2015

Liebe

Soil acidity management strategies throughout Western Australia

2

Working together to deliver multiple benefit messages to growers through a whole systems

approach to soil management

LIE00008

This publication is funded through the Grains Research and Development Corporation

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Project Partners Contact Information

Liebe Group PO Box 340 Dalwallinu WA 6609 Ph: (08) 9661 0570 Fax: (08) 9661 0575 Email: admin@liebegroup.org.au

Website: www.liebegroup.org.au

Mingenew Irwin Group PO Box 6 Mingenew WA 6522 Ph: (08) 9928 1645 Fax: (08) 9928 1540 Email: Debbie@mig.org.au Website: www.mig.org.au

Southern DIRT PO Box 291 Kojonup WA 6395 Ph: (08) 9831 1074 Email: admin@southerndirt.com.au Website: www.southerndirt.com.au

West Midlands Group PO Box 18 Dandaragan WA 6507 Ph: (08) 9651 4008 Fax: (08) 9651 4107 Email: anne.wilkins@wmgroup.org.au Website: www.wmgroup.org.au

Aglime of Australia PO Box 212 Belmont WA 6984 Ph: (08) 9277 5529 F: (08) 9277 5379 Email: steve@aglime.com.au

Website: www.aglime.com.au

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Publication Contributors

Department of Agriculture and Food, WA 20 Gregory St, Geraldton, WA, 6530 Wayne Parker Ph: (08)9956 8511 Email: wayne.parker@agric.wa.gov.au Website: www.agric.wa.gov.au Chad Reynolds Ph: (08) 9956 8573 Email: chad.reynolds@agric.wa.gov.au Website: www.agric.wa.gov.au

Disclaimer

While the information in this book is believed to be correct, no responsibility is accepted for its accuracy. The Liebe Group accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it. No liability is accepted for any statement, error or omission. Please note that permission by the author is required for article being reproduced or re-presented. The Liebe Group does not endorse any product or service included in this publication. These case studies are intended for growers to make more informed decisions about these practices, products or services.

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Contents Foreword ................................................................................................................................................. 6

Is your pH soil profile really what you think? ......................................................................................... 8

Soil Management Strategies for Improving pH on Red Loam............................................................... 14

“Wholesale tillage system” gets huge results from lime and soil amelioration ................................... 19

Innovation in the Wheatbelt ................................................................................................................. 23

Gabby Quoi Quoi Catchment scale pH monitoring for better soil acidity management ...................... 29

Alternative approaches to soil acidity .................................................................................................. 33

Mouldboard; killing two birds with one pass ....................................................................................... 38

Subsurface pH improvement with lime incorporation in a low rainfall zone ....................................... 45

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Foreword Soil acidification is a natural process however; modern farming systems accelerate the process through crop production (Gazey, P. 2015). Two of the main contributing factors to soil acidification in broadacre cropping systems are the use of ammonium based fertilisers and the export of alkaline products in the form of crop and livestock (Gazey & Ryan. 2015). Aluminium toxicity is one of the major subsoil constraints that is directly linked to soil acidity. Elevated levels of aluminium in the soil lead to root pruning resulting in decreased crop growth and yield. Generally aluminium toxicity will be an issue if soil pH is ≤ 4.3 (CaCl2) (Gazey & Ryan. Oct 2015). Farmers in the Northern Agricultural Region have experienced extreme climate volatility over the last 15 years including three severe droughts and a number of below average rainfall years. As a response to this farmers are looking to improve their farming systems through increasing water and nutrient use efficiencies and developing flexible farming systems. Managing soil acidity in this environment is a key component in improving farming systems.

It is estimated that more than 14.25 million hectares in the Western Australian Wheatbelt are acidic or at risk to become acidic, (Gazey et al, 2014) making acidity one of the major limiting production factors to modern day farming systems. In monetary terms this is estimated to cost the agricultural industry $498 million equating to 9% of WA’s annual crop (Herbert, 2009). As a consequence liming has been one of the major inputs in broadacre farming over the last 20 years. This project will determine the most effective liming strategy to undertake to maximise the return on investment. As part of Liebe Group’s previous GRDC (Grains Research and Development Corporation) funded projects ‘Growers critically analysing new technologies for improved farming systems’ 2006-2009 and ‘Improved stubble soil management practices for sustainable systems in the Liebe area’ 2009-2012, surveys of 60 growers in the Liebe area were conducted. This included approximately 50 members and 10 non-members each time. These surveys asked questions around liming including; ‘Do you lime?’ and ‘How many years ago did you start liming?’ In 2006, 94% farmers surveyed limed, with that number increasing to 100% in 2012, (Hollamby, 2012). Although liming had been in practice for an average of 17 years, when growers were asked what major issues are impacting their farming system, soil acidity is still one of the highest ranking issues. With the uptake of liming 100% but the issue continuing, further research is required to find out what is the best method to overcome soil acidity and barriers to full adoption of liming programs.

Funding has been awarded from GRDC to research the most appropriate liming strategy to maximise return on investment and increase knowledge around the economics of different soil pH management, products and techniques utilising the Lime Economic Calculator. This publication aims to provide growers with greater understanding of the innovative strategies that some growers are employing to improve their soil pH across Western Australia. Project Aims

Give growers in Western Australia the capacity to understand and better manage the economic and environmental impacts on acidic soils.

Give growers the knowledge and awareness of tools and information available to manage soil acidity.

Growers to become better equipped through development of new tools and information to make effective adoption decisions to manage soil acidity.

Growers maintaining viable farming systems through optimum management of their systems.

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References Gazey, C., Davies, S., Master, D. (2014) Soil Acidity: A Guide for WA Farmers and Consultants (2nd Edition) Bulletin 4858. Gazey, C., and Ryan, L. (2015) Causes of soil acidity. Retrieved November 5, 2015, from https://www.agric.wa.gov.au/soil-acidity/causes-soil-acidity Gazey, C., and Ryan, L. (2015) Effects of soil acidity. Retrieved November 5, 2015, from https://www.agric.wa.gov.au/soil-acidity/effects-soil-acidity

Gazey, P. (2015) Factsheet Soil Acidity. Retrieved November 5, 2015, from http://www.soilquality.org.au/factsheets/soil-acidity

Herbert, A. (2009) Opportunity cost of land degradation hazard in the south-west agricultural region. Resource management technical report 349, Department of Agriculture and Food, Western Australia.

Hollamby, N., Petersen, E. (2012) Liebe Group Technical Audit Results Executive Summary.

Recommended reading Gazey, C., Davies, S., Master, D. (2014). Soil Acidity: A Guide for WA Farmers and Consultants (2nd Edition) Bulletin 4858. (Bulletin 4858 can be posted by DAFWA on request. Email: liam.ryan@agric.wa.gov.au to request a free hardcopy. Distribution is supported by GRDC Project DAW00236 'Soil acidity is limiting grain yield). Davies, S., Gazey, C., Parker, W., Blackwell, P., Riethmuller, G., Wilkins, A., Negus, P., Hollins, T., Gartner, D., Lefroy, W. (2015) Lime incorporation into acidic subsoils – assessing cost, efficacy, value and novel approaches. http://www.giwa.org.au/pdfs/CR_2015/Davies_Steve_Lime_incorporation_into_acid_subsoils_FINAL.pdf

DAFWA Soil Acidity pages can be accessed on: https://www.agric.wa.gov.au/climate-land-water/soils/soil-constraints/soil-acidity

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Is your pH soil profile really what you think?

Fast Facts

Know soil pH levels before liming.

Examine plants to see if root growth is as expected.

Manage inputs to reduce production of acid. Aim Give growers the tools to measure the pH of their soils and understand how and why they should mitigate acid production. Background Stuart McAlpine is a broadacre farmer from Buntine, WA who has promoted soil health for many years and is passionate about increasing farmer knowledge in this area. By giving farmers the tools to investigate their soil health instantaneously and cheaply, Stuart believes that growers will become more aware of their soil health. Stuart was recognised as the 2015 ‘Soil Health Champion’ for the Northern Agricultural Region (NAR) in Kojonup. He is primarily interested in soils as he believes that through building resilience in the system, farmers will be better equipped to manage their risk profile more effectively in the poorer seasons, leading to more sustainable farming systems and businesses.

Lilly Martin, Liebe Group

Figure 1: Pasture with 1 t/ha lime in 2010 and 1 t/ha lime in 2012. Left hand sample showing alkaline soil on the top 4-5cm and acid soil below; right hand sample has been mixed (0-10cm) to represent a lab sample and showing an average pH of 6.5-7.

Figure 2: pH indicator testing showing the slow permeation of limesand two years after application. Left hand sample had 2 t/ha limesand, right hand sample is where the limesand was stockpiled in the paddock, estimated rate at 60 t/ha.

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After extensive soil testing around the state, Stuart has come to the conclusion that many farmers rely solely on lab analysis of soil results and need to get out into the paddocks with their shovels and have a dig to see what is really going on for themselves. Stuart feels that one of the most powerful tools a farmer has is their shovel and that growers should be looking at what is below the ground as well as above. Many farmers are under the impression that they are getting on top of their acidity, however; Stuart has seen several growers getting a shock when they are taken into the paddock for a dig. Stuart utilised existing soil sample results and revisited the sites to carry out comparative tests. The majority of soil samples sent for analysis are taken in 10cm increments which can sometimes mask the fact that the acidity is not where the grower believes (Figure 1). A visual assessment is a great opportunity to get farmers thinking about their pH management on a whole different level through understanding other ways that can assist in pH management. The big one for Stuart is that a ‘hot spot’ of acidity is generated quite often where fertiliser has been placed below the seed at seeding. This has been a great discussion point amongst growers around fertiliser efficiency in relation to pH (Table 1). When liming in a ‘no-till’ system, Stuart has found that the lime just sits on the top and gets tickled in gradually during seeding but generally does not move down the profile quick enough, even with high rates (Figure 1 & 2). This can result in the top 5cm becoming more alkaline (pH of 8-9 (CaCl2)) while leaving the bottom 6-10cm more acidic. For example, if the topsoil (10cm) had an average pH of 5.3, but in reality the top 2cm is 7 and the 6-10cm is 4.5, the plant’s roots will not establish optimally to make them resilient enough to perform well through drought periods. Through carrying out pH indicator tests Stuart has found that where alkaline meets acidic soil in the profile there is usually a defined layer of pH change. In saying this, Stuart believes that there are still farms which have not had enough product on the topsoil.

In comparison to when the lime has not been incorporated, Stuart has seen a variation in the different levels of incorporation of lime through the profile. However, it became very clear to Stuart that the limesand was not moving through the profile beyond the depth of the workings. Quite often you could see other factors influencing root growth through an acidic soil, for example when there was good biological activity in the rhizosphere (soil immediately surrounding the roots) and where there was good carbon levels there tended to be a better pH. It was also observed that where there were better carbon levels in the soil, the root growth was not as restricted as it was in some of the soils of the same pH where there was less carbon. Soils with a high proportion of organic matter generally have a high buffering capacity, whereby hydrogen ions are held onto the surface of organic matter rather than existing within the soil solution (Gazey & Ryan, 2015). Why should you monitor your soil closely? Monitoring soils can give an indication of what may be constraining crops; is it a physical, chemical or biological constraint? If growers do not identify the main issues, they can be difficult to address and will end up being costly. To aid in preventing these costly mistakes, a simple visual assessment of soil pH in the field related back to plant growth at that particular point in time can be a helpful tool. This will give growers a clearer picture of how their particular pH management is actually performing in the paddock, in terms of lime movement down the profile and the overall soil pH profile, compared to how they think their pH management is performing when looking solely at soil tests. Nutrient availability is best in soils with a pH range of 5.5-7.5 (CaCl2) (Quinlan, 2015). If your soil pH is not within this range, it is likely that you’re often encountering low fertiliser-use efficiency and roots may not be able to grow through acidic subsoil to reach subsoil nutrients (Table 1).

