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Issues & observations of inter-row sowingThe practice of inter-row sowing refers tocrops being sown in-between the previousyears’ stubble and has been widely adoptedby growers due to its compatibility withstubble retained systems. Satellite steering guidance systems

(auto-steer) has been the driving force behindits adoption and the system can providemany benefits as opposed to more traditionaldiagonal or angle seeding across stubble.

Benefits: A study conducted by Matthew McCallum(McCallum Agribusiness Consulting, SouthAustralia) found that inter-row sowing hada yield benefit in wheat crops of 6 per centfrom 2004 to 2007. The yield benefit waslargely due to a reduction in diseasepressure, better plant establishment andpossibly an improved micro-climate forwheat in standing stubble, for examplemore sunlight penetrating the stubblecanopy promoting faster growth forseedlings and protection from wind.Inter-row sowing can reduce crown rot

and root rot inoculum building up ininfected paddocks. Research by Dr StevenSimpfendorfer (NSW DPI) has shown thatsowing cereals between the previous cerealrows reduced the incidence of plants infectedwith crown rot by 45 per cent and the severity

KEY MESSAGES

Reduces the impact of diseases suchas crown rot in wheat on wheatrotations.

Can reduce hair-pinning of stubble indisc seeders.

Improves trash flow through theseeding machine, especially with tinedimplements and heav y stubble loads.

May reduce early up take of residualnutrients from previous crop for thefirst year.

May have less available moisture forseedlings than on-row on sandy soils.

Requires tractor guidance and stableinstrument tracking.

Offers other potential benefitsincluding improved water infiltration,increased timeliness of sowing andconservation (less erosion and anincrease in soil organic matter) andfuel savings.

inter-row sowingin stubble retained systems in Central West NSWProject code CWF00018

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of disease by 51 per cent across sites fromsouthern QLD to Walgett (NSW), althoughhe concedes the higher the amount ofcrown rot in previous cereal residue thehigher the likelihood of the pathogenmoving into the inter-row through stubblefragmentation. Inter-row sowing should beseen as part of an integrated diseasemanagement program and not as a form ofcontrol on its own.In-crop spraying is more efficient in

inter-row sown paddocks than those withslashed or mown stubble. Slashing stubblecan reduce herbicide efficacy if more than50% of the ground is covered by stubbleresidue.However, in sandy soils with low levels

of disease inoculum, on-row sowing mayproduce higher yields due to better moistureretention and wider availability of remainingnutrients from the previous year’s crop,particularly for seedlings.

Seeder setup:Blockages are perceived to be one of themajor issues with inter-row sowing, althoughmodifications to the profile and tine layoutcan reduce stubble clumping and blockages.Straight shanks instead of curved shanks

will ease the trash flow through the machine,while shanks that are slightly backwardsleaning are effective for facilitatingmovement of trash through the machine. Inter-tyne spacing of approximately

60cm is suitable for 3-4t/ha of wheatstubble cut at a height of 35cm.

What GPS accuracy is needed? The way to implement inter-row sowing isusing a 2cm RTK system with a base station.This allows for repeatable accuracy.

The sub-metre auto steer (10-20cm)doesn’t allow for the same level of repeatableaccuracy. It is important that the base stationremains in the same location for a particularpaddock year in year out. The auto steerprogram should have the ability to storeand recall an A/B line for a particularpaddock, as well as a nudge feature to movethe required distance to inter-row sow.

Issues and observations of row spacingSince the uptake of minimum till strategies,the ability to vary row spacing and sowwithin the inter-row has increased. Howeverthere are advantages and disadvantages todiffering row spacing (Brendan Scott et al).In Central West NSW, row spacings of

20cm on average are commonplace, with somefarmers in drier areas opting for widerspacing (out to 30 cm). Further east in higherrainfall areas a reduction in row spacing iscommon, depending on what crops are grown.

