Field assessment of surge and continuous furrow irrigation methods in relation to tillage systems

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1 Int. Agrophys., 217, 31, doi: /intg Field ssessment of surge nd continuous furrow irrigtion methods in reltion to tillge systems Mohmed A. Mttr 1,2 *, Mohmed A. El-Sdwy 2, Mmdouh A. Helmy 3, nd Hussien M. Sorour 3 1 Deprtment of Agriculturl Engineering, College of Food nd Agriculture Sciences, King Sud University, P.O. Box 24, Riydh 11451, Sudi Arbi 2 Agriculturl Engineering Reserch Institute (AEnRI), Agriculturl Reserch Center, P.O. Box 256, Giz, Egypt 3 Deprtment of Agriculturl Engineering, College of Agriculture, Kfr El-Sheikh University, Egypt Received April 11, 216; ccepted Jnury 3, 217 A b s t r c t. Surge flow irrigtion is one of the irrigtion techniques for controlling furrow irrigtion. The im of this study ws to investigte the effect of surge furrow irrigtion on wter mngement compred with continuous irrigtion for different tillge systems. An experimentl field ws treted with vrious tillge systems (mouldbord plough, chisel plough nd rotry plough) nd wter irrigtion ppliction methods (continuous flow, control) in which irrigtion wter ws pplied continuously, nd surge flow (3-surges, 4-surges nd 5-surges) in which irrigtion wter ws pplied intermittently until it reched the til end of the furrow. The results showed tht wter svings obtined using the surge technique were 18.58, nd 18.93% lower wter use thn with continuous flow, for the mouldbord, chisel nd rotry ploughs, respectively. The 3-surges tretment with the rotry plough reduced the dvnce time by 25.36% from tht for continuous irrigtion. The 4-surges tretment with the mouldbord plough hd the highest wter ppliction efficiency (88.13%). The 3-surges tretment with the rotry plough hd the highest distribution uniformity (85.1%). The rotry plough did not cuse s much soil ertion round the root system s the other tillge systems. The field reserch provided informtion bout surge flow, imed t reducing dvnce times nd incresing irrigtion efficiency. K e y w o r d s: irrigtion, ploughing system, wter ppliction efficiency, distribution uniformity, dvnce rte INTRODUCTION Surfce irrigtion is the oldest method of irrigtion. It is prcticed by flooding the soil surfce (border nd bsin irrigtion) or by running wter into smll ditches (furrows). Surge flow irrigtion is considered s mens to improve surfce irrigtion systems (Cholpnkulov et l., 25; Horst, 27; Jlli-Frhni et l., 1998; Trout, 1991). The surge ppliction of wter to surfce irrigtion systems is *Corresponding uthor e-mil: dr.mohmedmttr@gmil.com distinctly different from either sprinkle or trickle systems. Bishop et l. (1981) defined surge flow irrigtion s the intermittent ppliction of irrigtion wter to furrow or border, creting series of on nd off conditions of constnt or vrible time spns t the furrow inlet. The cycle time is the time between the beginning of one surge nd the beginning of the next. The surge wter pplictions led to discontinuity in the infiltrtion process. The result is often reduction in surfce lyer permebility. However, this effect widely vries depending on soil compction nd its prior wetting history, surfce wter velocities, nd the durtion of the on/off cycles (Stringhm nd Keller, 1979). The two bsic phenomen which ffect infiltrtion tht tkes plce during the intermittent off-time of surge flow irrigtion re the redistribution of infiltrtion wter in the soil profile nd prticle seling of the wetted soil surfce (Smni et l., 1985). Kemper et l. (1988) showed tht the mechnisms cusing the infiltrtion reduction in surge irrigtion include consolidtion of soil in the furrow beds nd seling of the furrow during the interruption of the flow. Trout (1991) found tht surfce sel formtion reduces infiltrtion by bout 5%. Knber (21) showed tht surge flow reduced the wter infiltrtion of surfce soil loosened by ploughing by 13-23% when compred with continuous flow, thus estblishing n unrivlled dvntge for level-furrow systems. Mny uthors nd investigtors (Eid, 1998; El-Zher et l., 1996; Horst et l., 27; Kifle et l., 28; Wng et l., 25) hve summrised the potentil benefits of using surge rther thn continuous irrigtion. Bishop et l. (1981) reported tht in surge furrow irrigtion experiment with cycle times of 2, 5, 1, nd 2 min nd with cycle 217 Institute of Agrophysics, Polish Acdemy of Sciences