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Table 1: Nutrient availability in relation to soil pH (Table adapted from Menjoulet, 2011).

Soil pH (CaCl2)

Nitrogen (%)

Phosphorous (%)

Potassium (%)

Average Unavailable Nutrients (%)

4.5

30

23

33

71.34

5.0

53

34

52

53.67

5.5

77

48

77

32.69

6.0

89

52

100

19.67

7.0

100

100

100

0.00

Note: Fullness of bucket represents total available nutrients.

How can you sample and evaluate your soils? Many paddocks have multiple soil types and shouldn’t be treated as one; however, traditional soil sampling can be costly and normally has a two week turn around. A soil pH test kit (Figure 3) is a way to get an immediate visual result that can give an estimate of your soil pH. Stuart has designed and made up some simple tools to help him take soil samples that give an undisturbed soil face to spray the indicator on and give an approximation of soil pH in the top 0-20cm of the soil profile (Figures 4 & 5).

What you need for doing in-paddock assessments of soil pH

Soil pH test kit

Soil corer/sampler with an exposed face

Shovel

Ruler

Hammer

Camera When out in the paddock taking soil samples, growers should look for signs of soil health such as; rooting depth, rhizobia on legumes, rhizosphere and soil smell (if the soil is sweet or sour smelling it can give an indication of aeration). The rhizosphere is the area in which root exudates (chemicals) are excreted by the plant (Walker et al, 2001). Exudates alter the chemical and physical properties of the rhizosphere and encourage symbiotic exchanges, whilst also inhibiting the growth of competing plants in some scenarios (Nardi et al, 2000). Stuart normally digs up a couple of plants to examine plant health in the root zone. Stuart has found that there is a definite correlation between how the roots behave in relation to the soil pH. He identified this from the profiling tools used to assess the soil pH profile out in the paddock. When digging up a plant root zone, (approximately 20cm3) for example, Stuart found that the root growth was a good indicator of where the bands of pH were. In some cases the roots would

Figure 3: Soil pH test kit used for soil sampling (available from Bunnings for $16.70, can test approximately 100 samples).

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be thick, then thin out and possibly thicken again. Where the roots thinned it usually indicated where there was a band of acidic soil. Initially Stuart was using an excavator to dig soil pits prompting him to develop the profiling tools (Figures 4 & 5) in an effort to make the process more efficient. These tools enable growers to quickly get a more complete picture of their soil pH profile in the paddock giving a greater understanding of how the pH profile is affecting root growth in relation to their crops health.

Benefits

Immediate visual assessment

Gives a clear picture of bands of pH through the profile

Cheap

Quick

Disadvantages

Not a precise test as increments are only to ½ a unit of pH

Figure 5: Soil corer/sampler with cover that screws on ensuring minimum soil disturbance.

Figure 4: Soil corers with open panel for viewing soil profile.

Figure 6: Examining root length of canola in Buntine, WA 2015.

Figure 7: Rhizosheath of wheat roots in Buntine, WA 2015.

Figure 8: Plants exhibiting healthy root growth in Buntine, WA 2015.

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Summary The key messages Stuart has taken from all the testing he has carried out is that there are many farmers applying lime and not really getting the results that they thought they were. Growers need to keep in mind that lime reacts to neutralise acidity when in contact with acid under wet conditions. If reapplying lime to topsoil with pH at or above 5.5 - 6 and not incorporating it there will not be a lot of acid to break down the calcium carbonate in the topsoil. Therefore, it is unlikely to give much of a return on investment in the short term because the lime will not move down the profile to treat the acidity at depth. Growers need to look at new ways to investigate their soil pH and utilise simple tools such as the pH indicator test to improve their understanding of soil pH throughout the profile. The profiling tools that Stuart uses give the grower an immediate visual assessment of their pH throughout the profile and where it changes in relation to depth. The pH indicator test gives farmers the opportunity to evaluate the mixing effect of mechanical incorporation methods on their own farms in a quick, easy and effective package and to understand what is happening in the soil with movement of liming products. Before deciding on what action to take growers need to have a greater understanding of where their pH levels are and what other constraints might be impacting the soil before addressing the issue/s. Some growers with high pH in the topsoil may be able to get more value out of money that has already been spent just by running a one way plough over the paddock and working the existing limesand down through the profile.

A soil can only perform to the ability of its greatest constraint, meaning if pH was the biggest constraint and this has been addressed, the next limiting factor will determine its potential. This is why it is important to understand your soils as it may be possible through correct identification to address more than one issue at a time, thus reducing costs and time. Other issues, such as sodic or hostile subsoils, need to be identified especially if planning to invert soils through mechanical means.

One of the biggest contributing factors to soil acidification is ammonium based fertilisers. Growers have the opportunity to manage these ammonium based fertilisers a lot better by matching supply and demand as closely as possible and minimising nitrogen losses through leaching, which contribute to soil acidification. Stuart feels strongly that growers cannot just rely on fixing their pH through applying lime and incorporating it but that they also have to become more strategic in managing acidifying inputs, such as ammonium based fertilisers.

Acknowledgements Case study funded by GRDC project LIE00008, “Working together to deliver multiple benefit messages to growers through a whole systems approach to soil management.” The Liebe Group would also like to thank Stuart McAlpine for sharing his experience, time and support. Paper reviewed by: Liam Ryan, DAFWA References Gazey, C., & Ryan, L. (2015). Soil pH - Soil pH Buffering. Retrieved 24/09/2015 from https://www.agric.wa.gov.au/soil-acidity/soil-ph?page=0%2C1

Menjoulet, B. (2011), Soil Fertility and Testing. University of Missouri. Retrieved 24/09/2015 from http://extension.missouri.edu/webster/documents/presentations/2011-10-13_SoilFertilityMeeting/2011-10-13_Soil_Fertility_and_Testing-BrieMenjoulet-Print.pdf

Nardi, S., Concheri, G., Pizzeghello D., Sturaro, A., Rella, R., Pavoli, G. (2000). Soil Organic Matter Mobilization by root exudates. Chemosphere, vol 5, p 653-658

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Quinlan, R. (2015) Optimising Soil Nutrition. Soil Quality Factsheet. Retrieved 24/09/2015 from http://www.soilquality.org.au/factsheets/optimising-soil-nutrition

Walker, T.S., Bais, P.B., Grotewold, E. and Vivanco, J. M. (2003) Root Exudation and Rhizosphere Biology. Plant Physiology, vol 123, p 44-51.

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Fast Facts

No significant yield responses to lime or incorporation were observed in 2014.

In 2015 there was a significant response to incorporation but not lime.

The impact of the incorporation systems is expected to be long term and in 2014 penetrometer testing showed large differences in the levels of restrictive compaction through the treatments.

Farm Details

FARM NAME Coolangatta

FARMERS Steve Rowe

LOCATION Wongoondy

AVERAGE RAINFALL 300mm

FARM SIZE Total size - 6000ha Arable - 4600ha

ENTREPRISE MIX % 100% Cropping

SOIL TYPES % 40% yellow sand, 22% gravel, 22% red sandy loam, 16% heavy red clay.

Aim To determine the best strategy for improving pH on red loam over a five year management period using applications of lime and soil amelioration treatments. Steve’s perception of subsurface acidity and the use of different tillage systems on soil health and crop yield Steve is very aware that he has a sub-surface acidity issue. He has regularly been applying a minimum of 2 t/ha of lime to between 500 and 700ha of his property on an annual basis. A large area of his property is yellow sand which is very responsive to lime. The remainder is a mix of gravel, red sandy loam and heavy red clay with low pH levels. Steve’s interest in this trial was generated by a knowledge gap. There appeared to be many different types of incorporation being used on yellow sandy soils to incorporate lime and increase pH but none or very little information about using them on red sandy loam. Some of the tillage treatments used are not practical for large scale application on red sandy loam, but Steve was happy to put them in place and compare the outcomes. Steve’s prediction of soil amelioration Steve believes that incorporation of lime is the best strategy for changing sub surface soil pH in the shortest time. He does not believe the mouldboard treatment will be used on a large scale on this soil type but is very interested to evaluate the results of the trial and decide on the best techniques to be used on his property. Background This research assesses the crop, vigour and yield response to lime application and the impact of different incorporation systems on the rate of change of surface and subsoil pH. The trial contains four replications of thirty five combinations of lime rates and incorporation systems. Extensive soil sampling was conducted at 10cm increments to a depth of 50cm to establish the base soil characteristics at this site and identify any variability between plots. Soil pH was lowest at the

Soil Management Strategies for Improving pH on Red Loam Debbie Gillam and Laura Dorman, Mingenew Irwin Group

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10 – 20cm depth (4.37 CaCl2) and highest at 40–50cm (4.97 CaCl2) (Table 1). The trial will enter into its third of five seasons in 2016. Table 1: Baseline pH (CaCl2) for trial site at Wongoondy.

Depth (cm) pH (CaCl2)

0-10 4.43 10-20 4.37 20-30 4.58 30-40 4.78 40-50 4.97

In August 2014, a field walk at the site was attended by over 40 growers. Grower feedback supported Steve’s interest in finding a suitable incorporation treatment for incorporating lime sand on red loam soils. Adoption Process The results of this research will impact what soil amelioration practices Steve uses in the future. Trial Layout Tillage Treatments: Lime Application Rates

38 inch off set disc Nil

Mouldboard 3 t/ha

One way plough 6 t/ha

Deep digger 12 t/ha

Spader

Nil tillage Results

Figure 1: Compaction under different tillage systems on red sandy loam. Notes: Compaction measurements were taken at the site in June, 2014 following opening season rainfall. The mouldboard plough treatments had the least compaction of all treatments to a depth of 30cm. The offset disc treatment measured the least soil resistance below 30cm. Root growth becomes inhibited at 1500 kPa with severe restriction occurs above 2500 kPa.

0

500

1000

1500

2000

2500

3000

3500

4000

0 200 400 600 800

Soil Resistance (Pascal's)

Depth (mm)

Nil AVG

Moulboard AVG

Spader AVG

Offset AVG

Deep Ripper AVG

70% restriction

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Table 2: Yield response to treatment in year 1.

