THE EFFECT OF CONSERVATION TILLAGE AND TOPOGRAPHIC POSITION ON SOIL PROPERTIES IN CENTRAL ILLINOIS

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1 Southern Illinois University Crbondle OpenSIUC Theses Theses nd Disserttions THE EFFECT OF CONSERVATION TILLAGE AND TOPOGRAPHIC POSITION ON SOIL PROPERTIES IN CENTRAL ILLINOIS Andrew Mellinger Southern Illinois University Crbondle, Follow this nd dditionl works t: Recommended Cittion Mellinger, Andrew, "THE EFFECT OF CONSERVATION TILLAGE AND TOPOGRAPHIC POSITION ON SOIL PROPERTIES IN CENTRAL ILLINOIS" (2015). Theses. Pper This Open Access Thesis is brought to you for free nd open ccess by the Theses nd Disserttions t OpenSIUC. It hs been ccepted for inclusion in Theses by n uthorized dministrtor of OpenSIUC. For more informtion, plese contct opensiuc@lib.siu.edu.

2 THE EFFECT OF CONSERVATION TILLAGE AND TOPOGRAPHIC POSITION ON SOIL PROPERTIES IN CENTRAL ILLINOIS By Andrew Mellinger B.S., Cornell University, 2012 A Thesis Submitted in Prtil Fulfillment of the Requirements For the Degree of Mster of Science Deprtment of Forestry in the Grdute School Southern Illinois University Crbondle December, 2015

3 THESIS APPROVAL THE EFFECT OF CONSERVATION TILLAGE AND TOPOGRAPHIC POSITION ON SOIL PROPERTIES IN CENTRAL ILLINOIS By Andrew M. Mellinger B.S., Cornell University, 2012 A Thesis Submitted in Prtil Fulfillment of the Requirements For the Degree of Mster of Science Approved by: Dr. Jon E. Schoonover, Chir Dr. Rchel L. Cook Dr. John W. Groninger Deprtment of Forestry in the Grdute School Southern Illinois University Crbondle December, 2015

4 AN ABSTRACT OF THE THESIS OF Andrew Mellinger, for the Mster of Science degree in Forestry, presented on July 30, 2015, t Southern Illinois University Crbondle. Title: THE EFFECT OF CONSERVATION TILLAGE AND TOPOGRAPHIC POSITION ON SOIL PROPERTIES IN CENTRAL ILLINOIS Mjor Professor: Dr. Jon E. Schoonover Since griculture begn, field mngement hs been t the forefront of expnding food production beyond previous limittions. Agriculturl productivity is closely relted to the physicl, chemicl, nd biologicl properties of the soil. Lndscpe position nd field mngement re mong primry fctors ffecting these soil properties. Delinetion of topogrphic positions of the field surfce by shpe (i.e., convex, concve, nd liner) chrcterizes res tht my ccumulte or lose soil nd nutrients either during discrete event or cumultively over severl growing sesons. Incresed soil compction, degrdtion of soil structure, nd erosion hve ll been ttributed to declining griculturl production. In ddition to the physicl disturbnce from cultivtion, erosion nd deposition of soil components in different lndscpe positions explin lrge prt of the heterogeneity of soil properties cross n griculture field. In response to this, conservtion tillge techniques, precision griculture, nd other novel mngement strtegies hve been developed to reduce negtive impcts conventionl row crop production such s nutrient pollution nd compction while optimizing frmer inputs. The objective of this project ws to evlute effects of topogrphic position nd conservtion tillge techniques on soil physicl, chemicl, nd biologicl properties on the field scle s well s correlte certin soil ttributes with suspended soil runoff collected during the sprinkle infiltrtion test. Soil fertility smpling ws completed every fll from 2011 to 2014 nd dditionl smpling of soil physicl properties ws tken in the spring between 2013 nd Differences between fll conservtion tillge tretments, no-till (NT), AerWy ertor (AA), i

5 nd Gret Plins Turbo-Till (GP), nd topogrphic positions, concve, convex nd liner were nlyzed. Sediment runoff nd erthworm biomss were lso collected in the fll in Results indicted significnt increse of soil orgnic mtter (12%-24%), wter stble ggregtes (78%-98%), phosphorus (43%-76%), nd ction exchnge cpcity (28%-35%) within concve over the convex lndscpe positions. Soil strength ws significntly lower in the field mnged with the GP verticl tillge disk compred with the AA field to depth of 27.5 cm nd the NT field to depth of 17.5 cm. Crop residue coverge (percent covered) ws more complete in the NT field (12%) nd the GP field (3%) compred with the AA field. Suspended sediment runoff ws negtively correlted with wter-stble ggregtes, C, nd Mg, but positively correlted with erthworm biomss. Extrctble nutrients nd soil physicl properties were lso strongly ffected by ir temperture nd precipittion throughout the study period. Chrcterizing soil properties within topogrphic positions hs potentil pplictions in precision griculture mngement, such s reducing excessive fertiliztion, nd identifying res of incresed pollution potentil. Evlution of the tndem effects of conservtion tillge tools nd topogrphic position within centrl Illinois is importnt in order for the optimiztion of production nd conservtion of resources. Physicl disturbnce from tillge nd the trnsport of sediment from eroded res to depositionl topogrphic positions re key fctors influencing the vribility of soil properties, crop productivity, nd potentil sediment-borne nutrient pollution within individul griculturl fields. ii

6 ACKNOWLEDGEMENTS I would like to cknowledge my primry dvisor Dr. Jon Schoonover for his ptience, guidnce, encourgement, nd dvice concerning this project. Much of wht I hve lerned during my grdute experience cn be ttributed to his vilbility nd enggement even when it ws difficult. I would lso like to thnk my committee members Dr. Rchel Cook nd Dr. John Groninger for their guidnce, time, nd energy throughout this project. I would lso like to sincerely thnk Jckeline Crim nd Derek Evns for their support, friendship, nd criticl ssistnce with this project. Without this help I would not hve been ble to complete this project. I would lso like to thnk ll my fellow grdute students, nd undergrdute students, Adm Colemn, Jrrod Armstrong, Audrey Sweet, Smnth Swnberg, Nthn Hoover, Jcqueline Lintzenich, Mtt Enger, Brooke Hggrty, Prbish Stresth, nd Ben Clevenger who ssisted me with this project nd even more importntly your friendship. I could not hve done it without you nd m so grteful to hve the privilege to know nd work with ll of you. I would lso like to thnk Ptti Cludry nd other dministrtive stff for your ssistnce. Lstly, I would like to thnk Jordn Constnce, my fmily here in Illinois, nd my wonderful prents nd siblings who ssisted me nd supported me through it ll. iii