2 22 M.A. MATTAR et l. rtio of.5 nd dischrge rte of 1.26 l s -1, surge flow irrigtion ws more effective during the first irrigtion thn in the second one. Izuno et l. (1985) noted tht continuous irrigtion dvnce required from 1.6 to 3.6 times s much wter s tht required for surge flow irrigtion in the furrows. Testezlf et l. (1987) showed tht, by controlling the on-off cycle nd the flow rte, surge flow could led to decresed deep percoltion nd run off t the lower end of the field. Purkey nd Wllender (1989) reported tht surge irrigtion reduced infiltrtion depths long the furrow compred with continuous flow tretments. Ismil et l. (1985) designed n utomtic drop gte device to control wter. They reported tht the surge flow tretments showed higher distribution uniformity, which indictes tht the depth of wter infiltrtion ws more uniform thn for continuous flow. Surge flow irrigtion lso hd higher potentil ppliction efficiency thn continuous irrigtion under the sme inflow, mening tht surge flow used less wter (El-Zher et l., 1996; Ismil et l., 1985; Osmn, 1991). Eid (1998) showed tht the increses in corn grin yield under surge flow tretment with.5 cycle rtio were % bove the yield of the continuous irrigtion, nd this tretment lso hd the highest wter utilistion efficiency vlues of kg m -3. Wng et l. (25) showed tht surge irrigtion with sediment-lden wter cn sve irrigtion wter nd improve irrigtion qulity. Horst et l. (27) observed tht the best irrigtion wter productivity ws chieved with surge flow on lternte furrows, which reduced irrigtion wter use by 44% nd led to high ppliction efficiency (85%). Kifle et l. (28) reported tht surge flow tretment with lower dischrge rtes nd lower cycle rtio performed better in reching the til end of the furrow, with n dvnce time 23% fster thn comprble continuous flow. The bulk density of soil influences soil strength for structurl purposes nd for trffic-support of vehicles, nimls, nd humns. It ffects plnt growth, wter infiltrtion into soil nd dringe from soil, power required to till soil, nd performnce of tillge tools. Sulimn et l. (1993) indicted tht tillge tretments decresed the vlues of bulk density below the corresponding vlue from no-tillge tretment. They found tht the tretment with chisel plough (one pss) is the most effective tretment in terms of the totl porosity. Tieb (1998) reported tht soil bulk density ws decresed fter tillge opertions. The reduction ws greter when the ploughing depth ws 5 cm nd less reduction ws found when the ploughing depth ws 2 cm. El-Beily (1995) reported tht the minimum vlues of moisture content were obtined fter ploughing opertions in soils treted by rotry plough. El-Gohry et l. (1988) reported tht fter using mouldbord plough, higher infiltrtion rte ws found thn fter using chisel plough. Shortges of wter hve become one of the principl cuses of poverty nd strvtion in the world. Irrigtion is vitl to ensure essentil moisture for plnt growth. However, to the best of our knowledge, no previous reserch hs studied the effects of surge flow nd tillge methods on irrigtion performnce. Therefore, the objectives of the present study re to: investigte the infiltrtion behviour for surge flow irrigtion compred with conventionl continuous flow under different tillge systems; study the effect of surge flow irrigtion on wter dvnce times nd wter svings for different tillge systems; nd select the best on-off times for surge flow irrigtion system. MATERIALS AND METHODS The experimentl re ws divided into three lrge plots with three replictions of ech plot; ech plot ws 17 m wide nd 95 m long. Ech plot ws divided into 4 strips. Ech strip ws used for specific tretment. The re of ech strip ws m 2. Ech tretment involved 5 furrows; the first, the third, nd the fifth were identiclly irrigted; the second nd fourth were non-irrigted furrows. Buffer furrows (1 m spcing) seprted the tretments. The soil type ws cly lom soil (32.5% snd, 37.5% silt nd 3% cly). The test ws conducted on 95 m long furrows hving slope of.4%. Mnning roughness coefficient (n) ws clculted from field observtions of the furrow cross-sectionl re, flow rtes, flow wter depths nd wter surfce width (Horst et l., 25). The vlue of n ws.37. The furrow spcing ws designed to be.7 m. Stkes were plced t regulr intervls (1 m) long ech furrow up to m from the furrow