Cereals:Ultimately the impact of row spacing oncereal crops is largely dependent on theseason’s rainfall, the time of sowing and thepotential yield of the crop. If a crop has ahigh yield potential then there is a greaternegative impact on the crop’s potential yieldas the row spacing increases, with specificreference to wheat and barley crops.In wheat on wheat rotations, diseases

such as crown rot are less likely to movefrom the previous stubble zone to the newcrop in wider rows. However, in many areasa reduction in the size of row spacing canresult in an increase in crop yield.It should be noted that by reducing row

spacing other issues may arise at sowing

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(such as blockages in machinery).Crops that are grown on wider row spacing

often tend to grow taller, which may leavethem vulnerable to lodging later in the season.

Pulses: Pulses often exhibit a positive response torow spacing out to a width of 25 cm in lowrainfall areas and 35 cm in high rainfallareas (GRDC 2011). However, different pulses can exhibit

different behaviour. A paper by SouthAustralian No-Till Farmers Association(Santfa) in 2013 titled “Many Variables inRow Width Equation” explores row widthtrial results on both grain and pulse cropsacross Australia including Central West NSW.

The benefits of wide row spacing in lupinsinclude:The ability to sow into large amounts of stubble.Obtaining more stable yields in lowrainfall environments.The potential use for inter row sprayingfor better weed control.Rows that are wider than 50 cm have a

higher yield potential when compared to thenarrower rows in warm, dry environmentsof low to medium rainfall. This is a directresult of the crop using less water during thewinter period, which leaves more soilmoisture for the pod filling period.Narrower rows (less than 50 cm) are

much more likely to yield better in cooler,longer season climates. Pulses such as peas andlentils that are grown on a wide row spacingof 30-60 cm generally have a greater poddingheight. It should be noted that harvestingheight can also be improved by using stubblesto form a trellis by inter row sowing.

Soil moisture: By reducing the width of row spacing it ispossible to conserve more moisture andminimise the degree of evaporation byincreasing the rate of canopy closure. Inconditions where wider row spacing ispreferred, stubble mulching within the interrow can be used to alleviate the negativeeffects of evaporation.Research has shown that water use by

wheat and barley was unaffected by the rowspacing. However, faba beans in wider rowspacing have been observed to use lessmoisture during their early growth stageswhich left more moisture for grain filling.

Weed control: Farmers that have adopted wider row spacinghave been experiencing higher weed burdenswithin the inter-row, with ryegrass beingthe main weed issue. By increasing the sizeof row spacing the crop’s ability to close thecanopy and to begin to shade out the weeds islimited. Glen Riethmuller (DAFWA)

demonstrated in 2005 that reducing croprow spacing from 27 cm to 18 cm resulted ina 38 per cent reduction in ryegrass seed set. A strategy to alleviate the issue may be theuse of IBS herbicides that are concentratedwithin the inter rows.

Establishment: There is a relationship between the responsesof cereals and broadleaf’s to row spacing andthe interaction with plant populations. Asrow spacing and seeding rate increases, thedistance between seeds declines. This canimpact on the final establishment for the crop.

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Off-row seeding and moisture availability: With the adoption of auto steer technologies,growers are now able to accurately place theseed wherever they see fit.In drier areas of Central West NSW,

minor improvements in soil wettingaround the seed can lead to majorimprovements in crop establishment.Wetting around the seed can be achievednaturally by more available storedmoisture under the previous year’sstanding stubble.Studies indicate that under no-tillage

systems, old and current crop rows providepathways for water movement within thesoil profile. Stubbles leave behind crowns,root channels and bio pores that are allcapable of trapping moisture within thestubble zone. These factors are capable ofimproving the soils wettability.However, it must also be considered that

disease transference could be an issue withcereal on cereal crops and hair-pinning mayoccur with small seeds such as canola.

Benefits of wider row spacing: A great deal of no-till operations are sowingcereals and canola on 20 to 30 cm rows andpulses on 30 to 65 cm rows between thestanding stubbles. Before adjusting rowspacing it is important to do an economicanalysis by the use of a benefits and costscomparison. Not every system suits everyfarm and individual considerations shouldbe taken into account. To obtain the fullbenefit of inter-row sowing, includingsavings on fuel, a controlled traffic systemmay be beneficial depending on soil type,farming enterprises and machinery set-up.