Lime Cultivation ppm2

Average Lime Yield

(t/ha)

Average Cultivation Yield (t/ha)

Average Interaction Yield (t/ha)

Grade

Returns ($/ha)

Nil

Nil 83

1.577

1.553 1.55 AUW1 $401 Off set Disc 90 1.694 1.75 AUW1 $453

Mouldboard 39 1.614 1.67 AUW1 $433 One way Plough 97 1.637 1.595 AUH2 $498

Spader 78 1.558 1.45 AUH2 $452 Deep Digger 88 1.551 1.54 AUH2 $480

3 t/ha Lime

Nil 95

1.622

1.535 AUW1 $398 Off set Disc 99 1.59 AUW1 $412

Mouldboard 46 1.653 AUW1 $428 One way Plough 104 1.64 AUH2 $512

Spader 91 1.588 AUH2 $495 Deep Digger 101 1.633 AUH2 $509

6 t/ha Lime

Nil 88

1.611

1.51 AUH2 $471 Off set Disc 103 1.665 AUW1 $431

Mouldboard 41 1.56 AUW1 $404 One way Plough 106 1.67 AUH2 $521

Spader 84 1.568 AUH2 $489 Deep Digger 85 1.588 AUH2 $495

12 t/ha Lime

Nil 85

1.637

1.533 AUW1 $397 Off set Disc 100 1.753 AUW1 $454

Mouldboard 50 1.628 AUW1 $422 One way Plough 92 1.615 AUH2 $504

Spader 85 1.718 AUH2 $536 Deep Digger 106 1.528 AUH2 $477

P value 0.464 0.016 0.456 L.S.D (0.05) NS 0.0916 NS CV % 9.1

Based on APW2 price of $300/t, 1st

November 2014. Treatment costs have not been removed from Returns $/ha. NS = Not significant.

Economic Analysis Table 3: Treatment costs ($/ha).

Treatment Individual Cost

($/ha) 3 t/ha Lime + treatment

6 t/ha Lime + treatment

12 t/ha Lime + treatment

Off set disc 45 108 171 297

Mould board 120 183 246 372

One way Plough 45 108 171 297

Spader 150 213 276 402

Deep digger 60 123 186 312

3 t/ha Lime 63

6 t/ha Lime 126

12 t/ha Lime 252

Based on-farm delivered lime price and average tillage treatment cost.

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Table 4: Yield responses to treatments in year 2.

Lime Cultivation Average

Lime Yield (t/ha)

Average Cultivation Yield

(t/ha)

Average Interaction Yield

(t/ha)

Returns ($/ha)

Nil

Nil

1.677

1.217 1.503 $449 Off set Disc 1.887 1.741 $521

Mouldboard 1.540 1.752 $524 One way Plough 1.878 1.808 $541

Spader 1.395 1.532 $458 Deep Digger 1.657 1.903 $569

3 t/ha Lime

Nil

1.585

1.331 $397 Off set Disc 1.736 $519

Mouldboard 1.424 $426 One way Plough 1.960 $586

Spader 1.341 $401 Deep Digger 1.974 $474

6 t/ha Lime

Nil

1.675

1.431 $427 Off set Disc 1.963 $587

Mouldboard 1.430 $427 One way Plough 2.165 $647

Spader 1.389 $415 Deep Digger 1.916 $573

12 t/ha Lime

Nil

1.698

1.632 $488 Off set Disc 1.864 $557

Mouldboard 1.527 $456 One way Plough 1.687 $504

Spader 1.418 $424 Deep Digger 2.129 $637

P value 0.182 <0.001 0.62 L.S.D (0.05) NS 0.1715 NS CV % 9.7

Based on APW1 at $299/t on 1st

November 2015. Assumption made on APW1 grade given that quality data not available at time of printing.

Benefits

Higher rates of lime may impact on the acidity issue at an increased rate.

One way ploughs and offset discs are accessible on most properties and allow for incorporation of lime without the full soil profile disturbance.

Disadvantages/Risks

Mouldboard plough treatments have left the surface of the paddock uneven and made traffic passing difficult.

Correct seed placement in hard setting soil is difficult after major soil incorporation and will influence emergence and paddock yield.

Application costs of 12 t/ha lime would discourage most growers from implementing. Summary Harvest in 2014 recorded no significant differences in yield between treatments. The 2015 harvest recorded a significant difference between cultivation treatments but not between lime treatments. It is expected that over the five year period of the trial more variation will be observed. An observation was that the highest plot yields corresponded with the high rates of lime application but statistically this observation was not significantly different across the trial.

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Due to the large amount of soil disturbance, unless the results of the research are significantly in favour of the benefits of mouldboard ploughing this practice, it will not be recommended. Acknowledgements This research is funded by GRDC project LIE00008, “Working together to deliver multiple benefit messages to growers through a whole systems approach to soil management.”

Many thanks to Steve Rowe for the trial site, his participation and support for this research.

Thanks to Afgri for supplying the mouldboard plough.

Thanks to the Mills family for suppling the one-way plough.

Thanks to the Broad family for suppling the spader.

Thanks to McIntosh & Son for supplying the Tiny 36 inch Grizzly offset disc and deep digger.

Thanks to Chris Leigh-Fairbank for his lime donation. Paper reviewed by: Wayne Parker, DAFWA

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“Wholesale tillage system” gets huge results from lime and soil amelioration

Fast Facts:

Ameliorated non-wetting topsoils and subsoil acidity.

A “once in 20 years” solution with sustained results.

Recouped full costs in first year.

Enabled a more cropping dominated rotation.

Approximately doubled pasture density. Farm Details

FARM NAME Homewood Farms

FARMER David Isbister

LOCATION Moora and Dandaragan, WA

AVERAGE RAINFALL 380-500mm

ENTREPRISE MIX % 75% crop (barley, wheat, canola, lupins), 25% livestock

SOIL TYPES % 30% river loam, 60% yellow sandplain, 10% gravel

Aim In 2012, David Isbister made the decision to combat non-wetting topsoils, subsoil acidity, and compaction. Up until about a decade ago, high reliable rainfall in the region meant that crops could be grown without particular attention to subsoils, and regularly spreading lime on top to maintain a pH of 5.0 or more was standard practice. But after 20 years the soil had continued to acidify at depth, and changing weather patterns combined with worsening non-wetting topsoils began to reduce profits. David decided to turn his established mindset of minimum tillage on its head by rolling out a “wholesale tillage system” to incorporate lime and other inputs at depth. The process is now 80% done and he plans to complete the remaining paddocks over the next two years.

Background On the sandplain soils around Moora and Dandaragan as well as elsewhere, minimum tillage has been the established mindset for decades. As a consequence the soils have not been cultivated for many years, contributing to a worsening problem of non-wetting topsoils (Davies et al, 2015). Years of soil testing also revealed acidity in the mid and subsoil, which restricted how deep crops’ roots could grow (Gazey and Ryan 2015). Compared to pH 6.0 at 0-10 cm, David found pH 4.5-5.0 at 10-20cm, and pH 3.8-4.5 at 20-30cm.

Tillage seemed the best way to tackle both aspects of the problem. Higher clay-content subsoil could be brought to the surface, non-wetting topsoil could be mixed and diluted through the top 40cm of the soil, and lime and other inputs incorporated at depth. As a result, the chances of good germination should improve (Davies et al, 2010) along with ongoing access to moisture and nutrients (Scanlan et al, 2013). Under ideal conditions crops on deep sands can root down to 2m, which greatly increases yield potential (Hamblin et al, 1988).

Trial and adoption of two new practices Since there are additional costs involved, David wanted to know what sort of tillage would produce the best returns. To answer that question he conducted a trial in 2010 comparing deep ripping,

Anne Wilkins, West Midlands Group

Figure 1: David Isbister, Homewood Farms, WA.

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mouldboard ploughing, and deep ripping and spading to the established practice of no tillage (the control).

Table 1: Different tillage practices and wheat yield responses, 2010 (year one). Practice Yield

(t/ha)

Yield Gain

(t/ha)

Percentage Gain (%)

Cost ($/ha)

ROI (%)

No tillage 2.4 0 0 0 0 Deep ripping 3.0 0.6 25 $50 67 Mouldboard ploughing 3.0 0.6 25 $120 20 Deep ripping & spading 3.6 1.2 50 $150 50

Deep ripping and spading requires the biggest investment since it takes two passes compared to one with mouldboarding, but the results in year one proved well worth it, with a 1.2 t/ha or 50% improvement in yield compared to the no tillage control case. Refer to Table 1 above, and Figures 2 and 3 below.

After further analysis over subsequent years, David generally favours deep ripping and spading because it provides a range of benefits in addition to the higher yield (See Table 2). David also recommends mouldboard ploughing where weeds are a serious issue.

In David’s experience, spading in February to April brings up enough moisture to seal the soil against wind erosion. He then puts off seeding until rain is forecast so as to not open the seal. In subsequent years he gets good results from minimal tillage and seeding earlier. He is now of the opinion that on his property spading once in 20-30 years will be enough. However, deep ripping and controlled traffic farming (CTF) is an ongoing requirement. David prefers spading compared to mouldboard ploughing because the tillage can be completed early in the year and this allows him to sow on time with minimal delays. Spading early also significantly decreases wind erosion and conserves moisture.

Figure 2: Rip line comparison between deep ripping and no deep ripping.

Figure 3: Spading vs. no spading.

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Table 2: Positives and negatives of different tillage systems for David Isbister. Issue Deep ripping & spading Mouldboard ploughing

Non-wetting topsoil Effective, mixes topsoil with subsoil Effective, inverts topsoil and subsoil

Getting lime to depth Effective, less stratification Effective

Weed control Buries 70% of weeds, chemicals more efficient

Buries 90% of weeds

Scheduling Spade it dry February-April so finished before seeding

Need fully wet soil profile so ploughing coincides with seeding

Moisture loss (year one) Spaded early so all later rain remains in soil

Turns up subsoil low in organic carbon that dries quickly

Wind erosion (year one) Spading leaves soil rough so less wind erosion

Inverted subsoil dries quickly so vulnerable to wind erosion

Compaction Effective, goes deeper through previous traffic hardpan

Effective, to less depth than deep ripping & spading

Seeding (after year one) Can seed early and dry Can seed early and dry

Crop establishment Faster, full benefit from initial rain Slower, less organic matter and more moisture loss

Economic analysis David’s costs were fully repaid by yield gains in the first year, and he expects to see sustained benefits for another 20 to 30 years. The results for other farmers may be different, depending on their soil conditions, the weather and the prices of inputs and grains at the time. Various factors will also determine whether it is best to employ a contractor or to buy the necessary equipment.

Using a mix of contractors and his own equipment, David’s average cost was $50/ha for ripping, plus $100/ha for spading, for a total of $150/ha. Mouldboard ploughing was less expensive, with an average cost of about $120/ha.

For David there have been four forms of economic benefits:

A wheat yield gain of 0.8-1.3 t/ha across the various paddocks in year one, with sustained yields in the subsequent three years of approximately 30% more than the control case.

More efficient weed control because pre-emergent chemicals perform better in moist topsoil and weeds germinate more evenly at the break of the season.

The ability to have a completely different rotation that is more cropping dominated, including canola germinating well in more paddocks.

Improved pasture density by approximately 100%, sustained for five years so far.

How much lime? The quantity of lime needed to produce good results will vary from property to property and paddock to paddock, so there is no rule of thumb. David relies on soil tests to tell him how much he should use where.

Since he and the generation before him on his property were early adopters of lime, he can now confidently point to tillage - the method of incorporation as opposed to the amount - as making the difference now.

Lime is a replacement input, so the ideal application rate is affected by production. For example, an application once in five years may be sufficient to maintain pH levels, but if the paddock is producing more then it will need a more frequent application.