inlet. The furrows were irrigted lterntely with different tillge systems. The inflow rte ws constnt over the irrigtion period in ll tretments. The wter ws pplied in pulses until it reched the til end of the furrow. Two fctors, ie plough nd irrigtion, were studied nd tested in this work. The three ploughing tretments were mouldbord plough with n optimum ploughing depth of 25 cm, chisel plough with n optimum ploughing depth of 2 cm, nd rotry plough with n optimum ploughing depth of 12 cm. The four irrigtion tretments were continuous flow (control); 3-surges irrigtion with on-times of 1, 19, nd 25 min, nd n off-time of 2 min between the surges; 4-surges irrigtion with on-times of 6 min, 11, 15, nd 18 min nd n off-time of 15 min between the surges; 5-surges irrigtion with on-times of 4, 8, 1, 12, nd 13 min nd n off-time of 1 min between the surges. Twelve tretments were evluted in cornfields. The on-time fctor (OTF) nd on-time cycle (OTC) were determined ccording to Younts et l. (1996), s follows: OTF = [CN] [CN-1] 1.52, (1) OTC = OTF OTC 1, (2)

3 SURGE AND CONTINUOUS FURROW IRRIGATION WITH TILLAGE SYSTEMS 221 where: CN is cycle number, nd OTC 1 is on-time for the first cycle. A three bottom mouldbord plough ws used. It ws composed of three bottoms fixed on cm high frme nd mnufctured from squre cross section of 1.16 cm width with thickness of 6 mm. The bottom ws 5 cm tll nd hd net cutting width of 35 cm; the totl cutting width of the plough ws 15 cm. The plough mss ws pproximtely kg. A seven shre chisel plough ws used. It ws composed of three rows with 5 m spcing between the rows. The shres were distributed in rows of 2, 2 nd 3 from front to rer with 5 cm spcing between shres in the sme row. The shre bem height ws 5 cm. The plough mss ws pproximtely kg. The working width of the rotry plough ws 19 cm. The distnce between flnges ws 25 cm. The length of the djustble rer shield ws 195 cm nd the width ws 5 cm. The dimeter of the rotor shft ws 7.64 cm. The depth shoe ws present to djust the depth of the cut. A blocked furrow infiltrometer ws used to mesure the infiltrtion rte of the soil in the field. The experiments were conducted to mesure the wter infiltrtion rtes under continuous nd surge pplictions of wter. Wter ws pplied to the top of the soil to mintin constnt wter level. This level ws recorded. For exmple, fter one minute certin volume of wter infiltrted the soil, the new level of wter ws recorded nd the difference between the redings gve the volume of wter which infiltrted the soil during the specified time intervl. The volumes of wter infiltrted t different time increments were mesured during the on-time. When the off-time begn, the depth of wter bove the soil ws drined. This process ws repeted for ech cycle time specified for ech tretment. The wter infiltrtion depths in the soil, which were recorded ginst time, were used to clculte the prmeters in the infiltrtion equtions for ech on-time. The simplest nd most commonly used pproximtion for infiltrtion is the Kostikov eqution which cn be written in generl terms for furrow irrigtion s (Wlker et l., 26): Z = k T, (3) where: Z is cumultive infiltrtion (mm), T is elpsed time of infiltrtion (min), k nd re empiricl coefficients, k hs units of mm min -. Inflow rtes were mesured by clibrted siphon tubes. The siphon tubes were 2 m in length nd 5 mm in dimeter. The siphon tubes were clibrted using bucket nd stopwtch while collecting constnt volume of wter which ws delivered from the siphon t different times. This clibrtion ws repeted mny times. The rte of dischrge used in this study ws 1.5 l s -1 for ech furrow. The wter dvnce nd recession times were recorded t ten points long ech furrow. These points were clled sttions. The on-off cycle time ws controlled with stopwtch. The time needed for wter to dvnce through the entire furrow ws recorded nd irrigtion ws terminted. All of the dvnce dt were fitted to power function of the following form to represent the reltionship between time nd the distnce tht wter hs dvnced cross the furrow. The pproch of Jmes (1993): x = p t r, (4) ws used, where: x is the distnce tht wter hs dvnced cross the furrow (m); t is time since the strt of dvnce (min), nd p nd r re fitted prmeters. Furrow irrigtion performnce indictors re wter ppliction efficiency (E ) nd distribution uniformity (DU). E is mngement performnce indictor