Optimising soil disturbance for erosion and runoff control in row crops.

Transcription

1 Ref: C0672 Optimising soil disturne for erosion nd runoff ontrol in row rops. Jonn Niziolomski, Ro Simmons, Jne Rikson nd Mike Hnn, Crnfield Soil nd Agri- Food Institute, Crnfield University, Crnfield, Bedfordshire, MK43 0AL. Astrt Lrge periods of re soil in omintion with onsite omption mke soil nd wter mngement highly pertinent to sprgus prodution. These n result in redued lnd essiility, plnt stress nd wter pollution in lol rivers from eroded sediment. On site omption llevtion with winged tine t 175 mm hs not redued runoff nd erosion events. In order to understnd this n investigtion into the effetiveness of the urrent winged tine under ontrolled onditions hs een onduted. The urrent prtie (winged tine) ws tested ginst four other tine onfigurtions (nrrow tine, winged tine with two shllow leding tines, nrrow tine with two shllow leding tines nd modified pr-plough) in soil dynmis testing fility t Crnfield University. Tine performne ws ssessed t three depths, on severl omption llevition, erosion ontrol nd prtility of pplition prmeters. Signifint differenes were oserved in ove nd elow ground disturne, surfe roughness, drught nd speifi drught etween ll tine onfigurtions t different depths. The urrent winged tine ws not found to e the most effetive for omption llevition, erosion ontrol or prtility t 175mm. However the effetiveness of the winged tine did inrese with depth. The modified pr-plough ws the most effetive t 175 mm. These results ould e used to inform future est prtie in sprgus prodution res nd similr row rops. Keywords: Infiltrtion, omption, shllow soil-disturne, roughness, porosity 1 Introdution Inpproprite soil nd wter mngement, generlly used y lk of doptle nd prtil options, n led to elerted soil erosion. Soil erosion degrdes griulturl lnd, thretening griulturl sustinility. In Englnd nd Wles 2.2 million tonnes of topsoil is lost nnully (SSLRC, 2000), osting the frming industry etween 180 nd 280 million (Grves et l., 2011). Row rops re ssoited with greter res of re soil throughout the growing seson s ompred with erels. These res of re soil loted etween the rop rows re regulrly trffiked, nd eome ompted, reting preferentil flow pths for runoff hnnelling nd onentrting flow. This in omintion with few soil nd wter mngement options mkes row rops prtiulrly suseptile to soil erosion. One suh row rop is sprgus. In the UK, sprgus urrently overs >2000 h, nd for erodile soils on sloping lnd n generte high rtes of runoff nd erosion. In order to Proeedings Interntionl Conferene of Agriulturl Engineering, Zurih, /8