7 TABLE OF CONTENTS THESIS ABSTRACT... i ACKNOWLEDGEMENTS... iii LIST OF FIGURES... vii LIST OF TABLES... vi CHAPTER INTRODUCTION AND LITERATURE REVIEW... 1 Bckground... 1 Purpose... 2 Tillge... 3 Soil Orgnic Mtter... 5 Crop Residue... 6 Erthworms... 6 Soil Aggregte Formtion... 7 Destruction of Soil Aggregtes... 8 Soil Moisture nd Infiltrtion... 9 Erosion Processes Soil Deposition Project Justifiction CHAPTER METHODS Study Are Smpling Design Field nd Lb Procedures Soil Physicl Property Anlysis Soil Chemicl Anlysis Topogrphic Position Anlysis CHAPTER RESULTS Compction Crop Residue Coverge Wter Stble Aggregtes Soil Temperture nd Moisture Soil Ctions nd Exchnge Cpcity iv

8 SOM, Nitrogen, Phosphorus, nd Crop Yield Soil properties relted to TSS of runoff wter Reltionships between soil chemicl properties over time CHAPTER 4: DISCUSSION Compction nd Crop Residue Disturbnce Soil Orgnic Mtter, CEC, nd WSA Erosion nd Deposition Sediment nd Nutrient Pollution Productivity nd Yield Limittions CHAPTER CONCLUSIONS Synthesis Mngement Implictions Future Reserch LITERATURE CITED APPENDICES... 2 VITA v

9 LIST OF TABLES Tble 1. Fertilizer ppliction rtes nd dte of ppliction Tble 2. Tretment effect p-vlues in the lest squres mens for soil test results from 0 to 15 cm soil depth Tble 3. Tretment effect significnce nd differences in the lest squres mens for soil strength results Tble 4. Annul precipittion, verge mximum dily ir temperture, volumetric wter content*, nd soil temperture* Tble 5. Averge mximum nd minimum tempertures nd totl precipittion from November through Mrch Tble 6. Correltions between SOM nd yield within ech yer nd between yers Tble 7. Correltions between soil properties nd totl suspended solids Tble 8. Soil chemicl property reltionships over time nd rottion vi

10 LIST OF FIGURES Figure 1. Aerwy Aertor, Gret Plins Turbo-Till, nd John Deere 1775NT Plnter Figure 2. The effect of bnk ngle on soil sher nd disturbnce using the Gret Plins nd Aerwy Aertor Figure 3. Loction of reserch fields nd study site with soil series boundries Flngn silt lom (154A) Drummer-Milford silty cly lom (722A) Figure 4. Position of 0.4 hectre smple plots nd topogrphic positions for soil physicl nlysis (A) nd chemicl nlysis (B)... Error! Bookmrk not defined. Figure 5. Soil bulk density in 2013 before tillge nd 2014 fter verticl tillge (A) nd within ech topogrphic position (B) Figure 6. Penetrtion resistnce nd depth before tillge spring 2013 (A nd B) nd fter verticl tillge spring 2014 (C nd D) Figure 7. Crop residue cover in 2013 before tillge nd 2014 fter verticl tillge (A) nd within ech topogrphic position (B) Figure 8. Wter stble ggregtes before tillge in 2013 nd fter verticl tillge in 2014 (A) nd within ech topogrphic position (B) Figure 9. Dily mximum ir temperture nd soil temperture during the growing seson in 2013 (A) nd growing seson in 2014 (B) Figure 10. Soil volumetric wter content nd dily precipittion in 2013 (A) nd 2014 (B) Figure 11. CEC post-hrvest within ech field (A) nd within ech topogrphic position (B) Figure 12. Soil orgnic mtter content fter hrvest within ech field (top) nd within ech topogrphic position (bottom) Figure 13. Applied nd residul nitrogen nd phosphorus for 2011 nd 2013 corn sesons vii

11 Figure 14. Residul phosphorus within ech topogrphic position Figure 15. Residul nitrte within ech tillge tretment (A) nd topogrphic position (B) Figure 16. Crop yield within ech field (A) nd within ech topogrphic position (B) Figure 17. Soil runoff over time within ech topogrphic position (A) nd totl runoff, first time intervl nd finl time intervl (B) Figure 18. Correltions between WSA nd TSS (left) nd erthworm biomss nd TSS (right). 50 Figure 19. Correltions between residul nitrte nd corn yield in 2011 (left) nd 2013 (right). 51 Figure 20. Correltions between residul nitrte nd soyben yield in 2012 (left) nd 2014 (right) Figure 21. Correltions between SOM nd CEC in 2011 (A), 2012 (B), 2013 (C), nd 2014 (D) viii

12 CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW Bckground The beginnings of griculture, which included cultivtion nd domestiction of species round 10,000 yers go, fundmentlly chnged the reltionship between humns nd our nturl environment (Brown et l., 2009). Continuing intensifiction of griculture hs llowed our culture nd popultion to grow. Recently, we hve become incresingly wre of consequences ssocited with our griculturl intensifiction nd disturbnce of more of the lndscpe. In order to reduce the finncil nd ecologicl costs of griculture production, conservtion griculture techniques, specificlly reduced tillge nd no- till, were developed to conserve nd increse the efficiency of griculturl resources (Hobbs et l., 2008). These mngement techniques retin more crop residue on the soil surfce nd optimize physicl disturbnce; conditions ssocited with reduced compction nd erosion which re primry determinnts of soil function nd stbility. Evlution of no-till techniques nd conservtion tillge compred to conventionl tillge hs ttrcted the ttention of soil scientists nd gronomists for mny yers. However, the effects of topogrphic position nd how topogrphic position intercts with tillge mngement to ffect vrition in soil properties receives much less ttention. While there were few exmples of interction between conservtion tillge effects nd topogrphic position effects in this study, topogrphic position ws found to be n importnt fctor ffecting soil vribility independently from conservtion tillge tretments. Topsoil, which holds much of the nutrients necessry for griculturl productivity s well s unique physicl properties, tends to be eroded from convex positions nd is deposited in concve positions even in lndscpes with subtle topogrphic 1

