22 questions you may ask about Controlled Traffic Farming in WA

Paul Blackwell, Stephen Davies, Glen Riethmuller, Derk Bakker, David Hall, Jeremy Lemon, James Hagan (DAFWA),

Bindi Isbister (North Stirlings Pallinup Natural Resources) and Stanley Yokwe (NACC).

Produced March 2013

Contents page

Question 1. Is it worth it for the farm business? 5

Question 2. How much does CTF cost? 5

Question 3. How do I remove residual compaction and when will it need doing again?6

Question 4. What are the main financial benefits of CTF to WA farming? 7

Question 5. What are the environmental benefits of CTF? 11

Question 6. New machinery is getting heavier, does that make soil compaction more of a problem or does reducing ground pressure with low inflation pressures and wider tyres, duals triples or tracks avoid increased compaction problems? 11

Question 7. If all WA soils do not respond to deep ripping why should CTF provide yield benefits to non-sandplain farms? 13

Question 8. Bare tramlines and tramlines with poor crop in them look a bit ugly and get full of weeds; surely that is a net loss of yield to the farm, isn’t it? 13 Question 9. What evidence of grain yield and quality loss from compaction can I look for on my farm?

13Question 10. Does it matter if the header does not fit? 14

Question 11. What can I do to control more traffic when I can spend very little? 14

Question 12. Spreading straw beyond 30 ft and burning header rows is creating ‘wavy’ crops with high and low nutrition zones. I am advised to move the header each year, but this will spread the compaction from harvest traffic. What should I do? 14

Question 13. Seeding capacity or seeding ha/day is my major cropping limitation due to dry autumns. I need to change to a wider seeder to do this and it will not match my cropping widths for CFT, what do you suggest? 15

Question 14. If I move out of full CTF to run a wider seeder and wider harvester that does not fit the permanent tramlines what will be the penalty? 16

Question 15. I cannot afford autosteer this year but I do have a simple GPS guidance system on the seeding tractor. How can I set up the bar to help steering for spraying, spreading and harvesting?

17Question 16. I can take out most shallow compaction by using long knife points and working deep at seeding, so why should I bother about controlling my cropping traffic? 17

Question 17. I have been told I can use smaller tractors and save on capital cost if I use CTF. Is this true? 17

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Question 18. I have seen cases of severe gully erosion in bare wheel tracks in wet years, especially where my neighbours have gone up and downhill and have removed their banks and filled in their drains. How can I avoid such problems? 17

Question 19. How do I manage tramlines in wet areas where they turn into long puddles and muddy ruts? 18

Question 20. The chaser bin is a pain. They are getting bigger and race all over the paddock. How can this be managed practically? 18

Question 21. Will CTF eventually lead to more fertiliser use efficiency? 19

Question 22. What happened to “Tramline Farming”? 19

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Responses to our 2012 field days at Binnu, Buntine and Grass Patch were very encouraging, so we have expanded the previous handout and added more questions and some answers.

Controlled traffic farming (CTF) is a proven method of improved crop production that can help prevent future subsurface soil compaction after deep tillage (deep ripping, deep working points, spading or inversion ploughing) and improve some soils without deep tillage.

The system can also result in reduced operating costs and greater environmental benefits through better soil health.

This should reduce water erosion through better soil structure, reduce greenhouse gas emissions and potentially improved fertiliser use efficiency.

All heavily laden wheels and tracks use permanent tramlines or wheel tracks. Most financial benefit comes from more yield and better grain quality.

Many farms are still missing out on large profit increases, despite using autosteer GPS guidance, because they have not moved all the heavily laden wheels (wheel loads > 1t) onto permanent tramlines.

CTF also offers more effective ways for smart cropping methods such as deep ripping between wide rows of broadleaf crops, disposal of weed seeds at harvest, sowing on or between previous crop rows and relay planting.

More detail is explained in the technical manual we are currently updating (http://www.agric.wa.gov.au/objtwr/imported_assets/content/lwe/land/cult/bulletin4607_complete.pdf).

Recent poor seasons and continuing poor terms of trade dictate a growing need for efficiencies of scale, especially to take advantage of valuable sowing and harvesting windows.

The capacity to combine improved efficiencies with minimising the negative effects of soil compaction on cropping is a considerable challenge for profitable dryland farming.

For farm enterprises with no current capacity for capital investment, but an interest in the potential benefits of CTF, we encourage the development of a long term plan. These workshops are intended to assist the development of such plans. We suggest a few guidelines to assist decision making to improve both efficiencies and traffic control at the end of this handout in the section ‘Compromise or Optimise’.