David aims to achieve pH 5.5 throughout the profile. For example, if the soil test shows pH 6.0 topsoil, pH 5.0 midsoil and pH 4.2 subsoil, then he applies 1.5-2.0 t/ha. From experience he knows that will result in less stratification two years later, with pH 5.5 in the topsoil through to pH 5.2 in the

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subsoil. But if the paddock was still in remedial phase with, for example, pH 4.5 throughout, then it might need 5-6 t/ha in one hit. There are good calculators available to help plan lime requirements.

Still more to learn David’s new spading and ripping tillage system has turned up two new issues for him to think about.

The first is what to do about nutrients. Phosphate is immobile so it does not leach down through the profile and most of it is found in the top 10cm. But spading mixes the topsoil and subsoil, diluting the phosphate through 30cm. So the standard method of testing the topsoil after spading doesn’t detect the nutrients that are accessible at lower levels once the acidity is rectified. The second issue is soil compaction which impedes root growth. In the past, the hardpan generally remained at 25-30cm even as the traffic on it increased.

After deep ripping through that layer, David has found that today’s heavier machinery pushes that compaction down to 35-45cm. As a result, he has decided that Controlled Traffic Farming (CTF) is critical to minimising the problem in the first instance, rather than hoping to remedy it later.

Summary Changing weather patterns have given farmers, particularly with non-wetting soils, reasons to think that minimal tillage systems are not sustainable on their own. In particular, there is a worsening problem of non-wetting topsoils and shallow crop rooting depth as a result of subsoil acidity and compaction which further restricts crop access to moisture.

David Isbister’s “once in 20 years” tillage system has convinced him that he can retain the benefits of minimal tillage while remediating the longer term harmful effects. In his experience, the costs were fully repaid in the first year and there have been substantial ongoing additional benefits.

Acknowledgements Case study funded by GRDC project LIE00008 “Working together to deliver multiple benefit messages to growers through a whole systems approach to soil management”. Thanks to David Isbister for sharing his time and experience.

Paper reviewed by: Stephen Davies, DAFWA

References Davies S, Blackwell P, Bakker D, Lemon J. (2015). Soil water repellence – overview. https://www.agric.wa.gov.au/water-repellence/soil-water-repellence-overview Davies S, Scanlan C, Best B (2010). Rotary spading and mouldboard ploughing water repellent sandplain soil fulfils promise. West Midlands Group research Annual 2010.

Gazey C, Ryan L. (2015) Effects of soil acidity. www.agric.wa.gov.au/soil-acidity/effects-soil-acidity

Hamblin A, Richards Q, Blake J. (1988). Crop growth across a toposequence controlled by depth of sand over clay. Australian Journal of Soil Research 26: 623-635.

Scanlan C, Davies S, Best B. (2013). Managing nutrition on soils that have been treated for water repellence by cultivation. Agribusiness Crop Updates, 25-26 February, Perth WA. http://www.giwa.org.au/_literature_125722/Scanlan,_Craig_et_al_-_Presentation_1

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Innovation in the Wheatbelt

Fast Facts

Cost of freight was the economic driver to investigate alternative lime options.

Reduced liming cost by unearthing an on-farm lime resource.

Reduced trace mineral inputs to maintenance levels.

Farm Details

FARM NAME R Nixon & Co

FARMERS Bob & Daniel Nixon & Family

LOCATION Kalannie, Western Australia

AVERAGE RAINFALL 300mm

FARM SIZE 15,000ha

ENTREPRISE MIX % Cropping: wheat, canola, barley Livestock: 1,200 breeding ewes

SOIL TYPES % Acid wodjil sandplain, gravel, clay loam, heavy clay, red morrel

Aim To find an alternative neutralising option to coastal limesand in order to reduce liming costs. Bob and Daniel’s perception of using morrel lime to ameliorate acidity on the farm Bob and Daniel focus on producing the same yields with fewer inputs, lowering their risk profile while increasing their gross margin, rather than trying to increase production like in the 90’s. One of the many cost saving initiatives that has come from this aim was identifying a viable on-farm lime source that is both quantifiable and economically justifiable. This enables the Nixon’s to lime the farm in a more cost efficient manner than sourcing limesand from the coast. Bob estimates that there is 250,000t of morrel lime available and that this source has an adequate neutralising value (NV) for combating acidity on the farm, “acidification is a function of production and can’t be avoided; in order to combat this you need bulk ameliorants not snake oils”. Every farm will not have this option available to them, but the Nixon’s feel that there has to be more farmers in WA who have a similar soil resource. There is potential for farmers to identify alkaline areas of their farms, test them, do the economics and discover if it would be a viable option for their

business. The further east you farm the likelihood increases that this could be a practical option for cutting the freight cost out of your liming program.

The neutralising value (NV) of your on-farm lime source can be low, yet still give a return on investment by reducing your freight cost. The importance of these factors is dependent on the NV% of the lime and the distance for freight. Currently the Nixon’s are applying 4 t/ha of morrel lime but once they bring the property pH up to requiring only maintenance rates, the on-farm resource is calculated to last for over 20 years.

Lilly Martin, Liebe Group

Figure 1: Loading morel lime onto the screener, Kalannie WA.

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The decline in autumn rainfall is having a major impact on crop establishment on the heavier soils. Liming the sandier soils is becoming even more important as these soils are becoming more important in driving profitability. Bringing up the pH of these soils and making the nutrients more available to crops at an earlier stage is vital.

Background The Nixon’s are no strangers to diversifying their family business and exploiting the natural resources of their farm. In 1978, Bob and Daniel’s father Robert Nixon opened up a gypsum mine, utilising the naturally occurring gypsum deposits in the salt lakes. Initially, most of the gypsum was mined for industrial purposes and as a soil conditioner for clay soils. In more recent times with the popularity of canola as a rotation increasing they have been supplying the local agricultural market with a sulfur replacement. The Nixon’s have a long held interest in geology and had the necessary skill set required to identify the farms naturally occurring resources, one of which is a 50ha paddock of red morrel soil. They first recognised that there was a substantial lime resource available to the farm through their knowledge of the physical landscape, soil types and local vegetation. A red morrel soil with calcium magnesium rocks visible on

the surface of the paddock and farm track and several tree species such as; Red Morrel (Eucalyptus longicornis), Gimlet and York Gum, another indicator that Bob and his father noticed was that “the soil powders up when you drive over it”.

Morrel soils are very fine textured meaning capillary rise brings moisture to the surface that then evaporates, accumulating salts on the surface, resulting in transient salinity even though the site is high on the landscape. All of these observations led the Nixon’s to carry out soil testing. The CSBP soil testing showed that the top 10cm has a pH >8 (CaCl2) and potassium (K) >600 mg/kg colwell, both of which are very high, highlighting to the Nixon’s that they had a valuable lime resource.

Adoption Process One of the biggest issues in liming for farmers is not the cost of the lime, but the cost of freight from the coast. The Nixon’s were averaging $33/t (lime and freight) landed in the paddock, a significant cost for their farm business, giving them the incentive to find an alternate option to coastal lime. They decided that it was time to do further research into the morrel soils characteristics and invested in soil testing to get a clear picture of what was actually available to them. Initially they dug a 3 meter pit and had each meter analysised (Table 1 & 2) the top meter

Figure 3: An initial test pit with calcium magnesium rocks visible.

Figure 2: Red Morrel (Eucalyptus longicornis) Kalannie WA.

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had the highest NV%. They extended this to four individual pits over the 50ha of red morrel soil type that they had identified. What they discovered was a viable economic lime source that was already on-farm! The Nixon’s started liming in 1994 with an average pH of 4.5 (CaCl2) on their acid sands. Over the last 20 years, 4–6 t/ha of limesand has been spread over the farm raising the average pH to above 5. The Nixon’s now intend to raise the average to a pH of 5.5–6 using the morrel lime. In 2012, the Nixon’s applied 4,000t of limesand on the farm at a rate of 2 t/ha. They started harvesting the morrel lime in 2013 with an initial 8,000t, which was spread at a rate of 4 t/ha. They doubled the rate from 2 t/ha to 4 t/ha due to the fact that the morrel lime has an NV of only 50%, but even at this high rate it is more economical. The bottom 35% of the morrel lime is very fine like a talcum powder which gives a very good diffusion across the paddock from the multi spreader. In 2015, the Nixon’s spread 12,000t over 3000ha of the farm, 300ha was also ploughed in using offset discs to 10-15cm. The combination of liming and ploughing raised the Nixon’s yield average by 0.6-0.7 t/ha over this 300ha. They estimate that this yield improvement is a 50:50 split between the improved pH and the ploughing effect. Lime Analysis The on-farm lime source has an average NV of 37-54% (Table 1) this is comparatively low when compared to other lime sources such as limesand. The Jurien Bay pit range is 84.7-94.1% (DAFWA Audit Limesand, 2015) and dolomite (Watheroo pit range 88.5 – 91.6%, (DAFWA Audit Dolomite, 2015). However, the fact that it is on-farm is the clincher in cutting freight costs. The Nixon’s are able to mine the morrel lime and have it in the paddock at two thirds of the cost of sourcing and carting limesand from the coast. This saving on freight allows them to invest what was ‘dead money’ back into the farms liming program. Table 1: Average soil analysis taken from the four initial test sites in Kalannie, W.A to a depth of 1m.

Soil Fines Ca Mg Na K NV Pit (NV) (ICPg) (ICPg) (ICPg) (ICPg) (CaCO3) % % % % % %

North West 37.1 13.4 4.8 0.2 0.2 54.2 North East 44.6 12.9 3.5 0.2 0.2 47.5 South West 34.6 12.0 4.4 0.2 0.2 49.0 South East 47.5 11.9 1.7 0.2 0.2 36.9

The morrel lime at Kalannie is a calcium and magnesium carbonate. It contains calcium (Ca) at 12.5%, magnesium (Mg) at 4.5% and small amount of potassium (K) at 0.2%. By increasing the farms overall pH the Nixon’s have made the phosphorus (P) bank more available to the crop (Scanlan et al,

Figure 4: Morrel lime after screening to 10mm.

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2015) and have been able to cut back P to maintenance levels as a result further lowering the cost of inputs. The money saved on phosphorous can then be redirected elsewhere in the budget. Table 2: Neutralising value of morrel lime in the top 900mm.

Depth (mm)

Neutralising Value % (CaCO3)

0 - 300 35.7 300 - 600 60.9 600 - 900 51.0

Economic Analysis The Nixon’s have turned one of their poorest producing paddocks averaging 0.3 t/ha in 2013 into an asset. There is no mining lease or royalties associated with the venture as they are not selling the mined lime, similar to claying on-farm. All the machinery required is readily available due to the downturn in the mining industry and is more affordable than ever. Now is the time for growers to capitalise on mining equipment as the machinery is currently good value for money. The Nixon’s have the advantage of having the equipment already due to their family gypsum business. However, rental costs of equipment have also decreased due to the mining downturn.

A screener can be rented out of Perth for approximately $300/hr. The screener has the capacity to screen 150 t/hr to 10mm, giving an average cost of $2/t. If you spread 3,000 ha/yr with morrel lime at 4 t/ha totaling 12,000t this would take approximately 80hrs to have your annual supply stockpiled and ready for the paddock.

Presently the Nixon’s use an excavator to mine the lime and are screening it to separate off the bigger rock particles. They intend to stockpile the dolomitic rocks which have an NV of 55%, until they have 20,000t before crushing.