Case study 1:Grower: Graham MasonLocation: ‘Westcourt’, Ungarie, NSWEnterprises: Continuous cropping; wheat,vetch, canola, barley, lupins.Soil and pH: Red soil with a pH of around 5.Property size: 2500 ha.

Overview: Graham follows a continuous cropping, no–till farming program. Some of his country istrending to acidic so he is currently limingthose areas. He last limed ten years ago andhas only just seen country slipping back.Most of Graham’s cropping is done on a

controlled traffic system and has been fornearly ten years, except for some paddocksthat have issues with contour banks androcky areas.

Issues and observations of controlled trafficfarming: One issue with controlled traffic farmingGraham has noticed is the occasional needfor renovating his tram tracks which arecurrently becoming quite depressed.However he sees this as an opportunity to

use a green manure crop on these paddocksbefore cultivating, as well as the chance touse different chemical groups with pre-emergent prior to sowing the following crop.Levelling of tracks is only done about

every ten years.One of Graham’s primary motivations

for moving into controlled traffic farmingwas after converting to a disc seeder andfinding it gave him a less than optimalperformance behind a heavy tractor even inheader tracks. By using tram tracks, hissowing efficiency with the disc seeder wasgreatly improved.

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The ability to inter-row sow was also akey factor in his decision, allowing him toaccurately sow with 2 cm accuracy.Graham sees a huge advantage in being

able to accurately sow between stubblerows; sowing into clean ground andavoiding stubble contact, yet still retainingthe stubble.Smaller seeds (such as canola) germinate

more evenly without stubble contact in thesoil, as well as not being covered by stubble.His system is still evolving and Graham

feels it will keep evolving as things change.He has encountered herbicide resistancedeveloping with ryegrass and black oatsand used a tyned implement as a controlstrategy. However, it then created problemsswitching back to a disc implement – so heis certainly finding challenges andlimitations within the system he needs toovercome.Another control strategy he uses for

resistance is brown manuring vetch(varying his chemicals) which gives 100%control of weeds as well as supplyingnitrogen and organic matter to his soils. Hethen follows the brown manure with canolawhich gives two years of good weed control.As stubble from previous crops builds up

in the rows Graham has found a disc seederto be superior over a tined implement inslicing through any old remaining crownsthat may be present.If a tined implement must be used

Graham may slash a paddock to aid infaster stubble breakdown.Although he has not physically recorded

fuel usage differences between tram trackand conventional, Graham has noticed theengine of the boom spray working muchharder if it deviates off the tram tracks.

His advice for anyone moving into acontrolled traffic system is to make sure the tracks are suitable to header use as it isthis component which is an integral part of avoiding soil compaction.

Soil health: The benefits to soil health of controlledtraffic farming that Graham has observedis a far better retention of moisture in hissoils, with soils being softer and much morefriable.

Listen to a podcast of Graham’s case studyor follow the link below:

http://cwfs.org.au/podcast/ inter-row-sowing-stubble- retained-farming-systems-2/

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Case study 2:Grower: Nick EckermannLocation: ‘Hillview’, Rankins Springs, NSWEnterprises: Continuous croppingSoil and pH: Loams with a pH of 5 to 5.5Property size: 10,000 ha

Overview: The Eckermann’s are broad-acre croppersand have not run livestock for ten years.They felt they were compromising their

farming country by running livestock in amixed farming operation due to soilmoisture decisions and compromises withweed management; deciding to concentratepurely on a stubble retained cropping system.

Issues and observations of controlled traffic farming: Nick explains they are not 100% controlledtraffic farming at this stage. They work on atwelve metre system but still use duals ontheir main tractor and header, though

everything is confined to a designatedwheel track area.Nick considers their operation currently

in a conversion phase and can see theirfuture cropping enterprise being 100%controlled traffic.They currently renovate their tram

tracks (sow over them) as it better suits theirsoil type rather than leaving them bare.The Eckermann’s primary motivation

for moving toward controlled trafficfarming was the desire to improve theirsoil’s water retention capability and keepsoil compaction to a minimum, after gaininginformation from various sources. The practice has evolved over a five or

six year period with the existing machineryspacing suiting the transition.Areas where they using controlled

traffic are already showing a markedimprovement in water infiltration andretention, resulting in increased crop yieldsover the traditionally farmed areas.