13 positions which my ffect these differences (Ppiernik et l., 2009). Soil erosion from convex lndscpe positions nd deposition in concve positions is widely understood conceptully, but it is rrely used to chrcterize fertility nd other soil ttributes within field sites with 0-2% slope. Anlyzing elevtion dt on the field scle llows the user to delinete subtle chnges in surfce topogrphy tht is difficult to observe t the ground level. This clssifiction ws completed by nlyzing digitl elevtion mp (DEM) using topogrphic position index nd utomted using GIS softwre (Jenness, 2006; Wiess, 2001). Soil smples tken in ech of these positions in this study indicte tht these slopes independently ffect soil properties or interct with other vribles to ffect soil properties over single seson. Chrcterizing soil properties within ech topogrphic position could lso be useful for precision griculture tools s well s identifying criticl source res of nutrient loss. Purpose This reserch project comprised two prts. First, the influence of three conservtion tillge prctices nd topogrphic position on soil physicl nd chemicl properties were quntified over multiple cropping sesons in corn-soyben rottion in centrl Illinois. Soil strength, soil bulk density (Bd), wter-stble ggregtes (WSA), volumetric wter content, nd crop residue coverge were quntified before nd fter tillge tretments were completed to determine the effects on soil properties. Differences in conservtion tillge mngement nd topogrphic position were considered independent fixed effects. Second, reltionships between stbility of soil ggregtes in wter (WSA), totl suspended solids of runoff wter, erthworm biomss, soil orgnic mtter (SOM), nd soil chemicl properties were ssessed. The reltionship between these soil properties nd totl suspended solids of runoff wter were evluted to determine if WSA, erthworm biomss, SOM, compction, nd soil chemistry were useful 2

14 indictors of soil erodibility. Dt collected in this study provides evidence of how field mngement nd topogrphic position my interct or independently ffect soil ttributes or reltionships between soil properties within this site nd their impcts on soil movement dynmics s overlnd flow. Few reserch projects ttempt to quntify the joint influence of topogrphic position nd different conservtion tillge prctices on soil properties in row-crop griculture in centrl Illinois. A co-ssessment of the suspended solids by collecting runoff wter from the Cornell sprinkle infiltrometer nd investigting the reltionships between soil ttributes nd this erosion is lso unique. Objectives of the study re s follows: 1. Determine the effect of soil topogrphic position nd verticl tillge mngement on soil physicl nd chemicl properties. 2. Investigte correltions between wter stble ggregte percentge of soil, erthworm biomss of soil, nd erodibility through the nlysis of totl suspended solids from runoff. 3. Assess reltionships mong soil properties nd how they re influenced by climte topogrphic position, fertiliztion rtes, nd verticl tillge. Tillge Tillge hs mny pplictions in mny frming systems. Weed control, pore spce, incorportion of residue, tilth, nutrient minerliztion, compction, pest control, seedbed preprtion, soil moisture, nd soil temperture cn be improved by tillge in the short term but re not lwys sustined for the long term (Hobbs et l., 2008). The dvntges nd disdvntges cn be complicted. For exmple, temporry relief of compction from tillge is ccompnied by increses in compction from the dditionl psses cross the field nd cn 3

15 crete root-restricting plow-pns. (Dum, 1996). An increse of soil orgnic mtter (SOM) minerliztion due to exposure nd ertion is ccomplished by more effective residue incorportion from tillge (Ky et l., 2002; Frey et l., 1999). However, the losses of ggregtes nd SOM from physicl disturbnce negtively ffects soil tilth in the long term which influences ese of tillge nd seedling emergence. (Soil Science Society of Americ, 2008) which is primry justifiction for tillge (Bere et l., 1994). Evidence from mny studies suggest short-term benefits of physicl nd chemicl function of soils from tillge re typiclly undermine long-term productivity with continul, nd/or excessive disturbnce. No-till nd conservtion tillge strtegies re lterntives to conventionl tillge which reduce the mount of soil disturbnce. Conservtion tillge is defined s more thn 30 percent crop residue left on the soil surfce fter ll fieldwork hs been completed (Soil Science Society of Americ, 2008). Conversely, conventionl tillge is defined s ny prctice tht retins less thn 30 percent of crop residue on the soil surfce nd employs both primry nd secondry tillge opertions (CTIC, 2002; Soil Science Society of Americ, 2008). According to studies done by Houx et l., (2011); Logsdon (2013); Roger-Estrde et l., (2010) nd mny others, Excessive soil disturbnce increses erosion directly through physicl disturbnce, nd indirectly influencing chemicl chrcteristics, nd disturbing biodiversity. Tillge hs lso been shown to ffect the stbility of soil ggregtes in wter, potentilly leding to incresed erosion nd instbility (Brthes & Roose, 2002). For exmple, stble ggregtes formed by mcro-orgnisms nd fungl hyphe re often more delicte thn other forms nd more susceptible to physicl destruction by tillge (Zhng & Schrder, 1993; Tisdll, 1994). Comprisons between conventionl tillge nd conservtion tillge were not evluted in this study however, these comprisons were helpful when evluting the difference between the two conservtion tillge 4

