Influence of no tillage controlled traffic system on soil physical properties in double cropping area of North China plain

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1 Afrin Journl of Biotehnology Vol. 11(4), pp , 12 Jnury, 2012 Aville online t DOI: /AJB ISSN Ademi Journls Full Length Reserh Pper Influene of no tillge ontrolled trffi system on soil physil properties in doule ropping re of North Chin plin Ri G. Rsily, Hongwen Li*, Jin He, Qingjie Wng nd Ciyun Lu Beijing Key Lortory of Optimized Design for Modern Agriulturl Equipment, College of Engineering, Chin Agriulturl University, Beijing , Chin. Aepted 19 Otoer, 2011 An eperiment ws onduted to determine the effets of tillge on soil properties in the field of mize (Ze mys L.) nd winter whet (Tritium estivum L.) nnul doule ropping region in North Chin Plin. Mesurements were mde following si yers (2005 to 2010) of three tillge tretments; no till with ontrolled trffi (NTCT), no till rndom trffiking (NTRT) nd onventionl tillge (CT) on silt lom ording to the USDA teture lssifition system soil in Ding distrit, whih lies in the suur of Beijing. Long term no till with ontrolled trffi signifintly (P < 0.05) inresed mroggregtes, infiltrtion rte, soil moisture, together with redutions in soil ulk density, soil omption in different lyers ompred with the no till rndom trffi nd trditionl mould ord tillge tretment urrently used in this region. Consequently, men winter whet nd summer mize yields for the NTCT tretment were improved y 2.8 nd 7.1% when ompred with the soils under no till rndom trffi, while huge improvement ws found when it ws ompred with onventionl ploughing mngement (4.2 nd 12.08% for whet nd mize, respetively). The long-term eperiment demonstrted tht notillge ontrolled trffi with residues retined, offers potentilly signifint improvement over the urrent frming systems in nnul doule ropping res of North Chin Plin. Key words: No tillge, ontrolled trffi, soil physil properties, North Chin Plin. INTRODUCTION The North Chin Plin is the min griulturl prodution re whih minly inludes the provines of Heei, Henn, Shndong, Beijing nd Tinjin with out 18 million hetres of frmlnd (18.3% of the ntionl totl), nd represents 20% of totl food prodution in Chin (Sun et l., 2007). The min ropping system in the North Chin Plin is n nnul two-rop system (summer mize nd winter whet) with n verge totl yerly yield of 15 t.h -1 (Li et l., 1997), in whih mize ws seeded in erly June immeditely fter the winter whet hrvest nd hrvested in the middle Septemer. Winter whet ws then seeded in erly Otoer nd hrvested in the following June. Over one million hetres of frmlnd re *Corresponding uthor. E-mil: lhwen@u.edu.n. Tel: now estimted to e under onservtion tillge in rid nd semirid regions of northern Chin (MGrry, 2005). Long-term food seurity nd environmentl qulity re losely linked to mintining soil qulity. Therefore, the ssessment of the effet of tillge prties on soil physil, hemil nd iologil prmeters provided fundmentl informtion out sustinility. The loss of topsoil due to erosion nd redution of soil orgni mtter under onventionl tillge prtie together with eslting fuel pries, hve led to the inresed implementtion of onservtion tillge prtie (Bssett, 2010). With regrds to eologil nd eonomil spet, the disussion out onventionl tillge system nd onservtion tillge system seems to e inresingly importnt. Generlly, the onventionl tillge prtie requires multiple pss of mhines for lnd preprtion like ploughing, hrrowing, ompting/leveling nd seeding while in onservtion tillge prtie, the seeding

