• Yield differences between soil types were less than seen in previous seasons on this paddock, although they did yield in expected order.
• Starting nitrogen levels were quite high (>100kg N/ha) due to previous crop history.
• Overall with the better responses to applied N being achieved on the better soils or where there was plenty of starting soil nitrogen, this experiment has given encouragement to the idea of managing soil types (or management zones) differentially for N.

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.

• 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

• Crop yields declined by an average of 31kg/ha/day when sowing was delayed from 20 May to 2 June.
• There was not any significant interactions between varieties in their response to delayed sowing time from 20 May to 15 June.
• The varieties Bunnu, EGA Bonnie Rock, Espada, Fang, Lincoln and Yandanooka produced screenings greater than 5% when sown in mid June. 

Dry sowing resulted in the poorest weed control at seeding and as a consequence this treatment was the weediest later in the year.

• Spray-seed drift during shielded spraying damaged the lupin plants in this trial.
• Lupins yielded well when sown in rows 50cm apart.

• Site experienced extended dry conditions after seeding due to late follow up rain.
• SACOA will continue local soil surfactant research and evaluations in 2004.

• No significant difference between treatments but interesting trend supporting combined use of protectant fungicides with soil surfactancts, delivered on furrow rather than on fertiliser (this is not a registered pattern of use).
• Warrants further investigation in 2005.

Management practices influence microbial activity by altering carbon availability and conditions reflecting rapid changes in the biological function of the soil, although the reserach is still in the preliminary stages this has been highlighted where increased microbial biomass and nutrient availability was associated with plots receiving high amounts of organic matter.

• Average yield increase of 0.3 t/ha or 12% where chaff was added. (Although in some seasons addition of chaff resulted in no yield benefit or a yield decline.)
• Microbial population has doubled where chaff was added.
• 650 kg/ha more nitrogen where chaff was added.
• Soil now holds 8 t/ha more organic carbon where chaff was added.

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

 

• There has been a drop in surfact pH for all the lime treatments.
• It is anticipated that further works will be carried out at this site.

• 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.

• The application of lime or dolomite increased soil pH significantly and increased exchangeable Ca and Mg, while the application of gypsum increased soil conductivity levels.
• The nodulation of lupins sown on the gypsum plots was impaired probably because of the high salt levels in the soil.
• Following a drier than average season, lupin yields were lowest where gypsum had been applied in the previous year but benefited from the application of lime or dolomite.

Lime or dolomite were both effective tools for increasing pH in this trial.

The use of gypsum in combination with either lime or dolomite gave the highest yields for both wheat and barley.

 

In all three trials there was no statistically significant yield response to additional post-emergent liquid nitrogen. Given the below average rainfall experienced in the district in this season, this result is probably not unexpected. 

For further comments please see the attached trial report.

This trial was an un-replicated farmer demonstration and results should be interpreted with caution. It is suggested to refer to national variety trial data over a number of seasons to get a better picture of variety performance. 

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.

• The yields of Mandalup and Balara were the same, however, Tanjil was a significantly lower yielding variety.
• Mandalup looks to be a good option for this environment with its high yield, metribuzin tolerance and early flowering.
• Mandalup did have a higher percentage of protein that Belara, however this was less than Tanjil.

• Mandalup set pods early compared to other than other varieties tested in this demonstration.
• Mandalup yielded significantly higher varieties. If it wasn't for a late rainfall event we would have expected a large difference in yield between Mandalup and the other varieties tested.

• 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.
   

• 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.
   

• 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.

 

• Sowing the shorter maturing varieties, Emu Rock and Corack in early May was less productive than sowing Cobra, Mace, Magenta and Wyalkatchem.
• In 2013, the varieties sown in late May were higher yielding than varieties sown in early May however, screenings of Magenta and Emu Rock were greater than 5%. This response will vary from season to season so the disadvantages and advantages of early sowing need to be clearly considered.
• Nitrogen application increased wheat yield by 4.8 kg/ha for each kilogram of nitrogen (averaged across variety and sowing time) in 2013. 

