Originl Reserch Article No-Tillge Impcts on Soil Hydrulic Properties Compred with Conventionl Tillge Mohmmdrez Khledin 1, 2*, Jen-Clude Milhol 1 nd Pierre Ruelle 1 1 UMR G-EAU Cemgref-Cird-Engref-IRD, PB 5095, 34196 Montpellier Cedex 05, Herult, FRANCE 2 Fculty of Agriculturl Sciences, University of Guiln, PB 41635, 1314 Rsht, Guiln, IRAN Received: 01.04.2012; Accepted: 11.10.2012; Avilble Online: 25.01.2013 ABSTRACT Soil hydrulic properties re very importnt in precision irrigtion, wter nd solute trnsport nd irrigtion scheduling. Tillge cn chnge ner surfce soil hydrulic properties. In this study Beerkn method ws used to better understnd tillge nd no-tillge impcts on trnsmission properties of topsoil. Beerkn is simple in situ method using single ring to mesure infiltrtion rte. This method depends on n lgorithm nmely BEST to estimte soil hydrulic properties. This study ws crried out t Cemgref experimentl sttion in Montpellier in the South-estern Frnce. Three different infiltrtion mesurement series were done in both no-tillge nd conventionl tillge tretments. The first infiltrtion mesurement series ws performed fter hrvest of durum whet; the second one ws performed fter sowing of corn nd finlly the lst one ws performed fter the hrvest of corn. By using those three series s input dt, BEST model estimted sturted hydrulic conductivity (Ks), sorptivity, the men chrcteristics of hydruliclly functionl pore size nd cpillry length. The results indicte tht fter hrvest, hydrulic properties were not significntly different; however fter sowing of corn, Ks ws significntly higher in CT system (p<0.05). These conditions should be tken in ccount to perform irrigtion, fertiliztion nd grochemicl gent pplictions. Key Words: Beerkn method, no-tillge, conventionl tillge, soil hydrulic properties INTRODUCTION No-tillge (NT) is n ecologicl pproch of soil mngement which hs higher efficiency thn conventionl tillge (CT) to improve soil qulity. However, the response to NT depends lrgely on the climtic conditions, mulch quntity on the soil surfce nd soil mngement (Khledin et l. 2012). Tillge lrgely influences pore size distribution. Soils under CT generlly hve lower bulk density nd ssocited with higher totl porosity within the ploughed lyer thn no tillge (Liepic et l. 2006). The reltionships between soil pore structure induced by tillge nd infiltrtion ply n importnt role in wter nd solutes trnsport chrcteristics in soil. An importnt function of soil is trnsmission of wter, which directly ffects plnt productivity nd environment. In NT, greter infiltrtion rte ws ttributed to greter contribution of flow-ctive mcro-pores mde by soil microorgnisms, worms, nd roots of preceding crops (Lmpurlnes nd Cntero-Mrtinez 2006). As cited by Ssl et l. (2006) such bio-pores re more effective for wter nd ir movement nd root growth, becuse they re more continuous, less tortuous, nd more stble thn mcro-pores creted during ploughing (Hubbrd et l. 2001). However the effects of soil tillge nd mngement on trnsmission properties re not uniform. The results of severl study showed tht no tillge s compred with CT hd greter (McGrry et l. 2000), similr (Ssl et l. 2006) or lower infiltrtion rte (Ferrers et l. 2000, Moret nd Arrue 2007). Studying soil properties requires the determintion of soil hydrulic prmeters. This is importnt for understnding nd chrcterizing the hydrologicl cycle nd trnsfer of contminnts with wter. Different functionl reltionships hve been proposed in literture to describe the reltionships between soil wter vribles i.e. soil wter content,, pressure hed, h, nd hydrulic conductivity, K (Lssbtere et l. 2006). In this context, the Beerkn method, which is simple in situ, using single ring infiltrtion, provides field soil hydrulic properties. This method depends on n lgorithm, BEST, which specificlly reltes to vn Genuchten s reltion (vn Genuchten 1980), for wter retention curve, h(θ), with the condition of Burdine (Burdine 1953), nd to Brooks nd Corey s (Brooks nd Corey 1964) reltion for hydrulic conductivity, K(θ). The hydrulic chrcteristic curves, h(θ) nd K(θ), were defined by their form nd scle prmeters. The BEST lgorithm enbles us to estimte those prmeters from prticle size distribution, dry bulk density nd from modelling the experimentl infiltrtion trils (Mubrk et l. 2009 nd 2010). The im of the reserch reported here ws to * Corresponding uthor: khledin@guiln.c.ir 213