2 ensure the eonomi nd environmentl sustinility of sprgus prodution in the light of the inresed frequeny of extreme rinfll events, runoff nd erosion must e ontrolled. Minimum or no tillge is ommonly dopted for erosion ontrol. Tillge n weken soil struture leving it vulnerle to erosion. However in ompted soil where struture is lredy wekened, tillge remins n importnt nd effetive mens of improving infiltrtion (Meek et l., 1992) nd inresing resistne to erosion. When omption ours ohesive fores exerted y soil loding keep the soil prtiles together. When this soil eomes wet these ohesive fores re wekened mking them vulnerle to dethment nd therefore suseptile to erosion (Mouzen et l., 2002). Tillge n llevite omption y reking through the ompted lyer inresing porosity. This inresed porosity llows wter to infiltrte, nd eome stored, reduing the volume of runoff. With redued runoff the entrinment of loose soil prtiles is lso redued. Inresing soil porosity mens n inrese in soil volume whih results in n re of loosened soil on the surfe. This loosened soil lso interts with runoff. It n redue surfe runoff volume y inresing surfe storge in newly reted surfe depressions. It n lso impede the runoff llowing time for the runoff to infiltrte, nd redue runoff veloity nd thus its erosivity (i.e. energy to deth nd trsnport soil prtiles). In sprgus prodution t Corey Frms shllow soil disturne t 175 mm is undertken to llevite omption whilst preventing dmge to the vlule sprgus root system. However this urrent method is not ddressing onsite omption dequtely, s lrge sle runoff nd erosion issues still persist. Erosion nd runoff redution n e hieved through omintion of shllow soil disturne nd pplition of surfe mulh. This hs een oserved from runoff erosion plots setup in sprgus furrows in 2011 (Niziolomski, 2011). However more reent oservtions from plots set up in the exessively wet yer of 2012 sw this effetiveness derese (Niziolomski, 2013). Different surfe mulh options (mulh type nd pplition rte) hve lredy een investigted (Niziolomski, 2013). Now, the effetiveness of the urrent shllow soil disturne prtie used on site for omption llevition hs een ompred under ontrolled lortory onditions with rnge of ommerilly ville nd innovtive lterntives. 2 Mterils nd methods 2.1 Tines Five tine onfigurtions were tested; winged tine (urrent prtie), nrrow tine (simple tine), winged tine with two shllow leding tines, nrrow tine with two shllow leding tines nd speifilly modified pr-plough (Figure 1). These were speifilly seleted, nd lrgely designed nd uilt for this experiment, sed on the following justifitions. The inlusion of shllow leding tines should enefit erosion ontrol s they n inrese the re of disturne with little or no inrese in horizontl fore (Spoor nd Godwin, 1978). The modified pr-plough ws seleted s n innovtive option; loosening either side of the omption zone, rther thn reking through it (Tthm, 1989). All tine onfigurtions were tested t three depths; 175 mm, 250 mm nd 350 mm. Testing t 175 mm depth reflets the pproximte depth of urrent on-site ultivtion, voiding sprgus root dmge. Onsite penetrometer studies demonstrted ompted lyer to depth nd onsequently deeper ultivtions were tested. 350 mm ws used s the mximum ultivtion depth efore the opertion is defined s su-soiling. A depth of 250 mm ws seleted s good middle ground etween the two. 2.2 Soil testing A soil in (20 x 1.7 x 0.7 m) filled with sterile, light sndy lom soil ws prepred in 50 mm lyers to the plnned depth of ultivtion. A 700 kg roller ws pplied to eh lyer to rete Proeedings Interntionl Conferene of Agriulturl Engineering, Zurih, /8

3 omption. A different numer of rolls reted different ulk densities. In this experiment 13 rolls were pplied to hieve ulk density of pproximtely 1.6 g m -3. This numer ws sertined from triplited sets of three undistured ores tken from 3 different res long the entrl line of the soil in following vrying numers of rolls. This ulk density nd soil type losely refleted the field ondition. Bulk density onsisteny ws heked throughout the experiment with eh new soil in preprtion y tking three single ulk density smples t three entrl points. One prepred, the proessor, with instrumented mounting points, ws fitted with the designed ultivtion equipment (tine). Two tests were rried out per soil in preprtion. The testing ws rried out in two phses; during the first phse eh tine ws tested t 175 mm depth, whilst the seond phse tested eh tine t 250 nd 350 mm depth. For oth stges, ll testing ws undertken on one tine t time. The order of implement testing ws rndomized. Implements were pulled through t pproximtely 2 km hr -1. During the seond stge, the depth of ultivtion for eh tine ws rndomised etween 250 nd 350 mm. However, the first test rried out t 350 mm required horizontl fore in exess of the proessors operting pility. Therefore it ws deided to redue the depth to 300 mm. After the ompletion of two implement runs, the horizontl nd vertil fores were reorded, nd three points were seleted t rndom long the ultivted re for surfe roughness nd ove nd elow ground disturne mesurement. 2.3 Vriles nd dt olletion Performne of the different tine onfigurtions n e divided into three tegories; omption llevition, erosion ontrol nd prtility of pplition. Comption llevition; indited y elow ground disturne. Erosion ontrol; indited y surfe roughenss nd ove nd elow ground disturne Prtil pplitions; indited y men drught fore nd speifi drught. Surfe roughness ws mesured oth horizontl (SR H ) nd prllel (SR P ) to the line of ultivtion. This tkes into ount oth wter pthwys identified in the field (Figure 2); wter from the rised eds into the wheelings (horizontl) nd then downslope in the entre of the wheelings (prllel). Roughness ws mesured t the sme point s ove nd elow ground disturne using the hin method (Sleh, 1993). The hin of known length ws refuly pled ross the distured surfe nd the horizontl distne overed y the hin ws mesured (Gilley nd Kottwih, 1995). This ws divided y the originl hin length nd sutrted from 1, to provide n index of roughness, within whih 0 equted to ompletely smooth surfe. Aove ground disturne (D AG ) ws mesured using profile meter 1 m long with pins t 2 m intervls. Used refully, this ptured the shpe of the disturne. One the pins were lmped in ple the shpe ws tred onto pper. The distne from the soil surfe line ws then mesured, nd the ross setionl re lulted. One ompleted, the re ws refully exvted of loose soil to revel the extent of the elow ground disturne. A profile meter ws used gin to mesure the ross setionl re of elow ground disturne (D BG ). Using horizontl (drught) fore mesurements it is possile to infer high or low fuel osts; with high drught fore ssoited with high fuel ost. A lirted Extended Otgonl Ring Trnsduer (EORT) mesured the horizontl nd vertil fores exerted, through series of strin guges on the tine mounting point. These mesurements were reorded y dt logging softwre (Dt quisition system lortory Version ). It is eqully importnt to onsider the effiieny of eh tine onfigurtion. Tht is the re of soil tht is distured for the drught fore required (speifi drught). This n e lulted Proeedings Interntionl Conferene of Agriulturl Engineering, Zurih, /8