nd DU chrcterises the irrigtion system (ASABE, 23). Wter ppliction efficiency (E ) ws clculted ccording to Wlker (1989) s follows: Ws E = 1, (5) W f where: W s is wter stored in the root zone of the plnts (corn root zone depth is cm) nd W f is wter delivered to ech tretment. Distribution uniformity (DU) ws determined s defined by Michel (1978) s follows: y D U = 1 1, d (6) where: d is the verge depth of wter stored long the run during the irrigtion nd y is the verge numericl devition from d. Dt of the present study were subjected to nlysis of vrince (ANOVA) in rndomised complete block design using CoStt (Version 6.33, CoHort, USA, ). Lest significnt differences (LSD) tests, t p.5, were pplied to compre the mens of mesured prmeters. RESULTS AND DISCUSSION The reltion between cumultive infiltrtion nd infiltrtion opportunity time for the three plough tretments under continuous flow is shown in Fig.1. At the sme time, the Figure shows the reltion between infiltrtion rte nd infiltrtion opportunity time. The highest cumultive infiltrted wter nd infiltrtion rte t ny time ws chieved by mouldbord ploughing rther thn using the chisel nd rotry types. This my be due to the lowest bulk density (1.11 g cm -3 ) nd the highest totl porosity (58.11%) ssocited with the mouldbord plough, while the rotry plough cused the highest bulk density (1.25 g cm -3 ) nd the lowest totl porosity (52.83%). For ech plough tretment, infiltrtion rtes were the highest when the soil ws reltively dry, then dropped to much lower rte fter period of

4 222 M.A. MATTAR et l. Cumltive infiltrtion (mm); Cum. Inf. "moldbord plow" Cum. Inf. "chisel plow" Cum. Inf. "rotry plow" Elpsed time of infiltrtion (min) Inf. rte "moldbord plow" Inf. rte "chisel plow" Inf. rte "rotryplow" Moldbord Moldbord plow plow Z Z = t.678 t.678 Chisel plow Chisel plow Z = 2.2 t.699 t.699 Rotry plow Z = 2.77 t.585 Rotry plow Z = 2.77 t.585 b Continuous flow 3-surges 22 1st 1surge 2 st Z = Z = t.671 t.671 2nd surge Z =.575 t nd surge Z =.575 t 3rd surge Z =.471 t rd surge Z =.471 t Fig. 1. Cumultive infiltrtion nd infiltrtion rte vs. elpsed time of infiltrtion for continuous flow under three different plow conditions. time, then becme lower nd lmost constnt fter more time, s the soil becme sturted with wter. The seling of the soil surfce nd the formtion of soil crusts, which re importnt elements in reducing high infiltrtion rtes, re cused prtly by wetting nd subsequent drying of the soil. The Kostikov eqution ws fitted to the cumultive infiltrtion dt from the continuous flow tretment for different plough systems s presented in Fig. 1. Contrsting the surge flow tretments with the continuous flow tretment under different plough conditions, the infiltrtion rte is plotted ginst elpsed time (excluding the surge off-time) in Figs 2 to 4. As shown in Fig. 2, the infiltrtion rte strts high t 215.9, nd mm h -1, nd drops to 61.2, 51.7 nd 29.2 mm h -1 fter 1 min of on-time for the 3-surges tretment under the mouldbord, chisel nd rotry ploughs, respectively. For the 4-surges tretment, the infiltrtion rte strts high t 222.6, nd mm h -1, nd drops to 7.5, 56.5 nd 35.3 mm h -1 fter 6 min under the mouldbord, chisel, nd rotry ploughs, respectively, s shown in Fig. 3. Similrly, the vlues for the 5-surges tretment strt high, t 266, 226 nd mm h -1, nd drop to 84.5, 7.6 nd 52.2 mm h -1 fter 4 min under the mouldbord, chisel nd rotry ploughs, respectively, s shown in Fig. 4. A rebound or jump phenomenon occurs, where the initil infiltrtion rte following the off-time is higher thn the infiltrtion rte mesured t the end of the preceding surge. This initil rte even exceeds the infiltrtion rte shown for continuous flow t the sme opportunity time. As the surge cycle proceeds, however, the infiltrtion rte rpidly declines. The rebound effect is evident cross ll three ploughs nd ll three surge flow tretments, s shown in Figs 2 to 4. The figures indicte tht the 3-, 4- nd 5-surges c st surge Z = 3.97 t.639 2nd surge Z =.463 t.99 3rd surge Z =.47 t st surge Z = 3.97 t nd surge Z =.463 t.99 3 rd surge Z =.47 t st surge Z = 3.14 t.643 2nd surge Z =.58 t.814 3rd surge Z =.45 t Elpsed time of infiltrtion (min) 1 st surge Z = 3.14 t nd surge Z =.58 t rd surge Z =.45 t.749 Fig. 2. Comprison of infiltrtion rtes for 3-surges nd continuous flow under: moldbord plow, b chisel plow, c rotry plow.

