• Minimal levels of fungus affected the crop.
• There was no difference in yield response between the two fungicide regimes implemented.
• In the dryer than average season the use of fungicide was not economical.

• The combined Simazine and Isoxaflutole (Treatment 1) resulted in the lowest early weed counts, with
less than 30 w eeds per m 2 at four weeks post emergence.
• Simazine and Isoxaflutole (Treatment 1) had a profound impact on inhibiting Medic growth relative to
other treatment styles.
• Application of Isoxaflutole & Terbuthylazine (Treatment 2) completely mitigated all weed species
except the medic.

• There were no significant differences between herbicide treatments due to the low weed burden.
• Attention to detail and good planning is essential when growing high-value legumes in the region.

• Grain yield was low across all high value legume treatments due to a combination of factors
• Attention to detail and good planning are essential to grow high value legumes in the region

• During the season, plant growth was measured using a Greenseeker to measure Normalised Vegetation Differential Index (NDVI) at early tillering (growth stage GS14), end of tillering (GS30), and at the end of stem elongation (GS40).
• This data has not been presented in this report.

• Significant weed burdens can impact yield of legume crops considerably if not controlled well with rotation or pre and post emergent herbicide options.
• Without control of weeds, soil borne diseases can be carried from legume phase into the cereal phase. 

• Preparation of paddocks is key to the success of legume crops such as chickpeas and field peas. Control of weeds prior to sowing is crucial and, rolling to level the seed bed post seeding improves the ability to harvest such crop types.
• Field peas and chickpeas are more susceptible to frost damage compared to canola or lupins.
• Canola remains a highly profitable non-cereal crop in Kalannie in 2018.
   

• Adequate pre and post emergent weed control is critical for maintaining yield potential and quality of grain legume crops.
• Canola remains the most profitable non-cereal crop type demonstrated at this site in 2018.
• Where vetch grain is not harvested and sold as feed, consideration of this legume crop type for its grazing value may be advantageous for a mixed farming system.
   

• Adequate control of weeds and sufficient plant densities resulted in a clean, competitive crop at the Carnamah site. Canola remains a high earning crop that commonly forms part of a crop rotation in many farming enterprises. Robust agronomy packages and prices of the legume types demonstrated by this project, means crops such as field peas and lentils have potential suitability in the Carnamah region.
• The need to harvest chickpeas early to match the logistics of harvest of the trial compromised the results for the chickpea treatments. Use of established management practices for the harvesting of chickpeas is required to reduce the incidence of yield loss at harvest time.
• The ranking of each species on profitability should be viewed in light of the highly variable price of pulses from year to year.
   

• A high application of potassium (K), 25 kg/ha and standard nitrogen (N) rates, 70 kg/ha improved wheat yield and grain quality up to 0.47 t/ha on mould boarded deep sand.
• In the presence of adequate potassium (> 40-50 mg/kg), in favourable seasons, wheat can respond to the application of N) fertiliser, resulting in high yield and protein. Where K is limited, returns from N are likely to be poor.
• The results indicate that a higher rate of K than banding 11 kg/ha K can lead to a significant increase in yield and profitability.
   

• Cultivation will often see improved yields in the first two seasons, particularly on lighter soils.
• The 2018 season saw 409 mm of growing season rainfall (GSR) resulting in a significant response to nitrogen (N) and a response to a residual high potassium (K) applied in 2017.
• In soils deficient in K (below 40-50mg/kg) at 0-10 cm, application of higher rates of top dressed K to take advantage of the residual benefits across seasons could be considered.
   

• The treatment plots with low or no potassium were observed to have less vigour (visual assessment) and plant density from emergence.
• High potassium treatments had lower screenings and higher yields independent of the rate of nitrogen applied.

 

• This site was unresponsive to nutrient treatments in 2017
• Treatments were adjusted to reflect grower standard practice due to drier than normal conditions at the beginning of winter.