The Nixon’s have been able to reduce their fertiliser inputs based on increased availability and nutrient cycling due to the farms average pH increasing. This value will be similar across both liming programs as it is a function of the average pH increase rather than the individual lime products.

Figure 6: Stockpiling morrel lime rocks at Kalannie for crushing.

Figure 5: Screening the morrel lime at Kalannie, WA.

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Table 3: Assumptions for economic analysis of 2 t/ha coastal limesand compared to 4 t/ha morrel lime (equivalent neutralising value) at Kalannie.

Input 2 t/ha Coastal Limesand ($/ha)

4 t/ha Morrel Soil ($/ha)

Freight 50 20 Excavator 0 4 Screener 0 8 Loader 0 8 Limesand 14 0 Spreading

1 8 10

Total costs 72 50 1Based on 2015 contractor rates. Limesand price $7/t.

Fixed lost revenue: 50ha out of grain production due to morel lime pit: (Average 2013 paddock yield * AWB 2014 average price = 0.3t/ha*$270/t*50ha) = $4,050/yr.

Benefits

Freight and truck maintenance costs reduced significantly.

Unlike limesand, morrel lime doesn’t blow when stockpiled due to its increased specific gravity.

Easier to get an even spread across the paddock due to its increased specific gravity.

Reduced fertiliser inputs.

Contains other desirable trace minerals such as; magnesium, potassium and calcium.

Good reactivity as bottom 35% is very fine and soluble. Disadvantages

10% increase in spreading cost due to the increased rates (potentially could be higher, dependant on specific gravity and spreader capacity).

Rhizoctonia was bad in paddocks that had lime ploughed in last year (2014).

Big range of particle sizes requiring screening.

Screening difficult after heavy rain. (With the 100mm rainfall event in July 2015 the lime has been damp and sticky resulting in difficulties in the screening process and could only screen to 15mm particle size).

Summary Growers throughout the Wheatbelt need to look at alternative methods of decreasing costs over their farm business as a result of tightening gross margins. There are many options available to growers in order to combat this issue such as; control traffic, liming, new varieties, increased

Figure 7 & 8: Morrel lime stockpiled for spreading in 2016.

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fertiliser efficiencies, better utilisation of scale, management of inputs or through innovations such as the Nixon’s. The cost of freight from the coast was the economic driver that pushed the Nixon’s to investigate the possibility of using the morrel soil as a substitute for limesand. This led the Nixon’s to turn one of their poorest producing paddocks into an asset, giving the farm a greater rate of return as a lime source than as a grain producing paddock. The paddock has the potential to supply the farm with 250,000t of morrel lime. Bob and Daniel are intending to let no product go to waste, even the topsoil will have a purpose fixing blow outs in the paddocks or may eventually be used to regenerate the mined paddock. The cost of freight from the coast increases the further east you farm. This means that even if a lime source that has an NV of lower than 50%, it may still be a viable option for your farm business. Individual farming businesses need to analysis their costs and investigate any feasible options available to them.

Acknowledgements This case study is funded by GRDC project LIE00008, “Working together to deliver multiple benefit messages to growers through a whole systems approach to soil management.” The Liebe Group would also like to thank the Nixon family for sharing their experience, time and support. Paper reviewed by: Wayne Parker, DAFWA References AgLime of Australia, Product Specifications (2015) Retrieved from http://www.aglime.com.au/aglimespecs/Aglime%20Jurien%202015-01-19.pdf Scanlan, C., Brennan, R., Sarre, G., Bowden, B., Hüberli, D., Harries, M., MacLeod B., and Miyan, S. (2013). Managing fertiliser inputs on high phosphorus status soils: incorporating soil constraints into decisions. Perth Crop Updates 2013. Watheroo Dolomitic Lime, Product Analysis (2015) Retrieved from http://www.dolomite.com.au/products/analysis-2/january-2015/

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Fast Facts

Measurement and monitoring is extremely valuable in managing soil acidity.

An initial soil pH survey of 287 sites in a 22,000 hectare catchment was completed in 1999 (T0). The study involved eight farming entities that form the Gabby Quoi Quoi Catchment Group. All sites were resampled in 2006 (T1), and will be sampled again in 2016 (T2).

Changes in soil pH between T0 and T1 were well correlated to lime application in the previous seven year period. Lime applied in this period was less than recommended, however where it was applied, results were clearly documented across the catchment.

Farmers in this catchment group have increased the amounts of lime applied since 2006, and soil pH is expected to reflect this. Better resource condition across the catchment is predicted.

This study is likely to be the first catchment scale monitoring project in Australia sampled on three occasions, showing trends over a 17 year timeframe.

Project Details

PROJECT AREA Gabby Quoi Quoi Catchment

FARMERS Gabby Quoi Quoi Catchment Group

LOCATION Konnongorring region

AVERAGE RAINFALL 375mm

CATCHMENT SIZE Total size - 22,000ha Arable - 15,000ha

ENTREPRISE MIX % 80% cropping 20% livestock

SOIL TYPES % Sands, duplex, sandy loams, loams and clays.

Aim Current pH of all sites will be compared across the catchment, and correlated to lime applied since 1999 with the detailed liming recommendations provided to all growers involved, for all paddocks sampled. Methodology Soil pH (0-10cm, 10-20cm) has been measured within paddocks of a dryland cereal-based farming system in the Central Agricultural Region of the WA wheatbelt. The initial sampling and detailed 10 year liming requirements for all sites (Lightfoot, 1999) was followed up in 2006 (Gazey et al, 2006) and will happen again in 2016. This study consists of 287 GPS-locatable sites, representing 60 paddocks on eight farms and covering 22,000ha of the Gabby Quoi Quoi Catchment, in the Konongorring region in the central wheatbelt of WA. Typically four to five sites per paddock were sampled and each site consisted of 10 cores (0-10cm and 10-20cm depth) taken in an 8m arc behind the sampling vehicle. For each depth the 10 cores collected from each site were bulked, mixed and subsampled. The process that will happen in 2016 is identical to what occurred in 2006 and in 1999. Background and rationale Farming causes soils to acidify through the addition of acid fertilisers, leaching of nitrates and removal of alkaline plant and animal products. Most of the WA wheatbelt soils have acidified since they were brought into agricultural production. Liming soils is standard practice in most agricultural systems to neutralise acidity, but is not yet routine practice in much of the WA wheatbelt. Over the past 15 years, lime use in the WA wheatbelt has increased considerably (although annual use is still

Gabby Quoi Quoi Catchment scale pH monitoring for better soil acidity management Steve Carr, Aglime Australia

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only circa 60% of what the Department of Agriculture and Food, Western Australia (DAFWA) estimates is required annually). The Gabby Quoi Quoi Group was innovative in recognising that taking measurements was key to managing acidity, because detecting change over time is critical. On this basis, the group commissioned Aglime of Australia to geolocate 287 sites, sampled to a depth of 20cm across eight farms in their 22,000 hectare catchment in 1999. Whilst the ability to geolocate sites on a farm in now considered common, it certainly was not back in 1999. The group will soon have a complete data set, sampled in 1999, 2006 and again in 2016 to show trends in their pH management over the past 17 years. WA farmers have historically applied lower rates of lime than are required to manage natural and farming induced soil acidification. The reasons for this are complex. Growers have traditionally been reluctant to invest in long-term solutions preferring to see more immediate returns from investing in annual applications of fertiliser. Between 1999 and 2006, members of the Gabby Quoi Quoi Group applied 4,500 tonnes of lime (circa 10% of the 10 year recommendation) which would have been very typical of most central wheatbelt farmers at that time. The soil pH data collected in 2006 reflected this, and highlighted to the farmers involved the value of point based sample sites to develop liming recommendations.

There has been a substantial increase (circa 4 fold) in lime applied in WA agriculture since 2006 (Figure 1). Many factors have contributed to the increase. Some key contributors to the changed perception of lime include: the Gabby Quoi Quoi study which showed pH decline when inadequate lime had been applied and the positive change when limed appropriately; the provision of government incentives to growers to sample soils to depth and understand the impact of subsoil acidity; consistent promotion of the need to increase lime use; publication of more long-term field trial response data showing lime responses last for a very long time; and more focus on correcting soil pH from farm consultants and company agronomists. Lime inputs over the past 10 years by the eight growers involved in the Gabby Quoi Quoi catchment are currently being collated, and will be correlated with soil pH change over the past ten years. By resampling again in 2016, we hope to compare lime use of the eight growers involved with the statewide (4 fold) increase in lime use since 2006.

Adoption Process The major focus of this study has been to demonstrate the importance of measurement (geo locations, pH at different time intervals and from different depths) in documenting and proving practice change. The adoption process has involved eight Gabby Quoi Quoi Group members documenting their lime use and soil pH at 287 monitoring sites, three times over the 17 year time frame. Lime use in WA is still well below (circa 60%) of the annual requirement suggested by DAFWA research. Despite this, there have been some promising changes, with significant increases on a statewide basis (Figure 1). Most Gabby Quoi Quoi growers have been like the majority of WA wheatbelt farmers and applied less than recommended lime rates. By resampling the whole catchment again in summer 2016 (T2), (i.e. third time in 17 years) and with the higher rates of lime that the Gabby Quoi Quoi members have applied since T1 in 2006, the current expectation is that the data will convince other farmers across Western Australia, that measurement and monitoring are extremely valuable in managing soil acidity. Benefits of the approach

Growers in the Gabby Quoi Quoi Catchment Group that adopt a measure and monitor approach to their soil pH status have a verifiable means of assessing their soil acidity management.

Other growers from similar farming systems can learn from the catchment group members that managing soil acidity adequately requires ongoing soil sampling and monitoring of pH change to depth over time, and applying adequate lime.

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Understanding subsoil pH provides more precise lime requirement knowledge and enables application where it is required and not just blanket liming of one rate of application across a paddock.

Results

A major risk is growers not adopting adequate liming programs.

There are many logistical issues associated with liming. Lime is generally a coastal resource, and large distances are involved in transport from the WA coast.

Farms in WA are typically large (3,000 to 4,000 hectares), and given soil acidity is common (80% of all surface soils are below optimum pH), large quantities of lime are required.

Transport is a large upfront cost, and to maximise efficiency many growers seek to take grain to Perth, backloading lime to their farm which requires considerable coordination and timing of linked operations.

Figure 1: Total lime applied in the WA wheatbelt (circa 18 million hectares) over the past 20 years (Gazey, DAFWA unpublished data). Note the consistent increases in total year sales associated with the timing of government supported extension programs specific to lime use and awareness.

Summary This unique study has provided many benefits. Firstly, the eight farmers involved in the Gabby Quoi Quoi Catchment have learnt more about their soils, and the need to manage soil acidity with recommendations derived from sound science. Secondly, farming entities in the surrounding vicinity, and further afield have been able to understand the impact, and apply the knowledge to their own circumstances. Detailed studies like this, over a considerable time frame, provide a sound basis to establish funding priorities and develop policy. The time frame required to detect catchment scale change is considerable, and many variables can impact. For example, if soils are well buffered or net acidification rates are low, then the time frame of 7-10 years shown in this study may not be applicable in other situations. Further Reading The full reports from the 1999 and 2006 sampling are available from Aglime of Australia, freecall 1800 644 951.

