1. Effect of cropping intensity, tillage, and residue cover on soil properties

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1 Number 200 July 9, Effect of cropping intensity, tillge, nd residue cover on soil properties 1 2. Fctors to consider before burning whet residue 5 3. Test weights in whet: Why some re high nd some re below verge this yer 7 4. No-till crop rottion reserch for centrl nd south centrl Knss 9 5. Wind dmge in corn Effect of cropping intensity, tillge, nd residue cover on soil properties To improve soil properties nd soil orgnic crbon (SOC) levels in the western hlf of Knss, producers will likely need to use combintion of no-till nd incresed cropping intensity. Rottions tht include fllow periods my deteriorte soil properties nd reduce SOC concentrtion due to reduced biomss input. Confirming this with reserch dt is not, however, s esy s it might seem. Becuse chnges in soil properties nd SOC concentrtion re often slow in semi-rid climtes, dt from long-term experiments re needed to better understnd the impcts of cropping systems on soil nd environment. Furthermore, most studies hve focused on tillge impcts rther thn on cropping system impcts. Incresing SOC concentrtion with intensive cropping systems my led to improved soil properties, but this issue hs been little reserched. Fortuntely, we hve unique opportunity t the Agriculturl Reserch Center t Hys to evlute the impct of different tillge tretments nd cropping systems from long-term study tht hs been ongoing for 33 yers on Crete silty cly lom soil. The experiment consists of five cropping systems (sorghum-fllow, continuous sorghum, whet-sorghum-fllow, whetfllow, nd continuous whet) mnged under reduced till nd no-till. In 2009, we ssessed severl soil properties from this long-term study. Study findings Of the cropping systems in this study, we found tht continuous whet hd the gretest beneficil impcts on ner-surfce soil physicl properties nd SOC concentrtion. For exmple: 1

2 * Continuous whet incresed soil structurl stbility (wet ggregte stbility) by two to five times over sorghum-fllow for the surfce 1-inch (2.5 cm) soil depth (Fig. 1). Men Weight Dimeter of Aggregtes (mm) B No-Till AB Reduced Till b b b B AB b A Sorghum-Fllow Continuous Sorghum Whet- Sorghum-Fllow Whet-Fllow Continuous Whet Fig. 1. The dimeter of wet ggregtes s ffected by five cropping systems. Soil ggregtes were lrgest in the no-till continuous whet plots. Brs with the sme letter within the sme tillge system re not significntly different. * Continuous whet nd whet-sorghum-fllow retined bout 13% more wter in the soil compred with sorghum-fllow in no-till. * Continuous whet lso incresed cumultive wter infiltrtion over other cropping systems under no-till (Fig. 2). Soil surfce seling nd crusting in crop-fllow systems cn reduce wter infiltrtion compred to rottions with permnent residue cover. The greter residue cover in intensive cropping systems cn lso reduce loss of wter through evportion nd runoff. In semirid soils, the increse in wter infiltrtion through intensifiction of cropping systems is criticl to cpture precipittion wter nd increse soil wter storge. 2

3 16 Cumultive Infiltrtion (cm) B No-Till B Reduced Till AB B A 2 0 Sorghum-Fllow Continuous Sorghum Whet- Sorghum-Fllow Whet-Fllow Continuous Whet Fig. 2. Cumultive wter infiltrtion fter 3 hours for five cropping systems under no-till nd reduced till. Mens with the sme letter within the sme tillge system re not significntly different. * The SOC concentrtion ws gretest in continuous whet nd lowest in sorghum-fllow in both tillge systems t the 1-inch soil depth (Fig. 3). Under no-till, continuous whet resulted in 50% greter SOC concentrtion thn whet-fllow, continuous sorghum, nd whet-sorghum-fllow nd 100% greter thn sorghum-fllow. Under reduced till, continuous whet hd greter SOC concentrtion thn continuous sorghum nd sorghum-fllow. The greter SOC concentrtion in continuous whet is ttributed to the greter nnulized return of crop residues compred with sorghum-fllow. No-till hd greter SOC concentrtion thn reduced till by bout 40 to 100%, depending on the cropping system, showing tht no-till is superior over reduced till for sequestering SOC (Fig. 3). Soil Orgnic Crbon (g kg -1 ) C b No-Till BC Reduced Till b BC b B b A 0 Sorghum-Fllow Continuous Sorghum Whet- Sorghum-Fllow Whet-Fllow Continuous Whet Fig. 3. Soil orgnic crbon concentrtion in top one-inch of soil for five cropping systems under no-till nd reduced till. Mens with the sme letter within the sme tillge system re not significntly different. Error brs re LSD (Lest significnt differences) vlues to compre tillge effects on SOC concentrtion within the sme cropping system. 3