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Reduced fuel use has not been noticeableto this point, though Nick is aware thatsingle wheel permanent tracks wouldundoubtedly give more efficiency.Taking on new country a few years

previously that had been conventionallyfarmed in a mixed farming operation, Nickobserved the soil was not as friable or aseasy to work as the country they had farmedusing no-till methods for some years.Issues and observations of inter-row

sowing: The Eckermann’s began inter-rowsowing in 2006 and had good success usingone bar on a 30cm spacing.Then in 2010, they switched to a disc

sowing system on 50 per cent of theirplanting operation but found they hadmore difficulty keeping within the rowswith this system.They returned to a single bar system but

this year are incorporating a satellitesteering guidance system into their farmingplant which will simplify the operationconsiderably.Nick is not considering changing their

row spacing, being happy with where theyare at now. He feels that with a guidancesystem the rows filling should not be an issue.It should also make sowing of small seeds suchas canola easier and improve germinationas they have tried most stubble managementtechniques in the past, but inter-rowsowing is by far the most effective.Break crops play an important role in

their cropping program, largely for diseasecontrol. Depending on seasons and marketsbetween 25% and 40% of their country issown to alternate crops of wheat, canola ifsoil moisture is sufficient and variouslegume crops which he prefers. Flexibilityremains the key.

Weed resistance is starting to become anissue and Nick has been using windrowburning the past couple of years as a newtool to combat this. He is also growing vetchfor brown manure or hay as anothermanagement option in paddocks where thereis suspected annual ryegrass resistance.

Soil Health: Nick is focused very much on stubbleretention in his cropping program and doesnot consider full burning of stubble a viabletool. Even if the stubble load is over threetonne a hectare (an amount possiblydetrimental to the following crop) he wouldrather take a short term yield loss for thelonger term benefits to the soil.Some of their lighter country can blow if

ground cover is insufficient. This, combinedwith increased soil retention and organicmaterial is the reason Nick and his familyare determined to tackle the manychallenges of inter-row sowing and fullstubble retention.

Listen to a podcast of Nick’s case study orfollow the link below:

http://cwfs.org.au/podcast/ inter-row-sowing-with- stubble-retained-farming-systems/

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Additional benefits were avoidingcontact with stubble from the previous yearwhen sowing wheat on wheat, particularlywhen yellow leaf spot was present.Then four years ago, he purchased a disc

planter on 50cm spacings to make the practiceeasier again. The wider spacing allows forcrops to be inter-row sown in successiveyears with no stubble contact. Althoughthis method perhaps reduces yield slightlyin wetter years he feels this is compensatedby increased yields in drier seasons.Reduced canopy cover in later sown

crops has not been an issue as they are ableto sow on time with the efficiencies ofcontrolled traffic farming.Fuel usage has been reduced even

further with the disc seeder combined withcontrolled traffic farming and he now usesup to a third less fuel than when farmingconventionally.With signs of weed resistance (ryegrass)

starting to appear, Geoff is now mixing hischemical groups and also spraying fencelines to control all volunteer weed seed set.He has also set up the header for narrow

windrow burning and this is a tool he’ll useinto the future.

Soil Health: Geoff classifies himself as a conservationfarmer and since switching to no-till andcontrolled traffic farming he has noticed adistinct improvement in his soil structure,being more friable with better moistureretention.Geoff puts sustainability and profitability

together and thinks they go hand in hand.He has been cautious about pushing formaximum profits at the expense of soilhealth and in ten or fifteen years hopes to

still be improving his farming methods,increasing diversity and remaining flexiblein his approach to utilizing all toolsavailable. His advice to other farmerscontemplating change in their farmingpractice is to set goals and try to achievethem, but not to become too rigid inimplementing new ideas if markets orseasons are adverse to a certain decision.