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Acknowledgements Case Study funded by GRDC project LIE00008, “Working together to deliver multiple benefit messages to growers through a whole systems approach to soil management.” We sincerely thank Maitland and Margaret Davey from the Gabby Quoi Quoi Catchment Group, who have both donated much time and effort into this study since its inception. Their dedication and commitment has been vital in the outcomes of this unique and extremely important study. Paper reviewed by: Chris Gazey, DAFWA References Lightfoot L, (1999), Soil pH survey and lime requirement advice for the Gabby Quoi Quoi Catchment Group. Aglime of Australia internal publication. Gazey C, Andrew J, York D, and Carr S (2006), Avon Catchment Council Soil acidification Monitoring Trial. Report on point based monitoring trial to identify how well the soil resources is being managed with respect to soil acidity, and the current status of the soil condition as a basis for subsequent monitoring efforts. National Land and Water Resources Audit.

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Fast Facts

Not all soils are created equal; every farm has its own complex and variable environments which will not always respond with increased yield to the standard practices endorsed by industry.

Farmers are the best resource for adopting and adapting new soil management practices to their local requirements.

Farmer-driven trials are key to rapidly optimising local strategies for ameliorating soil constraints and increasing the rate of adoption.

Seasons are as variable as soils, patience and long-term commitment will enhance the intimate knowledge farmers have of their land.

Farm Details

FARM NAME Red Hills

FARMERS John & Martina Pascoe

LOCATION Arthur River

AVERAGE RAINFALL 457mm

FARM SIZE Total size – 1,600ha Arable – 1,040ha

ENTREPRISE MIX 35% cropping, 65% sheep

SOIL TYPES Predominately granite and dolerite

Aims

To compare the effectiveness of three liming materials and a high silica fertiliser product incorporated with offset discs in reducing the effects of aluminium toxicity on crop production on soils with low pH at Red Hill.

To assess if alternative methods other than the traditional practice of topdressing limesand can be effective in reducing the effects of aluminium toxicity on crop production and raise soil pH at Red Hills.

To determine the most economical method for ameliorating the effects of aluminium toxicity on crop production at Red Hills.

Demonstrate that the most positive practice change farmers can make to alleviate soil constraints and maximise production long-term is to conduct their own trials.

John’s Perception John perceives that using lime to raise pH and ameliorate soil constraints, including aluminium toxicity, can only be effective when used in combination with land management practices developed on-farm according to specific local conditions. He is also of the opinion that limesand may not necessarily be the most economic and effective source of alkalising material for his enterprise, and that there may be other land management practices which could quickly and economically reduce the effects of aluminium toxicity on production without applying lime. John’s Prediction John predicts that it will take 3-4 years to see a beneficial change in soil pH or aluminium levels at the trial site and concedes that potentially these changes may be consistent across each of the treatments. This is not to say that John does not think he will see yield benefits, as he believes that dolomite has the potential to be more responsive than limesand on the lighter soils of this particular paddock and that the more readily available calcium in Optima Hi-Cal could also encourage a yield response compared to limesand at the site. In regards to which treatment will come out as the most

Alternative approaches to soil acidity Kayla Ringrose, Southern DIRT

34

economical for his enterprise, well that will be a waiting game and yield in these early days is not so imperative. Regardless of the outcome, John is confident that he will learn something valuable from this trial that will no doubt prove to be an asset in any future trials he does. Background Production on approximately 20% of the weaker white gum country at Red Hills appears to be limited by high levels of exchangeable soil aluminium (11.8% - 15.2%). While aluminium is a major component of soil, it is not essential for plant growth and tends to remain at harmless levels when present in soil types with a topsoil pH (CaCl2) of 5.5 and above (Gazey and Davies 2009). In soils with low topsoil pH, the aluminium component can increase to levels which adversely effects plant growth, as the more acidic the soil, the more soluble and therefore toxic the aluminium may become to the plant (Gazey and Davies 2009). It is widely accepted that the practice of applying alkaline minerals either by top-dressing or incorporating is the most effective way to reverse soil acidification. These materials, applied in adequate quantities, can neutralise the acidity and raise the soil pH. After a decade of observation, John came to the conclusion that the overall health of his paddocks seemed to improve with incorporation every 3-4 years with either offset discs or a plough when used for the purpose of incorporating lime or reducing stubble loads. Following years of trialling various products and observing the yield, soil health and economic benefits for himself, John now also applies soil microbes to his seed as standard practice. An increase in phosphate efficiency and a reduction in soil disease, especially rhizoctonia, have been the most noticeable changes he has observed in the paddock since using the product.

Being a firm advocate of farmers doing trials to answer their own questions, John decided to find out if these two separate practices (both of which have been observed to benefit soils specific to Red Hills), with the application of pH neutralising materials alternative to limesand, would succeed in quickly and economically alleviating the production loss in some of his paddocks with high aluminium levels. John has also used this trial as an opportunity to test a hypothesis he has recently been introduced to; that a fertiliser product high in silica (7.2%) and applied at a high rate could potentially tie up excess aluminium levels in his soils and therefore be an alternative option for reducing aluminium toxicity in the long-term without applying lime to raise pH.

Adoption Process John soil tested a paddock (0-10cm topsoil only) he had observed was showing signs of aluminium toxicity prior to seeding in 2014 and based on these results chose an area to locate the trial which showed the highest levels of aluminium he had ever seen on Red Hills (11.8% - 15.2% Total Exchangeable Ions). A standard rate of Australian Mineral Fertiliser (AMF) Premium Agricultural Blend Soil Microbe was applied to the seed (as per standard practice for John) with the following treatments then being applied in 0.6ha strips: 1) 500 kg/ha Optima Hi-Cal, 2) 1t/ha Lancelin Limesand, 3) 1t/ha Newdegate Dolomite, 4) 250 kg/ha AMF Crop Plus* and

5) Control (nil lime treatment or incorporation) *AMF Crop Plus contains 9% N; 8% P; 4.5% K; 10% S plus a host of micro nutrients

Each treatment was incorporated to a depth of 10-12cm using offset discs. The site was maintained prior and post seeding according to John’s standard practices and sown with Mitika oats at 100 kg/ha in both 2014 and 2015. The control plot received no application of a liming product or

35

incorporation with offset discs in 2014. The trial plots will receive no further treatment applications after 2014, including the fertiliser treatment. Trial Layout The trial site is located on duplex white gum country on Red Hills, 7km west of Arthur River. Each treatment strip is approximately 0.6ha total and runs east-west along a slope. Each of these strips were double spread 20m wide with a half rate to ensure the 10m of crop harvested from the middle of each strip had received an accurate full rate. The 10m strips remaining on either side of each treatment were not harvested and treated as a buffer zone.

Figure 1: Google earth map of trial site and trial design. Google Maps GPS Location: -33.351204, 116.962449.

Results Initial soil testing for site selection, ongoing comparisons, annual yield (using his on-site weigh bridge), and biannual follow-up soil tests for each treatment are John’s chosen methods for assessing the economic and soil health benefits of the practices he is trialling. In 2014, the Optima Hi-Cal yielded 3.2 t/ha, the Lancelin Limesand yielded 3.7 t/ha, the Newdegate Dolomite yielded 3.9 t/ha and the AMF Crop Plus yielded 5 t/ha.

The fertiliser treatment (AMF Crop Plus) produced a substantial increase in yield compared to other treatments in 2014, having provided an additional 22.5 kg N; 20 kg P; 11.25 kg K and 25 kg S to the treatment plot while also receiving the standard fertiliser regime applied to the entire site. An increase in yield in the first season following treatment application is therefore not surprising and it is important to note that the aim of this treatment is to assess if a one-off application at a high rate can reduce the effects of aluminium toxicity and produce a sustained improvement in yield without the need to apply lime to raise pH.

36

Economic Analysis Table 1: Economic analysis ($/ha) on 2014 yield.

Treatment Yield (t/ha) Gross Return ($/ha) Variable Costs ($/ha) Gross Margin ($/ha)

Optima Hi-Cal 3.2 $960.00 $274.85 $634.16 Lancelin Limesand 3.7 $1,110.00 $250.35 $809.64 Newdegate Dolomite 3.9 $1,170.00 $263.30 $856.17 AMF Crop Plus 5.0 $1,500.00 $426.00 $1,016.96 Control* 3.5 $1,050.00 $206.50 $795.24

*Control plot received no lime treatment or incorporation with offset discs in 2014. Cost of Mitika oats based on 2014 price average $300/tonne. N.B. Data calculated using the Simple Gross Margin Calculator supplied by the Soil Quality website. Estimated base rates for inputs excluding treatment costs and freight were used in the calculation. This analysis is a guide only which demonstrates the initial cost differences for implementing each treatment.

Benefits

The trial may indicate a treatment that effectively minimises the current costs associated with alleviating aluminium toxicity on soils with low pH at Red Hills.

Risks

Unfavourable seasonal conditions during 2015 have impacted on the validity of yield data in relation to the treatment effects at this early stage.

Summary John believes that conclusions must not be drawn too early from the results collected in the initial years of a trial and that it is the long-term effects of these treatments which most importantly need to be assessed. It can take some time for lime and dolomite to fully react with the acidic soil although incorporation with offset discs will help speed up the reaction. The 2015 season was very difficult with only 203mm of rainfall compared to the 457mm average for Red Hills. This resulted in reduced crop yields across the board for John this year, with the average yield on some paddocks in 2015 being less than one-third of that yielded during the 2014 season. The effects of these unfavourable seasonal conditions compromised the validity of taking yield data at the site, therefore John harvested the whole site and yielded a paddock average of 1.2 t/ha for the 2015 season. Prior to seeding in 2016, John will take his first set of post-treatment soil tests to determine if there are any early differences in soil pH and aluminium levels compared to the site selection samples. John believes that correlations between soil test results and yield assessments may begin to emerge at the three year mark and anticipates that the 2016 harvest will yield some interesting results. “I’m not there yet, it’s still early days” is John’s response when asked to summarise any of the main findings he has from the practice changes currently being trialed at Red Hills. However, he believes that regardless of the end results produced by this trial, the example it is setting that industry-endorsed practices for ameliorating soil constraints must first be adapted to local requirement through on-farm trials in order to be profitable long-term, providing the greatest benefit to other farmers. John’s take home messages “Get your own weigh bridge and do your own trials. They are a cheap investment and will allow you to efficiently and accurately determine if there are yield benefits to the practices you choose to trial.” Acknowledgements Case Study funded by GRDC project LIE00008, “Working together to deliver multiple benefit messages to growers through a whole systems approach to soil management.”

37

Thanks to John and Martina Pascoe for sharing their time and experience. Paper reviewed by: Stephen Davies, DAFWA References Gazey, C., and Davies, S. (2009). Soil Acidity A Guide for WA Farmers and Consultants. Bull 4784, Department of Agriculture and Food, West Australia.

38

Figure 1: An aerial image of the trial showing the strips of tillage across the paddock.