Increasing plant density is a tool to improve a crop’s competitiveness against weeds. This strategy did not adversely affect the yield of the varieties at the Liebe Main Trial Site in 2012. 

Nitrogen treatments did not significantly influence crop yield however, did influence grain protein. The soil nitrogen levels and season are likely to have influenced this result. Soil testing and understanding the crops requirements as the season unfolds are useful strategies to manage crop performance economically.

The environment is likely to have had the bigger influence on the performance of the varieties than plant density or nitrogen. Growing season rainfall for 2012 was lower than average and disease patches (likely Rhizoctonia) were evident at the trial. The water use efficiency at the site was 13 kg/mm given growing season rainfall (April to October) was 133mm (plus 34mm in January) and grain yields of 1.98 t/ha across whole trial.

Mace was the highest yielder with the best grain quality and being a hard variety gave the best gross margin. All other varieties didn’t make their base grade of APW2 with the exception of one Magenta treatment. Adding nitrogen had a negative impact on yields and therefore gross margins with the exception of Magenta 25N, which was able to scrape into a higher bin grade. 

• Due to the dry start to the season, germination across the trial paddock was very uneven, which may have influenced the yield results of the trial.
• It is anticipated that further soil sampling and analysis work will be carried out on this trial in 2009 to look at the residual effect of lime on the soil pH and aluminium toxicity.

• Monza efficacy on brome grass has not been reduced by the addition of these herbicides and insecticides at the final assessment.
• Some of the treatments were significantly different at the early timing, but the final assessment showed no significant difference.
• Crop phytotoxicity and crop yield were not measured.

• 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.

•  Yields showed a trend towards higher yields in mouldboard treatments compared to controls however, differences were not statistically significantly.
• Trial will be monitored in 2013 to discover any longer term impacts.

• This trial was an un-replicated farmer demonstration, results should be interpreted with caution.  
• Observations: 13/7/12: Crusting of the surface reduced germination in mouldboard ploughed strips.
• For further comments please see the attached trial report.

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

 

• Good growing conditions produced wheat yields of up to 5.0t/ha and canola yields of up to 2.6t/ha.
• There was no response to P in either crop where N was applied.

Compaction under the centre of cropping traffic wheelmarks, after deep ripping reduces yield; even in dry seasons.

The results confirm some suspicions of some observant farmers that a small amount of compaction, or 'firming' can be beneficial to crop yield.

Although the panic grasses at the Buntine site have shown excellent presistence, despite the extended dry conditions, there remains a question mark over the role of sub-tropical grasses in the north-eastern wheatbelt.

• Following drier than average seasonal rainfally, yields averaged 1.7t/ha at 31kg N/h and about 2.0t/ha with 73kg N/ha.
• There was no clear K response at either N level.
• Earlier plant testing suggested no response to K application was likely.

• The trial responded by 800kg/ha to 30kg N/ha and 1200kg/ha to 60kg N/ha.
• However, there were no significant responses to splitting or delaying the nitrogen applications.

• Technical difficulties limited the value of data collected from this trial.
• There was no yield response to nitrogen rate, source or placement but protein increased with N rate.
• Nitrogen-use efficiency was in general poor across all treatments although banded treatments were slightly better than broadcase applications.

• Urea increased wheat grain yield significantly over the nil when banded at sowing.
• There was no significant difference between urea, UAN or MAXamFLO when applied at the same rate of nitrogen and incorporated by sowing, banded or applied at pre-sow, banded and post.

Crop growth and yield potential were severely limited by one of the driest seasons on record at this site. Hence, the very poor grain yields and no response to nitrogen applications.

• There were no significant differences in yields between all varieties.
• Dry growing season conditions may have restricted growth of yield components resulting in an evening out of yield between varieties.

• 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.

• Drying soil conditions at the time of sowing, caused a poor initial germination of seedlings.
• Grain yield tended to increase as the rate of phosphorus fertiliser applied increased.
• The liquid NP source performed no better or worse than the solid NP source.

• Charano had a significantly higher mean biomass than the other annual species tested.
• There was no significant difference between Cadiz and Serena/Santiago pastures.