4 The greter concentrtion of SOC in intensive cropping systems hs mny ncillry benefits. Bulk density decresed while totl porosity, soil wter retention, nd cumultive wter infiltrtion incresed with n increse in SOC concentrtion within no-till. The proportion of mcroggregtes incresed wheres tht of microggregtes decresed with increses in SOC concentrtion. Continuous whet vs. continuous sorghum Improved soil conditions under continuous cropping systems with no fllow period re directly ttributed to their greter nnul return of crop residues thn under crop-fllow systems. But if tht is true, then the obvious question is: Why did continuous sorghum not hve the sme beneficil effect on soil physicl properties s continuous whet in this study? Why is SOC concentrtion lower in continuous sorghum thn in continuous whet when sorghum produces more biomss thn whet? The nswer hs to do with the differences in residue cover on the soil between those two crops. The uniform residue cover in whet most likely protected the soil surfce better thn the corse nd sprse sorghum residues. The soil surfce hs less protection with the wider row spcing in sorghum compred to whet, which increses soil temperture fluctutions nd evportion rtes, ccelertes the decomposition of residues, nd leds to reduction in SOC ccumultion. See Fig. 4 below for visul comprison of residue levels. 4

5 Fig. 4. Residue cover under continuous whet (top), sorghum-fllow-sorghum (middle), nd continuous sorghum (bottom) under no-till. Photos by Humberto Blnco, K-Stte Agriculturl Reserch Center-Hys. Summry Results of this study suggest tht reducing fllow periods coupled with no-till technology is potentil strtegy to improve soil physicl properties nd increse SOC concentrtion in the centrl Gret Plins. The greter wet ggregte stbility, soil wter retention, porosity, wter infiltrtion, nd SOC concentrtion in continuous whet thn in sorghum-fllow, prticulrly in no-till, indictes tht mngement systems which exclude summer fllow prctices nd mintin permnent protective cover on the soil surfce improve soil physicl properties nd sequester SOC. -- Humberto Blnco, Soil Mngement, Agriculturl Reserch Center-Hys -- Loyd Stone, Soil Wter Mngement -- Phil Sthlmn, Weed Scientist, Agriculturl Reserch Center-Hys 2. Fctors to consider before burning whet residue Mny producers my be plnning to burn their whet stubble this summer to help control volunteer plnts, weeds, nd certin diseses. While burning is inexpensive, producers should 5

6 understnd the true vlue of residue hed of time. Some of the informtion below comes from K-Stte Extension publiction MF-2604, The Vlue of Crop Residue. There re four min fctors to consider. Loss of nutrients The products of burned whet stubble re gses nd sh. Nutrients such s nitrogen (N) nd sulfur (S) re lrgely combustion products, while phosphorus (P) nd potssium (K) remin in the sh. When residue is burned, bout third of the N nd S will voltilize. The nutrients in the sh my remin for use by the plnts, if it doesn t blow wy first. Therefore, insted of cycling these importnt plnt nutrients bck into the soil, they cn essentilly become ir pollutnts when the residue is burned. Amounts of nutrients remining in whet stubble (ssuming 50 bu/c yield) Nutrient Pounds present in 5000 lbs of whet strw N 35 P 2 O 5 10 K 2 O 35 S 10 Protection from soil erosion Bre soil is subject to wind nd wter erosion. Without residue, the soil will receive the full impct of rindrops, thus incresing the mount of soil prticles tht my become detched during rinfll event. Bre, tilled soils cn lose up to 30 tons per cre topsoil nnully. In no-till or CRP systems where residue is left, nnul soil losses re often less thn 1 ton per cre. The detchment of soil prticles cn led to crusting of the soil surfce, which then contributes to greter mounts of sediment-lden runoff, nd thus, reduced wter infiltrtion nd drier soils. Leving residue on the field lso increses surfce roughness, which decreses the risk of both wind nd wter erosion. Most griculturl soils in Knss hve T vlue, or tolerble mount of soil loss, of between 4 nd 5 tons per cre per yer, which is bout equl to the thickness of dime. To prevent wter erosion, 30% ground cover or greter my be needed to reduce wter erosion to T or less, especilly in fields without erosion-control structures such s terrces. Stnding stubble is more effective t preventing wind erosion thn flt stubble. Moisture infiltrtion rtes nd conservtion Whet residue enhnces soil moisture by incresing rinfll infiltrtion into the soil. Residues physiclly protect the soil surfce nd keep it receptive to wter movement into nd through the soil surfce. Without physicl protection, wter nd soil will run off the surfce more quickly. Ponded infiltrtion rtes were mesured t Hesston in September Very low infiltrtion rtes (1.9 mm/hr) were observed for continuous winter whet in which the residue ws burned 6