Fast Facts

The results from this trial assisted Scott’s decision to buy a mouldboard plough to fit the need for lime incorporation and weed seed burial. Farm Details

FARM NAME Prowaka Spring

FARMER Scott Bowman

LOCATION Carnamah

AVERAGE RAINFALL 330mm

SOIL TYPES % Yellow deep sand/Sandy earths

Aim To determine the most suitable lime rate and method of lime incorporation to counter subsurface soil acidity. Farmer’s perception of subsurface acidity and root constraints Scott was made aware of the issues of subsurface pH after discussions with his agronomist and follow up soil testing in 2010. A large area of Prowaka Spring is productive yellow sand, in a medium rainfall zone, that has only received 1.5 t/ha lime since 2006 making it a suspect for subsurface pH issues. The baseline testing of the paddock used for the demonstration confirmed these soil pH suspicions. Further to this Scott had seen a yield response to deep ripping within the paddock indicating that there are subsoil compaction issues that need addressing. Farmer’s prediction of return from lime incorporation Seeing the results from the demonstration Scott believes amelioration of subsurface pH will improve productivity over the majority of Prowaka Spring. To this end he invested in a mouldboard plough, at the beginning of 2015, to incorporate lime into the profile, as well as lessen the impact of soil compaction and bury weed seeds. Background A lime incorporation trial was carried out by Scott Bowman in the Three Springs/Carnamah region of Western Australia. The soil is undulating sand plain consisting of yellow deep sand and sandy earths, which are a prominent soil type in the district. The acidic subsoils were evident in this trial paddock with soil samples at a depth of 10-20cm having a soil pH (CaCl2) range of 3.96-4.75. The paddock was first sown by Scott in 2006 when the property was purchased earlier that year. It is yellow deep sand, with a couple of loamy red ‘dykes’ that run through the centre of the paddock. As a productive paddock it has had two lupin crops and five wheat crops since 2006 and stubbles are grazed throughout the summer. Between 2006 and 2010 it received only 1.5 t/ha of lime on account of the tight finances caused by the poor 2006 and 2007 seasons.

Table 1: Pre-trial testing of the soil identified below target pH on the surface and between 10cm and 30cm.

Depth (cm) 0-10 10-20 20-30 30-40 40-50 50-60 pH (CaCl2) 5.28 4.28 4.75 5.26 5.42 5.54

Mouldboard; killing two birds with one pass Chad Reynolds & Wayne Parker, DAFWA Geraldton

39

Adoption Process This trial was critical for building understanding and assisting adoption of lime incorporation practices. Four different lime rates were initially spread across the trial area (0, 2, 4 and 6 t/ha). Lime incorporation was carried out using four different machine treatments (Table 2). Table 2: Details of tillage implements and a summary of their efficacy when assessed for lime incorporation. Efficacy Summary (adapted from Davies, S. 2014).

Incorporation implement (approx. cost range $/ha)

Overview of tillage by implement

Typical working depth (cm)

Depth of lime incorporation

achieved (cm)

Lateral spread of lime and incorporation efficacy

Rotary spader ($120-150/ha)

Rotating spades bury some topsoil while

lifting up some subsoil. About two-thirds of the topsoil

is buried below 10cm. Soil tends to

take on marbled appearance.

28-35 28-35

Very effective at mixing limed topsoil into the subsoil. Does lift some acidic subsoil to the surface so additional lime may be required in subsequent years. As spades

are offset, overlapping lime is incorporated through the entire profile to

the working depth, although pockets of acidic subsoil may remain.

Mouldboard plough ($100-150/ha)

Curved mouldboard shares lift, roll and

invert the soil aided by skimmers that

scalp the topsoil into the base of the furrow. Square

ploughs achieve a similar result.

28-35 28-35

Inversion buries limed topsoil in a layer and can bring a thick layer of acidic

subsoil to the surface that needs treating with more surface-applied lime.

Continuous ameliorated pathways are not always present if inversion has been

effective.

TopDown plough (>$100/ha)

A combination of leading offset discs then curved ripping tines, levelling discs

and packers.

20-35 20-25

Offset mixes well through to their working depth. Curved ripping tines then open a slot allowing surface soil to fall in to 20-25cm. This incorporation is a broad

‘V’ shape beginning at the width of the tine at the surface and finishing to a point

at 20-25cm. The curved tines also lift acidic subsurface soils to the surface in

seams. Not as effective in gravelly soils or soils with hard pans or layers that are

difficult to penetrate.

Offsets ($40/ha)

Standard offset (two-way) discs that

cultivate the topsoil. 10-15 10-15

Very little limed topsoil is incorporated into the subsoil layers due to inadequate working depth. Mixing will still improve

the reaction of the lime in the topsoil that may then allow for faster lime movement

into the subsoil.

40

Trial Layout Given the large size of the trial it was important to have control strips positioned throughout to enable the comparison of the incorporation treatments with nil lime incorporation. Table 3: Trial layout with four rates of lime application and five methods of incorporation.

Lime Rate (t/ha)

Incorporation Method

2 4 0 6

Topdown

Nil

Offsets

Mouldboard

Nil

Spading

Topdown

Nil

Offsets

Mouldboard

Nil

Topdown

Spading

Nil

Mouldboard

Offsets

Nil

Spading

Results

Figure 1: The impact of tillage on soil pH (CaCl2) at depth across all lime rates. Influence of lime rate insignificant in year one of the trial, see Table 4, as measured February 2015. Note: Large variability in soils at site.

-30

-25

-20

-15

-10

-5

0

4.0 4.5 5.0 5.5 6.0

Soil depth (cm)

Soil pH (CaCl2)

Nil

Mouldboard

Offset

Spading

TopDown

North

41

Table 4: Soil pH (CaCl2) corresponding to incorporation treatment and level of applied lime.

Incorporation Nil Mouldboard Offset Spading TopDown

Lime Rate (t/ha) 0 2 4 6 0 2 4 6 0 2 4 6 0 2 4 6 0 2 4 6

Topsoil (0-10cm) 5.6 5.9 5.8 6.3 4.5 4.3 4.6 4.4 5.9 6.1 5.8 6.2 5.4 5.6 5.8 6.0 5.5 5.7 6.4 6.4 Midsoil (10-20cm) 4.3 4.6 4.8 4.5 5.3 5.9 5.4 5.3 4.6 4.8 5.0 4.0 5.5 5.9 5.6 5.9 4.5 4.4 4.9 5.4 Subsoil (20-30cm) 4.4 4.6 5.2 4.3 4.6 5.4 5.3 5.7 4.4 4.7 5.4 4.0 4.4 4.8 4.8 4.9 4.1 4.4 4.9 4.8

Note: LSD; Not Significant due to large site variation.

42

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Nil Mouldboard Offset Spading Top Down

Yield (t/ha)

Treatments

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 2 4 6

Yield (t/ha)

Lime rate (t/ha)

Figure 2: Impact of machine incorporation, across all rates, on wheat grain yield in the first year, 2014.

Figure 3: Effect of lime rate, across all incorporation methods, on wheat grain yield in the first year, 2014, yield differences were not statistically significant, with respect to nil, given the large variation within treatments.

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Economic Analysis The cost of lime incorporation treatments varies in regard to the machine used and lime rate, as seen in Table 5. The rotary spader was the highest cost in this trial but it also one of the incorporation treatments that produced the highest wheat yields in the first year. Table 5: Costs and benefits related to lime application and machinery incorporation in the first year, 2014.

Machine incorporation

Lime rate (t/ha)

Yield (t/ha)

Treatment cost ($/ha)

Net Benefit Year 1 ($/ha)

ROI Year 1 ($/ha)

Nil

0 1.06 0 0 0.00

2 1.25 40 17 1.43

4 1.21 80 -35 0.56

6 1.05 120 -123 -0.03

Mouldboard ($125/ha)

0 1.51 125 10 1.08

2 1.65 165 12 1.07

4 1.56 205 -55 0.73

6 1.39 245 -146 0.40

Offset ($40/ha)

0 1.29 40 29 1.73

2 1.42 80 28 1.35

4 1.42 120 -12 0.90

6 1.24 160 -106 0.34

Spading ($135/ha)

0 1.56 135 15 1.11

2 1.69 175 14 1.08

4 1.78 215 1 1.00

6 1.55 255 -108 0.58

TopDown ($125/ha)

0 1.66 125 55 1.44

2 1.55 165 -18 0.89

4 1.52 205 -67 0.67

6 1.59 245 -86 0.65

Notes: Based on harvest 2014 cash price Geraldton Port Zone APW $300/t. Lime, transport and spreading costs were $20/t/ha. LSD 0.33 when comparing means within lime treatments.

Benefits

Soil amelioration has effectively reduced soil acidity problems down the profile to potentially provide long term benefits.

Machine incorporation has produced significantly higher yields within the first year. This is assumed through the increased mineralisation of soil organic nitrogen and removal of some compaction.

The deeper the lime incorporation achieved by the machine, the greater the influence on subsurface acidity.

Upfront soil amelioration costs may be paid off in first year with yield response to cultivation.

Disadvantages

Mouldboard plough brings acidic subsoil to the surface – this would require more lime to be applied post-ploughing to correct the surface pH.

Machine incorporation can cause soil erosion; ensure cultivation is carried out when the soil is wet and the paddock is sown with a cereal cover crop within 24hrs of incorporation.

44

Lime incorporation costs are high, up to $255/ha, in first year for the highest lime rate and most expensive machine cost (spading).

Correct seed placement with heavy implements is difficult after major tillage, which will influence emergence and paddock yield.

Summary The mouldboard plough and rotary spader brought the most benefit to subsurface soil acidity in this trial by incorporating the lime and increasing pH levels in the 10-30cm layer (Figure 1). The mouldboard achieved this benefit to a greater depth but brought acidic subsoil to the surface and so the surface will require another lime application to rectify. Soil inversion with the mouldboard plough has proved very valuable with multiple benefits, for the grower in this trial, to the extent that they are willing to purchase machinery to carry out this task further across the property. Within the first season, wheat yields were increased through machine incorporation using four different implements (Figure 2). This is one of the major benefits that will increase the profit of the system (Table 5). Obviously this first season will also involve initial costs associated with lime and machine usage but other similar trials show that this effectively increases yield profit over a number of years. Future years should result in higher income benefits for these treatments in this paddock. Acknowledgements This project is supported by the Northern Agricultural Catchments Council, through funding from the Australian Government’s National Landcare Programme. Thanks to Scott Bowman for his patience and support in hosting the trial on his property. Thanks to the neighbours and Cunninghams (Three Springs) for lending their machinery used in the trial. Thanks to Precision SoilTech for carrying out soil acidity tests prior to the trial going in.

Paper reviewed by: Stephen Davies, DAFWA References Davies S, (2014), Lime incorporation into acidic sandplain soils in the West Midlands – and beyond! West Midlands Group 2014 Research Annual.

45

Fast Facts

Future lime applications on any of Flannagan’s property will be incorporated.