2 Rsily et l n e done diretly in single pss with strw hopping mehnism tthed in the front of plnter. This onservtion tillge system imed to develop fvorle soil onditions nd sve energy. However, in rndom trffi onservtion tillge prtie, 60% of the ground re is eing trffiked y wheel using minimum tillge systems nd 100% for zero tillge systems (Tullerg, 1990; Rper et l., 1994; Rdford et l., 2000). Sine multiple wheel trffi strongly influenes the physil properties of soil, the onservtion tillge with ontrolled trffi lne is tken s one of the tretment in this study. Soil physil properties represents group of properties hving the sustntil impt on the different physilhemil nd iologil proessing in soil nd hene they should e kept optiml (Ll, 1991). For this reson, it is essentil to know the soil physil properties not only during the growing sesons ut lso fter the hrvest of griulturl rops in rop rottion s well s the hoie of the soil tillge method. Bulk density, porosity nd wter retention pity re usully reognized s importnt inditors of soil qulity. However, frming method n influene these y ltering soil physil properties. Continuous long term (11 yers) no tillge nd residue over prtie in semirid North Chin Plin led to signifint positive effets on soil properties. The enefits inluded signifintly greter soil orgni mtter ontent nd improved nutrient sttus, inresed mro-ggregte stility, higher proportions of mropores nd mesopores s well s enhned soil wter storge (He et l., 2011). Tillge nd wheel trffi n ffet soil struture y frgmenttion nd omption (Lmnde et l., 2003; Pglii et l., 2004), nd rete heterogeneity in tilled soil etween ompted nd unompted zones. MGrry (2001) identified this s the most serious environmentl prolem used y onventionl tillge. Frequent pssing of trtor with implements or mhines over ompting soil sometimes indues hrdly reprle hnges in the soil tht influene growth nd development of the plnts. One of the most effiient wys to derese the soil omption is y reduing the numer of working opertions (Fili, 2008). The study in North Chin plin showed tht ontrolled trffi onservtion tillge, onstrited omptions in ertin lnes, voiding unneessry energy dissiption on ompting nd undoing ompted soils wheeled y implement itself, nd lrgely improved oth tillge effiieny nd trffi effiieny (Wng et l., 2009). Most of the previous reports out the effet of tillge on soil struture hve een foused on onventionl tillge versus onservtion tillge (no tillge/minimum tillge) on one rop yer region, nd lso for the short period of time. This study ws done to investigte the effets on some soil physil properties in the two rops yer region with the omprison etween two onservtion tillge systems [no tillge with ontrolled trffi (NTCT), nd no tillge with rndom trffi (NTRT) ] with onventionl frming system (CT) prtie in the region. MATERIALS AND METHODS Site desription The eperiment ws onduted t Ding (39 7'N, 116 4'E) distrit, Beijing, during 2005 to Ding lies in south of Beijing in semi-humid region of North Chin Plin whih is 45 m ove se level. Averge nnul temperture is 11.9 C with 186 frost-free dys. Averge nnul rinfll is 526 mm in whih more thn 70% ours during June to Septemer. Doule ropping system with winter whet nd summer mize is the min ropping system prtie in this region. Soil is defined s silt lom ording to the USDA teture lssifition system, whih is low in orgni mtter (< 1%) nd slightly lkline (ph 7.7). Soil in this region is generlly desried s porous nd homogenous to onsiderle depth with limited vrine ross fields (He, 2007). Eperimentl design The eperimentl design used three tretments with three replitions in rndomized loks. Eh tretment ws 9 m wide nd 90 m long. The tretments inluded NTCT, NTRT nd onventionl (moldord plough) tillge (CT). The opertion shedule for eh tretment is presented in Tle 1. No tillge tretments were with full strw over (100% soil over). Stnding stule of 0.30 m height ws retined with ll whet strw left s soil over (out 3.8 t/h) fter whet hrvest nd mize stule were retined in the field during whet plnting period. The lyout of rop rows nd permnent trffi lnes (0.45 m for wheel trk) were designed to ommodte the hrteristis of the lol trtors nd plnters. Mesurements Soil smpling nlysis Soil smpling for soil physil properties mesurements ws rried out in June 2010 fter whet hrvest. Undistured soil smples using the 50.4 mm dimeter 50 mm long mnul stinless steel ore smpler were olleted from rndom lotion in ll three tretments. Three distured soil smples were olleted t 0 to 10, 10 to 20 nd 20 to 30 m soil depths in eh plot, nd mied to