5 SURGE AND CONTINUOUS FURROW IRRIGATION WITH TILLAGE SYSTEMS 223 Continuous flow 4-surges st surge Z = 3.3 t 1st surge Z = 3.3 t nd surge Z = t 2nd surge Z = t rd surge 3 rd surgez =.768 Z =.768 t.89 t th surge 4 th surgez =.75 Z =.75 t.862 t Continuous flow 5-surges st surge Z = t 1st surge Z = t nd surge Z = 1.51 t 2nd surge Z = 1.51 t rd surge Z = 1.82 t 3rd surge Z = 1.82 t th surge Z =.831 t 4th surge Z =.831 t th surge Z =.727 t 5th surge Z =.727 t b st surge Z = st surge Z = t nd Z =.921 2nd surge Z =.921 t rd Z = 3rd surge Z =.666 t th Z = 4th surge Z =.775 t b st surge Z = 3.82 t.587 1st surge Z = 3.82 t nd surge Z = t.826 2nd surge Z = t rd surge Z = 1.16 t rd surge Z = 1.16 t th surge Z =.719 t.8 1 4th surge Z =.719 t.8 5 th surge Z =.594 t.7 1 5th surge Z =.594 t c st surge Z = t.631 1st surge Z = t nd surge Z = nd surge Z = 1.25 t rd surge Z =.729 3rd surge Z =.729 t th surge Z =.85 4th surge Z =.85 t Elpsed time of infiltrtion (min) c st surge Z = t 1st surge Z = t nd surge Z = 1.21 t 2nd surge Z = 1.21 t rd surge Z =.9 t.645 3rd surge Z =.9 t th surge Z =.72 t th surge Z =.72 t th surge Z =.618 t th surge Z =.618 t Elpsed time of infiltrtion (min) Fig. 3. Comprison of infiltrtion rtes for 4-surges nd continuous flow under: moldbord plow, b chisel plow, c rotry plow. tretments reduced the qusi-stedy infiltrtion rte by 17.3, nd 27.1%; 14.2, 33.88, nd 35.22%; nd 2.34, nd 46.63% compred with the continuous flow tretment when using the mouldbord, chisel nd rotry ploughs, respectively. Consistent with findings by Knber (21), the gretest reductions in infiltrtion rtes were observed when the rotry plough ws used. This my be due Fig. 4. Comprison of infiltrtion rtes for 5-surges nd continuous flow under: moldbord plow, b chisel plow, c rotry plow. to the highest bulk density nd the lowest totl porosity. In most cses, the lst infiltrtion rtes mesured were lower with surge flow thn with continuous flow, despite shorter opportunity times for surge flows. Since infiltrtion rtes becme firly constnt by the end of most of the tests, the infiltrtion rtes my be termed qusi-stedy. This is in ccordnce with Butist nd Wllender (1985) nd

6 224 M.A. MATTAR et l. b c Advnced time (min) Advnced time (min) Advnced time (min) Continuous flow 3-surges 4-surges 5-surges Distnce (m) Fig. 5. Averge of dvnce time differences for continuous nd surge flow irrigtion under: moldbord plow, b chisel plow, c rotry plow. Testezlf et l. (1987). The typicl power function tht cn be chrcterised by the Kostikov reltionship is fitted in Figs 2 to 4 to the cumultive infiltrtion dt. The verge (first three irrigtions) dvnce time of the different irrigtion tretments for the three different tillge systems is illustrted in Fig. 5. The verge vlues of time required for wter to dvnce to the end of the furrow in the continuous flow cse were 75.1, 64.8, nd 63.3 min for the mouldbord, chisel, nd rotry