16 implements used in this study. Similr to differences between conservtion tillge nd conventionl tillge, differences in soil disturbnce between conservtion tillge methods my lso hve implictions for soil qulity nd sustinble crop production (DeLune & Sij, 2012; Brummer et l, 1999). Conservtion tillge retins some of the benefits from tillge while limiting the costs of excessive soil disturbnce from conventionl prctices. Specificlly evluted in this reserch, verticl tillge is conservtion tillge strtegy tht is primrily used for soil ertion, seedbed levelling nd residue mngement in the spring or fll. This is different from disc hrrows, secondry tillge tool used in conventionl tillge, which ngles ech disk bnk in order to turn the soil more ggressively covering more residue (Thilges, 2010; Figure 2). No-tillge, effectively removes tillge ctivities nd is sometimes completed in conjunction with occsionl subsoiling in the Midwest (Soil Science Society of Americ, 2008). Soil Orgnic Mtter Wnder et l. (2000) suggested SOM s n index of soil qulity becuse it is fctor in most soil physicl nd chemicl chrcteristics. Nichols et l. (2011) lso suggested tht SOM is strongly correlted to ggregte stbility content of the soil. Soil qulity monitoring of chnges in key prmeters over time is importnt for the formtion of sustinble frming prctices (Bldock et l., 2009). Soil ph nd SOM were determined to be the gretest indictors of soil helth by Bldock et l., (2009). Additionlly, SOM ws found to be useful in determining the extent of soil erosion s well s being indictive of generl soil productivity (Ppiernick et l., 2009; Wng et l., 2014). Nutrient dynmics nd soil physicl structure vry widely depending on the re nd climte, but trcking chnges in some indictors such s SOM, is useful for ll res (Cotching et l., 2010). 5

17 Crop Residue Surfce residue ws found by mny studies to be n importnt fctor in decresing erosion. Trumn et l. (2005) found tht no-tillge prctices in the southest United Sttes incresed wter stble ggregtes by 21 percent, infiltrtion soil strength by 3.5 times nd decresed sediment yield compred to conventionl prctices. They lso found tht 38 percent of erosion in the first 60 minutes of simulted rinfll nd 76 percent of erosion fter 120 minutes ws due to the presence of surfce residue in both conventionlly tilled nd no-tillge sites. The mount of surfce residue nd sediment yield from the no-tillge sites were lso positively correlted (Trumn et l., 2005). Mulumb nd Ll (2008) found tht 8 Mg/h residues in centrl Ohio incresed porosity up to 46 percent nd vilble wter cpcity up 35 percent. They lso determined wter stble ggregtes hd strong correltion to mounts of residue. In long term study by McVy et l. (2006) ggregte stbility incresed with less tillge but wter holding cpcity ws not ffected. Most of the differences observed in mny tillge studies occur in the first five cm of soil (McVy et l. 2006; Mulumb & Ll 2008). Also, mny tillge studies stress the importnce of precipittion nd temperture t the reserch site (McVy et l., 2006; Houx et l., 2011). Erthworms There re few terrestril ecosystems, with the exception of deserts, tht do not hve erthworms s prt of the ecosystem (Blkemore, 2007). Groups of worms cn be seprted into epigeic nd endogenic species. Epigeic worms re smll nd t cn tolerte highly vrible environment nd thrive in high levels of orgnic mtter like compost piles. Endogenic species live slightly deeper, derive nutrition from soil while burrowing horizontlly nd leving extensive csts; nd necic species which re lrge worms tht feed on litter they pull into deep, 6

18 semi-permnent burrows (Hynes et l, 2003). These groups hve distinct functions in soil nd ffect soil conditions in different wys (Lvelle et l, 1998). For exmple, Zhng nd Schder (1993) found the erthworm ingestion reduced wter stbility of ggregtes nd ggregte tensile strength fter drying thn nturl soil with the exception of Lumbricus terrestris csts nd while the tensile strength of the burrow ws higher its stbility in wter ws lower. Aporrectode cliginos csts, n endogeic species nd common in the study re, exhibited similr wter stbility to nturl soil like Lumbricus terrestris, but the burrow wlls were less stble in wter. The uthors suggested tht the selection of higher qulity food of these species cused the slightly higher wter stbility of the cst due to n increse in orgnic crbon. Furthermore, tht csts of both these species decresed WSA prticulrly in cly nd silt soils like the soil textures found t this study site (Zhng nd Schder 1997). Despite disturbing stbility of ggregtes in wter, erthworms hve been found to be useful s relible indictors of soil qulity, productivity, nd potentil toxicity (Brtz et l., 2013; Stork et l., 1991; Birks et l., 2004). Soil Aggregte Formtion A soil ggregte is collection of soil prticles/mterils tht gglomerte more strongly compred to the surrounding mteril (Kemper & Rosenu, 1986). There re two generl size clssifictions of soil ggregtes, microggregtes, clssified s less thn 250 μm, nd mcroggregtes, clssified s lrger thn 250 μm. Mcroggregtes re typiclly more loosely ssocited conglomertes of microggregtes nd other mterils (Edwrds et l., 1967; Odes et l., 1991). The strength of coherence nd size of ggregtes is determined by chemicl nd physicl properties of the mterils nd is medited by moisture content (Tisdll et l., 1982; Tisdll, 1994; Kemper & Rosenu, 1986). Inorgnic chemicl processes re more common in the formtion of smller ggregtes nd re typiclly stronger thn mcroggregtes (Tisdll et l., 7

19 1982). Plnts nd fungl orgnism interctions such s vesiculr rbusculr mycorrhizl ssocitions lso fcilitte formtion of soil ggregtes by physiclly connecting smller ggregtes nd estblishing mcroggregte structure. Polyscchrides relesed by roots, mcrofun (erthworms) nd hyphe lso chemiclly contribute to binding prticles nd microggregtes into lrger structures (Tisdll, 1994; Fonte et l., 2012). Destruction of Soil Aggregtes Physicl soil disturbnce nd ggregte destruction by physicl disturbnce provides good exmple of how properties tht form ggregtes re interrelted. Destruction of loosely ssocited mcroggregtes through disturbnce, such s tillge, destbilizes the nturl soil structure nd my decrese wter infiltrtion nd ertion (Bronick et l., 2005). Mcropores stbilized by delicte root nd fungl hyphe networks re esily destroyed by tillge (Tisdll, 1994). Besides the destruction of existing mcroggregte structure, soil disturbnce by tillge increses ertion nd exposed prticle surfce re nd subsequently bcteril minerliztion of SOM s well s rpidly chnging soil moisture (Bere et l., 1994; Bronick et l., 2005). Loss of SOM is prticulrly importnt becuse mny cultivted soil series re found to hve mcroggregtes stbilized by SOM nd biologicl ctivity (Tisdll, 1994; Six et l, 2000). The formtion of soil ggregtes helps preserve SOM nd protect it from minerliztion (Bronick et l., 2005; Bere et l., 1994). The movement nd concentrtion of orgnisms, orgnic structures, nd inorgnic crystlline bonds in n ggregte is controlled by moisture content nd ph. These tend lso to be vrible in cultivted lndscpe becuse of chemicl inputs nd, of course, physicl disturbnce. 8