Listen to a podcast of this case study orfollow the link below:

http://cwfs.org.au/podcast/ geoff-chase-inter-row- sowing/

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Case study 3:Grower: Geoff ChaseLocation: ‘Waitara’, Tottenham, NSWEnterprises: Angus cattle stud andcommercial herd, wheat, chickpeas, fababeans, lucerne hay, fodder (which is brownmanured for fallow as well as grazing).Soil and pH: Self cracking grey clay soilswith a pH of 7.8 – 8.Property size: 7,500 ha.

Overview: Geoff manages the cropping enterprises on‘Waitara’ while his son and daughter-in-lawmanage the Angus stud and cattle operation.Geoff runs a controlled traffic farming

system with everything on three metres,apart from chaser bins.The cattle are allowed to briefly graze

stubbles providing the top 100 cm of soil isdry. He finds it helps to control survivingweed seed and in years of heavy stubbleload can break up and spread the straw for

the following crop, although he prefersstanding stubble in most years. Paddocks arerarely cultivated, on average once every eightyears or so to regenerate paddocks and allowfor incorporation of pre-emergent spray.In the past couple of years Geoff has

moved away from canola in favour of fababeans as a break crop; for better nitrogenfixation and soil friability, though his corecrop is wheat. He has sown more chickpeasthan usual this year due to the strong prices.

Issues and observations of inter-row sowing:Geoff began inter-row sowing about eightyears ago. In the early days he was able toaccurately sow about 85 per cent of cropbetween the rows of the previous crop andimmediately saw the advantages of doing so.One advantage he quickly realised was

that sowing between the rows of stubbleproved easier on the machinery and usedless fuel. Another was the more accurateplacement of seed, with no stubble tointerfere with depth and seed soil contact.

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Latest research & updatesImplement guidance:New use of auto-steer technology has nowincluded the ability to have a seeder steerpartly independently of the tractor pullingit. This extra accuracy is particularly usefulin narrow rows and in avoiding two ormore years of remaining stubble.Implement guidance falls into two

categories – passive guidance and activeimplement guidance.Passive guidance combine GPS data

from mounted receivers on both the tractorand implement to auto-steer the tractorsuch that the implement always remains onthe intended guidance path. This is thecheapest option but requires the tractor tomove on and off track to keep theimplement on the targeted path. It is bestused combined with a stable seeder bar tominimize transient and random drift.Active implement guidance systems

guide the implement independently of thetractor. Active implement guidance is moreexpensive but the extra accuracy may bewarranted to improve cropping returns.This auto-steer is achieved by either a hitchcorrection where the tractor draw-bar or theimplement hitch tongue is hydraulicallyadjusted side-to-side to guide the implement,or by an implement steering kit whichactively directs the implement frame overthe guidance path using steerable wheels ordisc blades to generate a corrective force.http://www.protrakker.com/news-and-events/03-08-17-seeder-tracking-and-guidance-or-precise-row-sowing.aspx

References: McCallum.M.,Multiple benefits fromInter-row Sowing with 2cm RTK GPS.McCallum Agribusiness Consulting(2014) http://actfa. net/wp-content/uploads/2014/02/Multiple-Benefits-from-Inter-row- Sowing-with-2cm-RTK-GPS.pdf https://thestubbleproject.wordpress.com/inter-row-sowing/Brendan Scott (Charles SturtUniversity), Peter Martin (NSW DPI),Glen P. Riethmuller (Department ofAgriculture and Food) and GrahamCentre - “Row spacing of winter crops inbroad scale agriculture in southernAustralia”.“Crop Placement and row spacing factsheet” (GRDC)Glen Riethmuller (DAFWA)

AcknowledgementsGRDC, Graham Mason, NickEckermann, Geoff Chase and RogerTodd.

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Case study 4:Grower: Roger ToddLocation: ‘Wirrinun Pastoral Company’,Condobolin, NSWEnterprises: Controlled traffic farming on 2500 ha plus mixed farming withagistment stock.Property size: 5000 ha.