ploughs, respectively. This indictes tht wter dvnce rte ws the fstest for the rotry plough. This my be due to the highest bulk density nd the lowest totl porosity when the rotry plough ws used. This is in conformnce with Hmd et l. (1992). For the mouldbord plough, the verge vlues of dvnce time required for wter to rech the end of the furrow for 3-, 4- nd 5-surges tretments were 58.5, 64.3 nd.65 min, respectively (verge of min), s shown in Fig. 5. The corresponding vlues for the chisel plough were 51.3, 61. nd 59.1 min (verge of min); the corresponding vlues for the rotry plough were 47.25, 52.7 nd 54. min (verge of min). Therefore, in surge irrigtion tretments for mouldbord, chisel nd rotry plough conditions, wter reched the end of the furrow in 81.42, nd 81.7% of the time required for continuous flow tretment, respectively. This mens tht the surge irrigtion tretments sved 18.58, nd 18.93% of the time required for the continuous flow tretment to complete the dvnce phse for the mouldbord, chisel nd rotry ploughs, respectively. For ech plough system, the 3-surges tretment hd the fstest dvnce rte. This my be due to higher off-time between surges tht reduced infiltrtion rte, ccording to Smni et l. (1985). Generlly, the surge flow tretments hd fster dvnce rte thn the continuous ones (Horst et l., 27; Ismil, 23; Knber, 21; Kifle et l., 28; Ltif nd Ittefq, 1998). This my be ttributed to the redistribution of the infiltrted wter in the soil profile during the off-time, prticle seling of the wetted soil surfce, nd the cretion of smooth surfce for the next surge (Izdi et l., 199; Segeren nd Trout, 1991; Trout, 1991). The dvnce rte dt equtions for ll tretments re tbulted in Tble 1. The dvnce time equtions were sttisticlly obtined by regression on the dt from the irrigtion runs. The coefficient of determintion (R 2 ) vlues were generlly highly significnt. This mens tht the obtined difference is due to regression, while the devition from regression (error) is very smll in most of them nd nothing in the others. During the growing seson there were six irrigtions. The totl mounts of wter pplied to the different tretments re given in Tble 2. For the mouldbord plough tretments, the tble shows considerble reductions in the mount of wter pplied, 22.1, nd 19.24% by using 3-, 4- nd 5-surges tretments, respectively, compred with wter pplied to the continuous flow tretment. The corresponding reductions of the pplied wter for the chisel plough were 2.83, 5.86 nd 8.% in 3-, 4- nd 5-surges tretments, respectively. Also, for the rotry plough, the corresponding reductions of the pplied wter were 25.36, nd 14.69% in 3-, 4- nd 5-surges tretments, respectively. Therefore, the surge flow technique cused gret reduction in the totl volume of wter used compred to the volume used by the continuous flow technique. The best tretment for reducing pplied irrigtion wter ws the 3-surges tretment with the rotry plough tretment.