4 using the elow ground ross setionl re nd the men horizontl fore (drught). However for erosion ontrol the most effiient drught should lso inlude the re of ove ground disturne thus generting n erosion ontrol speifi drught (SD E ) (Figure 2). Results were nlysed using STATISTICA 12. Dt ws first heked for normllity using residul nlysis, nd then nlysed using Ftoril ANOVA. This ws followed, when signifint effets were oserved, y post-ho Fisher LSD nlysis. Following results nlysis ove nd elow ground soil disturne, horizontl nd prllel surfe roughness nd speifi drught were rnked using the Pugh mtrix (Burge, 2009). The winged tine ws pplied s the stndrd onfigurtion to whih ll others were ompred. Only sttistil differenes from the stndrd onfigurtion were onsidered. 3 Results 3.1 Comption llevition Out of the 5 tines tested, the urrent prtie winged tine did not generte signifintly higher levels of elow ground disturne for ny of the depths tested (Tle 1). At 175 mm the modified pr-plough reted lmost 1.5 times the loosened re. At 250 nd 300 mm the winged tine, modified pr-plough nd winged with shllow leding tines generted similr res of elow ground disturne. 3.2 Erosion Control Below ground disturne As with omption llevition, the modified pr-plough ws found to e most effetive in disturing greter volumes of soil t 175 mm, with the winged tine of equl effetiveness t 250 nd 300 mm depth Surfe roughness At 175 nd 250 mm no signifint differenes were oserved etween the SR H for eh tine. However, differenes were oserved for SR P, representing the min pthwy of runoff trvelling downslope. At 175 mm the Nrrow tine generted signifintly higher SR P thn ll other tines. At 250 mm the Nrrow tine ontinued to rete the most SR P, lthough sttistilly similr to tht reted y the Nrrow with shllow leding tine. At 300 mm depth the winged with shllow leding tines generted signifintly greter SR H, ut equl to tht of the nrrow with shllow leding tines. Further, three tine onfigurtions generted signifintly more SR P ; the Nrrow, Nrrow with shllow nd Winged with shllow Aove ground disturne The modified pr-plough generted signifintly greter re of D AG t 175 mm depth thn ll other tine onfigurtions. This ontinued t 250 mm, lthough it ws not sttistilly different to the winged with shllow tine onfigurtion. At 300 mm the modified pr-plough, winged tine nd winged with shllow tine reted signifintly higher D AG thn the nrrow nd nrrow with shllow tine onfigurtions. 3.3 Prtility of pplition The winged tine nd winged with shllow oth required signifintly greter men drught s ompred with ll other tine onfigurtions t 175 mm depth. The nrrow tine required the lest. At 250 mm ll drught fores hd inresed with the wing with shllow requiring signif- Proeedings Interntionl Conferene of Agriulturl Engineering, Zurih, /8