 

• Wheat yields were low, around 1 t/ha, as a result of low growing season rainfall in 2017.
• Treatments were adjusted to reflect standard grower practice due to drier than normal conditions at the beginning of winter.
• This site was unresponsive to nutrition treatments in 2017.

 

• Cost of treatments repaid in the first year.
• Grizzly/Control returned the best net margin in the first year.

RESEARCH QUESTION

Can incorporation of lime economically remediate a subsoil acidity constraint on gravel soils?

RESEARCH OBJECTIVES

• To evaluate four rates of lime
• To compare three methods of incorporating lime
• To investigate an optimal combination of application rate and method of incorporation for ameliorating soil acidity

 

BACKGROUND SUMMARY

Forest gravel soils are common in the medium to high rainfall zone of Southern Western Australia and are estimated to account for about 2.4 million hectares of the state's farming area.  Non-wetting and soil acidity issues are known to constrain the productivity of these soil types, which are common throughout the Southern DIRT region. Considering this, limited local research has been conducted in regards to the effects of incorporating lime as a method to alleviate these soil constraints more effectively and economically than the traditional method of top-dressing.

The trial was collaboratively designed by Southern DIRT R&D committee members and staff, Wes Lefroy of Precision SoilTech, and the landholders, Roger and Simon House.  The focus of the treatments was to;

a)  Utilise the most economic source of lime for the landowners,

b)  apply the lime at a range of rates representative of both local practice and industry endorsed practice, and

c)  incorporate the lime with equipment which are known to improve the movement of lime through the soil profile compared to top-dressing; while having minimal complicating factors (i.e. poor seed placement) which are commonly associated with other forms of deep tillage.

The trial is located 12 km north of Kojonup and was chosen for its combination of targeted soil type (forest gravel) and pH range (4.5 – 4.8 CaCl2) up to a depth of 60cm.

 

 

The methods for incorporating lime in the trial are offset discs and one way plough, with knife-points at seeding included as a control.  Both offset discs and one way ploughs are generally used for the shallow incorporation of lime, and in this trial the depth achieved was approximately 10cm for the offset discs and 12cm for the one way plough. Research has shown that these incorporation methods can be more effective than the standard practice of top-dressing lime at increasing soil pH at depth by mixing lime into the soil profile when adequate rates are applied. While the lime is mixed well to the working depth of the implements, neither of these methods have the capacity to incorporate lime to depths beyond 20 cm.

Both offset discs and one way ploughs are considered by local growers as more cost-effective options for incorporating lime when compared to other methods (i.e. rotary spading). Annual plot soil testing and harvest yield will be the primary indicators used to assess how quickly and effectively the various treatments are able to raise pH at depth and increase production on forest gravel soils constrained by subsoil acidity.

• Surface applied lime can take many years to ameliorate subsoil acidity.
• Ongoing acidification has resulted in lower subsoil pH’s and the depth of the acidic layer is increasing.
• This has generated renewed interest in one-off lime incorporation using strategic tillage to reduce the time required to ameliorate the subsoil acidity and to get a more rapid return on investment from applying lime.
• Effective amelioration of subsoil acidity requires the creation of continuous pathways of pH corrected soil from the soil surface through the acidic subsoil layer.

• Latest released variety ATR Snapper recorded the greatest yield and had the highest oil content at 0.95 t/ha and 45% oil content.
• Tanami (released 2006) recorded the lowest yield and also the lowest oil content, averaging 0.57 t/ha and 41.5% oil.
• Older varieties Tanami and Cobbler yielded significantly less than Snapper, demonstrating how newer varieties with similar agronomic attributes can be more profitable.

• Higher rainfall in 2015 allowed the crop to capitalise on extra nutrient availability with the top three treatments (canola, wheat and field pea) under a high input rotation.
• Low input on continuous wheat rotation is returning the highest gross margin in this scenario.

• As in 2014, there was a significant difference in yield, in response to the cultivation treatments but not between the lime treatments.
• Screenings in 2015 were much higher in the mouldboard and spaded plots than any other treatments. The percentage of screenings in these treatments increased with the increasing rate of lime.

