VRT Performance

Matching fertiliser inputs to productivity zones (VRT) was rarely the most profitable strategy. Table 1 summarises the 9 successful trials undertaken in 2006 and 2007. These were above 5 average production years for the Corrigin area. It is assumed that the low, medium or high fertiliser treatments were blanketed across the whole paddock. The VRT treatment involved apply low inputs to the poor productivity zone, medium inputs to the average productivity zone and high inputs to the good productivity zone. This summary shows that in 8 of the 9 trials a blanket application of low or medium fertiliser rates was the most profitable way to fertilise the paddocks. High inputs were never the most profitable approach. The VRT approach was only most profitable in 1 of the 9 trials. The high input treatment was the least profitable strategy in 6 of the 9 trials.

Phosphate responses

Many of the paddocks where we had our trials were un responsive to phosphate. Our research has shown that many soils now have sufficient levels of phosphate that crops either don’t respond to additional applied phosphate or the responses are very small. The WA wheat belt has been in a phosphate building phase since clearing. Many farms now have sufficient phosphate levels. Fertiliser regimes could now be reduced to a maintenance regime. This would offer significant savings to growers especially given that the price of phosphate has tripled in the past two years. There would also be some significant environmental benefits to preventing over fertilising.

Best Fit for VRT

We feel that in the Corrigin area the most economic use of VRT will be for patching out potassium on responsive soil types as well as ameliorating soil with applications of lime or gypsum in the areas which have the highest requirement, rather than blanket applications on areas that do not require amelioration. VRT could also be used for tactical applications of nitrogen. Where the paddock is blanketed with N and P for and average production season. In an above average season additional nitrogen should be applied to the high productivity zones where the demand for additional nitrogen is likely to be highest.

Precision farming tools such as EM surveys and yeild mapping can add greatly to our understanding of grain yield and quality variation across a paddock. The results of N fertiliser and sowing rates on Silverstar wheat demonstrated that:

• grain yield differences are determined by soil type.
• high sowing rates can contribute to lower screenings but does now guarantee lower screenings.

The larger scale trial work raised issues on how to interpret small scale plot work. There is a greater need for researchers and farmers to work together towards identifying and interpreting paddock variability, before large scale, and often costly, management practices are put in place. 

• The ameliorants were applied in 2014, where 3.0 t/ha of gypsum proved to be the most effective in increasing establishment.
• However all treatments have had no effect in subsequent seasons.

Higher apparent N recovery efficiency was recorded in the topdressed treatments than the mid-row banded treatments, particularly the one topdressed early before waterlogging (TDE). There was no real difference in the N recovery between the MRB rates (190 and 290 kg/ha).

• The wetting agent /humectant SE14 was applied at seeding to see if crop establishment was improved in a dry sown oat crop near Lake Grace on a soil without non-wetting issues
• Significantly more oat plants germinated at SE14 3L/ha + water 47L/ha compared to the nil
• There was no significant difference in plant establishment between two different water rates used for applying the wetting agent
• It is unknown whether the increased plant establishment resulted in increased yield, as yield was not recorded.

When using the BlacklegCM App the information contained within the predictions is an indication of potential, not a guarantee for profit. The results from the York trial, where it was more of a case of minimising the loss received rather than focusing on making a profit, showed that regardless of the predications made by the app there was always going to be a loss received at this site due to poor seasonal conditions. The BlacklegCM App is an ideal fit to provide an indication of risk to a canola crop from blackleg, and the potential economic impact of this decision (positive or negative), as the user inputs the parameters that they are assessing prior to undertaking the decision to execute this plan.

While the analysis of using the BlacklegCM app as a predictive tool could not be completed for the 2020 trial results, the data collected from this season’s trial was able to show that the new technology that has been developed to further enhance the growers ability to minimize the impact of blackleg infection is effective. The results also showed that Pioneer 44Y27 (RMR) yielded higher when compared to the BASF 3000 (MSS) used in the same trial sequence which correlated with the Stingray (MR) having a greater yield across both trial sites than the Bonito (MS) under blackleg pressure, supporting the benefits of robust blackleg resistance ratings from broader trials.

Extension of the app needs to be clear that the figures that the app develops are based on the background research, the parameters put into the app and that there is still a range of variability to allow for within the system.