20 Finlly, moisture content my be the most criticl vrible mediting ll of these processes, but moisture content disturbs ggregtes directly in two wys. First, since neither wetting nor cly minerl structure is homogenous in the soils found t this site, interspersed 2:1 cly minerls nd/or ggregtes swell while 1:1 illite cly minerls do not, cusing lrger ggregtes to sher into smller ggregtes (Kemper & Rosenu, 1986). Rpid wetting lso cuses gses within the ggregte to be trpped, leding to physicl rupturing of the ggregte (Kemper et l., 1985). Second, soluble bonding gents holding ggregtes together lso dissolve 6nd move s moisture contents rise. As moisture leves soil ggregtes, prticles begin to contrct nd solutes concentrte cementing djcent prticles together. Further drying cuses the ggregtes to become brittle nd if they re broken, moisture must be reintroduced to remobilize cementing gents to reform them (Kemper & Rosenu, 1986). Soil Moisture nd Infiltrtion Soil moisture content is importnt in determining the vribility of wter ggregte stbility, nd hs considerble influence on soil compction, plnt productivity, nd erosion. Likewise, soil temperture nd wter infiltrtion re criticl determinnts of soil moisture nd thus re importnt for most soil processes nd re mong s the primry fctors influencing erosion (Ben-Hur et l., 1992; Wng et l., 2014). Soil physicl ttributes, such s soil texture nd structure lso determine bse soil infiltrtion nd, ultimtely moisture. Fine textured, minerl soils hve incresed surfce re which increses wter holding cpcity nd decreses conductivity. The minerl portions hve high initil bsorption, but slow dsorption once sturtion is ttined (Rwls et l., 2004). Similr to fine textured minerl frction, soils with high SOM levels lso hve high surfce re nd high initil bsorption; however, since orgnic mterils re not symmetricl, mcropores re conserved llowing for greter infiltrtion rtes 9

21 even fter sturtion (Reeves, 1997). These crbon-bsed structures lso encourge incresed formtion of mcroggregtes (Tisdll, 1994; Beven et l., 1982). Plnts nd mcrofun lso help crete lrge mcropores tht ct s conduits for wter flow (Shipitlo et l., 2004; Beven et l., 1982). Disrupted ggregtes slke into fine prticles, which when mobilized clog pore spce, cusing surfce seling. (Yn et l., 2008; Ldo et l., 2004) As more prticles re exposed to chemicl nd physicl dispersion, they continue to become finer which llows them to move further nd more effectively clog pore spce (Wkindiki &Ben-Hur., 2002). The decrese in infiltrtion rtes increses potentil for surfce runoff nd subsequent sediment trnsport. Ldo nd others (2004) observed strong evidence tht soil ggregtes re both stbilized by SOM nd re highly relted to the extent of erosion. This ws due minly to lower surfce seling nd less chemicl dispersion of cly prticles within soil ggregtes. Plnts nd mcrofun lso help crete lrge mcropores tht ct s conduits for wter flow (Shipitlo et l., 2004). Erosion Processes Rindrop nd sheet erosion re typiclly observed on smller scle compred to sediment trnsport vi rills nd gullies nd lso predominting in this study. Although secondry in volume, rindrop nd wsh processes still represent n importnt source of sediment nd my predispose more dvnced erosion. Soil detchment by rindrops re destbilized chemiclly by introducing dispersing solutes nd physiclly by the force of impct (Plnchon et l., 2000). Dispersed nd seprted prticles my be entrined or my contribute to surfce crusting (Ldo et l., 2004). Deposition nd erosion of fine textured mteril is esily observed fter storm. 10

22 Development of microtopogrphy is lso primrily influenced by sheet erosion s well. Plnchon nd others (2000) found tht rindrop erosion explined much of the chnge of microtopogrphy in griculturl wtersheds over time nd the progression my be represented by the diffusion eqution. This microrelief lso my ffect the formtion of lrger relief formtions. Plnchon nd Mouche (2010) were eventully successful in creting unique physicl model describing evolution of microtopogrphy tht is vlidted by field dt nd lbortory experiments. The model prmeters re detchment rte, projection distnce, nd n nisotropy coefficient which expresses slope dependency of the other two prmeters. The model ccurtely predicts surfce roughness nd size of mounds developing under shelter such s the retention of mteril underneth smll stones nd vegettion. Rin drop erosion is best understood by nlyzing the processes fter impct (Plnchon et l., 2010). Ghdiri (2004) observed crtering of the rindrop is dependent nerly exclusively on rindrop size while crter shpe depends on the soil properties. It ws determined tht crtering bsorbs 13 to 23 percent of the energy post impct. Additionlly, the rim of entrined prticles round the center of the impct is lrger on the downslope side suggesting generl downwrd movement of soil prticles. Sediment cn be propelled by these impcts fr distnces, verge of 10 cm-20cm nd s fr s 1 m, depending on sediment size nd is lso oriented downslope (Leguédois, 2005). Continuing rin drop impcts lso crete thin lyer of wter hevily lden with entrined sediment on the surfce (Plnchon et l., 2010). Surfce crusting by the sorting of finer prticles nd submersion by this film lso protects underlying mterils from being trnsported. This promotes overlnd flow or sheet flow nd eventully more dvnced erosion structures (Ldo et l, 2004). Brthes & Roose (2002) observed reltionship between the stbility of ggregtes nd subsequent overlnd flow nd 11

