Diuron appears to be safe when applied pre-sowing of lupins at label rates, as there was no difference in yield between the Simazine alone and Diuron alone treatments.

 

• 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.

 

• Grazing once early in the season did not affect grain yield.
• Grain yields were reduced when varieties were grazed late in the season.
• Oats and barley showed better early vigour than the wheat varieties.

• Grazing once early in the season did not affect grain yield.
• Grain yields were reduced when varieties were grazed late in the season.
• Oats and barley showed better early vigour than the wheat varieties.

• The high nitrogen rates caused the plants to burn off in early August.
• Grain fill of earlier season varieties was affected by frost damage.

• There was significant rain in early April.
• It was very wet at the time of seeding.
• Reduced emergency due to soil crusting and seeding depth.
• There was adequte rain overall but dry at emergence.

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.

• There was a significant yield difference due to liming in the Magenta and Roe plots; however, the Buloke plots were not significantly different.
• Soil pH increased from 4.68 to 5.24.
• This iste had a massive radish seed bank after poor control in lupins in 2008.

• 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.

• Stubble height would appear to have a statistically significant effect on early lupin plant height.
• This effect, although trending towards a higher lower pod height on those plants, is not statistically significant in this trial.
• This trial had insufficient measurements taken to determine the mechanism that caused the plants growing in the tall residue to grow taller and have a higher first pod, and whether that led to an increase in yield.

• There was very little activity from the soil active herbicides due to conditions at the site.
• The idea that higher rates of soil active herbicide might be able to be used with the wide row system was not available to be tested due to the overall lack of response to the herbicide treatments.

• 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.

 

• The soil treatments investigated at these sites are considered to be ineffective for broad acre farming.
• Changes to nematode composition and microbial biomass were small and did not result in plant biomass production.
• Inprovements in the effectiveness of the soil treatments may occur when applied as seed dressings.

• Simizine damage early, affected growth.
• Lupin yields averaged 0.77t/ha.
• Protein levels averaged 34.3%.

• Plant densities varied with seed rate, time of planting and variety.
• Quinilock showed the greatest response in protein level to delayed planting time.

• The levels of resistance reported are from targeted problem ryegrass paddocks and are not a true indication of the area's overall resistance status.
• There is a high level of ryegrass resistance to 'fop' chemicals in these tests.

• Bambatsi Panic and Rhodes grass have good drought tolerance but maintaining a high plant density has proved difficult.
• Due to low rainfall seasons, more drought tolerant species are required on the site hence planting the saltbush alleys.
• Salinity varies over the site and therefore so does the ground cover, species composition and FOO.
• Roly-poly control can be achieved by spraying with 2,4-D Ester ad Garlon and rolling.

• Loose smut in barley is internally seed borne so if you are seeing infected heads then it means your grain souce was contaminated. It is the hardest of the smut diseases to control because it is an internally seed borne infection and most current seed treatments are not as effective on internally seed borne diseases.
• EverGol Prime has excellent local systemicity, being able to move across the seed wall and into the seed. It is an excellent option for control of loose smut.
• The applicaiton of Sakura into barley was not successful with the APVMA. Therefore we will not review the results as this component of the trial in regard to the interactions with pre-emergent herbicides.

Removal of subsoil compaction by deep ripping resulted in a 370 kg/ha (45%) yield benefit with spading giving an additional benefit of 12% (100 kg/ha) and mouldboard ploughing 39% (320 kg/ha) compared with the deep ripping treatment. Higher biomass and increased head density in the cultivation treatments are indicative of improved nutrient access and effcient use of available water through the season. Water use efficiency was 4.9 kg/ha/mm of growing season rainfall for the control treatment compared with 7.1 kg/ha/mm for ripped, 7.6 kg/ha/mm for spaded and 8.9 kg/ha/mm for mouldboard ploughing. Recent research is showing that nutrient availability is improved when top soil is buried by spading or mouldboard 
ploughing because nutrients become concentrated in the rootzone and less suscpetible to soil drying from evaporation, which can be the case when majority of the nutrients are on the soil surface, (Davies et al, 2012).

• Spading has mixed the non-wetting layer of soil in this paddock through the soil profile, resulting in an increase in crop yield in two out of past three years.
• Using the spader to mix lime and dolomite into the subsoil has improved the pH of the soil and increased yield. 
• Wind erosion is a big risk with spading and caused a yield decrease in 2010, the year the spading occurred. 
• Spading also reduces compaction at a similar level to deep ripping by physically breaking down any compacted layers in the top 30cm.
• Soil type is a large factor in the success of a spading operation; careful consideration must be given to this prior to commencing any spading program. 

 

• 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.

• Both Aramo and Bounty performed as expected in the field in accordance with the label recommendations.
• Conditions at time of spraying and for the rest of the season were not favourable, however, both products stood up and performed quite well when compared to the unsprayed areas.

• On average the wide row lupins yielded 115kg/ha higher than the narrow lupins.
• Simazine damage was very pronounced in this particular crop. However, damage in the wider rows appeared to be much less than that in the narrow rows.
• The same seeding and fertiliser rates were used for both treatments which made changing the bar over relatively quick.

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.

• Overall yields were low in this trial, mainly due to poor establishment and heavy week burden.
• Kaspa was the lowest yielding variety.
• The insect damage was significantly higher in Kaspa than all other varieties.
• Kaspa was released in Victoria and the late maturity of the variety would most probably cuase reduced yields when sown into drying soils in late June.