5 intly more fore thn ll other onfigurtions. The nrrow nd nrrow with shllow required the lest drught. At 300 mm drught fore inresed gin for ll onfigurtions. The modified pr-plough required the highest drught fore, nd the nrrow nd nrrow with shllow leding the lowest one gin. Considering SD E, signifint differenes were only oserved t 175 mm. At this depth the modified pr-plough, nrrow nd nrrow with shllow onfigurtion were the most effiient, generting the most D AG nd D BG for the lest drught. 3.4 Rnking Following the Pugh mtrix rnking method (Tle 2) the est rnked tine onfigurtion t 175 mm ws the modified pr-plough. At 250 mm it ws the nrrow with shllow leding, nd t 300 mm the winged with shllow onfigurtion. 4 Disussion From the results it is ler tht the urrent prtie winged tine is out performed y different tine onfigurtions for omption llevition, erosion ontrol properties nd prtility t the urrent ultivtion depth (175 mm). Applition of the winged tine t greter depth however, would result in etter omption llevition nd erosion redution, s suggested y the results t 250 nd 300 mm depth. The ineffetiveness of the winged tine t 175 mm depth is most likely due to the wings of the tine not eing fully sumerged into the soil profile, s oserved during testing. The ddition of wings to tines serves to inrese the lterl extent of disturne s the soil mss flows over the wings (Spoor, 2006). The loser the wings re to the soil surfe, the less soil lift ours nd susequently little dditionl soil is distured. Spoor nd Godwin (1978) suggest tht the ddition of wings to tines should inrese elow ground disturne y 50 %. However, in this study the winged tine hieved just 0.73 m 2 (21 %) dditionl elow ground disturne t 175 mm s ompred with the non-winged nrrow tine. At 250 nd 300 mm the winged tine reted over 50 % more elow ground disturne s ompred with the nrrow tine. This suggests tht with inresed depth the wings re disturing soil more effetively. Winged tines typilly rerrnge the soil more thn most tines s result of soil frturing oth from the tine point nd from soil movement over the wings (Spoor nd Godwin, 1978). Therefore in n erosion ontrol ontext it ould e expeted tht this would generte the gretest surfe roughness. However this study shows tht the gretest SR P ws hieved using the nrrow tine nd the gretest SR H y the tion of shllow leding tines. During testing it ws oserved tht resulting D AG from winged tines omprised of muh finer soil prtiles thn from nrrow tines. The soil frture nd prtil lift undertken y the nrrow tine left lrge lods of ompted soil on the surfe, generting rougher surfe. The redued roughness mesured y the winged tine n e ttriuted to the omined effet of soil rerrngement y the wings nd n inherently poor soil struture. The more the soil ws frtured, the looser the soil eme nd without ny inherent struture, the soil roke into very smll soil lods. This resulted in reltively smooth surfe. However, whilst lrge surfe lods re here viewed s enefiil to erosion ontrol under ontrolled onditions it is not onsidered so in the field. Spoor nd Godwin (1978) oserved tht rough surfe omprising of lrge lods of ompted soil ould e more likely to fll k into ple thn rerrnged soil, thus reduing the longevity of effet of the initil loosening. Therefore the smller lods oserved with winged tine disturne might e more effetive long term erosion ontrol mesure. The high drught fores oserved for the winged tine t 175 nd 250 mm re to e expeted. This onfigurtion hs greter re of tine-soil interfe thn other onfigurtions nd thus hs lrger mount of soil ontt s it is pulled through the soil. At 175 mm the modified pr-plough rnks s the most effetive tine onfigurtion for erosion ontrol. This is s result of the lrge ove nd elow ground disturne generted Proeedings Interntionl Conferene of Agriulturl Engineering, Zurih, /8

6 nd the effiieny rtio of drught required to re of distured soil. The high degree of ove nd elow ground disturne is to e expeted s two tines run in prllel through the soil reting two seprte disturne zones. The effet of two tines working in omintion lso results in inresed drught effiieny. If omption t depth is to e ddressed, the Pugh mtrix rnking suggests tht the nrrow with shllow leding tines would e most effetive t 250 mm, nd the winged with shllow leding tines t 300 mm. This highlights the enefits of dding shllow leding tines. The role of the shllow leding tine is to rek soil in the pth of the min tine, thus reduing the onfining fores (Spoor, 2006). This enles the min tine to rek through the soil using less drught nd inreses the re of elow ground disturne. Therefore whilst the winged tine is mongst the most effetive t 250 nd 300 mm depth, it is not the most effetive t the urrent ultivtion depth. This suggests tht if ultivtion is to ontinue t 175 mm, hnge of tine to the modified pr-plough would est llevite omption prolems. The optimum depth for omption llevition using the winged tine would e 250 mm. 5 Conlusions This study highlights the need to rete n erosion resistnt soil profile. This will eome espeilly importnt s limti onditions hnge with n inresed frequeny of hevy rinfll events. The opertion of the urrent prtie (winged tine) is impired, owing to the shllow depth of pplition. If ultivtion in sprgus prodution ontinues t 175 mm, results suggest tht the doption of the modified pr-plough hs the potentil to llevite onsite runoff nd erosion issues. However if the omption t depth is to e ddressed the winged tine ould e more effetively used t 250 nd 300 mm. However efore these results n e fully utilized, field testing should e undertken. This will ensure tht the pereived performne of eh tine onfigurtion under ontrolled onditions hs rel life effetiveness in the field. 6 Aknowledgements (optionl) Thnks to the Dougls Bomford Trust, Corey Frms nd EPSRC for supporting this reserh. 7 Referenes Burge, S. (2009) Systems Engineering Toolox. Aessed online; My 2014 URL: Gilley, J. E. nd Kottwitz, E. R. (1995) Rndom roughness ssessment y the pin nd hin method. Applied Engineering in Agriulture, 12(1), Grves, A., Morris, J., Deeks, L.K., Rikson, J., Kilewhite, M.G., Hrris, J.A. nd Frewell, T.S. (2011). The totl osts of soils degrdtion in Englnd nd Wles. Finl projet (SP1606) report to DEFRA. Meek, B. D., Rehel, E. R., Crter, L. M., DeTr, W. R., & Urie, A. L. (1992). Infiltrtion rte of sndy lom soil - effets of trffi, tillge nd plnt roots. Soil Siene Soiety of Ameri Journl, 56(3), Mouzen, A. M., Rmn, H., nd De Berdemeker, J. (2002). Effets of ulk density nd moisture ontent on seleted mehnil properties of sndy lom soil. Biosystems Engineering, 83(2), Proeedings Interntionl Conferene of Agriulturl Engineering, Zurih, /8