23 erosion both by nlyzing slking chrcteristics of soil smples nd in simulted rinfll study. Runoff, soil loss, nd solids dischrge ll hd very significnt negtive correltions with mcroggregtes while runoff intensity nd solid dischrge were negtively correlted with soil crbon. This grees with other studies looking t SOM nd WSA to estimte erosion potentil of lndscpe (Yn et l., 2008; Brthes et l., 2002; Ritchie et l., 2007; Le Bissonnis et l., 1998). Soil Deposition Erosion fundmentlly ffects the chemicl, biologicl, nd physicl spects of soil in ll res of the world (Chngere & Ll, 1997; Tylor et l, 2010; Dorn & Zeiss, 2000). Topogrphic position nd slope indicte loctions of deposition nd erosion res nd n fundmentlly ffects the chemicl, biologicl, nd physicl spects of soil (Weesies et. l., 1994; Lngdle et l., 1982; Ritchie et l., 2007). Chrcteriztion of the depositionl res is lso completed by trcking Cesium-137 with res of higher ctivity locted within the depositionl res nd lower ctivity in eroded res (Lowrnce et l., 1988; Ritchie et l., 2007). The buril of entrined fine prticles within the depositionl res lso my hve negtive effects on infiltrtion rte nd ertion which protect SOM from minerliztion. Other studies hve shown tht sediment trnsported vi runoff is both esily minerlized, dispersed nd no longer ggregted, therefore, SOM is not conserved within these depressions (Ll, 2003; Polykov & Ll, 2004). Whether erosion is sink or source of crbon is mtter of debte between soil scientists nd sedimentologists (Ll, 2005; Kirkels et l., 2014). Despite the disgreement on the finl fte of soil crbon, these studies provide evidence for the preferentil movement of the productive, finely textured soil mterils moving downslope. In study by Ppernik nd others (2009), soil orgnic crbon clerly eroded towrds 12

24 lower slope positions where it ccumulted cusing consistently higher mounts. Incresed crop productivity ws observed on the uplnd slopes when deposited soil ws pushed bck up the slope. However, more reserch ws deemed necessry by the uthors to determine the long term consequences of soil reloction. Another study by Polykov nd Ll (2004) observed similr soil crbon movement but lso observed n increse in soil crbon minerliztion. Depositionl res emitted 26 percent more crbon thn control sites suggesting crbon deposition is not sink but incresed with exposure from erosion. Crbon content nd erosion were lso relted to rinfll nd topogrphy consistent with most other studies mentioned previously. The influence of erosion on the globl crbon flux, which hs incresed ttention due to globl wrming, is not lwys greed upon mongst different disciplines. Sedimentologists view erosion s crbon sink, while soil scientists refer to it s source of emissions (Ll, 2005). In study by Ritchie nd collegues (2007) very similr reltionship ws observed between soil orgnic crbon nd elevtion nd depositionl res; however, soil orgnic crbon distribution by erosion ws nlyzed within the context of topogrphic position nd morphology. Uplnd slopes were found to contin less soil orgnic crbon similr to wht ws observed by Polykov nd Ll (2004), nd concve, toe slopes were found to hve higher levels soil crbon nd toe slopes lso hd deep ccumultions of these mterils (Ritchie et l., 2007). Project Justifiction Agriculture in the Midwest is typiclly lrge-scle, intensive, row-crop production on lrge, level fields. The incresing scle of production, mono-cropping, nd the size of equipment poses new chllenges for mngement of heterogeneous soils. In the pst, frmers worked smll fields, inputs were limited, nd they relied on creful djustments of their crop rottion, nd diversifiction in order remin productive. Technology supported by reserch re currently the 13

25 primry mens to increse griculture production nd efficiency. New tillge techniques nd equipment re beginning to be dopted nd evluted which limits soil disturbnce nd optimize field psses. For exmple, Globl Positioning Systems (GPS) technology in the lst 25 yers hve llowed frmers nd reserchers to sptilly relte dt t the field scle (Stfford, 2000). GPS tools provide the bility to record continuous elevtion dt, crete yield mps, nd pply vrible rtes of fertilizer nd seed bsed on loction (Brisco et l., 1998). Improvements in technology, nd the development of tools to ssist the frmer in understnding sptil vribility within their fields nd djust ccordingly. Evlution of some of these tools t the field scle by the scientific community is lso necessry nd is especilly vluble to the frmer when completed t the field scle. Topsoil erosion is strongly influenced by the intensity of runoff wter nd the shpe of the lndscpe. The ccumultion of topsoil nd nutrients in concve deposition res nd depletion in convex eroded res for vriety of resons is well documented nd supported by considerble reserch (Nering et l., 1989; Lobb et l., 1995; Lowrnce et l., 1988). Additionlly, the connection between these dynmics, soil properties, nd ultimtely productivity is lso well estblished (Chngere & Ll, 1997; Krvchenko & Bullock, 2000; Krvchenko et l., 2005; Ppiernik et l., 2009). Whether dissolved or bound to soil prticles, mobile nutrients influence the productive cpcity nd the potentil for nutrient pollution. This is especilly true for griculture fields where dditionl nutrients re pplied regulrly nd often t constnt rte over lrge res without tking soil heterogeneity into ccount (Vitousek et l., 2009). Knowledge of different mngement zones, res tht hve incresed or decresed cpcity for production, is importnt for optimiztion. Despite this, much of the reserch on the effect of topogrphic position hs been bsed either on subjective chrcteriztion of the lndscpe or 14

26 specific components of the topogrphy (eg. curvture, percent slope, flow ccumultion; Chngere nd Ll, 1997; Krvchenko nd Bullock, 2000). In lrge, level fields it is difficult to correctly identify these positions t eye level due to the incresed scle of the lndform shpes. Severl different geosptil tools nd methods hve been used to ssist identifiction of topogrphic positions nd the effect of these topogrphic positions (De Reu et l., 2013; Krvchenko et l, 2005; Weiss, 2001; Mitsov et l., 1995). This study utilizes method utomted by Weiss (2001) nlyzing the difference from men elevtion within set neighborhood clled topogrphic position index (TPI). Jenness (2006) further utomted lndscpe identifiction by creting n extension in ArcView tht uses negtive nd positive TPI vlues to chrcterize slope positions, nd vlues ner zero re considered level. This method ws dpted to fit the grdul rolling lndscpe found t the reserch site. 7.2 percent of the cells were identified s liner surfces with slopes greter thn two percent, nd were therefore omitted from the nlysis. Soil is not homogenous mixture of mterils. The collection of mterils tht mke up soil hve different physicl ttributes nd bilities to store nutrients. Officil soil series descriptions, topogrphy, lnd mngement, soil texture, fertility, nd climte region re ll good tools for plcing soils into generl clssifictions describing how they behve, however, investigting specific soil properties nd interctions between soil properties within these clssifictions is complicted. To simplify these reltionships, it is necessry to investigte generl behviors of soil t smller scle. Specificlly, primry determinnt of chemicl nd physicl dynmics is prticle size distribution nd surfce re (Tiessen et l., 1983). Both ction exchnge cpcity (CEC) nd SOM content re useful indictors of prticle surfce re nd chrge (Sollins et l., 1996). Fine textured minerl soil nd SOM typiclly hve high 15

