Active stubble management to enhance residue breakdown and subsequent crop management focus farm trials

Transcription

1 Active stubble mngement to enhnce residue brekdown nd subsequent crop mngement focus frm trils Nick Poole, Trcey Wylie nd Michel Stright FAR Austrli Bckground This report presents the results from the lrge plot focus frm trils of the Mintining Profitble Frming Systems with Retined Stubble in the Riverine Plins Region project, s described in the project overview on pge 10. Method Different methods of stubble mngement were trilled in four lrge (frm-scle) replicted trils during 2014, 2015 nd All results were sttisticlly nlysed using nlysis of vrince (ANOVA), with mens seprted using the unrestricted lest significnt difference (LSD) procedure. The different tril tretments re outlined in Tble 1. As the tril sites re moved ech yer to reflect one-off chnge in the system, ech yer of trils is referred to s time replicte : 2014 tril site: time replicte tril site: time replicte tril site: time replicte 3. After ech yer of field trils the site is returned to the frming co-opertor nd blnket-sown with crop of their choice, s described in Tble 1, Tble 2 nd Tble 3. At some sites the yield of the subsequent crop is lso mesured to determine whether one-off strtegic chnge hs ny long-term impcts through the rottion. TABLE 1 Stubble mngement project tril detils, 2016 (time replicte 3) Tril 1 Tril 2 Tril 3 Tril 4 Tril detils Coreen # Yrrwong Dookie Henty s NTSR* (control) NTSR t sowing Cultivte One pss One pss One pss One pss Cultivte t sowing One pss One pss One pss Burn stubble NTSR long stubble 36cm 34cm NTSR short stubble 15cm 15cm NTSR strw mown nd removed NTSR stubble mulched nd retined NTSR stubble mulched + 40kg extr nitrogen t sowing NTSR lupins sown for forge NTSR lupins sown for grin Tril plot dimensions (m) 40 x x x x 15 Frm drill used for tril Aus seeder DBS D-300 tine seeder Aus seeder DBS tine knife point Simplicity seeder/ knife point John Deere 1590 disc seeder Stubble loding (t/h) Stubble height (cm) Soil type description Lom over cly Self-mulching red lom over grey cly Red lom over cly Yellow brown erth Row spcing (cm) Crop nd rottion position Second cerel (brley) Second whet Second whet Cnol following whet # The site ws relocted to pddock ner Dysdle in 2014, ner Corow in 2015 nd ner Coreen in 2016 in order to mintin the required rottion position. * No-till stubble retention (NTSR) 12

2 TABLE 2 Site detils for 2016 crops sown onto 2015 stubble mngement tril sites (time replicte 2) Tril 1 Tril 2 Tril 3 Tril 4 Tril detils Corow # Yrrwong Dookie Henty s Crop type/vriety Whet/Trojn Cnol/45Y25 Cnol/Bonito Whet/Gregory Pddock burnt O Frmer hrvested O Plot hrvester O O O Tril plot dimensions (m) 40 x x x x 15 Frm drill used for tril Aus seeder DBS D-300 tine seeder Aus seeder DBS tine knife point Simplicity seeder/ knife point John Deere 1590 disc seeder Stubble loding (t/h) Stubble height (cm)* Soil type description Red brown erth Self-mulching red lom over grey cly Red cly Red brown erth Row spcing (cm) Crop nd rottion position Third whet Cnol following whet Cnol following whet Whet following cnol # The site ws relocted to pddock ner Dysdle in 2014, ner Corow in 2015 nd ner Coreen in 2016 in order to mintin the required rottion position. * Stubble height ws mesured post burn t sowing time. TABLE 3 Site detils for 2016 crops sown onto 2014 stubble mngement tril sites (time replicte 1) Tril 1 Tril 2 Tril 3 Tril 4 Tril detils Dysdle # Yrrwong Dookie Henty^ s Crop type/vriety Cnol/Bonito Cnol/Bonito Whet/Corck Whet/Wedgetil Pddock burnt O P O O Frmer hrvested P P P O Plot hrvester O O O O Tril plot dimensions 40 x 15m 40 x 18m 40 x 15m 40 x 15m Frm drill used for tril Aus seeder DBS D-300 tine seeder Aus seeder DBS tine knife point Simplicity seeder/ knife point John Deere 1590 disc seeder Stubble loding (t/h) Stubble height (cm)* Soil type description Hevy grey cly Self-mulching red lom over grey cly Red cly Yellow podzol-yellow brown erth Row spcing (cm) Crop nd rottion position Cnol following whet Cnol following brley Whet following cnol Grzing whet following ots # The site ws relocted to pddock ner Dysdle in 2014, ner Corow in 2015 nd ner Coreen 2016 in order to mintin the required rottion position. ^ The Henty site ws ffected by wterlogging nd ws grzed off nd left (not hrvested). * Stubble height ws mesured post burn t sowing time. RESEARCH AT WORK 13