Other subsoil constraintsIt is important to remember that compact soil is often not the only constraint to plant growth and nutrition in subsoils. Large areas of sandplain soils are acid enough to encourage aluminium toxicity to root growth. Many types of subsoil are hostile to root growth and plant nutrition due to abundant gravel or layers of rock.

In the more southern and central parts of the Wheatbelt the valleys often have duplex and clay soils with very saline and boron rich subsoils which inhibit root exploration. Many of these restrictions other than compaction may be very uneconomic to rectify easily and benefits from CTF may be less than quoted in this document.

The Caring For Country funded workshops are a useful forum for growers and consultants to get more up-to-date with this technology, especially now there are some farms in the state which have been using fully matching controlled traffic farming (CTF) for about ten years.

Possible questions you may ask, and our considered responses, are listed below.

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Question 1. Is it worth it for the farm business?

Answer: This is difficult to answer precisely because no farm keeps a paddock in ‘uncontrolled traffic’ and profitability of adjacent farms can be strongly influenced by other individual factors. However we can provide general guidance from results of field trials and experiments in WA (1997-2004) and economic modelling based on the results of those trials, Kingwell and Fuchsbichler (2011).

Figure 1. On the right we conservatively estimate that in a 1.2t/ha wheat year in WA at current prices there could be about $36 /ha benefit if auto steer is already being used and a $45 /ha benefit if auto steer has yet to be adopted by a farm moving to controlled traffic. The pie chart shows the amount gained from improved grain income and less use of inputs. If auto steer is already in use there are no gains in overlap reduction.

The analysis is based on a conservative 5 per cent grain yield increase 2.5 per cent shift to better grade and 10 per cent reduction of inputs and conservative conversion costs for central Wheatbelt farms. The trial results and the economic analysis are based on CTF systems where the residual soil compaction between the tramlines is removed when the system is first established.Real life applications of Control Traffic systems have seen examples of farmers being able to make significant reductions in their capital costs through the use of a smaller tractor as the result of established tramlines and lower draft requirements. This reduction in capital costs assist in the long term from lower interest payments and for the capital depreciation allowance to be reduced.

Question 2. How much does CTF cost?

Answer: It is hard to generalise because all farms differ in machinery and some are better matched in widths and wheeltracks of seeders, sprayers and headers than others. Changes for improvement of swath and track width can be progressive when each machine comes in for replacement. Many growers have used a least cost transition plan. Some key guidelines are:-

3:1 ratios between harvesting, spraying and seeding widths are most convenient for matching well to the paddock edge, but seem currently unrealistic at seeder widths of 18 m or more.

Track width matching to headers is often easier with tracked vehicles; tracks also provide better traction on a permanent tramline than single wheels can.

Modifications of swath widths and wheel track widths need careful consideration to avoid warranty issues and enable easy reversibility to not compromise trade-in value.

Guidance systems tend to be better value for money with higher precision systems (RTK).

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tramline

unripped

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bush

Question 3. How do I remove residual compaction and when will it need doing again?Answer: Residual subsoil compaction can be removed by deep cultivation e.g. deep ripping, spading, inversion ploughing and deep working points, (see P28-29 Subsoil Compaction - A guide for WA farmers and consultants; Stephen Davies DAFWA). It is most efficient to do this between existing permanent tramlines or wheel tracks or between fresh wheel tracks when a system is being set up or changed in spacing. That is not feasible for inversion ploughing, but spaders can be modified to preserve firm wheel tracks by temporary removal of selected spades.

CTF can allow the deep cultivation effect to persist for many years; see below.

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Most recent evidence of longevity of deep cultivation under CTF has come from Balla, near Northampton. Figure 3 below shows the weak zones in the yellow sandy subsoil which still remain ten years after deep ripping was done to 300mm in a trial at the farm. This gives confidence that CTF can enable investment in deep cultivation to provide long term benefits.

Figure 3. Long term evidence of persistence of deep ripping with CTF. The white lines are around two soft subsoil zones, excavated by hand, at Balla 2013. Ten years previously this soil was deep ripped to 300 mm (the depth of the steel tape) and the paddock has been in full CTF ever since.

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Figure 2. Evidence of soil loosening from deep ripping persisting for four years in a yellow sand at Buntine. The measurements in deep ripped zones are in line with the ripping tines. The tramlines were not deep ripped four years previously.

Question 4. What are the main financial benefits of CTF to WA farming?Answer: Grain yield and quality improvements.