27 surfce re nd chrge, which is relted to the cpcity of the prticle to hold onto soil nutrients nd directly relted to CEC (Gines et l., 1994). SOM is lso composed of orgnic forms of importnt nutrients, such s nitrogen (N) nd phosphorus (P), which cn be converted into plnt usble forms over time. Additionlly, SOM lso hs low prticle density becuse of the complex shpes of the orgnic mterils which llows SOM to erode nd deposit redily within griculturl fields (Ritchie et l., 2007; Bldock nd Nelson, 2000). While comprtively dense, finely textured minerl soil is esily suspended in wter becuse of its tiny prticle size mking it susceptible to erosion during runoff events (Ldo et l., 2004). Dt presented in this thesis, s well s severl other studies investigting soil erosion nd deposition, suggest fine soil mteril preferentilly moving from uplnd res to lower res of the field (Ppernik et l., 2009; Polykov & Ll, 2004; Ritchie et l., 2007). Due to the cpcity of these mterils to store nutrients, ny of the soil properties investigted here, especilly for extrctble nutrients in soil tests, re ffected by this preferentil reloction of fine minerl soil frctions nd SOM. The ccumultion of fine textured minerl soil is lso susceptible to runoff due to suspension, crusting, nd generlly poor dringe cusing incresed surfce runoff, however, some of these properties re llevited in soils with high SOM content (Ldo et l., 2004). It is importnt tht nturl processes nd formtions such s soil texture, topogrphic position, temperture, nd precipittion re not omitted from n nlysis. Both mngement, lndscpe, nd climte re very importnt. For exmple, in soil runoff experiment of severl wtersheds over 28 yers, 50 percent of the totl soil loss ws ttributed to three storms, however, only 30 percent of the verge soil loss ws collected in wtersheds with fields contoured with slope (Edwrds & Owens, 1991). 16

28 CHAPTER 2 METHODS Study Are The 100 hectre study site is locted long the southern border of Mcon County in centrl Illinois nd is pproximtely 1,200 meters (m) long by 800 m wide. Adjcent res round the study site re lso lrge scle row-crop griculture occsionlly bordered by smll frm rods. Ech of the three experimentl fields within the study site were pproximtely 30 hectres nd were seprted by 2.5 m wide grss buffer strip (Figure 3). The fields hd similr soils, were under the sme corn soyben rottion, fertilizer ppliction, nd pesticide ppliction schedules. The first nd northernmost field ws tilled with the AerWy Aertor (AA) fter corn hrvest, the center field is under no-till mngement, nd the third field is tilled with the Gret Plins Turbo-Till (GP) fter corn hrvest (Figure 1).. Figure 1. Aerwy Aertor, Gret Plins Turbo-Till, nd John Deere 1775NT Plnter 17

29 Figure 2. The effect of bnk ngle on soil sher nd disturbnce using the Gret Plins nd Aerwy Aertor. The dominnt soil order in these fields nd the surrounding re is Mollisol, very deep soil with thick, drk, surfce horizon nd t lest 5.8 g kg -1 orgnic crbon (Soil Science Society of Americ, 2008). The prent mteril of the soils found in this region is primrily loess cps on glcil till or outwsh. Drummer (Fine-silty, mixed, superctive, mesic Typic Endoquolls) nd Milford (Fine, mixed, superctive, mesic Typic Endoquolls) soil series re very similr, hve fine textures nd modertely to high mounts of cly (Soil Survey Stff, n.d.). Both series re highly chemiclly ctive nd re locted in temperte climte regime. These soils re often locted in the concve slopes nd re often wet with possible redox colortions due to very poor dringe. Flngn (Fine, smectitic, mesic Aquic Argiudolls) soil series hve less cly, re locted in convex slope positions, nd re better drined, lthough re still considered poorly drined (Soil Survey Stff, n.d.). Both of these soil series re common in the region, typiclly cultivted, nd re considered prime frmlnd or prime frmlnd if drined (Soil Survey Stff, 2012). Mximum dily ir tempertures were higher in 2011 compred to 18

30 2013 nd 2014 but were lower thn in The finl yer of the study ws the coolest, followed by 2013 nd then During the period of drought in 2012, the highest mximum dily tempertures nd the lowest dily precipittion mounts were recorded. Dily precipittion mounts were lower in 2013 thn 2014 nd 2011, but ll yers were considerbly higher thn 2012 (Tble 4). Smpling Design The field design is bsed on 0.4 h grid squre with GPS coordintes mrking smple point within ech smple plot outlined by the grid. Smple plots for chemicl nlysis were seprted into strt bsed on the topogrphic position nd n equl number of smples were rndomly selected from ech strt. The differences in the prmeters were nlyzed between the different strt nd field mngement but not in the context of the entire field. Soil smpling for wter stble ggregtes (WSA), soil strength, residue coverge, soil temperture, soil volumetric wter content (VWC), nd soil bulk density (Bd) were systemticlly smpled within every ninth smple plot within ech field. The loction of the soil smples collected for physicl nd chemicl nlysis is presented in Figure 4. 19

31 Aerwy No-till Gret Plins Figure 3. Loction of reserch fields nd study site with soil series boundries Flngn silt lom (154A) Drummer-Milford silty cly lom (722A) 20