• Compaction is a subsoil constraint in North Hyden sandy soils.
• The first year of results indicate that deep ripping can be profitable in these soil types in North Hyden.
• The site variation and the design of the demonstration highlighted the response is not guaranteed; more investigation is required to identify why certain parts of the demonstration were more responsive than others to deep ripping and how to map and identify soils responsive to deep ripping.

• The variable lime technology soil pH testing and subsequent variable lime rate applications have the potential to be an efficient method of ensuring that soil pH is in the target range for optimum plant growth.
• The variable lime technology has the potential to create savings for farmers addressing soil pH in pasture systems as evidenced in the case study on page 14. It should be noted though, that in some cases the variable lime technology soil measurements may identify a higher requirement for lime than that calculated from conventional testing.
• The trial analysis suggested that six out of the seven paddocks in the trial would have potential cost savings if variable or targeted liming was implemented when compared to conventional testing and lime application rates. The seventh paddock had a pH below target levels over the entire area and required a blanket lime application and there would have been no cost saving benefit in this case.
• For further key findings please see the attached trial report.

• Protein and yield responses may have been impacted by nitrogen residues in the soil from the two previous dry seasons.
• One treatment of 130kg/ha was also tested, however, due to an error during the harvesting of the trial and there being only one replicate of the treatment, the results have not been included.

An analysis of the soils PAWC needs to be conducted to determine yield potential of the soil types analysed to draw meaningful conclusions from these results.

The results indicate that the land owner may see economic benefit (as per Gross Margin) from the uptake of variable rate technology in paddocks with varying soil types such as this trial paddock.

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits. Fertiliser rates were selected after discussing with farmer that the lower yielding zones would never produce yields comparable to medium and high yielding zones, due to the low fertility and poor water and nutrient holding capacity of the soil. The farmer believed that that fertiliser was being wasted on the sand zones of his farm, and wanted to see if cutting fertiliser rates would be detrimental to yield in this zone.

• Centre pivot irrigation plots were surveyed using gamma radiometric and electromagnetic sensors.
• Soil moisture sensors with 3G logging devices were installed in contrasting soil types according to interpretation of the gamma radiometric data.
• Replicated yield and quality estimates were conducted on each soil type
• Yields and tuber classes varied significantly between soil types
• Experiments to determine optimal irrigation and fertiliser regimes for contrasting soil types will be conducted in 2017.

• Without this intensive mapping the paddock would have been either under or over limed and fertilised resulting in either a loss of productivity or a waste of fertiliser/lime dollars and possibly both.
• Whilst it’s economically beneficial to apply variable rate technology for a liming program, until more cost efficient soil testing methods are developed, the economic justification may not be there for soil nutrients.

In 2010, at Wass brothers’ property in Nyngan, a very wet season caused the normally poor performing areas to perform just as well as the good areas in this paddock regardless of additional nitrogen application. In other paddocks across the farm, there were significant yield differences across each paddock. However, in the previous years Wass’s have always wanted to apply N and have had mixed results possibly because of soil and water variability. Most seasons they have areas that burnout and areas which could use a higher application of N and give a better yield. In 2011, Hayden intended to try to understand what was driving these differences, and yield maps are a way of spatially determining different zones. Therefore, this trial was set up.

Because there was no effect of fertiliser on the yield it meant any potential benefit from VR was greatly reduced. This can likely be put down to the high levels of soil N recorded at the start of 2011. The trial does suggest that this paddock was over fertilised as there was no significant loss of yield from a 40kg/ha reduction in urea in either trial.

There was no response shown to varying nitrogen rates across the 4 yield zones on this paddock. This could be due to the adequate levels of nitrogen present before seeding as show in the 0-10 and 10-60cm soil test results and also reinforced with the NDVI esults, this would stem from good fertiliser history and rotation from the Harkness’s.This could give confidence that rates could be reduced on the lower yielding areas without risk of impacting on yield and consequently increasing gross margins across the paddock by saving wasted inputs on poorer performing soil types and leaving rates higher on better performing areas to maximise returns when seasons are more favourable.

The trial has indicated that the application of the high rate UAN (140L/ha) over the entire paddock still proved to be a more profitable than applying the low rate over the entire paddock, however the overall gross margin benefits are not as visible due to the low yielding sand zone only occupying 9ha (13%) of the paddock. However these results confirm that the adoption of PA is an economically sound decision, indicating that the grower could make a saving of $48/ha if that extra nitrogen was not applied to the low yielding area via the use of variable rate fertiliser application. The trial results have solidly indicated that the overall gross margin would be profitably affected not having to spend the extra $62/ha on fertiliser. The gain of $53/ha in the high yield zone with high rate N (140L) is a substantial increase in profit over the low rate (60L) showing there is benefits to adding N in these zones.