The type of incorporation is dependent on soil moisture conditions and time of year. Farm Details

FARM NAME Christian Brothers Ag School

FARMERS Mark and John Flannagan

LOCATION Tardun

AVERAGE RAINFALL 300mm

SOIL TYPES Shallow gravel, Yellow sand over gravel, Red loam

Aim To determine suitable lime rates and method of lime incorporation to counter subsurface soil acidity in low rainfall, variable soil type paddocks. Farmer’s perception of subsurface acidity and root constraints Mark sees the impact of subsurface acidity during periods of in-season drought. Acidic or compacted soils do not yield as the roots cannot access the moisture deeper in the profile. Soils with these constraints are relatively easy to distinguish and make up a lot of the soil in and around Tardun and Pindar. The “poverty bush” growing in patches along the fence line and the gravels in the trial paddock indicate that the paddock is probably low in pH. Farmer’s prediction of return from lime incorporation The results of lime incorporation are clear throughout the property. Limed paddocks are greener for longer at the end of the season than those not yet limed. The returns for liming come through improved yields and reduced fertiliser inputs, both of which are very important in the low rainfall northern wheatbelt. However, the lime needs to be incorporated as rainfall is not great enough or often enough, to wet up and activate surface lime. Mark notes that in the last couple of years the poverty bush has not been encroaching into paddocks that have had lime incorporated. Background A lime incorporation trial was carried out by the Flannagan’s in the locality of Tardun in Western Australia. With the intention to determine the fastest way to improve soils in this paddock that vary according to the landscape. The paddock in the trial has soil types typical of the whole property, with good quality red loams, sand and shallow gravels throughout. Soil pH was low, pH (CaCl2) 4, across the majority of the paddock. The shallow gravel and sand over gravel, in the northern and middle areas of the paddock respectively, were extremely acidic pH (CaCl2) 3.5-4.2. The loamy soils, at the southern end of the paddock and the valley floor, were below target pH 5.5 in the surface but continuously improved below 10cm with pH>6.2. Flannagan’s bought the property at the end of 2012 and 2013 was their first season cropping the property. Previously the paddocks had long history of leasees using low cost production systems. There has been negligible lime applied prior to 2013. The paddock was soil tested in 2013 before this lime incorporation trial was carried out. Twenty one soil cores were taken across the paddock

Subsurface pH improvement with lime incorporation in a low rainfall zone Wayne Parker & Chad Reynolds, DAFWA Geraldton

46

showing acidity throughout the profile. Figure 1 shows acidity as related to the soil type and location across the paddock. The southern section of the paddock is a loamy soil and was above target pH (CaCl2) of 4.8 in the subsurface soil.

Adoption Process This trial was critical for building understanding and assisting adoption of lime incorporation practices. Three different lime rates were initially spread across the trial area (0, 2 and 4 t/ha). Lime incorporation was carried out using two different incorporation treatments (Table 2). Trial Layout Given the large size of the trial it was important to have control strips positioned throughout to enable the comparison of the incorporation treatments with nil lime incorporation. Table 1: Trial layout with 3 rates of lime application, 0, 2 and 4 t/ha, and 2 methods of incorporation, Top Down Plough, Small Grizzly offset plough and No incorporation.

Plot 27 Top Down 4 Top Down

Plot 26 Top Down 2 Top Down

Plot 25 Top Down 0 Top Down

Plot 24 No incorporation 4 No incorporation

Plot 23 No incorporation 2 No incorporation

Plot 22 No incorporation 0 No incorporation

Plot 21 Grizzly 4 Grizzly

Plot 20 Grizzly 2 Grizzly

Plot 19 Grizzly 0 Grizzly

Plot 18 Top Down 4 Top Down

Plot 17 Top Down 2 Top Down

Plot 16 Top Down 0 Top Down

Plot 15 No incorporation 4 No incorporation

Plot 14 No incorporation 2 No incorporation

Plot 13 No incorporation 0 No incorporation

Plot 12 Grizzly 4 Grizzly

Plot 11 Grizzly 2 Grizzly

Plot 10 Grizzly 0 Grizzly

Plot 9 Top Down 4 Top Down

Plot 8 Top Down 2 Top Down

Plot7 Top Down 0 Top Down

Plot 6 Grizzly 4 Grizzly

Plot 5 Grizzly 2 Grizzly

Plot 4 Grizzly 0 Grizzly

Plot 3 No incorporation 4 No incorporation

Plot 2 No incorporation 2 No incorporation

Plot 1 No incorporation 0 No incorporation

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Table 2: Details of tillage implements and a summary of their efficacy when assessed for lime incorporation. Efficacy summary (adapted from Davies, S. 2014).

Incorporation implement (approx. cost range $/ha)

Overview of tillage by implement

Typical working depth (cm)

Depth of lime incorporation

achieved (cm)

Lateral spread of lime and incorporation efficacy

Offsets ($40/ha)

Standard offset (two-way) discs that cultivate the topsoil.

10-15 10-15 Very little limed topsoil is incorporated into the subsoil layers due to inadequate working depth. Mixing will still improve

the reaction of the lime in the topsoil that may then allow for faster lime movement

into the subsoil.

TopDown plough (>$100/ha)

A combination of leading offset discs then curved ripping tines, levelling discs

and packers.

20-35 20-25

Offset discs mixes well through to their working depth. Curved ripping tines then open a slot allowing surface soil to fall in to 20-25cm. This incorporation is a broad

‘V’ shape beginning at the width of the tine at the surface and finishing to a point

at 20-25cm. The curved tines also lift acidic subsurface soils to the surface in

seams. Not as effective in gravelly soils or soils with hard pans or layers that are

difficult to penetrate.

Results

Figure 1: The soil pH of paddock before the lime incorporation was carried out in 2013, showing the paddock average as well as specific soil types within the paddock.

-40

-35

-30

-25

-20

-15

-10

-5

0

3 3.5 4 4.5 5 5.5 6 6.5 7

Soil Depth (cm)

Soil pH (CaCl2)

All samples

North

Mid

South

48

Figure 2: An indication of the pH v pH across the paddock from North to South. These measurements were taken in April 2015 and include all different lime rates and incorporation methods.

Figure 3: Soil pH after tillage and 0 t/ha lime. Measurements were taken in April 2015 two seasons after lime application.

-35

-30

-25

-20

-15

-10

-5

0

3.8 4.3 4.8 5.3 5.8

Soil Depth (cm)

Soil pH (CaCl2)

North

Mid

South

-40

-35

-30

-25

-20

-15

-10

-5

0

4 4.5 5 5.5 6

Soil Depth

(cm)

Soil pH (CaCl2)

Nil

Grizzly

TopDown

49

Figure 4: Soil pH after tillage and 2 t/ha lime. Measurements were taken in April 2015 two seasons after lime application.

Figure 5: Soil pH after tillage and 4 t/ha lime. Measurements were taken in April 2015 two seasons after lime application.

-40

-35

-30

-25

-20

-15

-10

-5

0

4 4.5 5 5.5 6

Soil Depth

(cm)

Soil pH (CaCl2)

Nil

Grizzly

TopDown

-40

-35

-30

-25

-20

-15

-10

-5

0

4 4.5 5 5.5 6

Soil Depth (cm)

Soil pH (CaCl2)

Nil

Grizzly

TopDown

50

Table 3: Wheat yield at Tardun across all treatments in 2014, as taken from harvest yield monitor.

Incorporation Lime Rate

(t/ha)

Min Yield (t/ha)

Max Yield (t/ha)

Mean Yield (t/ha)

Standard Deviation

(±t/ha)

CV (%)

Nil 0 0.43 2.79 1.53 0.38 25 2 0.53 2.65 1.62 0.38 24 4 0.54 2.74 1.63 0.38 23 Grizzly 0 0.39 2.46 1.49 0.34 23 2 0.70 2.65 1.62 0.38 24 4 0.50 2.66 1.62 0.37 23 Top down 0 0.39 2.51 1.47 0.37 25 2 0.56 2.74 1.56 0.39 25 4 0.64 2.67 1.63 0.35 22

Note: Large standard deviation and coefficient of variation.

Economic Analysis The cost of lime incorporation treatments varies in regard to the machine used and lime rate, as seen in Table 4. The more expensive incorporation does not provide a positive return on investment after two years within this rainfall zone.

Table 4: Return on Investment (ROI) from lime application.

Incorporation

Lime Rate

Treatment Cost

Yield (t/ha)

Net Benefit ($/ha) After

ROI ($/ha) After

(t/ha) ($/ha) 2013 2014 2013 2014 2013 2014

0 0 0.43 1.53 0 0 0 0 Nil 2 40 0.45 1.63 -34 -4 -0.86 -0.11

4 80 0.44 1.63 -77 -47 -0.96 -0.59

0 40 0.52 1.49 -14 -26 -0.36 -0.66 Grizzly 2 80 0.54 1.62 -49 -22 -0.61 -0.27 (@ $40/ha) 4 120 0.57 1.62 -80 -53 -0.67 -0.44

0 125 0.44 1.47 -122 -140 -0.98 -1.12 TopDown 2 165 0.48 1.56 -151 -142 -0.91 -0.86 (@ $125/ha) 4 205 0.52 1.63 -179 -149 -0.87 -0.73

APW Gtn ($/t)

285 300 CV (%) >20%

Note: Average plot yield data provided by Craig Topham of Agrarian Management, raw data unavailable for analysis of separate soil zones. Reduced fertiliser input has not been taken into account when calculating return of investment. APW prices based on an average for Geraldton deliveries in each season.

Benefits

Soil amelioration through lime application and incorporation has effectively reduced soil acidity problems down the profile to potentially provide long term benefits.

Machine incorporation has produced slightly higher yields within the first year. This is likely a cultivation effect from increased mineralisation of soil organic nitrogen and removal of some compaction.

The deeper the lime incorporation achieved by the machine, the greater the influence on subsurface acidity.

Lime application has slightly increased yields, particularly in the second year, to begin paying expenses of this soil treatment.

Disadvantages

Machine incorporation can leave the soil bare increasing the risk of soil erosion. To reduce the risk, ensure cultivation is carried out when the soil is wet to depth and the paddock is sown to a cereal cover crop within 24 hours of incorporation.

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Cost of incorporation escalates with increasing depth resulting in a slower return on the investment.

The low rainfall zone provides greater risk for return on investment in incorporation in the short term.

Time must be spent ensuring correct seeding set up as there is increased risk of poor emergence and establishment through sowing too deep.

Incorporation without lime does not improve soil pH (Figure 3).

Summary The response of yield and return on investment will be specific to soil type and rainfall. The lower the rainfall the longer the return on the investment will take. Incorporation does speed up the return by putting lime into the acidic subsoil. While yield responses were seen in the paddock these did not translate to positive returns in the first two seasons. In this trial reduced fertiliser input has not been taken into account when calculating return of investment. As soils become less acidic the availability of nutrients, P, K and N, in particular, increases. As a result growers are able to reduce the fertiliser input, and therefore cost, to reach yield potential. Incorporation does speed up the pH improvement of the subsurface soil as seen in Figures 3, 4 and 5. At this site, with a drier environment, there appears to be no distinct yield advantage of the TopDown plough when compared to the Grizzly. The TopDown was most effective at incorporating lime to depth.

The positive impact of liming and incorporation has been visible throughout the seasons of 2014 and 2015. Areas without lime become apparent during periods of stress in the season; this is replicated in harvest yields. Yield differences in 2015 were observed when looking at the yield map produced by the harvester. Harvest data for 2015 uncollated at the time of print.

Mark commented that 2015 was an exceptional season for the Pindar and Tardun regions. Previously acidic and poor performing gravel soils that had lime incorporated, were yielding in excess of 2 t/ha, while non-limed gravels less than 1 t/ha. Acknowledgements Thanks to Mark and John Flannagan for their patience and support in hosting and harvesting the trial on their property. Thanks to Precision SoilTech for carrying out soil acidity tests prior to the trial commencing. This project is supported by the Northern Agricultural Catchments Council, through funding from the Australian Government’s National Landcare Programme. Paper reviewed by: Stephen Davies, DAFWA