3 Tril 1: Coreen, NSW Sowing dte: 4 My 2016 Rottion: Second cerel (brley) Vriety: Brley cv Hindmrsh, lupins cv Mndelup Stubble: Whet (vrious tretments pplied) Stubble lod t sowing: 7.0t/h Rinfll: GSR: 567mm (April October) Summer rinfll: 80mm Soil nitrogen t sowing: 111kg N/h NTSR (control) nd 103kg N/h multidisc (0 60cm) Key points There were significnt increses in dry mtter (DM) ccumultion, nitrogen (N) uptke nd crop cnopy greenness where brley ws estblished following cultivtion with one pss of the multidisc, which ws most evident where dditionl nitrogen ws dded t sowing. Although there ws trend for cultivted stubble with dditionl sowing nitrogen to yield more thn burning, there were no significnt yield differences in the tril. Growing fb ben crop insted of second whet crop incresed the yield of the following whet by t/h in 2016 compred with 2t/h dvntge in the following whet crop in Adequte nitrogen vilbility in the third whet crop, combined with higher yield potentil, nd poor nodultion in the fb bens, ppers to be prtly the reson for the smller yield benefit in Across three yers of field trils, none of the different stubble mngement tretments hve been superior to the no-till stubble retention (NTSR) control, despite differences in DM production. Results i) Estblishment nd crop structure With sufficient moisture levels t sowing there were no differences in crop estblishment five weeks fter sowing (Tble 4). Tiller numbers were reltively high nd differed between the tretments. Tiller numbers vried from 3.9 tillers per plnt in burnt plots to 5.3 tillers per plnt in cultivted plots, when ssessed t the second node stge (GS32). However, there were no differences in hed numbers between tretments, with n verge of just more thn 400 heds/m 2. TABLE 4 Plnt counts 9 June 2016, three-lef stge (GS13); tiller counts 28 July 2016, second-node stge (GS32) nd hed counts 19 November 2016, hrvest (GS99) Crop growth stge GS13 GS32 GS99 Plnts/m² Tillers/m² Heds/m² NTSR (control) b 406 Cultivted (one pss) Cultivted (one pss) b 440 Burnt b 387 Men LSD ii) Dry mtter production nd nitrogen uptke Plots tht hd been cultivted with dditionl nitrogen t sowing produced significntly more DM t first node (GS31), compred with both the NTSR (control) nd burnt tretment. The cultivted tretments lso produced significntly more DM t flowering (GS69) compred with the NTSR plots (Tble 5). By hrvest there were no significnt differences in DM production between ny of the tretments. Similr trends were pprent in the nitrogen uptke figures t first node (GS31), with more nitrogen present in the cultivted nd cultivted plus 40kg N/h compred with the burnt tretment nd the control plots. At lter ssessments there were no significnt differences in nitrogen content between the different stubble tretments (Tble 6). iii) Green lef retention differences The NTSR plots were not s green t key ssessment growth stges s the burnt nd cultivted plots; observtions confirmed by normlised difference vegettion index (NDVI) redings (Figure 1). The presence of stubble (brown vegettion) in the NTSR plots my hve prtly influenced erlier NDVI redings, compred with the burnt tretment redings. Crops TABLE 5 Dry mtter 15 July 2016, first node (GS31); 18 August 2016, flg lef fully emerged (GS39); 26 September 2016, end of flowering (GS69) nd 21 November 2016, t physiologicl mturity (GS95 99) Dry mtter (t/h) GS31 GS39 GS69 GS95 99 NTSR (control) 1.17 bc b 9.37 Cultivted (one pss) 1.49 b Cultivted (one pss) Burnt 1.06 c b 8.41 Men LSD

4 TABLE 6 Nitrogen uptke in crop 15 July 2016, first node (GS31); 18 August 2016, flg lef fully emerged (GS39); 26 September 2016, end of flowering (GS69) nd 21 November 2016, t physiologicl mturity (GS95 99) Nitrogen uptke in dry mtter (kg N/h) GS31 GS39 GS69 GS95 99 NTSR (control) 55 b Cultivted (one pss) Cultivted (one pss) Burnt 42 b Men LSD NDVI (0 1) NTSR (control) Cultivted (one pss) Cultivted (one pss) Burnt tretments over the NTSR (control) for brley t this site (Tble 7); result consistent with previous yers of field trils in second whet in this region. The only significnt difference in grin qulity ws lower protein level in cultivted plots tht did not receive nitrogen t sowing. v) Three-yer results (time replictes 1, 2 nd 3) yield dt For the pst three yers replicted lrge block stubble mngement tril hs been estblished in different pddock on the Coreen focus frm. The tril set-up in 2014 (yer one of the experiment) is referred to s the time replicte 1 in the tril series, the tril set-up in yer two is time replicte 2 nd in the third yer it is time replicte 3. After ech tril hs been completed the tril re reverts to being commercil frm crop undergoing uniform mngement. The stubble mngement for ll subsequent yers hs therefore been uniform cross ll tril plots nd dictted by commercil frm opertions. In ech subsequent yer the tril re hs then been revisited in order to ssess ny crryover yield effects of the stubble mngement tretments set up in yer one on yields of the frm crop in the following yers GS31 GS39 GS69 Growth stge FIGURE 1 Influence of stubble mngement on brley crop cnopy NDVI ssessed July first node (GS31); 18 August 2016, flg lef fully emerged (GS39) nd 26 September 2016, end of flowering (GS69) Error brs presented s mesure of LSD estblished following cultivtion hd higher NDVI vlues, which pper to be correlted to higher DM nd nitrogen content up to the end of flowering (GS69). iv) Yield nd grin qulity The tril ws hrvested on 9 December While the cultivted plus 40kg N/h tretment recorded the highest yield, nd the burnt tretment recorded the lowest, these yields were not significntly different. Therefore, there were no significnt yield dvntges of ny stubble The results from this focus frm during the pst three yers show the rnk order of stubble mngement tretments hs been similr, with significnt differences in yield only recorded during 2015 when the cultivted plus 40kg N/h tretment significntly outyielded the burnt tretment (Figure 2). While similr trends were observed during 2016, the yield differences were not significnt. Despite benefits of erlier DM production nd disese control (yellow lef spot) from burning, no yield dvntge hs been observed due to burning over NTSR (control) t this tril site during the pst three sesons of stubble mngement trils. vi) 2015 stubble mngement tretments influence on 2016 whet yields The stubble mngement tril hs not only been set up to exmine the influence of different stubble mngement techniques on the subsequent crop, but lso to ssess TABLE 7 Whet yield, protein, test weight, screenings nd thousnd seed weight (TSW) 9 December 2016, t hrvest (GS99) Yield nd qulity Yield (t/h) Protein Test weight (kg/hl) Screenings TSW (g) NTSR (control) Cultivted (one pss) b Cultivted (one pss) Burnt Men LSD RESEARCH AT WORK 15