form single omposite smple for eh depth nd for ggregte stility mesurements. All the mesurements were replited three times. Bulk density, soil grvimetri wter ontent nd totl soil porosity In eh plot, nine rndom soil smples were tken in the depth of 0 to 10, 10 to 20 nd 20 to 30 m, nd then weighed wet, dried t 105 C for 48 h nd weighed gin to determine ulk density nd soil grvimetri wter ontent. Totl porosity (TP) ws lulted from ulk density (BD) nd the prtile density ws mesured (tht is, 2.65 mg/m 3 ) (Ssl et l., 2006). Soil wter-stle ggregtion Soil wter-stle ggregte distriution ws determined y pling the soil smple on nest of sieves, immersing diretly in wter nd gitting the sieves up nd down 35 mm t 30 yles min 1 for 15 min. Smples remining on eh sieve were dried nd proportions of wet stle ggregtes > 2, 2 to 1, 1 to 0.5, 0.5 to 0.25 nd < 0.25 mm were lulted. The frtion of miro-ggregtes were tken

3 858 Afr. J. Biotehnol. Tle 1. The opertion shedules for NTCT, NTRT nd CT tretments in Ding during the eperimentl yers from 2005 to Prmeter Jn Fe Mr Apr My June July Aug Sept Ot Nov De Mize Rotry ploughing + plnting (CT) No-till plnting (NTCT nd NTRT) Sprying (NTCT nd NTRT) Hrvesting (CT) Hrvesting + residue hopping (NTCT nd NTRT) Whet Ploughing/hrrowing/ Leveling/ plnting (CT) No-till whet plnting (NTCT nd NTRT) Irrigtion (NTCT, NTRT nd CT) Hrvesting whet (NTCT, NTRT nd CT) NTCT, No till ontrol trffi; NTRT, no till rndom trffi; CT, onventionl tillge. s those < 0.25 mm (Odes nd Wters, 1991). All the mesurements were replited three times. vlues were mde on the sis of the lest signifint differene (L.S.D.). Soil omption The soil omption dt were olleted in Ferury during the dry period of whet seson. The soil omption ws mesured y the SC900 Field Sout Soil omption meter, Spetrum Tehnologies, In. The soil omption of different tillge systems were mesured t the depths from 0 to 30 m in the intervl of 2.5 m. All the mesurements were replited three times. Infiltrtion rte Infiltrtion of wter into the soil ws determined in eh tretment using doule ring infiltrometer (Bouwer, 1986) with 30 m inner dimeter nd 60 m outer dimeter ylinder inserted 10 m into the soil t the eperiment field. Wter entering the soil ws mesured with lirted Mrriot ottle. A onstnt wter hed of 20 mm ws mintined in oth rings. Infiltrtion mesurements were mde t three seprte rndomly seleted points in eh tretment. Yield Whet nd mize grin yields were determined t 12% moisture ontent y mnully hrvesting 3 m length of rows tken rndomly in eh plot with three replitions in eh yer. Sttistil nlysis The SPSS nlytil softwre pkge ws used for ll sttistil nlyses. Men vlues were lulted for eh of the mesurements, nd ANOVA ws used to ssess the effets of onservtion tillge on the mesured vriles. When this indited signifint F-vlue (P < 0.05), multiple omprisons of men RESULTS AND DISCUSSION Bulk density, soil grvimetri wter ontent nd totl soil porosity Soil ulk density is first pproimtion of potentil hnges in soil struture with improved mngement (Arshd et l., 1999). Men soil ulk density in 0 to 10 m from NTCT (rop zone), NTRT, CT nd Wheel Trk (WT) in NTCT field were 1.25, 1.26, 1.05 nd 1.45 g/m 3, respetively. This shows tht the ulk density in NTCT ws 16.67% nd NTRT ws 16%; signifintly higher (P < 0.05) thn the CT nd WT whih ws 13.8 nd 13.1% higher (P < 0.05) thn NTCT nd NTRT, respetively. Men soil ulk density in 10 to 30 m depth ws signifint etween NTCT nd NTRT tretments (P < 0.05) with NTRT ulk density of 5.8% in 10 to 20 m nd 5.6% in 20 to 30 m higher thn NTCT tretment, demonstrting the inrese in ulk density whih ourred in the NTRT tretment; this ws proly used y wheel trffi. Men ulk densities of CT nd WT in 20 nd 30 m were signifintly high (P < 0.05) when ompred with NTCT nd NTRT tretments (Figure 1). The greter ulk density in this lyer of the onventionl tretment indited the development of ompted hrd pn eneth tillge depth used y the trffi ssoited with tillge. The hnges of soil ulk density were onsistent with the findings of Mou et l. (1999), who showed tht soil ulk density in 20 to 30 m soil depth in northern Chin ws 5.4% lower for no-tillge

