Soil Water Distribution and Irrigation Uniformity Under Alternative Furrow Irrigation

Agricultural Sciences in ChinaVol.2 No.7_ 786 - 790July 2003Soil Water Distribution and Irrigation Uniformity UnderAlternative Furrow IrrigationPAN Ying-hua', KANG Shao-zhong，DU Tai-sheng2 and Y ANG Xiu-ying3(' State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau , Institute of Water and SoilConservation,Chinese Academy of Sciences/Ministry of Waler Resources, Yangling 712100, P. R. China;' Key Laboratoryof Agriculural Soil and Water Engineering in Arid Area，Norhrwest Science and Technology University of Agricultureand Forestry, Yangling 712100, P. R. China ;' Wirweri Instiute of Water Conserancy, Wuwei 73000, P. R. Chinu)Abstract: Field experiments were conducted to investigate the spatial-temporal distribution and the uni-formity of soil water under alternative furrow rrigation in spring maize field in Gansu Province, Resultsshowed that during the crop growing season, alternative drying and wetting furrows could incur crops to en-dure a water stress, thus the adsorptive ability of root system could be enhanced. As there was no zero fluxplane between irigated furrows and non-irrigated furrows under alternative furrow irrigation, lateral infiltra-tion of water was obvlously increased, thus decreasing the deep percolation, Compared with the conventionalirrigation, although the water consumptlon in alternative furrow irrigation was reduced, the uniformity of soilwater was not obviously affected,Key words: Alternative furrow irrlgation, Soil water distribution, Uniformity of irrigation waterDrought and water shortage are the majorrigation (CRAFI) is a new irigation technologyproblems in arid and semiarid areas where agricul-and an innovation of traditional furrow irriga-ture relies greatly on irrigation. For example, intionh. Compared with sprinkler rrigation and miOasis areas in Minqin, Gansu Province, traditionalcro irrigation which were developed recently,furrow irrigation and broader irrigation are theCRAFI is characterized by a low cost and an ease ofmost common irrigation systems. Whilst drip anduse, which has a great potential in field irrigationsprinkler irrigation are the possible options, theirin a large scale. Results from both pot experimentsuses tend to be restricted to vegetables, fruit treesin phytotron and field experiments on maizeand flowers that have higher economic values.showed that CRAFI could not only increase bothTherefore, they are seldom used in field crop pro-the total weight of root system and the root- shootduction. Strong evaporation and wind may alsoratio, but also increase the distribution uniformitylimit the use of sprinkler irrigation. In addition,of the root system. Compared with conventionallower water use efficiency and serious waste of wa-furrow irrigation (CFI), irrigation water use effi-ter are the main problems in traditional irrigationciency was obviously increased and more thansystems, which aggravates the scarcity of water33.3% of water was saved by CRAFI [2-4J.resources. Therefore, to improve the traditionalThe objective of this paper is to investigate theirrigation systems, and to regulate the distributionsoil water distribution and the irrigation uniformityof water resources in a better way, are the effectiveby CRAFI, in order to understand the patterns ofways to increase water use efficiency (WUE), thussoil water infiltration and the dynamics of soil watersaving water use in agricultural production.during the growing season of spring maize. TheseControlled roots-divided alternative furrow ir-results could provide a sripntific basis for the re-中国煤化工PAN Ying hua(1973), Ph D candidete, Tel; 8-2-7033579, E-mail, pan-xMHCNMHGSoil Water Distribution and Irigation Uniformity under Alternative Furrow Irigation787duction of irrigation water use and for the increas-2644 mm, 25 times of the annual precipitation,ing of WUE.From July to September，the precipitation accountsfor 60% of the annual total. Sunshine hours ex-1 Materials and Methodsceed 3 010 h, while the accumulated temperature.1 Climatic conditions of the experiment station≥10°C is3 147. 8C. Depth of ground water tableThe field experiment was conducted at Xiao-is 13- 18 m.bakou Irrigation Experiment Station (38° 05' N,1.2 Soil conditions103*03' E)，Minqin, Gansu Province. This areaSoils are sandy loam with a moderate organicliesin an arid zone with a limited precipitation, amatter content. Gravimetric field capacity are 22. 2higher evaporation, a higher temperature diffe-- 23. 5% in the upper 1 m soil profile. The averagerence between day and night, and a long durationsoil bulk density is 1.49 g cms.of sunshine. The mean annual precipitation in thisTable 1 shows the soil water characteristicarea is about 110 mm，most of which is hardly a- curves in the upper 1 m of the soil profile measuredvailable to crop growth. Annual evaporation iswith a pressure plate.Table 1 Simulated result of soil retention curve and specific water volume equationtLayerSimulated equationRelative coffirientSpecifie volume(ern)0-20”S(0)= 0. 