5 Yield (t/h) b NTSR (control) b Cultivted (one pss) FIGURE 2 Yield dt from time replicte trils 1, 2 nd 3 the Dysdle (red brown erth), Corow (hevy grey cly) nd Coreen (lom over cly) trils for 2014, 2015 nd 2016 cv Whistler (whet) in 2014, cv Mce (whet) in 2015, cv Hindmrsh (brley) in 2016 Yield brs for the sme yer with different letters re regrded s sttisticlly different. Note: The three trils were crried out on the sme frm but not on the sme tril site. During 2014 the cultivtion tretments were estblished with two psses of multidisc, while in 2015 nd 2016 single pss ws used. whether there re ny rottionl effects on following crops. For exmple, does burning or cultivting between the first nd second whet crop impct yield performnce the yer fter the second whet? Tble 8 shows the performnce of commercil whet crop (cv Trojn) sown during 2016 into the lrge block 2015 stubble mngement tril. As the fb ben crops sown in 2015 suffered from poor nodultion they do not represent n effective legume brek crop. The stubble mngement tretments crried out during the 2015 tril (time replicte 2) did not significntly influence the following third whet crop (cv Trojn), lthough there ws trend for crops estblished by cultivtion or NTSR to yield more thn crops following Cultivted (one pss) Stubble tretment b Burnt TABLE 8 Whet yield, protein, test weight nd screenings t Corow, yield nd qulity 2015 stubble tretments Yield (t/h) Protein Test weight (kg/hl) Screenings NTSR (control) 6.72 b b 2.4 Cultivted (one pss) 6.53 b b 2.5 Cultivted (one pss) 6.66 b b 2.2 Burnt 5.90 b b 1.6 Fb bens (green mnure) Fb bens (grin) b 1.7 Men LSD burning during Whet yields following fb bens, which nodulted poorly, were t/h higher yielding thn third continuous whet crop, s compred with 2t/h dvntge in the 2014 (time replicte 1) tril. Although whet yields were higher following fb bens, there ws no difference in protein levels between tretments. This indictes greter nitrogen offtke, lthough the extr nitrogen offtke is reltively smll nd sttisticlly insignificnt in the tril sequence. The nitrogen offtke in grin following fb bens equted to 112kg N/h (verge of forge nd grin fb ben tretments) versus 104kg N/h in the third whet estblished with NTSR (control). The difference in the previous yer s reserch (2015 commercil crop sown over 2014 tril site) ws 111kg N/h offtke following fb bens versus 57kg N/h following whet, however in 2016 the host frmer pplied 108kg N/h cross his whet crop compred with 53kg N/h during Fb bens sown longside second whet stubble mngement tretments in July nd then September in