determine whether or not NT system improves soil hydrulic prmeters s compred with CT. The results of this study cn help us to better understnd the NT impcts on wter nd solutes trnsfer in soils. MATERIALS AND METHODS A field experiment under irrigtion condition ws estblished t the experimentl sttion of Cemgref t Montpellier in the South-estern Frnce. The verge nnul rinfll is 780 mm yer-1 (1991-2011). Evportion exceeds rinfll throughout the yer under this Mediterrnen climte. Those climte dt were monitored t wether sttion within the experimentl sttion. Two different tillge tretments i.e. CT nd NT hve been pplied since 2000. The precedent crop residue ws kept in the field. Retined residues were incorported if tilled (CT), or left on the surfce with NT. This pper dels with the two cropping sesons i.e. 2005-2006 nd 2006-2007. In CT plots, primry tillge for durum whet with disc hrrow ws done to chop nd bury the residues t the end of July 2005. Secondry tillge with plough ws performed t the beginning of October. Depth of the tillge ws close to 25cm in verge. By using hrrow, seedbed ws prepred nd durum whet sowing ws performed using seeder. Durum whet ws sown in both CT nd NT in November 2005. In NT plots, specific seeder for NT nmely Semeto ws used. After hrvest in June 28, the experiment re ws left completely fllow over summer. The first infiltrtion mesurement series ws performed from 17 to 23 July 2006 pproximtely one month fter durum whet hrvest. In October 2006, mixed of ot, vetch nd rpe ws plnted in NT tretment s cover crop nd ws destroyed by glyphoste in April 2007 before sowing corn. In CT plots, t the end of July disc hrrow ws used to chop nd bury the residues of durum whet. At the middle of November tillge with plough ws performed. Depth of the tillge ws close to 25cm in verge. Using hrrow, seedbed ws prepred nd corn sowing ws performed by the specific seeder. In NT plot, fter destroying the cover crop we used only the sme seeder for NT. The second infiltrtion mesurement series ws done in My 2007 one month fter sowing. The third infiltrtion mesurement series ws done in September 2007, fter hrvest. Infiltrtion mesurements were performed in ten rndomly selected sites of ech plot. Soil smples were tken from the sme sites to determine prticle size nd initil soil humidity. Soil bulk density (ρd) ws determined using gmm probe (Troxler 3440). For the instlltion of the cylinder, the surfce residue or vegettion is removed while the roots remin in situ. Then the cylinder is positioned t the soil surfce nd driven 1 cm into to the soil to void lterl losses of ponded wter t the soil surfce. A defined volume of wter is dded into the cylinder (15-20 cm of dimeter) t time zero, nd the time elpsed during the infiltrtion should be mesured. When the first volume hs completely infiltrted, immeditely the second known volume of wter is dded, nd cumultive time is recorded. The procedure is repeted for series of bout 8 to 15 known volumes nd cumultive infiltrtion is recorded. Finlly, the dt set is mde up of number of discrete points (ti, Ii). At the end of the experiment, the sturted soil is smpled to determine the sturted volumetric wter content (for more detils refer to (Brud et l. 2005, Lssbtere et l. 2006). In this study, the BEST lgorithm ws used to determine soil hydrulic properties through the vn Genuchten eqution for the wter retention curve, h() (Eq. (1)) with the Burdine condition (Eq. (2)) nd the Brooks nd Corey reltion (Eq. (3)) for the soil hydrulic conductivity curve, K(h) (Burdine 1953, Brooks nd Corey 1964, vn Genuchten 1980): h h r s r vg n m 1 Eq. 1 2 m 1 Eq. 2 n 214