Evidence from long term field trials in WAField trial evidence with farm scale investigations of CTF between 1997 and 2000 in WA show about 10 per cent more yield and better grain quality than uncontrolled traffic systems. Detail is in Table 1 the results from a long term trial in the Northern Agricultural Region with farm machinery on yellow sand.

All the measured yields used the farm header and included bare tramlines. The trial used the 90 ft farm sprayer, 30 ft farm header and a 30 ft research seeder with a small tractor for the CTF system. The normal traffic system used the 50 ft farm seeder with a larger tractor. The whole paddock was deep ripped in the first year. For CTF two ripper tines were lifted to keep firm tramlines. Thanks to the Critch family, DAFWA and GRDC.

More recent measurements of soil compaction effects on yield

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Figure 4. Yield estimated for each row of crop in 2012 on yellow sand deep ripped in 2010 at Buntine.

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Extreme examples of yield loss can still be found in relatively low rainfall seasons, as in Figure 4 on the left. Mace was grown on 120 mm of growing season rainfall in 2012 two years after deep ripping in pasture.A reasonable estimate of income loss from yield and grain quality was $73 /ha for this site, when compared to possible yield from a realistic CTF system; an 11 per cent improvement of income (from Blackwell and Davies 2013).

Firming deep ripped sand alongside wheelmarks.

Detailed measurements in 2004 found interesting yield improvements alongside wheelings on deep ripped sand at sites with contrasting growing season rainfall; Figure 5a and 5b below.

Figure 5a. Yields in or alongside wheelings at Buntine, 275mm GSR and sown with knife points.

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Figure 5b. Yields in or alongside wheelings at Buntine, 170 mm GSR and sown with single discs.

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Location of the crop sampling in the centre or at the edge of wheel

marks

The improved edge row yields could compensate for yield loss in the wheelmark, sometimes for a net positive effect of the wheeling. The best option may not to increase the amount of wheeling on deep ripped sand!

It may be better to roll the soil after deep ripping with a heavy roller and obtain yield increase from firming everywhere but in the wheel marks.

Effects of CTF on heavier textures soils than sands

A long term field experiment on a red loam in South Australia with a similar climate to WA helps to understand what CTF can do for heavier soils than sand. Figure 6 shows that just the avoidance of heavy wheelings enabled soil macropores (cracks and tunnels from soil animals and roots) to increase within six years allowing better infiltration of water into the soil. Grain yields between the wheeltracks were improved between 12 – 17 per cent by CTF during the six years. Such soils and those with higher clay content may only need the traffic to be controlled for structural improvement; tillage may not be essential.

Figure 6. Visible soil porosity (left) and surface water infiltration (right) after six years of CTF (CT) or uncontrolled traffic (C). Error bars are one standard deviation; Ellis et al. (1992).

Recent measurements on duplex soils and clays in the WA southern WheatbeltPreliminary analysis of data in paddocks without CTF is showing some contrasting effects of cropping traffic on crop performance according to soil type. The sandy duplex site in Table 2 shows effects more like those seen on sands, however a site on clay soil shows more similarity in the wheeled and unwheeled crop yield in a dry season.

Table 2. Estimates of cropping traffic effects in 2012 in the southern Wheatbelt of WA.

unwheeled wheeledSandy duplex Yield (t/ha) barley 3.1 2.6

Screenings (%) 29 45

Clay Yield (t/ha) wheat 1.5 1.5

Screenings (%) 1.0 1.4

Comparison of traffic effects on yield on a range of soil types in a relatively good season

Field trials during 2003 in WA using yields within and outside wheelmarks from real farm equipment for seeding, spraying and spreading were used to calculate the effects of CTF using real wheeling patterns. The measured yields were applied to an uncontrolled traffic pattern or a CTF traffic pattern and the net yields of the whole systems calculated. Current grain prices were used to calculate the estimated financial benefits of CTF for some contrasting soil types. Results are shown in the table below.

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Table 3. Calculated estimates of CTF benefit over normal traffic from field wheeling trials.

Location Soil type Deep ripping CTF benefit $/haMullewa (1999) Yellow sand yes 19

Wubin (2003) Alkaline clay yes 21

no 16

Lake Varley (2003) Sodic clay yes 21

no 5

Esperance (2003) Sandy gravel Yes 16.5

no 11

CTF was found to provide about $15-20 /ha benefit in a first season for contrasting soil types if deep cultivation had been used to remove residual compaction. The trial years were relatively productive seasons and less or nil response would be expected in dry seasons. Thus the predicted benefits using economic models use safer, more conservative, figures for yield improvement; about five per cent rather than 10 per cent.