• There was no significant pH changes within the first year of the demonstration however there was a trend for an increase in subsoil pH of 0.2-0.3 pH units following deep banding of lime.
• Predicted some of the lime deep banded in 2001 would remain undissolved and further pH increases should take place subsequently.
• Despite not significantly changing soil pH, there were first year yield responses in wheat following ripping, and the injection of lime.
• From a perspective to have lime react, it would seem imperative to have a deep tillage operation every few years.  Once a certain portion of lime has reacted, the residual lime then sits in a highly alkaline (caused by the dissolution of some of the lime applied) zone, within a highly acidic soil.  The chance of the excess lime present deep in the soil profile coming into contact with acid soil, to subsequently react and change more of the overall soil pH appears to be reliant upon some degree of mechanical intervention.

• A unique trial design (double up of each plot) was designed to allow destructive biomass sampling, and grain yield measurement
• This trial site was primarily used in a ‘screening function’- to evaluate any negative impact of lime of a variety of different legumes which was considered to be happening during the mid 1990’s. The key concern was to investigate if manganese deficiency was induced by liming
• The trial was sown to lupins in 1994, wheat in 1995.  Data not available
• Yield responses (negative) were apparently not noted in the early years following establishment of the trial.  Positive yield response did occur, several years post trial establishment
• The double up design allowed comparison of lime sources on many different species.  For example, in 1996, narrow leaf and yellow lupins were compared.  No data available
• In 1997 the trial was sown to wheat, no yield responses reported
• In 1998, the trial was sown to a diverse mix of new pasture legumes that were at various stages of evaluation prior to commercial release.  Some of the material screened, that subsequently was commercialised included Cadiz French serradella, Santorini and Charano yellow serradella, Casbah Biserrula, Prima gland clover and finally Bartolo bladder clover.  The primary focus of this work was to assess any negative impacts of lime on legumes.  No negative impacts reported.
• The inclusion of this trial into this sampling regime, was primarily because of the known (high rates) of lime subsequently applied by the cooperating farmer, and the focus to see if these high rates had changed soil pH deeper in the profile, which did not occur initially.

• There was rapid change in soil pH at this site in the first few years following the establishment of this trial.

• Despite the initial changes in soil pH, there were no positive grain yield responses between 1996-1999.

• In the 2000 wheat crop, there was a negative response to 2t/ha in 2000. 

• There has been a dramatic decline in soil pH across all treatments since 2000, despite a total of 4t/ha of lime being applied across the site (two applications of 2t/ha in circa 2009 and 2013.

• The source of the subsequent applications of lime applied by the farmer is unknown

• During the first few years of this trial being monitored, there were significant changes in soil pH due to the application of lime, and these changes resulted in significant grain response

• The ‘top up’ application (1.5t/ha, across all initial lime rates of 0, 1 and 2t/ha)) of lime applied in 2006 (10 years post trial establishment) has had dramatic impact on current soil pH.  Unfortunately, grain yields have not been monitored post the top up lime application.

• The 2016 pH measurements provide clear evidence inadequate lime has been applied to counter inherent and ongoing soil acidification. From a starting surface pH of 4.8 over a subsurface of 4.6 (in 1996), the highest rate of lime applied has been 2t (1996) and a further 1.5t (2006) is simply insufficient to lift soil pH above the DAFWA stated targets (5.5 over 4.8).

• Despite soil pH being under target, this trial provides a clear demonstration of the best soil pH profile being associated with the highest rate of lime application.  Collecting grain yields would be valuable

•    During the early years following trial establishment, there was no grain yield response measured
•    In 2004/2005, some 8 years post initial lime treatment, strong visual responses to lime became apparent
•    The ‘top up’ application (1.5t/ha, across all initial lime rates of 0, 1 and 2t/ha)) of lime applied in 2005 (9 years post trial establishment) has had dramatic impact on current soil pH, and the soil pH profiles now reflect lime applied
•    Only the highest rate of lime treatment (initial 2t/ha) followed by the 1.5t/ha in 2005 have a soil pH profile above the DAFWA recommendations (5.5 in the surface, over 4.8 at depth)
 

• Yield loss to crown rot varied significantly among wheat and barley varieties ranging from 0.4 to 1.1 t/ha for wheat and 0.5 to 1.8 t/ha for barley.
• An understanding of the crown rot disease history of a paddock and choosing varieties with appropriate disease resistance ranking can improve crop yield substantially.