The Drummer ryegrass is a valuable source of early feed and can greatly improve stocking rates if managed in a rotational grazing system.

• All plants performed poorly on the shallow gravel with moisture stress becoming evident.
• Weed control was poor with wild radish competing strongly with the perennials for moisture.
• The trial will continue for the next 2 years with more results becoming available during this time, including palability, feed value and persistence.

• Atriplex nummularia (Old man saltbush, 79.2% survival), Atriplex rhagodioides (Silver saltbush, 77.1% survival), and Rhagodia parabolica (Mealy saltbush, 76% survival) are the species with the highest survival rates.
• Weed control was poor with wild radish competing strongly with the perennials for moisture.
• The trial will continue next year with more results becoming available during this time, including palability, feed value and persistence.

• This demonstration suggests that there is a trend towards higher yields as a result of ploughing stubbles.
• The cost of ploughing stubbles is relatively low and it may be an effective way to increase soil organic matter.

Standard farmer practice of 'pasture topping' in the previous year, followed by a knock down around the seasons break, remain the best practice before sowing saltbush or bluebush by seed.

• 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.

• There was no significant yield increase by applying fertiliser at seeding on this particular acidic sand for season 2003.
• Protein increased with fertiliser application.

• Calingiri generallly yielded higher than Arrino, had slightly higher protein and screenings.
• The highest yielding treatment of each variety were the district input treatments.
• The district input treatments of each variety returned the highest gross return per hectare and although Calingiri yielded higher, Arrino provided slighly higher returns, having slightly better grain quality.

District input, high input and active input treatments produced the highest yields in both Arrino and Calingiri.

Crop vigour: the low input treatments showed the least amount of vigour; a direct result of minimal nitrogen and a low seeding rate.

This trial was severely limited by dry conditions, with yields ranging from 0.16 to 0.42t/ha with not significant differences between any variety or management input level.

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

• 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.

Slender iceplant exhibits a germination quality that increases its chance of survival.

Good iceplant control results were achieved with Broadstrike, diflufenican and diuron in various mixtures in these trials.

• Seasonal conditions reduced the potential impacts of the pre-emergent herbicides evaluated in this trial with sowing taking place under dry conditions. The top 5 cm was dry with little follow up moisture although there was enough to get the crop out of the ground. The effects of pre-emergent herbicides are generally more pronounced under very moist conditions particularly under intense heavy rain events at seeding or when the top soil is saturated for an extended period at plant establishment.
• In this trial neither yield or weed density were significantly different between the herbicide treatments.
• Weed plant densities were extremely variable within each treatment so caution should be taken when comparing grass weed efficacy in this trial.

Standard farmer practice of 'pasture topping' in the previous year, followed by a knock down around the seasons break, remain the best practice before sowing saltbush or bluebush by seed.

Standard farmer practice of 'pasture topping' in the previous year, followed by a knock down around the seasons break, remain the best practice before sowing saltbush or bluebush by seed.

• Dry pre-furrowing of sandy loam pasture at Pindar in 2003 resulted in a yield benefit estimated at $26.5/ha.
• Grain quality was not changed by pre-furrowing in this trial.

The higher yielding zone of the paddock did not require more DAPSZC than the lower yielding zones. Such on-farm experiments have a great potential to inform and improve paddock management for increased profits and environmental outcomes by using inputs more wisely.

Although this trial yielded less than half the other NVT trials conducted in AgZone 1 in 2006 there is some consistency with their results and the ranking of these varieties in this trial.

Cassab lentils provided the best yield results; howerver, these results weren't consistent due to herbicide drift.

• Wtih three continuous wheat years, all the varieties were very responsive to 120kg N/ha. 
• Increasing seed density is a good management tool for weeds in wheat. At this site, yields increased with increasing seed density without a reduction in grain quality.

• A field trial was conducted at Pthara in 2009. Twenty-four wheat breeding lines from various Australian breeding companies were selected and sown at three times of sowing in a randomised block design with three replications.
• At this site, most of the AH varieties achieved more than 13% protein at all sowing times times except TOS1.

The Jibberding site showed a positive and linear response to increasing P with no PR-70.