K K s r s r Eq. 3 where n nd m re the dimensionless shpe prmeters of the wter retention curve nd vg is simply clled the lph-prmeter of the vn Genuchten model (m 1). Ks is the sturted hydrulic conductivity (m s 1) nd is the shpe prmeter of the soil hydrulic conductivity reltionship. By those dt s input, BEST, 3D infiltrtion model cn estimte sturted hydrulic conductivity, sorptivity, the men chrcteristic of hydruliclly functionl pore size nd cpillry length. Soil totl porosity (TP) ws clculted s the function of totl volume not occupied by soil ssuming prticle density (ρs) of 2.65 Mg m-3 using Eq. 4. Tretment effects on mesured vribles were tested by nlysis of vrince (ANOVA) t P<0.05 using SPSS softwre pckge. In the event tht significnt F-vlues were found in nlysis of vrince, differences mong tretments were seprted using lest significnt differences (LSD). RESULTS AND DISCUSSION TP=1-(ρd/ρs) Eq. 4 Tble 1 presents the prticle size, texture, orgnic mtter nd orgnic crbon of soil t both plots. There is the sme soil texture ccording to USDA soil clssifiction system. There is more orgnic mtter nd orgnic crbon in NT plot s the long-term benefits of NT system. The verge of bulk density, totl porosity nd three outputs of BEST i.e. sorptivity, cpillry length (αh) nd the men chrcteristic of hydruliclly functionl pore size (m) of soil surfce, re shown in Tble 2. One month fter the plnting dte of corn in 2007, bulk density ws significntly different s compred with hrvest of 2006 nd 2007, being the lowest mong others. This is relted to soil preprtion before sowing in CT. The results of Osunbitn et l. (2005) re in greement with these findings. In NT, bulk density hs being decresed from 1.47 in 2006 to 1.32 g cm-3 in the beginning of 2007 seson. Tht cn be ssocited with the cover crop effects, producing more bio-pore due to the decyed root chnnels or the mcro-pore mde by soil fun (Mubrk et l. 2009). In 2007, one month fter sowing, bulk density ws not significntly different in CT nd NT. The soil bulk density ws higher in CT (1.47 vs. 1.42 g cm- 3) fter the hrvest of corn in 2007; however the difference ws not significnt. The bulk density incresed with time in CT from the beginning of seson to hrvest s the soil grdully get compcted under the influence of irrigtion nd rinfll nd prticle resettlement (Osunbitn et l. 2005). Totl porosity ws higher in CT except of 2007 hrvest; however the differences were not significnt. Higher porosity in CT ws reported by Glb nd Kulig (2008). Tble 1. Some soil physicl nd chemicl properties t the Cemgref experimentl sttion (ll soil properties presented here re for 0-30 cm). Tretments Cly Silt Snd Texture (USDA) Orgnic mtter Conventionl tillge 18 42 40 lom 1.55 0.91 No-tillge 17 39 44 lom 1.76 1.02 Orgnic crbon 215
Tble 2. The verge of bulk density, totl porosity, sorptivity, cpillry length (αh) nd the men chrcteristic of hydruliclly functionl pore size (m) of soil surfce mesured t hrvest of durum whet (July 2006) nd fter sowing of corn (My 2007) in conventionl tillge (CT) nd no-tillge (NT) tretments. Mesuring time Plots Bulk density (Mg.m-3) Totl Porosity Sorptivity (mm.s-0.5) h (mm) m (mm) 2006 CT 1.35 49c 0.857 67b 0.12 Hrvest NT 1.47b 45b 0.741b 69b 0.11b 2007 CT 1.26c 52c 0.715b 49c 0.17b Sowing NT 1.32c 50c 0.563bc 87b 0.12b 2007 CT 1.47b 45b 0.422c 40c 0.19c Hrvest NT 1.42b 46b 0.467c 89d 0.09 * Dt within the sme column followed by the sme letter re not significntly different t the probbility level p<0.05. Sorptivity vlues, being indictive of soil wter diffusivity nd thus unsturted hydrulic conductivity ws higher in CT thn NT beside of 2007 hrvest; however the difference ws not significnt between tillge tretments. These results should be considered s pproximte vlues, since initil soil moisture content ws not identicl mong ll mesurements. Higher sorptivity in CT ws reported by McGrry et l. (2000). Sorptivity, which is wter uptke by soil when there is no grvittionl effect, is good index of how the tillge tretments hve influenced soil structure. It provides informtion on the soil bsorption rte nd vries with initil wter content nd structurl stbility. In this study αh nd m were ssessed in CT nd NT. m ws not significntly different in CT nd NT for both 2006 nd 2007 fter sowing, but it ws significntly lower in 2007 fter hrvest (0.19 vs. 0.09 mm in CT nd NT, respectively). In 2006, αh ws not significntly different in CT nd NT (67 vs. 69 mm in CT nd NT, respectively). But in 2007, it decresed nd increses significntly in CT nd NT, respectively s compred with 2006. However the difference between CT nd NT ws not significnt. The reduction of αh in CT cn be relted to decresing in bulk density. In CT, decresing in αh nd incresing in m reflect the chnges in pore sizes nd hydrulic conductivity due to soil loosening mde by tillge. In NT 2007, the increse in αh cn be due to different pore size