6 Tril 2: Yrrwong, Victori Sowing dte: 28 April 2016 Rottion: Second whet Vriety: Corck Stubble: Whet (vrious tretments pplied) Stubble lod t sowing: Long stubble 4.7t/h, short stubble 4.3t/h Rinfll: GSR: 604mm (April October) Summer rinfll: 125mm Soil nitrogen t sowing: 64kg N/h NTSR (control) nd 60kg N/h multidisc (0 60cm) Key points Despite differences in DM production erly in the seson, there were no differences in yield or grin protein due to stubble mngement tretments (burning, removing strw, cultivting or NTSR). There ws non-significnt trend for burning to produce smll yield gins (4 5%) over NTSR, result seemingly linked to higher DM production. With higher yield potentil for 2016, pplying nitrogen t sowing significntly incresed grin yield nd protein when stubble ws cultivted. However this my be due to optiml nitrogen mngement rther thn stubble mngement. In ll three sesons of trils ( ), there ws more DM ccumultion erlier in the seson nd smll non-significnt yield gins (3 5%) when stubbles were burnt; however with shrp finish to the 2015 seson, burning significntly reduced yield compred with NTSR (12.5% yield decrese). Stubble mngement options tht support high DM production erlier in the seson (i.e. stubble removl) cn be beneficil when yield potentil is higher (2014 nd 2016) nd either neutrl or disdvntgeous in sesons when yield potentil is lower (2015). Results i) Estblishment nd crop structure The NTSR short stubble tretment significntly reduced plnt estblishment compred with tretments where stubble (strw) ws removed or burnt. As the short stubble ws prepred by cutting the long stubble fter hrvest (lte Mrch/erly April), the cut strw on the ground my hve creted mulching effect, which my hve impeded plnt emergence. Other tretments, such s the NTSR long stubble nd cultivtion tretments, were not significntly different from the strw removed or burnt plots (Tble 9). By second node (GS32) the long stubble tretments hd significntly reduced tiller numbers reltive to the other tretments, which followed through to significnt reduction in hed number in the long stubble plus nitrogen tretment. ii) Dry mtter production The lower tiller number recorded with NTSR long stubble (control) t second node (GS32) correlted to less DM ccumultion compred with the other tretments. The burnt tretment produced significntly more DM throughout the seson (Tble 10). Up until grin fill there ws lg in DM production in the NTSR long stubble tretment compred with NSTR short stubble tretment, which ws not pprent t the hrvest ssessment; indicting lter compenstion in these tretments. The reduction in DM ccumultion with NTSR long stubble (control) correlted to decresed nitrogen uptke in the crop cnopy t GS32 compred with the burnt or cultivted tretments (Tble 11). The difference in nitrogen uptke between long nd short stubble tretments ws not significntly different despite there being significntly more DM following short stubble when ssessed t the sme growth stge. At erly grin fill (GS71) ll the NTSR tretments hd significntly lower crop cnopy nitrogen contents compred with the other stubble tretments, lthough this ws offset in the NTSR long stubble tretment. The dditionl nitrogen t sowing generted smll increse in nitrogen offtke compred with the TABLE 9 Plnt counts nd vigour 10 June 2016, one tiller (GS21); tiller counts 2 August 2016, second node (GS32) nd hed counts 6 December 2016, hrvest (GS99) Crop growth stge NTSR long stubble (control) NTSR long stubble Plnts/m² Tillers/m² Heds/m² GS11 GS32 GS b 248 b 266 bc 153 b 271 b 225 c NTSR short stubble 140 b b Strw removed b Cultivted (one pss) 146 b b Cultivte (one pss) 152 b Burnt b Men LSD RESEARCH AT WORK 17

7 18 TABLE 10 Dry mtter 2 August 2016, second node (GS32); 5 September 2016, mid-booting (GS45); 12 October 2016, wtery ripe grin (GS71) nd 6 December, hrvest (GS99) Dry mtter (t/h) GS32 GS45 GS71 GS99 NTSR long 1.57 b 5.13 b 8.82 d bc stubble (control) NTSR long 1.53 b 5.74 b 9.65 cd c stubble NTSR short stubble b bc bc Strw removed bc bc Cultivted (one pss) b b bc Cultivte (one pss) b b Burnt Men LSD TABLE 11 Nitrogen uptke in biomss 2 August 2016, second node (GS32); 5 September 2016, mid-booting (GS45); 12 October 2016, wtery ripe grin (GS71) nd 6 December, hrvest (GS99) Nitrogen uptke in biomss (kg N/h) GS32 GS45 GS71 GS99 NTSR long 49 c b 93 b stubble (control) NTSR long 51 c b 95 b stubble NTSR short stubble 54 bc b 98 b Strw removed 55 bc b Cultivted (one pss) 61 b Cultivte (one pss) Burnt 60 b b Men LSD NTSR (control), but where the stubble ws cultivted there ws no increse in nitrogen offtke t hrvest due to extr nitrogen t sowing compred with the cultivtion only tretment. iii) Photosyntheticlly ctive rdition (PAR) During the pst three sesons ( ) one of the most consistent effects of the stubble mngement tretments in NTSR systems hs been the influence of stubble length on DM production. There is consistent reduction in tillering nd DM production in longer stubble. In prt this ppers to be linked with nitrogen vilbility nd temperture, but s these fctors could not completely explin this effect, in 2016 for the first time the reserch tem looked t differences in light interception by the growing crop cnopy; more ccurtely described s photosyntheticlly ctive rdition (PAR). During the winter months (June nd July 2016) the influence of the different stubble mngement tretments on PAR ws ssessed. The results reveled reductions in PAR of more thn 50% compred with short stubble NTSR (Figure 3). Burnt plots cptured the most PAR, but this ws only slightly more thn the cultivtion nd NTSR short stubble tretments. Although the PAR will be influenced by the Sun s zenith (high point in the sky) the results clerly show the bility to cpture vilble sunlight is key difference between long nd short stubble tretments nd could be the mjor fctor in why there is reduced tillers nd lg in DM production with long stubble. iv) Green lef retention t the stem elongtion nd erly grin-fill stges At second node (GS32) nd booting (GS45) the burnt nd cultivted tretments resulted in higher NDVI crop cnopy scores (Figure 4). This incresed greenness of the cnopy ws evident in the NDVI ssessments (conducted with the Greenseeker ) t GS32 nd GS45. All NDVI scores declined t erly grin fill (GS71) but cultivtion with extr nitrogen nd burnt stubble plots still gve higher NDVI redings thn NTSR short stubble nd NTSR long stubble tretments. v) Disese levels There were no pprecible levels of disese in the tril, result tht is linked to the better resistnce of Corck to yellow lef spot (YLS) compred with Young, vriety used in previous yers. % PAR vilble to crop NTSR (long stubble) NTSR (short stubble) Cultivted (one pss) Stubble tretment GS21 Burnt GS22 FIGURE 3 Influence of stubble tretment on vilbility of photosyntheticlly ctive rdition (PAR) on 10 June 2016 (GS21) nd 15 June 2016 (GS21/22) t the Yrrwong tril site *The error brs re mesure of LSD Note: 10 June redings were tken t 1pm with the verge bove-cnopy PAR mesuring 866µmol/m 2 /s, in the nm wvebnd 15 June redings were tken t 10m with the verge bove cnopy PAR mesuring 733µmol/m 2 /s 1, in the nm wvebnd