4 Soil grvimetri wter ontent (%) Bulk density (g/m3) Rsily et l NTCT NTRT CT WT Depth (m) Figure 1. Men soil ulk density (g/m 3 ) of the three tretments (NTCT, NTRT, CT) nd wheel trk (WT) in 0 to 30 m soil profile. Mens within the sme olumn followed y the sme letter re not signifintly different t P NTCT NTRT CT Depth (m) Figure 2. Men soil grvimetri wter ontent (%) of the three tretments in 0 to 30 m soil profile. Mens within the sme olumn followed y the sme letter re not signifintly different t P thn for onventionl tillge fter five yers. The results lso oinided with the findings of Sef et l. (2011), where the highest soil ulk density vlues were found with the rotry tiller with roller t oth 0 to 5 m nd 5 to 10 m soil depths; this ws due to the roller used whih used more soil omption thn in the rotry tiller nd onventionl frming systems. The effets of tillge systems on soil grvimetri wter ontent were found sttistilly signifint (P < 0.05) in the depth of 0 to 10, 10 to 20 nd 20 to 30 m (Figure 2). No tillge systems (NTCT nd NTRT) onserved more soil moisture ompred to the onventionl tillge (CT). Hjsi (2003) lso reported tht soil grvimetri wter ontent pity is inresed y reduing soil tillge intensity. The moldord plow used in CT used more moisture loss euse it inverted the soil in the tillge depth. The highest temperture ws found in CT in ll level of depths followed y NTRT nd NTCT. The totl soil porosity in 0 to 10 m soil lyer ws found to e 60.38% in CT while only 52.7, nd 45.38% were found in NTCT, NTRT nd WT. However, s the depth inreses (10 to 30 m), CT nd WT totl soil porosity ws signifintly less (P < 0.05) in omprison with NTCT nd NTRT whih is illustrted in Figure 3.

5 Totl soil porosity (%) 860 Afr. J. Biotehnol NTCT NTRT CT WT Depth (m) Figure 3. Men totl soil porosity (%) of the 3 tretments (NTCT, NTRT, CT) nd wheel trk (WT) in 0 to 30 m soil profile. Mens within the sme olumn followed y the sme letter re not signifintly different t P Tle 2. Soil wet stle ggregte size lsses (mm) t 0 to 0.10, 0.10 to 0.20 nd 0.20 to 0.30 m depths (%). Soil depth (m) 0 to 0.10 Tretment Aggregte Mro Miro > 2 2 to 1 1 to 0.25 < 0.25 > 0.25 < 0.25 NTCT NTRT CT to 0.20 NTCT NTRT CT to 0.30 NTCT NTRT CT Vlues within olumn in the sme depth followed y the sme letters re not signifint (P > 0.05). These results re onsistent with those of He et l. (2011) nd demonstrted the negtive long-term effets of onventionl tillge on mro- nd meso-pore volumes. Soil wter-stle ggregtion Soil ggregtes re influened y orgni mtter nd orgnisms present in the soil, soil teture, rop rottion nd tillge prties. Soil ggregtion is n importnt vrile, influening soil struture nd soil erosion (Eldridge nd Leys, 2003). Tle 2 illustrtes the tretment effets on ggregte wet stility in two size lsses nd for three tretments t 0 to 10, 10 to 20 nd 20 to 30 m depths. Signifint (P < 0.05) tretment differenes ould e seen in the size distriution of wterstle soil ggregtes. In long term no-till soil oth in NTCT nd NTRT, the perentge of wter-stle ggregtes of the lrgest size lss (> 2 mm) ws pproimtely twie tht in ploughed soil (CT) in ll 0 to 10, 10 to 20 nd 20 to 30 m depths, whih ws onsistent with the findings of Li et l. (2007) in long term no-till soil, where the perentge of wter-stle ggregtes of the lrgest size lss (> 2 mm) ws pproimtely twie tht in ploughed soil in oth 0 to 0.10 nd 0.10 to 0.20 m. The highest perentge of lrgest size lss (> 2 mm) ws found in NTCT with 23.7, 30.5 nd 36.8% in 0 to 10, 10 to 20 nd 20 to 30 m, respetively; signifintly higher (P < 0.05) thn NTRT. Similrly, the perentge of wter-stle ggregtes of