 

The Carlshausen’s had previously grown Calingiri noodle wheat but abandoned the variety in 2015 due to bad lodging in the 2014 season and consistent 0.1 t/ha lower yields than Mace. In 2015 they wanted to see if the new noodle variety Zen was able to match Mace (the only wheat currently grown on their property) in terms of yield and quality. Mace is a short to mid maturity Australian hard wheat with Wyalkatchem major parent and Stylet minor parent. Zen is a mid to long maturity Australian noodle wheat bred from Calingiri and Wyalkatchem.

Mace and Zen were compared in two locations of the same paddock. The soil type was similar at the two locations, but varied in their elevation.

This demonstration was conducted using farmer equipment. Farm scale demonstrations are a valuable way to explore new varieties, products, or practices, complimenting results which are produced through more scientifically rigorous, small plot trials. Please refer to NVT for a replicated view of the varieties in your area.

• Barley yields averaged 1.78 t/ha compared to 1.64 t/ha for wheat.
• The barley and wheat varieties differed in their response to added nitrogen (N). Cobra, Mace and Wyalkatchem yields increased at 40 kg/ha of N as did yields of Compass, La Trobe and IGB1337. The other varieties were not responsive to added N.
• Barley had a higher tillering capacity than wheat.
• Grain quality and price will influence the profitability of added N. The current high prices for barley grain make it a profitable option. However, barley is less tolerant to acid soils and so site selection is important, as is a good understanding of grain quality and end price.

• Crop germination was poor on the mouldboard plots and compaction is still a big issue on these plots.
• Bentonite clay has shown no effect on organic carbon %.

 

• Tedera geminated well on gutless sand in Watheroo
• It is expected that the first tedera cultivars will be released to a commercial partner in 2015.
• Tedera can persist with an average rainfall of 150mm and up to 5 months in drought.

 

• In a low yielding season canola yield reached a plateau at between 20 and 40 plants/m².
• Hybrid canola reached a plateau at lower density than open-pollinated canola.
• Canola yield held up at high density well, even though plants became severely stressed in early winter and early spring.
• Hybrid canola had a significant yield advantage over open-pollinated (OP) canola in a below average season.

• In a low yielding season canola yield reached a plateau at between 20 and 40 plants/m².
• Hybrid canola reached the plateau at lower density than open-pollinated canola.
• Optimum density ranged from 10 plants/m² for hybrid canola to over 65 plants/m² for open-pollinated (OP) Triazine tolerant (TT) canola.
• Hybrid canola had a significant yield advantage over open-pollinated canola in a below average season.

This demonstration was conducted using farmer equipment. Farm scale demonstrations are a valuable way to explore new varieties, products or practices, complimenting results which are produced through more scientifically rigorous, small plot trials.

• A two spray or double knock strategy (including cultivation or another non-herbicide treatment) is often required for complete control in fencelines with the first application early in the season followed by another one later in the season (after the seeding and post-harvest operations are over).
• Tank mixes of residual herbicides plus a knockdown give the best control for the first application.
• A single application of a mixture of Uragan® (bromacil) and paraquat early in the season gives excellent weed control on fencelines.
• The addition of Alliance® (mixture of amitrole and paraquat) as the knockdown gives good broadleaf control.
• Glyphosate can still be used but intensive monitoring and complete seed set control is required to prevent resistance from developing.