Other financial benefits include:- Less inputs if autosteer has not yet been adopted (about 10 per cent input reduction) Less fuel use from better traction on firmer tramlines Better floatation for more timely spraying and spreading Use of smaller tractors to save capital cost

Fuel is saved by firmer running of heavily loaded wheels and tracks on well-established and maintained permanent tramlines will reduce the rolling resistance and enable the same speed and traction to be maintained for the same draft load. Some case studies and calculations have estimated whole farm fuel savings to be about 20-25 per cent.

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Question 5. What are the environmental benefits of CTF?Answer: Environmental benefits may flow from better vehicle performance and improved soil health, resulting in:-

Less greenhouse gas production through less fuel use More efficient fertiliser use and less greenhouse gas emission, especially on ‘heavy’ soils (*) Less runoff and water erosion, due to better soil permeability and a well-designed CTF layout. Better interception of leaching nutrients, as in Figure 7 below; thus lower risk of polluting water

supplies (*) Better fertiliser use efficiency from lower leaching risks on sandy soils (*)

(*) these aspects require further research for clarification.

Question 6. New machinery is getting heavier, does that make soil compaction more of a problem or does reducing ground pressure with low inflation pressures and wider tyres, duals triples or tracks avoid increased compaction problems?

Answer: Heavier wheel and track loads are putting increasing pressure on our subsoils. Subsoil compaction may restrict availability of deeper moisture and nutrients if the soil is compressed too much.

Unfortunately, despite many commercial claims, reducing inflation pressure is not enough compensation for increased wheel or track loads. Measurements and modeling of soil stresses from agricultural vehicles show that increasing the load on a tyre or track makes the subsoil experience increasing stress and to greater depth. Lowering the surface pressure from a tyre or using tracks mainly reduces pressure on the topsoil, but in the subsoil the stresses can remain high.

Recent measurements of deep compaction from very heavy equipment on WA agricultural soils are shown in Figure 8 for claying equipment and seismic survey trucks.

As axle loading increased the depth of maximum soil strength increased from 40 to about 50-70 cm. The deeper compaction from the trucks was rectified by two winged tines pulled at 70 cm depth by a D4 tracked tractor. The effect of claying in wet conditions is probably less than the seismic trucks because the axle load of the claying grader would cycle between empty and full conditions, while the seismic truck axle load is constant in travel.

Some recent chaser bin models have 20 t axle loads when fully laden, heavier than the seismic survey trucks axle loads considered above.

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Figure 7. Modelled wheat root growth in sandy soil based on trial data assuming non-limiting moisture. The faster root growth should intercept more leaching nutrients (from Davies and Lacey 2011).

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Figure 8. Profiles of cone resistance from claying deep sands at Esperance with carry graders and at Geraldton with seismic trucks. The carry grader was 14 t fully loaded; thus averaging about 7.5 t axle load. The figure includes profiles from bush and unclayed sites with normal cropping compaction. The seismic trucks were 30 t on two axles and did three passes on yellow sand (Ys Trk) and white sand over gravel (SoG Trk); from Blackwell et al. (2013).

Yield consequences of restricted rooting depth are illustrated by the Figure 9 using the model ‘Yield Prophet’. Restriction of root growth to 400 mm depth would reduce yield from about 2.5 t/ha to 1 t/ha in such a season as 2005. Keep in mind that even slowing the root growth of non-legume crops can reduce their capacity to keep up with leaching nutrients in a wet year and lead to more need for N and K top-up fertiliser application.

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Figure 9. Predicted wheat yield for different maximum depths of root growth for a red loam ( ) and for a yellow sand ( ). Using Yield Prophet and seasonal data from Pindar 2005 with representative nitrogen profiles; from Blackwell et al. (2013).

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< Root growth slowed< Root growth stopped

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Question 7. If all WA soils do not respond to deep ripping why should CTF provide yield benefits to non-sandplain farms?

Answer: Evidence of CTF and deep ripping providing yield responses and financial benefits on soils other than sands in presented in Table 3. Deep ripping can cause no benefit or loss if biomass is high and springs hot and dry. Better root growth gives better access to nitrogen and soil disturbance by ripping mineralises nitrogen. Applied N should be less in possible drier seasons or drier and warmer locations.

Question 8. Bare tramlines and tramlines with poor crop in them look a bit ugly and get full of weeds; surely that is a net loss of yield to the farm, isn’t it?

Answer: This is deceptive. Trial results from WA showing an about 10 per cent yield increase is calculated including the area of bare tramlines. Crop grown on the tramlines is also very good competition with weeds in cereals and helps reduce erosion risk.