7 SURGE AND CONTINUOUS FURROW IRRIGATION WITH TILLAGE SYSTEMS 225 T b l e 1. Advnce eqution nd totl mount of pplied wter with continuous nd surge flow irrigtion under three different plows Plow tretments Irrigtion tretments Advnce eqution x = pt r Totl mount of pplied wter p r R 2 m 3 h -1 % of continuous Continuous Moldbord 3-surges surges surges Continuous Chisel 3-surges surges surges Continuous Rotry 3-surges surges surges T b l e 2. Adjusted prmeters for the fit of the Kostikov infiltrtion eqution to surge tretments dt (Z = k`t ) for different tillge systems Tretments Moldbord plow Chisel plow Rotry plow k` k` k` surges surges surges

8 226 M.A. MATTAR et l. 1 A.T. "continuous flow" A.T. "3-surges" R.T. "continuous flow" R.T. "3-surges" 1 A.T. "continuous flow" A.T. "4-surges" R.T. "continuous flow" R.T. "4-surges" 1 A.T. "continuous flow" A.T. "5-surges" R.T. "continuous flow" R.T. "5-surges" b c Distnce (m) Distnce (m) Distnce (m) Fig. 6. Comprison of dvnce (A.T.) nd recession (R.T.) times for continuous nd surge flow irrigtion under: moldbord plow, b chisel plow, c rotry plow. The continuous infiltrtion depth t ech sttion on the furrow ws clculted by using opportunity times which re clculted s the difference between the dvnce (A.T.) nd recession time (R.T.) s shown in Fig. 6, with the Kostikov eqution for the cumultive infiltrtion depth (Fig. 1). In Fig. 6, the surge flow tretments showed tht the opportunity time ws found by mesuring the difference between the A.T. nd R.T. for ech surge. The infiltrtion depth of the surge flow ws found from the typicl power function s shown in Figs 2 to 4. In the surge flow tretments, the verge typicl infiltrtion depths were compred with the depths of wter pplied in ech surge to check the infiltrtion depth for ech sttion. Therefore, the coefficient k of the Kostikov eqution ws djusted to become k` wheres, the exponent constnt remined the sme, s presented in Tble 2. In ech surge, the djusted infiltrtion depth t ech sttion nd the verge of infiltrtion depths mong the sttions were computed s check for the djusted eqution. The verge of the infiltrtion depths ws found to equl the depth of inflow. The djusted infiltrtion depths t ech

9 SURGE AND CONTINUOUS FURROW IRRIGATION WITH TILLAGE SYSTEMS 227 Depth infiltrted (mm) Distnce (m) Distnce (m) Distnce (m) b Depth infiltrted (mm) c Depth infiltrted (mm) Continuous flow 3-surges Continuous flow 4-surges Continuous flow 5-surges Fig. 7. Infiltrted wter distribution curves for continuous nd surge flow irrigtion under: moldbord plow, b chisel plow, c rotry plow. Continuous flow 3-surges 4-surges 5-surges Continuous flow 3-surges 4-surges 5-surges Wter ppliction efficiency (%) bc b b bc bc d c c e f g Moldbord plow Chisel plow Rotry plow Distribution uniformity (%) b bc bcd bcd bc cde bcd cd ef def bc Moldbord plow Chisel plow Rotry plow Fig. 8. Wter ppliction efficiency nd distribution uniformity of continuous nd surge flow irrigtion under three tillge systems. Different letters on top columns show significnt differences between irrigtion tretments cross tillge systems t.5 level of probbility (p <.5) by the lest significnt difference (LSD) test. Brs give the mens ± stndrd error of the men (n = 3).

10 228 M.A. MATTAR et l. T b l e 3. Anlysis of vrinces on the effect of experimentl fctors nd their interctions on wter ppliction efficiency (E ) nd distribution uniformity (DU) Fctor E DU Tillge systems Moldbord b Chisel b b Rotry c p-vlue <.1 <.1 LSD Irrigtion tretment Continuous c surges b.92 b 4-surges bc 5-surges c p-vlue <.1 <.1 LSD Tillge x irrigtion p-vlue < Mens followed by the sme letters in column of ech experimentl fctors re not significntly different t p <.5 ccording to the LSD test. loction long the furrow re plotted in Fig. 7 nd the infiltrtion depths for continuous flow re drwn in the sme figure. The wter ppliction efficiency (E ) for continuous flow nd surge flow tretments under different tillge systems is depicted in Fig. 8. Tble 3 shows summry of the nlysis of vrince on the E vlues cross the irrigtion tretments nd tillge systems. From the nlysis, it ws found tht there were significnt differences (p <.1) between the irrigtion tretments. There ws significnt (p <.1) interction effect between the irrigtion tretments nd tillge systems for E. Irrespective of the irrigtion tretments, significnt (p <.1) chnges in E between plough tretments were noted. The E vlues for continuous flow were 48.51, nd 27.4% under mouldbord, chisel nd rotry ploughs, respectively. In the 3-surges tretments, the E vlues exceeded continuous flow vlues by 73.57, nd % for the mouldbord, chisel, nd