Overview: Roger runs a controlled traffic farmingsystem with a six year rotation of longfallow, canola, wheat, chickpeas and barley.He tends to stick with this rotationregardless of what markets are doing, onlyreplacing (chickpeas and canola) with longfallow in extremely dry years.He sows at 30cm spacing on a three metre

wheelbase, with a twelve metre disc seederand a thirty six metre boom spray. Moistureretention is the driving force behind most ofRoger’s cropping decisions.

Issues and observations of controlled traffic farming: Roger was motivated to move into controlledtraffic farming in 2003.His red soils compact quite easily and the

combination of no-till and tram tracks haveallowed for improved water infiltration intohis farming country, particularly duringsummer storm events.He renovates his tram tracks about every

six years and uses that as a chance toincorporate lime (after chickpeas and beforewheat) and gypsum (before canola).The tram tracks have given Roger

noticeable fuel savings. On established tramlines he is using 2.5 l/ha of diesel, compared to5 to 5.5 l/ha on the mixed farming country.

Another benefit of CTF is that in wetseasons he can get on country quicker thanconventional farming, with only some areasof headlands becoming boggy.

Issues and observations of inter-row sowing: Inter-row sowing was not a driving force toRoger adopting controlled traffic farming,although he finds it a convenient tool. Hefinds his stubble loads are usually notexcessive in the majority of years and hisdisc seeder can handle it well. Hair-pinninghas not been an issue when stubble isknocked down.One thing Roger has noticed is that where

stubble has been knocked down as opposedto standing, he is seeing more vigour ingerminating crops, except for chickpeas. He puts this down to less shading and iscontemplating knocking more stubble downin coming years to open the canopy. Hewould prefer that to burning and althougha late, cool burn is an option, he is aware ofnutrients that are being lost in doing so.He is also exploring his sowing direction,

currently sowing half his crop in a north/south direction and half east/west.Disease is not an issue Roger has had to

deal with as his rotations keep carry over toa minimum. But he is finding the rows arestarting to fill with remaining stubble ofprevious crops, again prompting him to knockstubble down for more rapid decomposition.

Soil Health: The main driver for Roger is retainingmoisture and he has no doubt that hisprofitability due to increased yields hasincreased through the adoption ofcontrolled traffic farming.(Phone interview conducted April 2016)

12 Central West Farming Systems Inter-row sowing

Disclaimer Any recommendations, suggestions oropinions contained in this publication donot necessarily represent the policy or viewsof the Central West Farming Systems Inc.(CWFS) or the Grains Research andDevelopment Corporation (GRDC). Noperson should act on the basis of thecontents of this publication without firstobtaining specific, independentprofessional advice. CWFS, GRDC andcontributors to these guidelines mayidentify products by proprietary or tradenames to help readers identify particulartypes of products. We do not endorse orrecommend the products of anymanufacturer referred to. Other productsmay perform as well as or better than thosereferred to specifically. CWFS and GRDCwill not be liable for any loss, damage, costor expense incurred or arising by reason ofany person using or relying on theinformation in this publication.

This guideline has been developed byCentral West Farming Systems Inc. (CWFS)as par t of the Maintaining ProfitableFarming Systems with Retained Stubbleinitiative, funded by the Grains Researchand Development Corporation (GRDC).The initiative involves farming systemsgroups in Victoria, South Australia,southern and central New South Walesand Tasmania collaborating to validatecurrent research at a local level andaddress issues for growers that impactthe profitabilit y of cropping systems withstubble; including pests, diseases,weeds, nutrition and the physicalaspects of sowing and establishing cropsin heav y residues.

During 2012 discussions with localproducers resulted in CWFS identif ying13 subjects that impact on themanagement decisions for producers inCentral West NSW.

Since then CWFS has under taken a rangeof research, development and extension(RD&E) activities focusing on thesesubjects. These publications are anattempt to capture those activities andprovide regionally specific guidelines forproducers aiming to retain stubble inCentral West NSW.

A primary par t of this work has been tocorrelate existing resources and researchfrom several organisations and CWFSthanks these respective organisations fortheir work. CWFS and the GRDC alsothank the exper ts who technicallyreviewed these guidelines.