6 Soil omption (Kp) Rsily et l NTCT NTRT CT Depth (m) Figure 4. Men soil omption (Kp) of the three tretments (NTCT, NTRT, CT) in 0 to 30 m soil profile. Mens within the sme olumn followed y the sme letter re not signifintly different t P the smllest size lss (< 0.25) ws greter in CT. Mroggregtes onstituted 56, 60 nd 39% in NTCT tretment of 0 to 10, 10 to 20 nd 20 to 30 m depths, respetively, wheres NTRT tretment onstituted 53, 54 nd 52% ompred with 34, 42 nd 41% for CT tretment. These results greed with those of MHugh et l. (2004) who demonstrted the dmging effets of hevy trtor nd mhinery wheels on soil physil properties suh s soil ggregtes distriution, nd its impt on wter vilility to plnt roots. Soil omption Figure 4 illustrtes the soil omption in response to different tillge systems fter si yers of plnting whet nd mize rops. The soil omption ws inresed y inresing soil depth in ll of the tretments. The effets of tillge systems on the soil omption were not signifint etween tretments till the depth of 5 m. However, s the depth inreses, the soil omption level of NTRT ws found to e signifintly higher thn NTCT (P < 0.05) from the depths of 12.5 m, wheres it ws non signifint with CT till the depth of 17.5 m. CT ws found to e higher (P < 0.05) thn NTCT in ll the depths from 10 m. In the depth of 20 to 30, ll the tretments were highly signifint etween eh other. The results indite tht ontrolled trffi onservtion tillge ould minimize the omption of wheel trffi, mke field opertion timely nd preisely, improve soil struture s well s inrese soil moisture on rop zone, whih is enefiil to rop estlishment nd growth (Wng et l., 2005). The results lso gree with the findings of Tullerg (1990), tht trffiking y wheeled frm mhines were ommon in griulturl opertions even in zero tillge systems. Infiltrtion rte Soil wter infiltrtion rte under NTCT, NTRT nd CT deresed with time (Figure 5). In the eginning stge of the infiltrtion test, differenes etween the infiltrtion rtes of NTCT, NTRT nd CT plots were negligile, proly due to the similrity of soil physil properties in the upper lyer. However, when wter infiltrted into deeper soil lyers, NTCT nd NTRT plots showed signifintly (P < 0.05) higher infiltrtion rtes thn CT plots. Consequently, totl infiltrtion under NTCT nd NTRT tretment ws greter, nd finl (stedy stte) infiltrtion rte for NTCT (22.0 mm min -1 ) nd NTRT plots (19.0 mm min -1 ) ws pproimtely five times tht of the CT plots (4.0 mm min -1 ). The greter finl infiltrtion rte in the plots under NT ws proly own to the residue retention of the surfe, less disturne to the ontinuity of wter onduting pores (Ahry nd Sood, 1992) nd inresed lrge ( > 2 mm) ggregte stility (Jin He et l., 2009). In CT soils, the degrdtion t 20 to 30 m depth fter si yers of onventionl ploughing signifintly redued mro-ggregtes nd inresed deep soil omption, therey deresing wter infiltrtion. These results onfirm those of Wng et l. (2001) who reported tht finl infiltrtion rte under notillge with residue over (3 yers) ws 1.5 to 1.6 times tht of onventionl moldord plough in northern Chin. Yield During the first three yers of growing sesons, men

7 Infiltrtion rte (mm) 862 Afr. J. Biotehnol NTCT NTRT CT LSD (P < 0.05) Time (min) Figure 5. Chnges in soil infiltrtion rte within 120 min under NTCT, NTRT nd CT tretments. Tle 3. Men yield for winter whet for NTCT, NTRT nd CT tretments during eperiment period (2005 to 2010). Yer Tretment Grin per spike Yer 1 Thousnd grin weight (g) Yield (t/h) NTCT NTRT CT Yer 2 Yer 3 Yer 4 NTCT NTRT CT NTCT NTRT CT NTCT NTRT CT Yer 5 NTCT NTRT CT Mens within the sme olumn in the sme yer followed y the sme letters re not signifint (P > 0.05). winter whet yield nd yield omponents were less ffeted etween the tretments. In the first yer, NTRT tretment showed higher vlues (6.7 nd 7.3% in omprison with NTCT nd CT, respetively) on yield with signifint differene (P < 0.05), wheres in the seond yer, ll the tretments were not signifintly different. In the third nd fourth yer, the men yield vlue of NTCT nd NTRT were non signifint (P > 0.05) ut were signifint with CT tretment. However, in the finl yer (fifth yer) of the eperimentl period, winter whet yield of NTCT tretment ws 2.8 nd 4.2% higher thn NTRT nd CT tretments, respetively, with signifint differene t P < Men five yers grins per spike remined non signifint etween ll the