Question 9. What evidence of grain yield and quality loss from compaction can I look for on my farm?

Answer: Linear patterns of delayed flowering, especially in lupins and canola; often zones about 3 m wide on the same spacing as the seeder, especially on sandplain, poor growth and yield in wheel tracks from a wet harvest or a change of direction in seeding; these can show up in NDVI images.

Figure 10. NDVI images from paddocks in the South Coast region in 2008; Bakker and Poulish (2009). On the left poor growth from cropping traffic is in the dark pattern. On the right the traffic is from left to right and associated with the dark patterns in the crop growth image.

The image on the left represents part of an area that had 39 per cent affected by poor growth due to cropping traffic. Those affected strips yielded 5.9 t/ha biomass compared to 8 t/ha in the better areas. Using a harvest index of 35 per cent at the time of the year (10 Oct) the low yielding areas would cause a yield reduction of 0.29 t/ha which at $300 /t would equate to $87 /ha due to uncontrolled traffic. The image on the right reflects the maximum area affected by Rhizoctonia and some other edge effects. These patterns of disease infection are also related to cropping traffic patterns.

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Question 10. Does it matter if the header does not fit?

Answer: Soil compaction is generally more damaging during seeding, spraying and spreading because the soil is usually wetter and weaker. Harvest is more often in dry soil conditions and compaction will be less than in wet. However, even if the topsoil is dry but there has been rain before harvest the subsoil may be moist and deep compaction can occur. Wet soil conditions may become more common. Subsoil compaction is more difficult to correct than topsoil compaction. The general experience with CTF is that full matching to the header is the most effective in the long term.

Question 11. What can I do to control more traffic when I can spend very little?

Answer: We have received many suggestions for smart low cost options to improve cropping traffic control. They can be found at the end of this handout in the section “Compromise or Optimise”.

Question 12. Spreading straw beyond 30 ft and burning header rows is creating ‘wavy’ crops with high and low nutrition zones. I am advised to move the header each year, but this will spread the compaction from harvest traffic. What should I do?

Answer: This is a tricky one. Most headers wider than 30 ft have great difficulty spreading the straw evenly. Some 40 ft wide headers in CTF have been using conveyer belts and extra spinners to spread more evenly at that width. Such modifications may be the best long term solution, especially if the chaff can be delivered onto the tramline or to a new location to burn windrows without moving the header off the tramlines. A possible short term solution may be to run the header (in dry years with a dry soil profile and maybe high yielding years) exactly between the tracks used in the previous season. This will tend to even out straw spreading and reduce fertility ‘waves’. If the soil needs deep ripping, perhaps two more tines can be lifted on the wings of the ripper to give a more firm track for the header in an ‘in between’ position. There seems to be much opportunity for creative thought here without compromising the CTF system too much.

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Question 13. Seeding capacity or seeding ha/day is my major cropping limitation due to dry autumns. I need to change to a wider seeder to do this and it will not match my cropping widths for CFT, what do you suggest?

Answer: This is challenging. There are other ways to increase seeding capacity than just width. Seeding capacity can also be increased by:-

Increasing forward speed; see Figure 11. Increasing air cart capacity; see Figure 11. Increasing loading rate when re-filling

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Figure 11. Calculated effect of seeding speed and seeder width on seeding capacity 10 hr/day and 100 per cent seeding efficiency. The anticipated benefits of speed increase and loading frequency are shown as a path with arrows. Doubled air bin size assumes a current downtime of 20 minutes to prepare for refill and restart seeding. The number of refills is halved, giving 50 per cent less time when not seeding or loading (from Blackwell et al. 2013).

Some growers have been widening their row spacing up to 15 inches and using twin rows or fuzzy rows of crop to allow about 20 per cent greater forward speed, to about 14 kph, thus a greater seeding capacity without using a wider bar.

Other useful strategies growers have used are:- Plan for an eventual double width bar which allows the use of the same permanent tramlines as some

have (e.g. 30 to 60 ft and recently 40 to 80 ft). Care is needed for seeding the paddock edges, some equipment can shut off for overlaps more easily than others.

Increase seeder width by 1.5 times so every second tramline matches, that is 40 to 60 ft, 60 to 90 ft. Running two seeders which match their system and use two small tractors, though this additional cost

needs careful consideration.

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Question 14. If I move out of full CTF to run a wider seeder and wider harvester that does not fit the permanent tramlines what will be the penalty?