 

• Deep ripping dry sand was more effective with two passes (or shallow leading tines); less cloddy.
• Yield benefits of 410 kg/ha (18%) from deep ripping were mainly due to better head fill. Better head fill was probably due to better cooling of the crop in hot weather due to better supply of moisture.
• Extra moisture seemed to be from rain which infiltrated deeper in the ripped soil to avoid more evaporative loss than the unripped soil.
• A controlled traffic system will better protect the investment in deep ripping and extend the benefits. Deep ripping costs will also be reduced when the permanent tramlines are left unripped; seeding can also be easier with better flotation on permanent tramlines.

 

• Crop production is often a source of greenhouse gas (GHG) emissions including nitrous oxide (N2O).
• Increasing organic carbon (C) in the surface soil increased N2O emissions from a cropped soil in the Western Australian grainbelt, however, losses were low by international standards.
• Greatest N2O emissions occurred in response to summer-autumn rainfall events.

 

• Sowing wheat 75mm deep compared to 40mm deep reduced crop establishment by up to 62% and wheat yield by up to 24%.
• Within the same variety small seed was much more sensitive to deep sowing than large seed.
• Corack and Mace were the least sensitive varieties to deep sowing in terms of yield.
• Growers should endeavour to use seed larger than 35 g/thousand seeds, especially if sowing into stressful conditions.

• Reduced yield experienced on cultivation treatment with the drying out effect at seeding.
• More root biomass in the early part of the season with cultivation.
• With no sub soil moisture cultivation did not have the desired effects on yield.

 

• Spading has buried the non-wetting layer of soil in this paddock, resulting in an increase in crop yield in two of the past three years.
• Using a spader to mix lime and dolomite into the subsoil has improved soil pH soil and increased yield.

NVT is a national program of comparative crop variety testing with standardised trial management, data generation, collection and dissemination. The program is supported by the Australian Government and growers through the Grains Research Development Corporation and is managed by the Australian Crop Accreditation System Limited.

• Application of knockdown and in-crop herbicides from diverse modes of action at early and late stages provided excellent radish control (97 to 100%).
• A higher gross margin came from the 60 kg/ha seed rate than the 120 kg/ha in 2014 season mainly due to greater grain yield and lower seed costs at 60 kg/ha.
• Increasing pressure on knockdown, in-crop herbicides from diverse modes of action, and seed rate reduced gross margin but provided superior radish control.
• Wild radish has developed resistance to most of the available selective and non-selective herbicides including glyphosate in Western Australia. It is important that an integrated weed management (IWM) approach including as many weed control options as possible should be adopted by growers to manage wild radish.

 

• Organic matter treatments showed greater early vigour, but this was not reflected in yield due to the dry season.

 

NVT is a national program of comparative crop variety testing with standardised trial management, data generation, collection and dissemination. The program is supported by the Australian Government and growers through the Grains Research Development Corporation and is managed by the Australian Crop Accreditation System Limited.

• In furrow remediation could be useful in managing acidity generated by fertiliser placement.
• CalSap® is a liquid product which can be used to manage acidity generated by fertiliser in the furrow.

 

• Cereal rye has done an excellent job of providing ground cover on poor windblown sand.
• Approximately 4 t/ha of biomass was produced by the cereal rye.
• Using a mouldboard plough to incorporate cereal rye has increased soil organic carbon in the subsoil but decreased topsoil levels.

This is the 3rd wheat crop where there has been no benefit in yield or quality due to mouldboard ploughing.

 

• There was no response to topdressed muriate of potash but a 0.3 t/ha response to K banded in K-Till Extra.
• Nitrogen (N) use efficiency was maximised with K-Till Extra.
• Potassium (K) was a more limiting nutrient than N.
• Dry conditions frequently experienced in the Wheatbelt limit the effectiveness of topdressed K.

Low input of continuous wheat is returning the highest gross margin in this scenario.