00078 -4.14920.9182C(0)-2 774. 3560 8.143220-40S(8)= 0. 00088 -4.26700.9111C(B)=2 372. 8620 5.261040- 60S(6)= 0. 0008 -.4700.8672C(0)=2 282. 6460 8.47160-80S(0)= 0. 00080 -4.6230.9016C(6)= 2215. 5800.60180- 100S(0)一0. 00090 -4.8420. 9877C(0)=1 869. 8020 5.942+AveragtS(6) = 0. 000808 -4.54740.9770C(0) =2253. 3089 8.3674”S(0): MPa; 0; cm/cm ; C(6): 1/cm1.3 Experimental designing each irrigation. During the whole growing sea-Maize was planted in field ridges and irrigatedson of spring maize, irrigation was applied sevenby furrow irrigation. Furrows were covered withtimes, i.e. ，at seedling (May 30 - June 3), joint-plastic films. The section of furrow was trapezoi-ing (June 16 - 20)，flowering (July 1 - 5), headingdal with a depth of 30 cm, a width of 60 cm, a (July 15 - 19), earing (July 29 - August 2), fllinglength of 62 cm, and both the bottom and the top(August 9- 13), ripening (August 18 - 22).width of 40 cm. Each furrow had an irrigated area1.4 Measurementsof63 m? with a slope of 0. 4%. Sowing date wasSoil surface water contents were measured be-from April 11 to April 20, and sowing depth wasfore and after irigation using the oven drying2.5 cm. Each ridge had two rows of maize with amethod, while a neutron probe was used to mea-plant spaceof 12- 13 cm. The ridge space was 25 - sure soil water contents from 20 to 100 cm depth30 cm, and the furrow space was 70 - 75 cm.by 20 cm increments. Neutron probe access tubesThe experimental design included three irriga-were placed at 10 m intervals along furrows to ana-tion treatments, i.e. ，alternative furrow irrigationlyze soil water distributions for each treatment,(AFI), fixed furrow irrigation (FFI) and conven-Profile soil water contents were measured at eachtional furrow irrigation (CFI). AFI means that onepoint along furrows before rrigation. During wa-of the two neighboring furrows was alternately ir-ter infiltration after irrigation, soil moisture wasrigated during consecutive irrigations. FFI meansmeasured at a certain time interval (1 h or 2 h) atthat irrigation was only applied to one of the twoeach中国煤化工neutron probes.neighboring furrows. CFI was the conventionalMeathree consecu-method, in which every furrow was irrigated dur-tiveMYHC NMH Gd.788PAN Ying hua etaldecreased during the whole growing season. Using2 ResultsAFI, soil water contents both in irrigated and non-2.1 The changes of soil water during crop growingitrigated furrows decreased and increased alter-seasonnately. In addition, there was an obvious differ-Fig. 1 shows the changes of soil water contentence in soil moisture between irrigated furrow andin three irrigation systems during the whole grow-non-irrigated furrow, from which it could be de-ing season of maize. It can be seen from Fig.1 thatduced that the lateral infiltration was more obvioussoil water content increased and decreased alter-by AFI. For the three irrigation systems, duringnately before and after irrigation both for CFI andthe later growing period when maize was about toFFI. By CFI，soil water content in the ridges de-be ripening， crop water consumption decreased,creased in the early period of growing season.causing a slight increase in soil water contentWhile by FFI, the variations of soil water content(compared with the data obtained at day 120 ofin the ridges showed the same tendency as in themaize's growth). .irrigated furrows, i, e.，decreased and increased alter-2.2 Soil water content before and after rrigationnately, but soil water content in non-irrigated furrowsFig.2 shows the profile of soil water contentbefore and after the fourth irigation (July 16).官40After irrigation, as soil water was consumed, soil信35----Rowwater content between the irrigated and non- irri-30gated furrows of AFI remained different till next25irrigation. That is to say, there existed a differ-20ence in soil water potential between furrows. Itsuggests that AFI could cause part of crop root0 49668095108120129141system to be in a wet zone with a higher soil wa-Days(d)ter content, while others in a drier zone with a(a) Conventional furow irigalion (CFI)lower soil water content. Therefore under AFI,lrigated furrowcrop root system could experience a short time of35Non-imigated furowdrought, the adsorptivity of root system couldthus be stimulated.2.3 Soil water distribution along furrows15Soil water distribution along furrows can b49 668095108120129141expressed by irrigation uniformity, which was cal-Day's (d)culated using the Christiansen uniformity coeffi~(b)Fixed furow iatoi(FFn)cient:- Bast fr、名10.-01亘35..