7 ech yer prior to disking nd plnting the following crop. In contrst, high infiltrtion rtes (13.3 mm/hr) were observed for no-till whet/grin sorghum rottion. Another wy residue increses soil moisture is by reducing evportion rtes. Evportion rtes cn decline drmticlly when the soil is protected with residue. Residue blocks solr rdition from the sun nd keeps the soil surfce cooler. Soil qulity concerns Over time, the continued burning of croplnd could significntly degrde soil orgnic mtter levels. By continully burning residue, soil orgnic mtter is not llowed to rebuild. Soil orgnic mtter is beneficil for plnt growth s it contributes to wter holding cpcity nd ction exchnge cpcity. Soil orgnic mtter binds soil prticles into ggregtes, which increses porosity nd soil structure nd thus, increses wter infiltrtion nd decreses the potentil for soil erosion. One burn, however, will not significntly reduce the orgnic mtter content of soil. If producers do choose to burn their whet stubble, timing is importnt. It s best to burn s lte s possible, close to the time when the next crop is plnted. This minimizes the time tht the field will be without residue cover nd vulnerble to erosion. Before choosing to burn residue, producers should check with the USDA Nturl Resources Conservtion Service nd/or the Frm Service Agency to find out if this will ffect their complince in ny conservtion progrms. -- DeAnn Presley, Environmentl Soil Science nd Soil nd Wter Mngement Specilist denn@ksu.edu 3. Test weights in whet: Why some re high nd some re below verge this yer Whet test weights re good in some res of Knss this yer, nd below verge in other res. Why the vrition? Possible fctors include drought stress, tempertures during grin fill, wterlogging, diseses, whet strek mosic dmge, nd riny wether t hrvest. All of these fctors interct with kernel numbers nd vriety. When whet forms n verge of two kernels per spikelet, the environment hs reltively less impct on test weight since it is esier for the plnts to fill the grin under these conditions. When whet tries to form three or more kernels per spikelet, the environment my hve greter impct on test weight. In tht sitution, ny stress on the plnts during grin fill will hve greter chnce of cusing low test weights. In ddition, some vrieties nturlly tend to hve higher test weights thn others. High test weights re usully the result of combintion of dequte moisture nd long, cool grin fill period. Low test weights cn hve severl cuses. Drought stress is probbly the min cuse of low test weights overll. Whet under drought stress rects in severl wys. The plnts will normlly llocte most of the vilble nutrients nd wter to the first kernel or two in the mesh. These kernels my be smll, but often hve high 7

8 protein nd dequte test weight. The remining kernels will be denied the necessry nutrients nd wter, however. If these flowers or kernels were not borted, then they will be shriveled nd hve low test weight. Het stress during grin fill cn cuse the plnts to shut down the nutrient flow to grin, which cn result in low test weights in most kernels on the hed. Premture deth due to het stress is one of the most common resons for low test weights in lte-mturing vrieties in Knss. Het stress ws not fctor in low test weights this yer, however. Wterlogging cn reduce test weights by the sme mens shutting down the nutrient nd wter flow to grin. When roots re wterlogged, they re deprived of oxygen nd cnnot function normlly. This ultimtely reduces grin fill, especilly when the wterlogged conditions lst for severl dys or more during grin fill. A fll infection of whet strek mosic cn lso reduce test weight, by cusing seson-long disruption of nutrient flow to the kernels. A combintion of drought stress nd whet strek mosic cn result in very low test weights. In other yers, lef rust nd stripe rust hve cused test weight reductions. When diseses, in combintion with drought some yers, cuse premture deth of the flg lef t or before the soft dough stge, this often results in shriveled grin nd low test weight. When premture deth of the flg lef occurs lter, in the hrd dough stge, there is usully little or no effect on test weight. Rins t hrvest time cn lower the test weights by 2-3 points or more lmost overnight. In this cse, the reson for the low test weight is tht the rin cuses the whet kernels to swell something like puffed whet cerel. Test weight is mesure of how much grin weight cn be plced in given volume. Prior to the rin, the whet kernels could be pcked well into bushel. When it rins, kernels swell nd upon drying, the kernels do not shrink bck to their originl volume, shpe, nd smoothness. This results in more spce between kernels, nd they will not pck into bushel s well s they did before the rin. The result is lower test weight. But this does not reduce the totl number of pounds of grin produced per cre. There is no rel grin yield loss the number of bushels per cre will be incresed but the weight per bushel will be reduced. Thousnd kernel weight (TKW) is better indiction of whet seed qulity thn test weight. TKW is simply the weight of 1,000 kernels. If the TKW of the seed is greter thn 30 grms, the whet is more likely to hve good germintion, emergence, nd tillering potentil. -- Jim Shroyer, Extension Agronomy Stte Leder jshroyer@ksu.edu 8