• The combination of Triazine Tolerant (TT) and Roundup Ready (RR) herbicide provided superior control of ryegrass and wild radish over individual chemistry treatments.
• Canola is an important rotational winter crop however, with increasing herbicide resistance across multiple chemistries in WA, growers are experiencing increasingly limited options with the current herbicide tolerance technologies available.
• Hyola RT® Technology allows the combination of strong knockdown and residual broad-spectrum herbicides from different herbicide groups and modes of action, targeting a wide range of weed species.
•  Hyola RT® will provide an important role in addressing the increasing Clethodim resistance problem.
• RT® dual herbicide tolerant Hybrids have now demonstrated their value as a new competitive integrated weed management (IWM) tool, also providing increased convenience and flexibility of in-crop weed control.

• We observed no significant differences in grain yield (GY) between any treatments due to low yield potential and reasonable soil nitrogen (N) levels at seeding.
• Timing of N application had no effect on GY. This is consistent with last years’ results at Wubin.
• Canola oil percentage decreased as N rate increased. High rates of N reduced oil significantly, consistent with last year at Wubin.
• The higher the rate of N the more rapidly oil percentage reduced, consistent with last year at Wubin.
• Gross margins (GM) decreased as N rates increased; all GM figures are negative due to poor GY, however, Sturt performed better than Pioneer 43Y23RR due to the higher seed costs associated with Roundup Ready (RR) seed.

• There were significant differences in grain yield (GY) between treatments (N kg/ha and timing), however, GY was particularly low in all treatments. 
• Total nitrogen (N) increased GY significantly up to 30kg N/ha.
• Canola oil percentage decreased as N rate increased. High rates of N reduced oil significantly.
• Applying N late (12 weeks after sowing (WAS) reduced canola oil percentage, however, not significantly.
• Gross margins decreased as N rates increased, but all gross margins (GM) were negative due to poor GY. Sturt had better gross margins than Pioneer 43Y23RR due to the higher seed costs associated with RR seed.
• Pioneer 43Y23RR produced higher GY at all rates and timings of applied N other than 10N seeding and 20N 12WAS.

At three field sites in WA, increased wheat yield was achieved at lower nitrogen (N) application rates when N was balanced with appropriate phosphorous (P), potassium (K) and sulphur (S) applications. Wheat yield was driven by the ratio of N to P and K rather than the absolute concentrations of the nutrients and it is possible to increase profit margins by balancing nutrient inputs.

The level of background nutrients present in the soil at sowing was a key factor in determining the responsiveness of yield to fertiliser applications and how profitable the fertiliser treatments were. Pre-season soil testing to determine the level of residual nutrients will allow growers to balance their nutrient inputs and help to maximise profits.

• The average sowing rate in low rainfall zones is 50 kg/ha.
• Increasing seeding rates is generally not helpful for yield as moisture is limiting in this zone.
• Higher seeding rates can have other benefits such as reducing weed burdens.

• This demonstration was conducted using farmer equipment.
• Farm scale demonstrations are a valuable way to explore new varieties, products and practices, complimenting results which are produced through more scientifically rigorous, small plot trials.

Three years after application of lime, soil pH (CaCl2) increased by 0.68–1.45 units at 0–10 cm depth, 0.20–0.47 units at 10–20 cm and 0.08–0.18 at 20–30 cm depth. • Lime reduced density of ryegrass by 42% and barley grass density by 67%, improved barley crop vigour by up to 13%, and increased barley grain yield by up to 7% in 2013. • Boxer Gold in 2013 season together with Sakura and simazine in previous seasons reduced annual ryegrass density by 96% and barley grass density by 99%, improved barley crop vigour by up to 15%, and increased barley grain yield by up to 16%. • Lime effect on efficacy of herbicides in controlling weeds was not evident.

Three years after application of lime, soil pH increased by about 1 unit at the top soil and 0.08-0.26 units at the sub-soil layers. • The effect of liming improved crop vigour in 2013 by up to 16% and this effect reduced wild radish density by 50%. This reduction was however not significant, most likely due to low radish densities and a high level of variability. • Velocity together with simazine in previous seasons reduced wild radish density by 98% in 2013 season and improved crop vigour by up to 16%. • Lime increased barley grain yield by up to 6% and Velocity by up to 8%. • Lime effect on herbicide efficacy to control radish in barley crop was not evident.