distribution in the surfce lyer. The difference in h vlues should be interpreted resulting from differences in the soil pore system, which my hve been induced by the tillge mngement. The differences in bulk density observed together with the greter mcro-porosity probbly induced by root or soil fun in the surfce lyer (Mubrk et l. 2010). Sturted hydrulic conductivity (Ks) in both CT nd NT tretments re shown in Figure 1. Ks ws not significntly different in CT nd NT tretments in 2006, however Ks ws higher in CT. Tht cn be due to higher plnt density in CT, hving more decyed root chnnels (264 vs. 200 plnts m-2 in CT nd NT, respectively). Furthermore, totl porosity which cn ffect on Ks ws higher in CT. Osunbitn et l. (2005) found strong nd positive regression between soil hydrulic conductivity nd totl porosity with R2 vlue of 0.96 for both NT nd CT. The reltionships were significnt t 5% probbility level. 216
Ks (cm.h -1 ) J. BIOL. ENVIRON. SCI., 6 5 b 4 3 2 1 0 CT NT CT NT CT NT 2006 t hrvest 2007 t sowing 2007 t hrvest Figure 1. The verge of sturted hydrulic conductivity in the soil surfce mesured fter hrvest of durum whet (July 2006) nd fter sowing nd hrvest of corn (My nd September 2007, respectively) in conventionl tillge (CT) nd no-tillge (NT) tretments. Different letters within tillge systems indicte significnt differences (p<0.05). Ks ws significntly different in 2007 fter sowing, being higher in CT thn NT. This cn be relted to soil preprtion in CT tretment before plnting resulting in lower bulk density. In contrst, Ks ws not significntly different in CT tretment for 2006 nd 2007, however Ks ws higher in 2007 (4.66 in 2007 s compred with 3.35 cm h-1 in 2006). For NT tretment, the difference ws not significnt for 2006 nd 2007. However, Ks ws higher in 2006 (2.79 in 2006 s compred with 2.51 cm h-1 in 2007). In spite of expected increse of Ks, due to soil decompction i.e. decresing bulk density from 1.47 in 2006 to 1.32 Mg m-3 in 2007, Ks decresed in NT 2007. The Ks diminution could be due to different pore size distribution nd their orienttion rther thn to totl porosity in the surfce lyer. Ks depends not only on totl porosity but lso, nd primrily, on the size of the conducting pores. Crcks, worm holes, nd decyed root chnnels my ffect flow in different wys. Anken et l. (2004) found tht preferentil flow chnnels were more continuous, even though mcroporosity ws smller in NT s compred with moldbord plow or chisel plow. It is possible tht differences in orgnic mtter nd orgnic crbon (Tble 1) cused the differences in Ks in CT nd NT s ttested by some pedo-trnsfer functions (Rwls et l. 2005). Although NT cn promote or preserve preferentil flow chnnels or mcroporosity in soils, other surfce or subsurfce chrcteristics in NT my hve constrined wter movement. Probbly the presence of n orgnic lyer overlying the soil restricts wter movement. Prtilly nd well decomposed orgnic mtter in NT cn form this lyer. The importnce of this orgnic lyer ctully regulting soil hydrologicl process hs importnt impliction for crop production (Shrrt et l. 2006). After the hrvest of 2007 in CT, Ks ws significntly lower. The sturted hydrulic conductivity of CT generlly decresed with time fter sowing due to soil resettlement nd compction effects of irrigtion nd rinfll (Krib et l. 2001 nd Mubrk et l. 2009). Ks ws lower in NT fter the hrvest of corn in 2007, however the difference ws not significnt. CONCLUSIONS Soil tillge is defined s mechnicl or soil-stirring ctions exerted on soil to modify soil conditions for the purpose of nurturing crops. Results of vrious investigtions from lmost ll world climtic zones suggest tht plowing often revels common soil-relted problems such s soil compction, soil erosion, deteriorted wter percoltion, nd high energy nd time requirement (El Titi 2003). As response to those problems, conservtion tillge, including no-tillge (NT) ws proposed. This system hs often higher efficiency thn conventionl tillge (CT) to improve soil properties. Modifictions of soil structure by soil tillge cuse chnges in conductivity nd permebility chrcteristics for wter nd solute trnsport in soils nd their sptil distribution. Using tillge 217