8 Rsily et l. 863 Tle 4. Men yield for mize for NTCT, NTRT nd CT tretments during eperiment period. Yer Tretment Kernel row numer per yer Yer 1 Kernel numer per row Hundred kernel weight (g) Yield (t/h) NTCT NTRT CT Yer 2 NTCT NTRT CT Yer 3 NTCT NTRT CT Yer 4 NTCT NTRT CT NTCT Yer 5 NTRT CT Mens within the sme olumn in the sme yer followed y the sme letters re not signifint (P > 0.05). tretments in ll the eperimentl period s well s thousnd kernel weight for NTCT nd NTRT whih were not signifint etween tretments ut were highly signifint with CT tretment during the eperimentl period. For mize prodution, higher vlues of oth yield omponents nd yield were oserved in NTCT tretment. In the verge of five yers, yield omponents in NTCT tretment were higher thn tht in NTRT nd CT tretments with signifint differene in men hundred kernel weight (4.98% with NTRT nd 3.94 % with CT). Consequently, higher yield ws pronouned in NTCT tretment. In the first yer, the inrese in yield ws 7.7 nd 6.8% ompred with NTRT nd CT, respetively. In the finl yer of the eperimentl period, yield in NTCT ws 12.08% signifintly (P < 0.05) higher thn tht in CT, nd 7.1% higher thn NTRT tretments whih ws lso signifintly higher (5.34%) thn CT tretment. Chen et l. (2008) demonstrted tht even with 20% of lnd used for permnent trffi lnes, overll men whet yield in ontrolled trffi tretments ws 10% higher thn tht in CT tretment, nd the differenes were signifint (P < 0.05) in four of eight yers etween 1999 nd 2006 whih greed with the results found in this study. The soil physil properties ftors otined in this study signified the resons for quiring higher yield in NTCT when ompred with NTRT nd CT tretments. Conlusion The dt from this study showed severl signifint hnges in the physil properties of soil fter si yers of no till ontrolled trffi mngement when ompred with the no till rndom trffi nd onventionl tillge of whet nd mize prodution in North Chin Plin, whih re s follows: 1. Signifint inrese in mro-ggregtes, infiltrtion rte, soil moisture, together with redutions in soil ulk density, soil omption in different lyers under no till ontrolled trffi, ompred with the no till rndom trffi nd onventionl mould ord tillge tretment urrently used in this region. 2. Winter whet nd summer mize yields for the NTCT tretment were improved y 2.8 nd 7.1% ompred to

9 864 Afr. J. Biotehnol. the soils under no till rndom trffi nd huge improvement ws found when ompred with the onventionl ploughing mngement (4.2% for whet nd 12.08% for mize). 3. The long-term eperiment demonstrted tht no-tillge ontrolled trffi with residues retined, offers potentilly signifint improvement over the urrent frming systems in nnul doule ropping res of North Chin Plin. These improvements in the physil ondition of soils under ontrolled trffi re generlly in greement with those reported for similr tretments in Loess Plteu of Chin nd Austrli. 4. From the perspetive of sustinle development, more long-term reserh on the reltionships etween onservtion tillge, soil struture, rop produtivity nd environmentl integrity is needed in nnul doule ropping res in North Chin Plin. ACKNOWLEDGEMENTS This work ws supported y Beijing Nturl Siene Foundtion (Finne Numer: ) for the study on the pplition nd ron sequestrtion potentil of whole-yer onservtion tillge in two rops yer region of Beijing's suur. The uthors thnk ll the postgrdute students working in the Conservtion Tillge Reserh Centre, Ministry of Agriulture, who provided their input to this work. REFERENCES Ahry CL, Sood MC (1992). Effet of tillge methods on soil physil properties nd wter epense of rie on n idi Alfisol. J. Indin So. Soil Si. 40: Arshd MA, Frnzlueers AJ, Azooz RH (1999). Components of surfe soil struture under onventionl nd no-tillge in northwestern Cnd. Soil Tillge Res. 53: Bssett TS (2010). A omprison of the effets of tillge on soil physil properties nd miroil tivity t different levels of nitrogen fertilizer t gourton frm, Loskop, Kwzulu-Ntl. Msters Thesis. Fulty of Siene nd Agriulture, University of KwZulu-Ntl, Pietermritzurg, South Afri. Bouwer H (1986). Intke rte: ylinder infiltrometer. 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