Answer: Residual compaction comes from tramlines that are no longer used, but sown into.From measurements at one farm this year residual compaction from old tramlines reduced yield by 24 per cent; this equated to a loss of grain production value of $195 /ha. The tramlines in the CTF system of the farm were about 12 m apart and each pair of tramlines harvested by one pass of the 12 m front header. Residual compaction from previous tramlines would lose x $195 /ha over 2 x 2 rows in the header front width; thus by calculating this loss over the whole header width about $17 /ha (Figure 12). Row spacing for this example is at 10 inches.

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Figure 12. Effect of different levels of lost crop value in residual wheelings on overall loss of crop value. The estimate is for either for two full wheelings or two half wheelings (from Blackwell and Davies 2013). If a seeder fitting a CTF system is changed for a moderately wider one which does not fit the permanent tramlines there will be residual wheelings from the original tramlines. This is about two tramlines per header width (full wheeling in Figure 12). For large increases, about doubling (for example 12 m to 24+ m) there will be additional wheelings from the new seeder which reduce crop value by about half a seeder wheeling per header width.

Thus by addition these crop value penalties of moving out of CTF may be in the order of $15-30 /ha each year. Additionally there will be increased costs from fuel use. These costs need careful comparison to estimated benefits from the improved seeding capacity.

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Question 15. I cannot afford autosteer this year but I do have a simple GPS guidance system on the seeding tractor. How can I set up the bar to help steering for spraying, spreading and harvesting?

Answer: Two missing rows to match your sprayer wheels will be okay in non-cereal, crops, but bare tramlines may become very grassy without some cereal crop in them. An alternative is to form a central guide row by increasing the row spacing in the middle of the bar (pushing the two middle tines further apart) or making a central ‘twin’ row by pushing two centre tines closer together. For most row spacings this will be a visible guide to follow until the crop canopy closes and for wider row spacings (12-15 inches) and lower rainfall seasons the central row pattern will be obvious to follow at harvest. [See page 22 of the Tramline Farming Technical Manual]

Question 16. I can take out most shallow compaction by using long knife points and working deep at seeding, so why should I bother about controlling my cropping traffic?

Answer: This is true, of course, but if you are doing it every year to break up annual compaction it is a cost you would mainly avoid with good initial deep soil loosening and subsequent use of shallow points or discs in CTF. You will also be using more draft, fuel and wear and tear compared to the shallow digging mostly needed in CTF. Your strategy will also not correct the deeper subsoil compaction which can still accumulate. However this can be a low cost alternative to separate deep ripping; see the last section on ‘Compromise or Optimise’.

Question 17. I have been told I can use smaller tractors and save on capital cost if I use CTF. Is this true?

Answer: The lower draft operations from CTF have often enabled a smaller less powerful and lower capital cost tractor for seeding. Such a smaller tractor and less expensive tractor may be more convenient and efficient to use on other farm operations (for example; chaser bins).

Question 18. I have seen cases of severe gully erosion in bare wheel tracks in wet years, especially where my neighbours have gone up and downhill and have removed their banks and filled in their drains. How can I avoid such problems?

Answer: For slopes greater than about 2 per cent this is a very high risk in high rainfall conditions. Lowering the bank sufficiently to be able to drive the bar over safely and maintaining full crop cover and full stubble retention, sowing crop in the tramlines, will reduce the risk. Seeding can work over lowered banks, but spraying and harvesting may need to stop as they are traversed, then the banks sprayed or harvested in a separate operation.Managing surface water flow onto the paddock may also be valuable to avoid water erosion in tramlines. This can be done with small interceptor or diversion banks on the upslope boundaries of the paddock, if this is convenient. More detail and suggestions can be found in the “Management of overland flow in downhill tramline farming” on the Liebe Group website (http://www.liebegroup.asn.au/nlpdown.html).

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Question 19. How do I manage tramlines in wet areas where they turn into long puddles and muddy ruts?