8 NDVI (scle 0 1) NTSR long stubble (control) NTSR short stubble Cultivted (one pss) Burnt GS32 GS45 GS71 Assessment timing FIGURE 4 Influence of stubble mngement on resultnt crop cnopy NDVI (0 1 scle) ssessed t stem elongtion (GS32), booting (GS45) nd erly grin fill (GS71) *The error brs re mesure of LSD vi) Grin yield nd qulity NTSR long stubble Strw removed Cultivte (one pss) The tril ws hrvested on 12 December There were sttisticl differences in grin yield nd qulity s result of stubble mngement. Despite lg in DM ccumultion t stem elongtion (GS32) with the NTSR long stubble tretment there ws no difference in yield between long nd short stubble tretments (Tble 12). There ws lso no yield dvntge ssocited with strw removl. Burning the previous whet crop residues gve smll, non-significnt yield increse (4 5%) over ll NTSR tretments, result similr to tht observed during Cultivtion produced no yield benefits over the NTSR long stubble (control) tretment. The high in-seson rinfll nd high yield potentil ment crops responded to extr nitrogen pplied t sowing, which is evident in both the NTSR nd cultivted plots. In both cses pplying 40kg N/h t sowing resulted in significntly higher grin protein nd significntly more yield with cultivtion (0.79t/h). Where no extr nitrogen ws pplied t sowing the effect of the different stubble mngement tretments (burnt, cultivted, strw removed nd NTSR) hd no impct on grin qulity. vii) Three-yer results (time replictes 1, 2 nd 3) yield dt The stubble mngement tril hs been estblished in the sme crop rottion position on different pddocks during the pst three yers. There hve been only few significnt yield effects ssocited with stubble mngement over the three yers of trils. In 2016 there were significnt yield increses when dditionl nitrogen ws pplied t sowing, however removing the influence of tretments with dditionl nitrogen, there were no significnt differences in yield between burning, cultivting nd strw removl, compred with NTSR (Figure 5). Although burning hs incresed DM production in ll three yers it hs not generted ny sttisticl yield dvntges, with only smll, non-significnt trend suggesting 3 5% yield benefit. With the hrder finish during 2015, the burnt tretment hd significntly less grin yield compred with NTSR short stubble, with the greter biomss of the burnt tretment possibly being disdvntge in such seson. viii) 2015 stubble mngement tretments influence on 2016 cnol yields Different stubble mngement tretments estblished pre-sowing during 2015 resulted in significnt differences in whet yields during 2015, with the NTSR short stubble tretment significntly incresing whet yields compred with strw removl nd burning. However, these tretment effects did not follow through to hve ny effect on the yield of commercil crop of cnol sown cross the 2015 site during 2016 (Tble 13). TABLE 12 Whet yield, test weight, protein, screenings, hrvest index (HI) nd thousnd seed weight (TSW) 12 December 2016, t hrvest (GS99) Yield (t/h) Protein Test weight (kg/hl) Screenings NTSR long stubble (control) 5.86 bc 8.5 c bc 46.6 c NTSR long stubble 6.19 b 9.7 b b bc NTSR short stubble 5.81 bc 8.9 c b 49.3 bc 48.7 b Strw removed 5.6 c 8.6 c b 48.3 bc 49.0 Cultivted (one pss) 5.9 bc 9.1 bc b 49.7 bc 49.3 Cultivte (one pss) b 52.0 b 49.9 Burnt 6.12 bc 8.9 c b 42.8 c 50.0 Men LSD HI TSW (g) RESEARCH AT WORK 19

9 Yield t/h bc b b b b b b Long stubble control (NTSR) b Long stubble (NTSR) b Strw removed bc Cultivted (one pss) Stubble tretment Cultivte (one pss) Burnt bc bc Short stubble (NTSR) FIGURE 5 Yield dt from the three Yrrwong trils for 2014, 2015 (cv Young) nd 2016 (cv Corck). Note: The NTSR short stubble ws not prt of the 2014 list of tretments. Yield brs cross tretments for the sme yer with different letters re regrded s sttisticlly different. TABLE 13 Cnol yield in the 2016 commercil crop following different stubble mngement tretments set up in the 2015 stubble mngement site nd the 2015 whet yield 2015 stubble mngement tretments (ll blocks were burnt before the 2016 crop) 2015 second whet yield (t/h) 2016 cnol yield (t/h) NTSR long stubble (control) 3.13 b 2.76 NTSR long stubble 3.20 b 2.73 NTSR short stubble Strw removed 3.03 b 2.72 Cultivted (one pss) 3.10 b 2.75 Cultivte (one pss) 3.05 b 2.69 Burnt 2.93 b 2.73 Men LSD Influence of stubble height on sunlight interception in the NTSR long stubble (left) nd NTSR short stubble (right) t the Yrrwong site, 20 My,