32 21

33 Field nd Lb Procedures Fields were ll ripped before the initition of the study in The verticl tillge implements, the AerWy Aertor (AA) nd the Gret Plins Turbo-Till (GP), were used on fields one nd three, respectively, following corn hrvest in 2011 nd No other tillge ws done in ny study field over the four yers of this study. The GP hd n pproximte working depth between four nd six centimeters nd the AA hd n pproximte working depth of 20 cm (USDA-NRCS 2, 2010). A John Deere 1770 no-tillge plnter (Deere nd Compny, Moline, IL) ws used for plnting on ll the fields. The Aertor utilizes pointed Shttertine pddles tht verticlly mix the soil to brek up compction. Optionl 250 kg concrete bllsts were dded to help increse the penetrtion depth of the tines (Sf-Hollnd Equipment Ltd., Norwich, Ontrio). The GP utilizes two rows of verticl coulters spced t ten inches for leving five inch totl spcing between till lines followed by rolling hrrow nd reel (Gret Plins Mnufcturing, Slin, KS). Anhydrous mmoni mixed with N-serve ws pplied in the fll following soyben hrvest. Dimmonium phosphte (DAP) ws lso pplied in the fll of 2010 nd in the spring before corn plnting in Fll pplictions of nhydrous mmoni + N-serve, DAP, nd potsh were pplied using vrible rte technology (VRT). An dditionl ppliction of nitrogen fertilizer (28-0-0) ws pplied during corn plnting in Lime ws pplied lte in the fll of 2011 nd potsh ws brodcst in the winter of 2012 (Tble 1). Fertiliztion ws completed fter soil smples were collected. Rtes nd ppliction methods were widely representtive for the region. 22

34 Tble 1. Fertilizer ppliction rtes nd dte of ppliction Appliction Avg. N-P-K Lime Seson Totl Fll Spring Fll Spring Fll Spring All rtes re verge ppliction over the entire site presented in kg h -1 Soil Physicl Property Anlysis Soil physicl properties (i.e., VWC, temperture, soil strength, bulk density, residue coverge, nd WSA) were mesured t every ninth smple point in the spring before plnting corn (2013) nd before plnting soybens (2014). Soil VWC ws mesured with Spectrum Technologies WterScout SM 100 soil moisture sensor, nd externl temperture sensor t depth of four centimeters connected to Spectrum Technologies Wtchdog TM dt loggers (Spectrum Technologies, Auror, IL). Continuous VWC nd soil tempertures were mesured t ll 9 smple points in ech of the three fields during the 2013 nd 2014 growing sesons. The sensors remined in the field only during the growing seson nd were removed over the winter months nd during periods of hevy vehicle trffic. Soil strength ws determined using RIMIK CP40II penetrometer (ICT Interntionl, Toowoomb, Austrli). Soil strength mesurements were repeted nine times t ech of the selected sites. Bulk density ws determined to depth of 15 cm using n AMS bulk density core with 292 cm 3 sleeves. Soil compction ws evluted by nlyzing both bulk density nd soil strength dt. Residue coverge ws determined by tking photo of frmed, 1-m 2 plot nd the photos were nlyzed using WinDIAS imge softwre (Delt T, Cmbridge, UK). 23

35 Smples for WSA were tken to depth of 10 cm. After drying nd sieving the smples, wter stble ggregtes were quntified using wet sieving technique dpted from Kemper nd Rosenu (1986). Infiltrtion nd soil runoff rtes were mesured t every third of the selected smple points for totl of three per field using Cornell Sprinkle Infiltrometer (Ogden et. l, 1997). During the infiltrtion test for MN in the fll of 2014, the runoff wter ws collected to nlyze the totl suspended solids. Due to the smll size of the ring nd the low velocity of the rin drops, this runoff test ws limited to soil entrined by suspension only nd ws not ffected by slope or flow energy. Additionl WSA nlysis of the soil surfce ws collected by gently scrping the soil surfce in n re similr to the re of the infiltrtion ring. Runoff wter ws collected t six minute intervls for 30 minutes llowing the timing nd mgnitude of soil runoff to be observed. The first time intervl smple, the finl time intervl smple nd composite of ll the smples were used in the correltion mtrix. Erthworm biomss ws collected from four 20 cm by 20 cm squre by 20 cm deep in four crdinl directions round the runoff tests. Soil Chemicl Anlysis A composite smple of nine soil smples tken for chemicl nlysis t ech smple point to 15 cm soil depth fter hrvest ech yer. Smples were nlyzed for soil orgnic mtter (SOM), totl CEC by summtion (CECsum), Melich III extrctble phosphorus, potssium, sulfur, clcium, nd mgnesium s well s mmonium nd nitrte vi 1.0 N KCl extrction with cdmium reduction (Mehlich, 1984; Dhnke, 1990). Soil smples were ir-dried, ground to pss 2 mm sieve, nd nlyzed by Brookside lbortories. CECsum ws estimted by combining the mount of extrcted ctions ssuming there is no exchngeble cidity (Ross, 1995). SOM ws determined by loss t ignition when heted to 360 degrees Celsius.. 24

36 Topogrphic Position Anlysis The nlysis of digitl elevtion model (DEM) using vlues from the TPI nd utomted in ArcView (ESRI, 1996) by Jenness (2006) nd ws completed in ArcMp (ESRI, 2014). The topogrphic positions were seprted into regions clssified concve positions, liner positions, nd convex positions. A circulr neighborhood nlysis of elevtion 100 pixels round ech 10 m by 10 m pixel within the DEM for this nlysis. Rectngulr neighborhood shpes, nd different neighborhood sizes were compred, however, the 10 m x 10 m cell size nd 100 m 2 produced the most clerly defined delinetions between topogrphic positions. TPI vlues were clculted by tking the men elevtion of ech neighborhood with the subject cell s the center. The elevtion of subject cell is subtrcted from the men elevtion of the neighborhood cells. Every cell is defined in reltion to its surrounding cells position is ssigned bsed on whether the TPI vlue is positive (convex), negtive (concve) or ner zero (liner Soil smple plots were rndomly or systemticlly selected with ech topogrphic position within ech field so tht there ws n equl mount of topogrphic positions in ech field. Dt Anlysis Dt were orgnized with Microsoft Excel nd nlyzed using the PROC MIXED commnd in SAS version 9.4 (SAS Institute Cry, NC). A mixed model repeted mesures nlysis ws used to test differences between topogrphic position, time, field, field*time interction, nd topogrphic position*time interction. Significnce ws mesured t 0.05 significnce level. Tukey s multiple comprisons djustment of the p-vlues for the lest-squres mens ws completed for the fixed effects in order to get the best pirwise comprisons despite unequl smple sizes. Log nd squre root trnsformtions were used where necessry to chieve 25