7 Niziolomski, J.C. (2011). Critil evlution of the role of su-soiling nd mulhing in the ontrol of runoff nd erosion from sprgus furrows. (Unpulished Mster of Siene Thesis) Crnfield University, UK. Niziolomski, J.C., Simmons, R.W., Rikson, R.J. nd Hnn, M. (2013). Optimising soil erosion nd runoff from sprgus: se study from the UK. Unpulished onferene pper t: XIIIth Interntionl Asprgus Symposium, Otoer 16-18, 2013, Nnhng, Chin. Sleh, A. (1993). Soil roughness mesurement: Chin method. Journl of Soil nd Wter Conservtion, 48(6), Spoor, G. nd Godwin, R. J. (1978). An experimentl investigtion into the deep loosening of soil y rigid tines. Journl of Agriulturl Reserh, 23, Spoor, G. (2006). Allevition of soil omption: requirements, equipment nd tehniques. Soil Use nd Mngement, 22, Soil Survey nd Lnd Reserh Centre. (2000). Soil protetion in the UK. Crnfield University, UK. Tthm, S. E. B. (1989). The uses nd ontrol of trmline erosion. (Unpulished Thesis) Crnfield University, Crnfield University, Crnfield, UK. Figure 1. Tines tested. The first row show the tines side-on, nd the seond row shows them hed-on.. nrrow tine, : winged tine, : modified pr-plough, d: nrrow with two shllow leding nd e: winged with two shllow leding. Rised ed Rised ed Wheeling Figure 2. Wter runoff pthwys from n sprgus ed system. Surfe wter flows (non dshed line) from the rest of the rised eds (dshed lines)into the wheeling nd downslope. SD E = D AG + D BG / D Proeedings Interntionl Conferene of Agriulturl Engineering, Zurih, /8

8 Eqution 1. Clulting speifi drught for erosion ontrol. SD E ; Speifi drught for erosion ontro (kn m -2 ), D AG ; Aove ground disturne (m 2 ), D BG ; Below ground disturne (m2), D; drught (kn). Tle 1. Results for eh tine onfigurtion t ll three tested depths. Different letters following results for eh vrile within eh ultivtion depth denote sttistil differenes (p = <0.05). Tine D BG (m 2 ) SR H SR P D AG (m 2 ) Drught fore (kn) SD E (kn m -2 ) 175 mm 1 Nrrow Winged Prplough Nrrow_Shllow Winged_Shllow mm 1 Nrrow Winged Prplough Nrrow_Shllow Winged_Shllow mm 1 Nrrow Winged Prplough Nrrow_Shllow Winged_Shllow d Tle 2. Results of Pugh mtrix rnking for the erosion ontrol properties of eh tine onfigurtion t the three tested ultivtion depths. Tine onfigurtion Cultivtion depth (mm) Modified pr-plough Winged Nrrow Nrrow with shllow Winged with shllow Proeedings Interntionl Conferene of Agriulturl Engineering, Zurih, /8