resulted in incresing some hydrulic chrcteristics of topsoil, however these effects of tillge re short lived. So tht in the environmentl point of view there is higher risk of pollution trnsport in CT system especilly fter soil opertion. The differences in CT nd NT cn be relted to different soil lyer which exist in the topsoil of NT which cn cuse sptil heterogenity of hydrulic properties of the porous medi while tillge hs the homogeniztion effects in the topsoil of CT system. More study is necessry to better understnd the porous medi under NT system especilly over the growing seson. REFERENCES Anken T, Weisskopf P, Zihlmnn U, Forrer H, Jns J, nd Perhcov K (2004). Long-term tillge system effects under moist cool conditions in Switzerlnd. Soil Till Reserch 78: 171 183. Brud I, De Condpp D, Sori JM, Hverkmp R, Angulo-Jrmillo R, Glle S, nd Vuclin M (2005). Use of Scled forms of the infiltrtion eqution for the estimtion of unsturted soil hydrulics properties (the Beerkn method). Eur. J. Soil Science 56: 361-374. Brooks RH, nd Corey CT (1964). Hydrulics properties of porous medi. Hydrol., Pper 3., Colordo Stte University, Fort Collins. Burdine NT (1953). Reltive permebility clcultion from pore size distribution dt. Petr Trns Trns Am Inst Min Metll Eng 198: 71-77. El Titi A (2003). Soil Tillge in Agroecosystems. CRC Press LLC, USA. Ferrers LA, Cost JL, Grci FO, nd Pecorri C (2000). Effect of no-tillge on some physicl properties of structurl degrded Petroclcic Pleudoll of southern Pmp of Argentin. Soil Till Reserch 54: 31 39. Grdner WR (1958). Some stedy-stte solutions of the unsturted moisture flow eqution with ppliction to evportion from wter tble. Soil Science 85: 228 232. Glb T, nd Kulig B (2008). Effect of mulch nd tillge system on soil porosity under whet (Triticum estivum). Soil Till Reserch 99: 169-178. Hubbrd RK, Lowrnce RR, nd Willims RG (2001). Preferentil flow in clyey Costl Plin soil s ffected by tillge. ASAE 261 262. Khledin MR, Milhol JC nd Ruelle P (2012). Yield nd Energy Requirement of Durum Whet under No-Tillge nd Conventionl Tillge in the Mediterrnen Climte. Journl of Biologicl nd Environmentl Sciences, 6(16):59-65. Krib M, Hllire V, Curmi P, nd Lhmr R (2001). Effect of vrious cultivtion methods on the structure nd hydrulic properties of soil in semi-rid climte. Soil Till Reserch 60: 43 53. Lmpurlnes J, nd Cntero-Mrtinez C (2006). Hydrulic conductivity, residue cover nd soil surfce roughness under different tillge systems in semirid conditions. Soil Till Reserch 85(1-2): 13-26. Lssbtere L, Angulo-Jrmillo R, Sori Uglde JM, Cuenc R, Brud I, nd Hverkmp R (2006). Beerkn estimtion of soil trnsfer prmeters through infiltrtion experiments BEST. SSSA Journl 70: 521 532. Lipiec J, Kus J, Slowinsk-Jurkiewicz A, nd Noslewicz A (2006). Soil porosity nd wter infiltrtion s influenced by tillge methods. Soil Till Reserch 89: 210-220. McGrry D, Bridge BJ, nd Rdford BJ (2000). Contrsting soil physicl properties fter zero nd trditionl tillge of n lluvil soil in the semi-rid subtropics. Soil Till Reserch 53(2): 105-115. Moret D, nd Arrue JL (2007). Dynmics of soil hydrulic properties during fllow s ffected by tillge. Soil Till Reserch 96: 103-113. Mubrk I, Angulo-Jrmillo R, Milhol JC, Ruelle P, Boivin P, nd Khledin MR (2009). Temporl vribility in soil hydrulic properties under drip irrigtion. Geoderm 150: 158-165. Mubrk I, Milhol JC, Angulo-Jrmillo R, Ruelle P, Khledin MR, nd Vuclin M (2010). Sptil nlysis of soil surfce hydrulic properties: Is infiltrtion method dependent? Agr Wter Mnge 97: 1517-1526. Osunbitn JA, Oyedele DJ, nd Adeklu KO (2005). Tillge effects on bulk density, hydrulic conductivity nd strength of lomy snd soil in southwestern Nigeri. Soil Till Reserch 82(1): 57-64. Rwls WJ, Nemes A, nd Pchepsky YA (2005). Effect of soil orgnic mtter on soil hydrulic properties, in development of pedotrnsfer functions in soil hydrology, edited by Pchepsky, Y.A., nd Rwls, W.J. pp. 95-114, Elsevier, Amsterdm. Ssl MC, Andriulo AE, nd Tbod MA (2006). Soil porosity chrcteristics nd wter movement under zero tillge in silty soils in Argentinin Pmps. Soil Till Reserch 87(1): 9-18. Shrrtt BS, Zhng M, nd Sprrow S (2006). Twenty yers of tillge reserch in subrctic Alsk: I. Impct on soil hydrulic properties. Soil Till Reserch 91: 82 88. Vn Genuchten MT (1980). A closed form eqution for predicting the hydrulic conductivity of unsturted soils. SSSA Journl 44: 892-898. 218