9 4. No-till crop rottion reserch for centrl nd south centrl Knss Beginning in 2001, we estblished 10 three-yer rottions ll of them under totl no-till conditions nd one continuous cropping system t the Hrvey County Experiment Field. Dt collection begn in 2004, three yers fter the rottions were initited. This llowed time for ll crops in ech rottion to be grown t lest once. Detils of the production prctices cn be found on the web t: Annul precipittion during ws ner to or bove norml (bout 33 inches) in ll but one yer, which ws substntilly dryer thn usul. The combined July nd August rinfll verged bout 1.6 inches bove norml, fvoring the prctice of doublecropping fter whet. The five-yer verge yields of two crops were ffected most by the preceding crops in the rottion. Whet. Averged over , whet yields were highest by wide mrgin when whet followed soybens, t bout 57 bushels per cre. Whet yielded 7 bushels less when following corn, nd 10 bushels less when following sunflowers. When Fusrium Hed Blight occurred in 2007, the highest incidence of the disese occurred where whet followed corn. Full-seson grin sorghum. The highest five-yer verge yields for full-seson grin sorghum cme when sorghum followed either whet (sorghum yield = 107 bu/cre) or full-seson soybens (sorghum yield = 103 bu/cre). Yields were bout 4-7 bushels lower where grin sorghum followed whet/doublecropped soybens; nd bout bushels lower where it followed whet/doublecropped grin sorghum, or nother crop of full-seson grin sorghum. Corn hd two unusully good growing sesons nd one tht ws well below verge, but it ws not significntly ffected by preceding crops in most yers. However, the emerging trend over the five-yer period ws for top corn yields ( bu/cre) to occur fter whet or whet/doublecropped soybens. The yield dvntge ws 2-4 bushels per cre compred to corn fter full-seson soyben nd 4 to 6 bushels per cre compred to corn fter grin sorghum. On verge, doublecropped soybens fter whet hd little effect on the yield of the following corn crop. Sunflower yields essentilly were not ffected by the preceding crops. In the comprison of no-till rottions, not only the yields of individul crops should be considered, but lso the overll level of production nd the net profit or loss per cre during the entire life of the rottion. Producers cn tke the s described below s reference point for clculting the potentil profitbility of these no-till rottions under their own conditions. 9

10 Rottion 1: Whet - Corn - Soybens Whet Corn Soybens Rottion 2: Whet/Doublecropped Soybens Corn - Soybens Whet Doublecropped soybens Corn Soybens Rottion 3: Whet Soybens - Corn Whet Soybens Corn Rottion 4: Whet Grin Sorghum - Soybens Whet Grin sorghum Soybens Rottion 5: Whet/Doublecropped Soybens Grin Sorghum - Soybens Whet Doublecropped soybens Grin sorghum Soybens Rottion 6: Whet/Doublecropped Grin Sorghum Grin Sorghum - Soybens Whet Doublecropped sorghum Grin sorghum Soybens

11 Rottion 7: Whet Grin Sorghum - Sunflowers Whet Grin sorghum Sunflowers 1568 (lbs/cre) +44 Rottion 8: Whet/Doublecropped Soybens Grin Sorghum - Sunflowers Whet Doublecropped soybens Grin sorghum Sunflowers 1511 (lbs/cre) -13 Rottion 9: Whet/Doublecropped Grin Sorghum Grin Sorghum - Sunflowers Whet Doublecropped sorghum Grin sorghum Sunflowers 1494 (lbs/cre) -30 Rottion 10: Grin Sorghum Corn - Soybens Grin sorghum Corn Soybens Rottion 11: Continuous Grin Sorghum 4-yer verge yield Grin sorghum Mrk Clssen, Agronomist-in-Chrge, Hrvey County Experiment Field, Retired mclsse@ksu.edu 11