Answer: This can be very messy and not easy to fix. The problem is mainly caused by weak wet soil and wheels that sink too easily. Soil weakness can be minimised by not digging up the tramline too much. If crop is sown into the tramline some use a shorter point and one grower at least uses disc planting units in the wheel track zones and tines for the rest of the bar.If these rows of crop are a problem at harvest (still green or poor grain) some growers have considered putting a guard, for example, split PVC tube, over the knife in those places so the tramline rows are not taken into the header. Obviously this would work well if the header width matches the seeder somehow. Deep cultivation operations such as deep ripping can be modified to not rip the tramline zones, even if the deep ripper width does not match the seeder width. Operations like ploughing or spading inevitably leave all the soil loose and need more careful operations to minimise sinkage; this may take some seasons of gradual firming and clever grading of soil to the rear of wheels or tracks (e.g. with rolling chains or a tramline renovator) to fill in deep wheelmarks. The first season after such cultivation will always be very challenging. Perhaps the ultimate is gravelling but surface water control onto and over the paddock may be more important. Wheel sinkage risk can be minimised by maximum use of tracked vehicles and clever use of dual wheels. Some growers have used dual wheels on their tractors which are inflated less than the inner tyres; one even used a smaller diameter dual. This allows the dual to come into contact with the soil mainly when the inner starts to sink and better floatation is needed, eg on headland and in wetter hollows. In extreme wet areas some growers have had to run their sprayers and spreaders on another, wider, set of tramlines just to avoid the ruts from the seeding tractor. Dropping chaff and straw into the tramline is another strategy which may help strengthen wet boggy soil and eventually allow better floatation.

Question 20. The chaser bin is a pain. They are getting bigger and race all over the paddock. How can this be managed practically?

Answer: Perhaps there are two issues here; the convenience of chasing depending on the paddock shape and tramline direction and the ability of the chaser bin to run on the adjacent tramline when the header is unloading.Sometimes very long paddocks can be harvested more conveniently when the tramlines do not run in the longest direction. When the harvesting is on tramlines in the shorter direction the chaser bin may find it easier to continue to a headland for unloading, rather than run off the tramlines when full as it may often have to do on very long tramlines.Unloading headers into chasers on the run when headers are greater than 30’ is challenging, because auger extensions are difficult beyond this distance. There are designs of receival platforms fitted to chasers and they are becoming more common to allow unloading to distances of 40 ft or more. As headers are designed with increasingly wider fronts and even longer delivery augers the possibility of headers tipping over when unloading sideways increases. There have been recent discussions of innovations for unloading into a chaser bin to the rear of a header. This may improve the compatibility of CTF and chaser bin use with large headers.

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Question 21. Will CTF eventually lead to more fertiliser use efficiency?

Answer: This is a very interesting issue and in principle there may be some benefits like this because compact soil of all textures can lead to poorer oxygen supply in the soil due to the remaining macropores being smaller and poorly connected, especially in heavier soils. Then oxygen has great difficulty diffusing to the microbes in the soil and they begin to use other sources of energy, principally nitrate. This robs N from the crop. There may also be less beneficial nutrient transformations by soil microbes when the soil is in poor health. Better and more unlimited root growth should also have a better opportunity to intercept nutrients in the soil that could otherwise leach or become unavailable; see Question 5. Anecdotes from Eastern Australia have often referred to a smaller applied fertiliser requirement in long term CT for the same yield, but good field experiments to clarify this are hard to find. Perhaps the best estimate we currently have is from two neighbouring farms in WA with similar soil types, fertiliser use and rotations. A summary of their soil test results before the 2011 season is below; courtesy of Quenten Knight from Precision Agronomics Australia.

35

4.75

1.5

20

31.39

0

5

10

15

20

25

30

35

40

NO3 mg/kg NH3 mg/kg OC%

mg/

kg o

r %

CTF nonCTF

Question 22. What happened to “Tramline Farming”?

Answer: This is a label we used about 10 years ago to distinguish information and systems based in WA from CTF information from Eastern Australia. There were minor differences then, but today CTF information is more inclusive nationally and the system is being adopted in Europe and North America; so we are keeping a common label. There are still a variety of terminologies being used for wheeltracks/tramlines/wheelways and other features, but as long as they all result in common benefits the words we use are not so important. DAFWA’s technical guide (Bulletin 4607, http://www.agric.wa.gov.au/objtwr/imported_assets/content/lwe/land/cult/bulletin4607_complete.pdf) uses Tramline Farming terminology and may be able to answer questions we have not covered here; the updated version may change the terminology to Controlled Traffic Farming.

As with many collections of technical advice we do not present specific recipes for specific locations. Instead we try and explain the principles behind the processes causing the problem and the guideline on which the possible solutions are based. We hope this will help the reader appreciate how these parameters may be applied to their own situation. Once farmers and land managers are armed with this understanding they can often implement the appropriate solutions for their landscape and circumstances.

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Soil samples were collected from both farms from similar soils. The fully matched CTF system, established for about 8 years, has 57% more nitrate, 63% more ammonium and 8% more organic carbon. The yields of the CTF farm are higher than the non-CTF. Perhaps the soil N is accumulating because the CTF crop is using applied N more efficiently and could have used less N fertiliser for the same yield. Further investigations would be needed.