rotry ploughs, respectively. The vlue of E for the rotry plough ws 5.81% less thn tht obtined for the mouldbord plough. Higher vlues of E were obtined by incresing the number of surges from three to four. In the 4-surges tretments, the E vlues exceeded continuous flow vlues by 81.68, nd 29.2% for the mouldbord, chisel nd rotry ploughs, respectively. Going from four to five surges, there ws decrese in most vlues of E. In the 5-surges tretments, the E vlues for mouldbord, chisel nd rotry ploughs were 88.6, nd 83.86%, respectively. Using 5-surges with the different tillge systems gve E vlues tht exceeded continuous flow vlues by 81.52, nd 21.15%. From these clcultions, the E vlues for surge flow tretments were higher thn those for continuous ones. This cn be ttributed to the rpid dvnce of the wterfront for surge flow tretments (Ismil et l., 1985, 24; Knber, 21; Kifle et l., 28). On the other hnd, the E vlue for the 4-surges tretment with the mouldbord plough ws the highest. This might be due to the mouldbord cusing lower bulk density nd higher totl porosity thn the others. The effects of the irrigtion tretments nd tillge systems on distribution uniformity (DU) re lso shown in Fig. 8. Sttisticlly significnt differences (p <.1) in DU were found between irrigtion tretments (Tble 3). There ws lso significnt difference in DU (p <.1) between different tillge systems, irrespective of the irrigtion tretments. The DU vlues for continuous flow tretments were 79.41, nd 89.33% under mouldbord, chisel nd rotry ploughs, respectively. Although continuous flow tretments showed higher DU vlues for some tillge systems, significnt interctions between irrigtion tretments nd tillge systems (p >.5) were not observed, s shown in Fig. 8. The vlues of DU for the surge flow tretments were lower thn those for the continuous flow tretments under different tillge systems. This my be becuse the soil is ble to retin high mount of wter. Compred with continuous flow, the DU vlues for 3-surges irrigtion decresed by.35, 8.79 nd 4.84% for the mouldbord, chisel nd rotry ploughs, respectively, while the vlues of DU for 4-surges were 2.43, nd 8.73% lower. The 5-surges tretments hd DU vlues tht decresed drsticlly, nd were 15.64, nd 1.66% less thn those from the continuous flow tretments, for the mouldbord, chisel nd rotry ploughs, respectively. Generlly, the DU vlues for the rotry plough were the highest. This my be ttributed to the highest bulk density nd the lowest totl porosity. Also, trend is observed in Fig. 8; in surge flow tretments, the DU vlue for the 3-surges tretment with the rotry plough ws the highest, due to the highest offtime (2 min).

11 SURGE AND CONTINUOUS FURROW IRRIGATION WITH TILLAGE SYSTEMS 229 CONCLUSIONS 1. Surge flow tretments required less time to complete the dvnce phse thn continuous flow tretments. Therefore, less wter ws consumed to chieve given dvnce distnce. The 3-surges tretment with the rotry plough hd the fstest dvnce rte. 2. The surge flow cused reduction in the qusi-stedy infiltrtion rtes for the three studied ploughs, despite shorter opportunity times for the surge tretments. 3. Wter ppliction efficiency for surge flow tretments gve the highest vlues, thus indicting good system mngement compred with continuous flow tretments. On the contrry, distribution uniformity gve the lowest vlues for surge flow tretments, indicting inpproprite system performnce. 4. Future investigtions need to study the effects of surge irrigtion on dvnce rtes, considering soil type, cross-sectionl chrcteristics of the furrow, longitudinl slope of the furrow, nd inflow rtes. Conflict of interest: The Authors do not declre conflict of interest. ACKNOWLEDGEMENTS With sincere respect nd grtitude we would like to express deep thnks to the Denship of Scientific Reserch, King Sud University nd Agriculture Reserch Center, College of Food nd Agriculture Sciences, for finncil support, sponsorship, nd encourgement. REFERENCES ASABE, 23. Evlution of irrigtion furrows. EP In: ASABE Stndrds (Ed. M.I. Joseph). ASABE, Butist E. nd Wllender W.W., Sptil vribility of infiltrtion in furrows. Trns. ASABE, 28(6), , Bishop A.A., Wlker W.R., Allen N.L., nd Poole G.J., Furrow dvnce rtes surge flow systems. J. Irrigtion Dringe Division, ASCE, 17 (IR3), Cholpnkulov E.D., Inchenkov O.P., Predes P., nd Pereir L.S., 25. Strtegies for irrigtion scheduling to cope with wter scrcity. In: Irrigtion Mngement for Combting Desertifiction in the Arl Se Bsin. Assessment nd Tools (Eds L.S. Pereir, V.A. Dukhovny, M.G. Horst). Vit Color Publisher, Tshkent, Uzbekistn. 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