• With a dry warm summer few grass weeds were present.
• Wet weeds controlled well with sprays.
• Trial germinated well.

These results show a strong tend towards N applied and what is remaining in the soil after the failed wheat crop.

• Organic amendments improved ‘soil health’ in terms of free living nematode community structure.
• The Tilled + Organic Matter treatment had a more well balanced soil microbial system than other treatments.
• Numbers of omnivorous and predatory nematodes are quite low in comparison to other cropped soils around Australia, thus room for improvement.
• Soils have improved, as the number of omnivorous nematodes in 2013 significantly increased in organic amended treatments, in comparison to 2011.

The double incorporation of trifluralin method is designed to minimise the number of ryegrass that emerge from the edge of the furrow wall. However, there was no effect of incorporation with rolling harrows, or the snake chian on ryegrass density in the furrow of this trial.

• Germination of half the species at each trial site was above 33 plants/m2.
• Although most of the speices achieved this good germination many of the plants have now died or are looking very water stressed.
• On visual assessment, both Rhodes species and Signal grass have experienced the highest survival rates and are looking the least water stressed.
• The grasses would benefit greatly from a summer rainfall event.

• Germination of half the species at each trial site was above 33 plants/m2.
• Although most of the speices achieved this good germination many of the plants have now died or are looking very water stressed.
• On visual assessment, both Rhodes species and Signal grass have experienced the highest survival rates and are looking the least water stressed.
• The grasses would benefit greatly from a summer rainfall event.

• In 2006 Buntine received 100mm less rainfall than the average rainfall for that area.
• The largest rainfall event for the year was in January and therefore would have greatly benefited the sub-tropical perennial grasses. 

• Grazing pressure is greatest in winter, with volunteer pasutre providing the majority of the value.
• The stocking rates used on the improved pastures are also relatively high.
• Crop stubbles provide the majority of the grazing value in summer and autumn however they are grazed at very low stocking rates.

 

Cattle are brought onto the property from stations from June to September at an average weight of about 140kg/ha and then leave from mid-October to mid-February at approximately 300kg/ha.

Cattle are brought onto the property from stations from June to September at an average weight of about 140kg/ha and then leave from mid-October to mid-February at approximately 300kg/ha.

Cattle are brought onto the property from stations from June to September at an average weight of about 140kg/ha and then leave from mid-October to mid-February at approximately 300kg/ha.

Significant responses have been shown at other sites with suface lime treatments and deep ripping to 30cm, so using test strips to test responsiveness of a soil to these more treatments is a good option.

This demonstration showed there may be a large deep ripping effect, given the control gave the largest yield increase.

 

• Both the oats and the ryegrass recovered very quickly from each graxing, however, the legumes were very slow to start growing as expected.
• The treatments in this trial were set up for intensive strip grazing.
• The pasture and DSE carrying capacities are representative of this type of system.

• 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.

• 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.

• 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 APW wheat and Wyalkatchem had the highest gross margin.
• Yield is still the major target; however, quality is important and in the future there may be more pressure put on farmers by the end-users to get exacty what they want.

• Under sowing hard seeded Serradella seems to be an economical and sustainable way of establishing pastures the year after a wheat crop, particularly if pods are produced in the farm.
• Sowing depth had no significant effect on germination or plant density, however, it is recommended not to bury too deep pods of Serradella (max 2-3cm) to avoid seedling losses.
• Weed control in the plots was very poor, this could have been a result of no use of wetter with the application of Raptor.

• Moisture: Ironstone was found across some plots at depth which made any plot response to weed control difficult to measure so that there was more difference due to sub-soil constraints, rather than the individual treatments. Moisture readings were inconsistent and yields were therefore not taken.
• Weed control: Glyphosate is a very important base component when dealing with a mixture of summer weeds. The trial confirmed previous growers who experience and demonstrated summer grasses required high rates of glyphosate, at these high rates glyphosate provides excellent melon control. The Roundup Attack at 1.8 L/ha stand-alone gave the best control of grass and melons. All mixes containing Roundup Attack at 1.2 L/ha gave acceptable control of grasses and excellent control of melons when ester was added. With melons, the Triclopyr standalone was poor, but with Roundup Attack added had an additive effect, improving control significantly. Whilst no oil was used, perhaps the performance of the bottom three mixes may have given a better result with oil. Ally (metsulfuron) had an additive effect with the grasses but was antagonistic with the melons.

• Visually, the effects of the metribuzin treatments showed that both the metribuzin and the metribuzin/brodal/simizine treatments adversely affected the variety Tanjil the most.
• Quilinock and Kalya were the highest yielding varieties.

As expected melaleucas had a greater survival on the site across all treatments when compared wtih the eucalypts as they are better adapted to saline conditions.

• Varieties in this trial did not show a response to extra applied nitrogen at this site which was in pasture for the previous 3 years. Possible reasons are low rainfall and plants being water limited and/or sufficient background levels of nitrogen available for the crop in this soil type. 
• In this season results showed a benefit in seeding early, providing greater growing season and therefore yield benefit, averaging 210 kg/ha higher. 

• There was very little disease pressure at this particular demonstraiton site.
• This trial should be repeated under a number of different conditions with varying disease pressure to get a better understanding of the true value of fungicides in low rainfall areas.

There was a small discernable response in early season biomass to N applied at seeding at the sampling on 29 August August.

• Yield differences between soil types were less than seen in previous seasons on this paddock.
• Yield responded to an extra 25kg/ha N at sowing on the deep yellow sand over gravel and shallow gravel yielded around 2.5t/ha.

• 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.