Photo courtesy of Brady Green Nabawa

References

The use of high resolution imagery in broad acre cropping Derk Bakker and Grey Poulish, Crop Updates 2009

Davies D L and Lacey A (2011) Subsurface compaction - A guide for WA farmers and consultants. Department of Agriculture and Food, Western Australia Bulletin 4818

Kingwell R and Fuchsbichler A (2011) The whole-farm benefits of controlled traffic farming: An Australian appraisal. Agricultural Systems 104: p513–521. http://www.sciencedirect.com/science/article/pii/S0308521X11000461

Blackwell P and Davies S (2013) Controlled Traffic Farming (CTF) value to low rainfall croppers; especially using deep tillage; Liebe Local Research and Development Results. P 141-147.

Blackwell P, Hagan J, Davies S, Riethmuller G, Bakker D, Hall D, Knight Q, Lemon J, Yokwe S and Isbister B (2013) Pathways to more grain farming profit by CTF in WA Agribusiness Crop Updates; Burswood Perth.

Ellis T, Sedeghatpour S and Hignett C (1992) Effects of deep tillage and wheel traffic on crop root growth. In Australian Society of Soil Science Inc. 4th National Conference Adelaide, South Australia.

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Line up your wheels for long term management of subsoil compaction

Carry heavy loads here

Better soil health for crops and

pastures Better soil

health for crops and pastures

Better soil health for crops

and pastures

5. Use deep working points on the seeder, but not where the sprayer will run, to break out as much of the residual compaction as possible; this may need progressively deeper working.

6. Select contractors who can fit your system and ensure that they understand why you are in a CTF system so they don’t drive anywhere.

Seeding efficiency priorities

1. Try to improve daily seeding rate first by increases of speed, perhaps by changes of row spacing and openers too.

2. Consider getting a bigger capacity air cart and faster loading systems before increasing seeder width.3. Try to double seeder width to allow refitting onto tramlines or existing wheelings.

Harvesting efficiency priorities

1. The main priority seems to be to use the widest front possible and travel as quickly as the threshing efficiency allows

There do not seem to be many operational features which can be changed to improve harvesting efficiency and maintain the same harvesting width when a chaser bin is used to unload on the run.

Then consider combinations of the main priorities to enable most benefit at least cost.

Longer term strategies

Each farm and circumstance will be different, but it may be possible to use the above strategies for short term benefits of compaction control and still have a medium to long term plan to modify track widths and operating width that enables more and more of the heavy loads to stay on permanent wheeltracks.

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COMPROMISE or OPTIMISE?How can cropping traffic be best controlled and improvements to dryland cropping efficiency be maintained?There are two general guidelines;

1. Cropping traffic control to keep heavy gear on the same wheelings each year improves cropping profitability.

2. Maximum area sown or harvested per day can make most efficient use of suitable soil, crop and weather conditions to improve cropping profitability.

The combination of these guidelines may provide more optimum systems for practicality and profitability. This may come from identifying priorities for traffic control and priorities for efficiency.

Traffic control priorities (with use of auto steer)

1. Ensure season to season traffic does run over the same soil

a. Casual setting of A-B lines can cause variations in the location and angle of wheelings from cropping traffic each season; this allows a build up of residual compaction each year. Residual compaction reduces yield.

b. Setting different A-B lines for different operations (for example, seeding and spraying) can make avoidable residual compaction in the same season if the seeder and sprayer widths match (2:1 or 3:1) and the sprayer and seeding tractor tracks can match.

c. Careful use of guidance files set up for each paddock and used each year will control traffic and possibly at little cost.

d. Plan to match the seeding, spreading and spraying traffic as well as possible; they are most likely to run over moist soil and spraying is the most frequent in-crop traffic.

e. Try to match the wheel track of the air cart to the seeding tractor, especially the inner dual. Air boxes tend to make the most compaction at seeding due to high axle loads and the common use of single wheels.

f. Consider using a ‘three wheel’ tramline if the sprayer and seeding tractor do not have matching tracks, at least one sprayer wheel runs on a seeding tractor wheel track and one wheelmark from spraying will be avoided.

g. Attempt to get some of the spreader traffic on some of the spraying and seeding wheeltracks for some of the passes, by careful choice of spreading widths.

2. When seeder width is increased, then change the sprayer boom width to match two or three times the seeder width. This will keep more cropping traffic controlled and improve seeding efficiency.

3. When header front width is increased try and match some of the header tracks to existing wheelings from spraying and seeding.

4. Move chaser bins onto header tracks (at least one wheel) especially when loading if possible.

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