-.RowWest furrowN百豆30fwhere cU, is the Christiansen uniformity coef-ficient; 0, is the observed water content for the ith1grid, cm*/cm2 ; 0 is the mean water content alongfurrows, and N is the number of grids.Days (团)Table 2 shows that AFI did not affect the irri-(C) Alemative frrow imigation (AFI)gation uniformitv. with its irrigation uniformity中国煤化工Fige 1 The changes in soll water content in three irigationsystems during the growing season of maizeHCNMHGSoil Water Distribution and Irrigation Uniformity under Alternative Furrow Irigation789Volunettic soil water comtenl (em cm)Vohumetie soil water content (em! ecur)Volbunetrie soil water eontet (cm cm'l)D15_2025301015202530015202530100上300t40-官40个食405050|盟50莫60豆60}7078080 t90100100L+7-17- + 7-14 Non-imigated furow- +7-14 Non-rigared furow7-17 No-irrigated furow士7-17 Noririgated furow- +- 7-14 Imigated furow+7-1十7-14 Iiganede furow→←7 14 Imigted furow)Conventional furow imigtion (CFI)(6) Fiked furow igtion(FF)(C)Altemative frrow igation (AFI)7-14,7-17 represent July 14 and July 17, resectivelyFg.2 The changes in soll water content of three inrigaton sytens before and after irigationTable 2 Irigaton uniformity of three rrigation systems')TrrigationIrrigation amountIrigation-Datetreatmentfor each furtow( m' )Infiow(m2' 851)uniformityJume17CFI1. 860.950, 85FFI3.720.870. 950. 88July 21.860.830.86AFI0.88July 10. 86FI0. 87July 300, 950. 85FF0.820.85August 100. 900.93August 190.89FF10. 92。0.91”Owing to the filure of the first irigation,n there is no deta of its iriation unformityFig. 3 ilustrates dynamics of soil water for thelayer intended to increase with time. After watersame layer(z= 30 cm) of the three irrigation sys-in fu中国煤化工y into soil, ow-tems. It can be seen from Fig. 3 that for the threeing tMYHCNMHGevaporation andirrigation systems, soil water content at the samewatelsoil water con-790PAN Ying-hua etaltent decreased gradually after reaching a maximumConclusionsvalue. Because of the difference in soil water con-tent, there existed a gradient of water potential be-Since the development of AFI, a lot of experi-tween irrigated furrows, ridges and non-irrigatedments on soil water distribution under AFI havefurrows, which enabled soil water to infiltrate lat-been carried out. Compared with CFI, crop rooterally into ridges, thus increasing the water up-system under AFI can experience a period oftake by crops. By CFI, soil water content in ridgesdrought because of the alternative drying and wet-did not change dramatically, while it increasedting during crop growing season, so that its ad-with time under FFI and AFI. There were almostsorptivity was increased. This is also the principleno changes in soil water content in non-irrigatedon which the AFI is based C1]. In addition, due tofurrows of AFI and FFI, which remained nearlythe difference in soil water content between irriga-the same as before irrigation.ted and non irigated furrows, the lateral infiltra-tion of soil water was inereased. In the meantime,o Irigated furowAFI didn't affect irrigation uniformity.20 tOn the other hand, AFI could increase wateruse efficiency and crop photosynthetic rates, whileit has the least effect on maize yield. To achievethe same yield, AFI could save 1/3 irrigation watercompared with CFI. Further information can befound in relative references C5-)].40 50 60Time (h)References()Conventicnal furow imigation[1] KangSZ, ZhangJ H, LiangZS, HuX T, Cai H J. The-。 -migated furowcontrolled alternative irigation -A new approach for water35十Row+ -Noo-imigated furowsaving regulation in farmland. Agricultural Research in theArid Areas, 1997 ,15<1);1 - 6. (in Chinese)25 t[2] KangSZ, Liangzs, Hu w, ZhangJ H. Water use eficienr2u tcy of controlled alternate irigation on ro-divided maiseplants. Agricultural Water Management, 1998, 38:69 - 76.[3] LiangZS, KangSZ, Hu w, ZhangJ H, GroJF. Effetr ofcontolled roots divided alternative irigation on water use ef-1020304050607080ficiency. Transactiomof CSAE, 1997， 13(4): 58-64. (inChinese)[4] L.iangZS, KangSZ, ZhangJ H, GaoJ F. Effect on warer(b) Fixed frrow imigationuse eficiency and water saving by controlled root divided小-。Imigated furowternative rrigation. Scientia Agricultura Sinica, 1998. 31二Noirigatet frw80 H(5) ;88 - 90. (in Chinese)2s[5] KangSZ, ShiPZ. Pan Y H, LiangZs. HuX T, Zhang JH. Soil water dstribution, uniformity and water use eficien-cy under alternate furrow rrigatin in arid areas, IrrigationScience. 2000,19:181 -190..63 Kang sZ, LiangZS, PanYH, ShiP z. ZhangJ H. Alter-20 30)s0 70nate furrow irigation for maize production in an arid area.Time (h) .Agricultural Water Management, 200 45:267 - 274.(C) Alenative fuTo inigationl7] PanY H, Kang s Z. Irigation waler ifilration in furrows中国煤化工Trow rgirion TrasarFig.3 The dynamics of soil water in soil profile (z= 30 cm). (in Chinese)MHCNMHG