10 Tril 3: Dookie, Victori Sowing dte: 12 My 2016 Rottion: Second whet Vriety: Corck Stubble: Whet (vrious tretments pplied) Stubble lod t sowing: 7.9 t/h Rinfll: GSR: 509mm (April October) Summer rinfll: 130mm Soil nitrogen: 110kg N/h control NTSR, 102kg N/h multidisc (0 60cm) Key points A growing seson rinfll of 509mm resulted in verge yields of 5.8t/h compred with 2.4t/h in 2015 nd 5.5t/h in 2014 for the equivlent tril in second whet rottion position. Trnsient wterlogging influenced the results of the tril nd gve vrible yield effects resulting in high LSD of 1.02t/h. As consequence, there were no yield differences during 2016 due to stubble mngement, with ll tretments chieving 5 6t/h yields, screenings less thn 1% nd grin protein levels bove 10.5%. Though there ws trend for the burnt nd strw removed tretments to increse plnt estblishment nd erly DM production compred with NTSR long stubble (control), the trend for these tretments to be higher yielding (3 7%) ws not sttisticlly significnt. Across the three yers of the tril, NTSR long stubble hs reduced erly DM production in ll yers, however it hs only significntly reduced yield compred with other stubble tretments during 2014 (0.7t/h decrese). The significnt yield reduction in 2014, due to long stubble, resulted in significnt increse in cnol yields during However, the influence of stubble mngement tretments set up in 2014 hd no effect on the yield of whet in 2016, following cnol. thn 20 plnts/m 2 ). At first node (GS31), the NTSR long stubble tretment hd significntly fewer tillers compred with the short stubble nd other tretments (Tble 14). Burning stubble produced the highest tiller number (445 tillers/m 2 ), however the dvntge over the NTSR short stubble tretment ws not significnt. At mturity there were no significnt differences in hed numbers between the different tretments nd the lrge rnge in tiller number (pproximtely 150 tillers/m 2 ) ws nrrowed with only n pproximte rnge of 50 heds/ m 2 between tretments. ii) Dry mtter production nd nitrogen uptke in the crop cnopy The NTSR long stubble tretment produced significntly less DM t first node (GS31), result tht correltes to observtions on tiller numbers (Tble 14 nd 15). At erly grin fill (GS71) the burnt tretment still mintined n increse in DM over NTSR long stubble. Although the short stubble tretment tended to produce more DM thn long stubble during er emergence (GS55) nd t erly grin fill (GS71), these differences were not sttisticlly significnt, with no difference between the two tretments t physiologicl mturity (GS95 99); result noted in previous yers. The lower DM production under the NTSR long stubble tretment compred with other tretments lso equted to lower nitrogen uptke in the cnopy t first node (GS31), however there were no differences in nitrogen uptke t lter ssessment times (Tble 16). iii) Disese levels Assessments for disese reveled only trce levels of yellow lef spot (YLS), result similr to tht seen t the Yrrwong site. Agin, this is thought to be linked to greter resistnce rting of Corck to this disese. There TABLE 14 Plnt counts nd vigour 8 June 2016, two lef (GS12); tiller counts 2 August 2016, first node (GS31) nd hed counts 30 November 2016, physiologicl mturity (GS95 99) Crop growth stge Plnts/m² Tillers/m² Heds/m² GS12 GS31 GS99 NTSR long stubble 135 b 296 c 356 NTSR short stubble 133 b 389 b 383 Results i) Estblishment nd crop structure Burning the strw resulted in significntly higher plnt popultion thn ll NTSR nd cultivtion tretments, however the differences were reltively smll (less Cultivted (one pss) 136 b 363 bc 391 Strw removed 141 b 378 b 343 Burnt Men LSD RESEARCH AT WORK 21

11 TABLE 15 Dry mtter 2 August 2016, first node (GS31); 19 September 2014, hed hlf emerged (GS55); 17 October, wtery ripe grin (GS71) nd 30 November, physiologicl mturity (GS95 99) Dry mtter (t/h) GS31 GS55 GS71 GS95 99 NTSR long stubble 0.76 b b 14.1 NTSR short stubble b 14.0 Cultivted (one pss) b 12.5 Strw removed b 12.9 Burnt Men LSD TABLE 16 Nitrogen uptke in dry mtter 2 August 2016, first node (GS31); 19 September 2014, hed hlf emerged (GS55); 17 October, wtery ripe grin (GS71) nd 30 November, physiologicl mturity (GS95 99) Nitrogen uptke (kg N/h) GS31 GS55 GS71 GS95 99 NTSR long stubble 32 b b 71 NTSR short stubble Cultivted (one pss) b 73 Strw removed b 52 Burnt 50 s b 79 Men LSD were trces of lef rust t the end of the seson, but no observble differences in disese between tretments. iv) Green lef retention The soft finish to the seson produced conditions suitble for n extended grin fill period, unlike the het stress of 2015, lthough it ws evident tht trnsient wterlogging in prts of the tril precluded this from hppening to the extent tht might be suggested by vilble wter nd tempertures. Assessments of the crop cnopy, using NDVI, reveled initil differences t first node (GS31), however these differences were not mesured lter in the seson, t hlf hed emerged (GS55) nd erly grin fill (GS71) (Figure 6). Long nd short stubble NTSR recorded lower crop cnopy greenness compred with the burnt plots t first node (GS31), but not when ssessed lter. v) Yield nd grin qulity The tril ws hrvested on 13 December The yield results t this site were highly vrible s prts of the tril site were subject to wterlogging during the growing seson. As result, there were no significnt differences between the different stubble mngement tretments (Tble 17). Yield results nd grin qulity were bsed on three replictes s the fourth replicte ws bdly ffected by wterlogging. The yield rnge in the tril ws t/h, which is similr to results chieved in 2014 t this site. There were no sttisticl differences in grin qulity (Tble 17). vi) Three-yer results (time replicte 1, 2 nd 3) yield dt For the pst three yers replicted lrge block stubble mngement tril hs been estblished in different NDVI (0 1) NTSR long stubble NTSR short stubble Cultivted (one pss) Burnt Strw removed GS31 GS55 GS71 Crop growth stge FIGURE 6 Influence of stubble mngement on crop cnopy NDVI (0 1 scle)* *The error brs re mesure of LSD TABLE 17 Whet yield, protein, test weight, screenings nd thousnd seed weight (TSW) 13 December 2016, t hrvest (GS99) Yield nd qulity Yield (t/h) Protein Test weight (kg/hl) Screenings NTSR long stubble NTSR short stubble Cultivted (one pss) Strw removed Burnt Men LSD TSW (g) 22

