 89: 257–267.

Kang, S., Z. Liang, Y. Pan and J. Zhang, 2000. Alternate furrow irrigation for maize production in an arid area. Agricultural Water Management 45: 267-274

Karajeh, F., V. Mukhamedjanov and F. Vyshepolskiy, 2000. On-farm water and drainage management strategy in Kazakhstan’s Arys-Turkestan area. 49: 35-50. Taraz, Kazakstan.

Kassa Teddla, 2001. Performance evaluation of surface irrigation methods at melka worer. M.Sc. Thesis, Alemaya University.

Kenneth, H.S., 1988. Irrigation Systems and Water Application Efficiencies. California State University, Fresno, California.

Kirda, C., M. Cetin, Y. Dasgan, S. Topcu, H. Kaman, B. Ekici, M.R. Derici, A.I. Ozguven, 2004. Yield response of greenhouse-grown tomato to partial root drying and conventional deficit irrigation. Agricultural Water Management 69: 191–201.

Leib, B.G., H.W. Caspari, C.A. Redulla, P.K. Andrews, J.D. Jabro, 2006. Partial rootzone drying and deficit irrigation of ‘Fuji’ apples in a semi-arid climate. Irrig. Sci. 24: 85–99.

Mahmood, S., 2004. Development and calibration of surge irrigation performance evaluation model. PhD Dissertation, university of engineering and technology, Lahore, Pakistan.

Mahmood, S., M.A. Kahan, M. Latif, and J.K. Sial, 2003. Application of surge irrigation on borders for water saving and wheat production: first year study result. Italy Journal of Agronomy 7(1): 49 – 55.

Majumdar, D. K., 2002. Irrigation Water Management, Principles and Practice. New Delhi,

Michael, A.M., 2008. Irrigation Theory and Practices. Jupiter offset printer Delhi. Mintesinot Behailu, H. Verplancke, E. Vanranst, Mitiku Haile, 2004. Examining traditional irrigation methods, irrigation scheduling, and alternate furrows irrigation on vertisols in northern Ethiopia. Agricultural Water Management 64: 17-27

Minwiyelet Nigatu, 2004. Evaluation of surge flow on the infiltration process and performance of furrow irrigation at Awash Melkassa. M.Sc. Thesis, Alemaya University.

Mitslal Gebreslassie, 2008. Performance of alternate and conventional furrow irrigation method on transpiration rate, root development, and water use efficiency of maize at Dire Dawa. MSc Thesis Haramaya University, Haramaya, Ethiopia.

Morries, M. and Vicki, L., 2006. Measuring and Conserving Irrigation Water. ATTRA Puplication No. P280. NCAT.

Mulubrehan Kifle, 2007. Evaluation of surge flow furrow irrigation at Mekelle, Northern Ethiopia. M.Sc. Thesis, Alemaya University.

Robinson, M. & R.C. Ward, 1990. Principle of Hydrology. McGaw-Hill Book Company, London.

Rogers, D.H., F.R. Mahbub, A. Trooien, T.P. Clark, G.A. Baras, and M. Kyle, 1997. Efficiencies and water losses of irrigation systems. Irrigation Water Management series. Kansas, U.S.A

Solomon K., 1988. Irrigation Systems and Water Application Efficiencies: Irrigation Note. California State University, Fresno, California 93740-0018, CATI.

Staney, W.C. and B. Yerima, 1992. Improvement of soil services for agricultural development: guidelines for soil sampling and fertility evaluation. Ministry of Natural Resources Development and Environmental Protection, Addis Ababa, Ethiopia.

Stone, J. F., and D. L. Nofzger, 1993. Water use and yields of cotton grown under wide spaced furrow irrigation. Agricultural Water Management 24: 27-38 66

Stephens, W. and T. Hess, 1999. Systems approach to water management. Agricultural Water Management. 40: 3-13.

Walker, R.W., 2003. Surface Irrigation Simulation, Evaluation, and Design. Guide and Technical Documentation. Biological and Irrigation Engineering Utah State University.

Walker, W.R and G.V. Skogerboe, 1987. Surface Irrigation: Theory and Practice. Prince- Hall, Engelwood Cliff, NJ, pp.212-234.

Webber, H.A., C.A. Madramootoo, M. Bourgault, M.G. Horst, G. Stulina, D.L. Smith, 2006. Water use efficiency of common bean and green gram grown using alternate furrow and deficit irrigation. Agricultural water management 86: 259 – 268.

Wisconsin Department of Natural Resource (WDNR), 2004. Site evaluation for storm water infiltration. http://docs.goodle.com(16/08/2010)

Wolaita Zone Finance and Economic Development Department, 2005. Zonal basic socio-economic and demographic information.

Woldesenbet Gebre, 2005. Evaluating alternate furrow irrigation for potato production in sub-humid area of east Gojam, Alemaya University.

Yonts, C.D, E. Joel, and E. Dean, 1995. Surge flow irrigation. University of Nebraska. Fact Publication. Electronic version issued July 1995.

Yonts, C.D., D.E. Eisenhauer and D. Fekersilassie, 1996. Impact of surge irrigation on furrow water advance. Transition of ASAE 39 (1): 973-979.

Zegbe-Dominguez, J.A., M.H. Behboudian, A. Lang, B.E. Clothier, 2003. Deficit irrigation and partial root-zone drying maintain fruit dry mass and enhance fruit quality in ‘Petopride’ processing tomato. Sci. Hort. 98, 505–510.

Zhang, J.H., W.S. Jia, S.Z. Kang, 2001. Partial root zone irrigation. Its physiological consequences and impact on water use efficiency. Acta Bot. Boreali-Occident. Sin. 21 (2): 191–197.

Zhang, J., S. Kang, Z. Liang, Y.Z. Pan, P. Shi, Y.H. Pan, Z.S. Liang, X.T. Hu, 2000. Soil water distribution, uniformity, and water use efficiency under alternate furrow irrigation in arid areas. Irrigation Sci. 19: 181-190.

7. APPENDICES

7.1. Appendix I Tables

Appendix Table 1. Meteorological data (Hawassa Meteorological Agency)

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 2. Monthly average meteorological data

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 3. Determination of ET0 with penman-monteith

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 4. Irrigation scheduling (CROPWAT-output)

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 5. Soil data for irrigation scheduling

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 6. Onion crop data for irrigation scheduling

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 7. Crop water requirement

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 8. Cycle time, on time, off time and number of surges at different growth stage of crop

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 9. Performance indices at initial growth Stage

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 10. Performance indices at development growth stage

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 11. Performance indices at mid-season growth stage

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 12. Average performance indices of the three-growth stage

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 13. Average onion yield along the furrow length

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 14. Total onion yield (kg/ha)

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 15. Crop water use efficiency (kg/m3)

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 16. Irrigation water use efficiency (kg/m3)

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 17. Summary of two-way ANOVA table for the performance indices

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 17. Continued

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 18. Two-way table for performance indices

Abbildung in dieser Leseprobe nicht enthalten

Appendix Table 19. Infiltration data of the soil at the experimental site

Abbildung in dieser Leseprobe nicht enthalten

[...]