12 5. Wind dmge in corn Corn is silking in much of Knss. This is criticl time for determining yield. Lef re loss due to hil or insect feeding nd drought stress re prticulrly dmging t this stge in the development of the corn plnt. Storms tht generte high winds in the dys leding up to tsselling nd silking cn cuse green snp, pinched stlks, nd/or root lodging. We hve hd few reports of this type of dmge over the pst couple of weeks. This hppens somewhere lmost every yer nd gronomists in other sttes often hve ddressed this topic. Much of the following informtion ws obtined from rticles written by R.L. (Bob) Nielsen, Agronomy Deprtment, Purdue University, nd Roger Elmore nd Lori Abendroth, Iow Stte Deprtment of Agronomy, nd George Cummins, Iow Stte University Extension, Green snp refers to stlk brekge resulting from high winds. The yield effect of green snp dmge depends on the percentge of field ffected nd whether the stlk brekge occurs bove or below the er, but is usully serious regrdless. Stlk brekge below the er results in zero yield for tht plnt. Stlk brekge bove the er results in significnt yield loss due to the loss of upper cnopy photosynthesis cpcity for tht plnt. The erlier in crop development tht green snp occurs, the more the plnt is ble to compenste by incresing the size of the remining ers, or perhps by setting dditionl ers. Even so, yield losses cn be significnt. Corn is most susceptible to greensnp just prior to tsseling, when it is growing rpidly. If green snp occurs t tht time, there is little opportunity for neighboring plnts to compenste becuse er size hs lrgely been determined. In these situtions yield loss from broken plnts is directly relted to stnd loss (i.e., 10 percent broken plnts will result in 10 percent yield reduction). Hybrids vry drmticlly in their tolernce to greensnp. Severl compnies provide growers with greensnp rtings tht my prove useful in selecting less susceptible hybrids. Stge of growth ffects brekge too. In the period just before tsseling, even few dys cn mke big difference in the extent of dmge. Fctors tht increse erly seson growth tend to increse brekge susceptibility, such s high N, P, nd K rtes; spring-pplied N; tillge; nd high orgnic mtter. A storm tht pssed through Mnhttn on the night of July 3 generted high wind gusts tht cused green snp in corn popultion study t the Agronomy Frm. The corn ws t bout V13 to V14 when the storm cme through 9 to 10 dys before silking. One of the two hybrids in the study hd much worse green snp thn the other, 14% vs. 1% verged over the different popultions. The green snp ws generlly worse s popultion incresed. In fct, it verged less thn 2% in ll popultions under 30,000 plnts per cre. Even the more susceptible hybrid verged less thn 5% green snp if the popultion ws 26,000 plnts per cre or less. So, t popultions recommended for the re, green snp nd the resulting yield loss likely will be miniml in these plots. However, green snp nd yield losses will be significnt (more thn 25%) in plots of the susceptible hybrid plnted t the upper end of the recommended popultion rnge (30,000 + plnts per cre). 12

13 Some plnts do not completely snp, resulting in pinching. Pinching is the crushing of stlk tissue on one side of the stlk cusing the plnt to len over but still remin ttched nd intct. Wind cn lso cuse root lodging (plnts uprooted nd lying nerly flt to the ground), especilly when ssocited with hevy rins nd wet soils. Pinched nd root-lodged corn will recover or strighten up to vrying degrees depending on the growth stge of the crop. Generlly, younger corn hs greter bility to strighten up with miniml goose-necking thn older corn. Yield effects of root lodging re difficult to predict becuse they depend on whether soil moisture remins dequte for root regenertion, the severity of root dmge due to the uprooting nture of root lodging, nd the degree of goose-necking tht develops nd its effect on the hrvestbility of the crop. -- Krig Roozeboom, Crop Production nd Cropping Systems Specilist These e-updtes re regulr weekly item from K-Stte Extension Agronomy nd Steve Wtson, Agronomy e- Updte Editor. All of the Reserch nd Extension fculty in Agronomy will be involved s sources from time to time. If you hve ny questions or suggestions for topics you'd like to hve us ddress in this weekly updte, contct Steve Wtson, swtson@ksu.edu, or Jim Shroyer, Reserch nd Extension Crop Production Specilist nd Stte Extension Agronomy Leder jshroyer@ksu.edu 13