12 Dookie site on 8 June 2016 (GS12) pddock on the Dookie focus frm. The tril set-up in 2014 (yer one of the experiment) is referred to s time replicte 1 in the tril series, the tril set up in yer two is time replicte 2 nd in the third yer it is time replicte 3. After ech tril hs been completed the tril re reverts to being commercil frm crop undergoing uniform mngement. The stubble mngement for ll subsequent yers hs been uniform cross the tril re nd dictted by commercil frm opertions. In ech subsequent yer the tril re hs then been remrked in order to ssess ny yield effects of stubble mngement set-up in yer one on yields in the yer two nd three frm crop. The yield results from ech time replicte tril t the Dookie focus frm hve shown only one significnt yield difference due to stubble mngement over the three yers the tril hs run. In 2014 the NTSR long stubble (45cm) tretment significntly reduced yield by pproximtely 0.7t/h, compred with other tretments, including NTSR short stubble tretment. This equtes to yield reduction of 0.25t/h for every 10cm increse in stubble height bove 15cm, ssuming it is liner response between yield nd stubble height (Figure 7). Although significnt yield reduction ssocited with long stubble ws only observed in 2014, there hs been evidence in ll three yers tht long stubble hs significntly decresed DM production, resulting in less tillering nd reduced crop cnopy greenness. In some sesons, this reduction in crop cnopy greenness hs been reversed lter in the seson, with NTSR tretments being greener t grin fill. This ws most pronounced during 2015, nd ws lso ssocited with slower phenologicl development of the crop. In stressed seson with yields of 2.5t/h these greenness/ phenologicl differences did not influence yield b Yield (t/h) Short stubble (NTSR) Long stubble (NTSR) Cultivted (one pss) Strw removed Burnt Stubble tretment FIGURE 7 Yield dt from 2014, 2015 nd 2016 stubble mngement trils conducted in the whet-on-whet rottion position (time replicte 1, 2 nd 3), cv Corck (2014), cv Mce (2015) nd cv Corck (2016) Yield brs for the sme yer with different letters re regrded s sttisticlly different. RESEARCH AT WORK 23

13 vii) Time replicte 1 yield dt Looking t crop productivity on the sme tril site over three yers reveled tht stubble mngement tretments during 2014 significntly influenced cnol yields in 2015 but hd no effect on whet yields in The significnt reduction in yield cused by NTSR long stubble in 2014 significntly incresed commercil cnol yields during 2015, even though the site ws burnt following the 2014 tril, before sowing the cnol. The higher cnol yields in 2015 re likely due to greter stored wter or unused nitrogen retined in the lower-yielding NTSR long stubble plots. There were no flow-on effects from stubble mngement in 2014 on 2016 whet yields (Tble 18). viii) 2015 tril tretments 2016 cnol yield dt The 2015 stubble mngement tril t the Dookie focus frm ws sown to commercil crop of cnol during The 2015 second whet tril stubbles were burnt in preprtion for the commercil cnol crop. Despite lrge visul differences in crop ppernce in 2015 with NTSR long stubble plots being greener (Reserch for the Riverine Plins 2016, p22) nd slightly less developed, there were no yield differences due to stubble mngement tretments in either the 2015 tril, sown to whet or the following cnol crop, when sown over the 2015 stubble tretments with yield rnge of 0.2t/h cross the site in both sesons (Tble 19). TABLE cnol yields nd 2016 whet yields, on the site of the 2014 stubble mngement tril, which ws sown to second whet (time replicte 1) 2014 stubble mngement (2015 ll tril blocks burnt prior to cnol) 2014 tril results, second whet yield 2015 cnol yield 2016 whet yield NTSR long stubble 5.0 b NTSR short stubble b 7.1 Cultivted (one pss) b 7.2 Strw removed b 6.9 Burnt b 7.1 Men LSD TABLE cnol yields, on the site of the 2015 stubble mngement tril, which ws sown to second whet (time replicte 2) 2015 stubble mngement (2016 ll tril blocks burnt prior to cnol) 2015 tril results, second whet yield 2016 cnol yield NTSR long stubble NTSR short stubble Cultivted (one pss) Strw removed Burn Men LSD NTSR long stubble 2 August 2016 (GS31) Burnt stubble 2 August 2016 (GS31) 24

14 Tril 4: Henty, NSW Sowing dte: 10 April 2016 Rottion: Whet stubble Vriety: Cnol 650 TT Stubble: Whet (vrious tretments pplied) Stubble lod t sowing: 6.6t/h Rinfll: GSR: 619mm (April October) Summer rinfll: 145mm Soil nitrogen t sowing: 106kg N/h NTSR (control), 101kg N/h multidisc (0 60cm) Key points Tril results were highly vrible, with no significnt differences in cnol yield lthough there ws trend for the cultivtion tretments to be higher yielding. Cnol 650TT showed higher DM ccumultion t flowering where the seedbed hd been cultivted (multidisc) compred with the NTSR control, lthough dding nitrogen to the NTSR tretment negted this effect. The 2016 results were similr to 2014 when cultivtion before sowing significntly incresed cnol yields. Results i) Estblishment nd crop structure There were no significnt differences in crop estblishment in terms of crop nd weed plnt popultions, however plnt estblishment ws significntly more vigorous where the seedbed hd been cultivted (Tble 20). ii) Dry mtter production nd nitrogen uptke in the crop cnopy While the results were highly vrible, the NTSR (control) nd mulched tretments generlly produced less DM thn the cultivted tretment, up to the mid-flower ssessment (Tble 21). Erly DM production ws incresed by either cultivtion nd/or dding nitrogen to the NTSR (control), but by hrvest there were no significnt differences in DM between tretments (Tble 21). Similr trends re observed in the nitrogen uptke dt (Tble 22). iii) Yield There were no significnt yield differences due to stubble mngement, with vrible yield results due to trnsient wterlogging cross the tril site. There ws nonsignificnt trend for crops in the cultivted tretment to yield more, result tht ws significnt in 2014 when cultivted crops significntly out-yielded the NTSR (control) blocks (Tble 23). TABLE 21 Dry mtter 11 July 2016, green bud (GS51); 9 August 2016, mid-flower (GS65); 26 September 2016, 50% pods reched finl size (GS75) nd 11 November, hrvest (GS99) Dry mtter (t/h) GS51 GS65 GS75 GS99 NTSR (control) 1.64 b 3.70 c 6.90 b 9.76 NTSR bc 6.09 b 7.98 Mulched 1.69 b 3.91 bc 7.58 b 8.31 Mulched 1.58 b 4.19 bc Cultivte (one pss) 1.84 b b 8.33 Cultivte (one pss) 1.75 b 5.12 b 7.49 b 8.87 Men LSD TABLE 20 Plnt nd weed counts 3 My 2016, three leves unfolded (GS13) nd vigour score 17 July 2016, green bud stge (GS51) Cnopy composition GS13 GS51 TABLE 22 Nitrogen uptke in dry mtter 11 July 2016, green bud (GS51); 9 August 2016, mid-flower (GS65); 26 September 2016, 50% pods reched finl size (GS75) nd 11 November, hrvest (GS99) Nitrogen uptke (kg N/h) plnts/m² weeds/m² Vigour GS51 GS65 GS75 GS99 NTSR (control) bc NTSR b Mulched bc Mulched c Cultivte (one pss) NTSR (control) 86 bc 117 bc 141 b 151 NTSR bc 114 b 153 Mulched 96 bc 94 c 161 b 91 b Mulched 82 c 167 b b Cultivte (one pss) 111 b 132 bc 132 b 98 b Cultivte (one pss) bc Cultivte (one pss) 94 bc b 165 Men LSD Men LSD RESEARCH AT WORK 25

15 NTSR (control) tretment, 3 June 2016, 4 6 leves TABLE 23 Cnol yield nd % of tril site men 6 December 2016, t hrvest (GS99) Yield NTSR (control) NTSR Mulched Mulched Cultivte (one pss) Cultivte (one pss) (t/h) Men 2.53 LSD 0.72 iv) Three-yer results (time replictes 1, 2 nd 3) yield dt The yield results from yer one of ech tril run t the Henty focus frm (time replictes 1, 2 nd 3) hve shown vrible results, but similr trends (Figure 8). This trend hs been for cnol crops to yield more following cultivtion compred with the NTSR (control) tretment, though it ws only in 2014 tht the yield dvntge of Cultivted tretment, 3 June 2016, 4 6 leves cultivtion (by multidisc) ws sttisticlly significnt. In ll three yers the tril site hs been subjected to vrible mounts of wterlogging, which ws prticulrly problemtic in erly spring cross ll three yers. Acknowledgements Thnks to the frmer co-opertors t ech of these sites: Corow/Coreen: Tomlinson Ag Yrrwong: Telewong Pty Ltd Dookie: Ludemn Brothers Henty: Peter Cmpbell This work ws crried out s prt of the Riverine Plins Inc GRDC funded project Mintining Profitble Frming Systems with Retined Stubble in the Riverine Plins Region ( ). Contct Michel Stright Foundtion for Arble Reserch, Austrli E: michel.stright@fr.org.nz Yield t/h c b bc b bc NTSR NTSR + 40kg N/h Mulched Mulched + 40kg N/h Stubble tretment Cultivted Cultivted + 40kg N/h FIGURE 8 Yield dt from 2014, 2015 nd 2016 stubble mngement trils crried out in cnol following whet (time replictes 1, 2 nd 3), cv GT50 RR (2014), cv 314 TT Monol (2015) nd cv Hyol 650 TT (2016) 26