Applying nitrogen on the sand soil zones has consistently delivered sound economic returns. The highest ROI achieved in the sand west zone ($123.20) and sand east zone ($37.85) was in the 115 and 130kg urea/ha treatments respectively. Applying nitrogen in the clay zone however failed to deliver an economic eturn and this has been realised in this paddock before. This trial highlighted that variable rate nitrogen is highly applicable to paddocks with high degrees of spatial variability in order to maximise yield and/or return on investment in individual paddock zones.

• Each soil zone was nitrogen responsive at varying levels.
• Low EM zones (sands and sand-loams) were very responsive - 41-61% increase in yield achieved by applying the top rate of urea.
• High EM zones (clay-loams) were moderately responsive - 10-22% increase in yield achieved.
• Applying high rates of nitrogen to high EM (clay-loam) zones proved to be un-economical.

With good soil phosphorus reserves ‘P replacement’ is a safe and viable option that will help farmers manage their inputs and maintain soil fertility in high yielding areas of the paddock.

This year there was no big benefit from variable rate fertilizer in relation to yield. This is not unexpected given the dry season.

This trial gives some confidence that cutting fertilizer in particular P back on the low zone did not impact yield and had the best gross margin, therefore is a good strategy to reduce costs on the lower performing parts of the paddocks. This is consistent with current DAFWA and GRDC research findings that less phosphorus can be applied on soils with good P history without penalizing yield. Similarly it demonstrated the potential to reduce rates on the higher production zones depending on the season as tissue tests indicated adequate nitrogen just prior to the late N application. It is likely there was also more nitrogen available as a result of ripping increasing nitrogen mineralization and plant root access to water and nutrients. Reducing N applied after ripping is a recommended strategy to reduce the risk of the producing high biomass and the crop haying off early with a dry finish.

The estimated yield potential of the zones was not reached with the high zone about 1.5 t/ha below potential. This is consistent with farm observations that found there was a penalty of about 1 t/ha for crops sown later than 7 days from the 22nd May crops in this dry season.

High resolution six meter imagery was found to be very useful to identify management issues and map non-wetting soils, particularly the early July image which highlighted emergence issues. The non-wetting areas can be mapped and treated by ploughing those areas paddock not the whole reducing the cost of treatment. Ground-truthing showed the 6m resolution was high enough to identify problems with the bar such as running out of fertilizer. These are management issues that can be adjusted to improve efficiency and production to improve yield. 

In the case study paddock the imagery has highlighted issues that were not evident from the yield maps such as residual compaction from old corners and where the ripper and spader lifted over a water pipe (the red line in the top north east corner). This paddock has been deep ripped twice but old compaction is still visible suggesting it is beyond the current ripping depth of 400mm. The late season imagery was too late to see any big differences in biomass. An optimal time to capture imagery appears to be mid-July.

Applying low fertilizer to the low production zone is both a good economic strategy to improve profitability and prevents over fertilizing that increases the risk of nutrient leaching in these pale sands that have limited capacity to store nutrients.

On upper Eyre Peninsula few people use EM38 mapping to support the use of VRT. Currently yield maps and paddock knowledge are the most commonly used methods for determining production zones within paddocks. The demonstrations show that increasing fertiliser rates did not have an effect on yields but yields did follow EM38 mapped soil zones.

Additional N did not have an economic advantage in this season. Paddock and demonstration site suffered from the dry 6 weeks period mid season. Stem rust devastated potential 3 ton crop reducing yield by 50%. This combination resulted in poor yields, low test weight and high screenings. Good soil showed improved protein over deeper sand regardless of extra N applied. Extra N marginally improved protein but not enough economically to apply more.

• Additional N did not have an economic advantage in this season.
• Paddock and demonstration site suffered from the dry 6 weeks period mid season.
• Stem rust devastated potential 3 ton crop reducing yield by 50%. This combination resulted in poor yields, low test weight and high screenings.
• Good soil showed improved protein over deeper sand regardless of extra N applied.
• Extra N marginally improved protein but not enough economically to apply more.

KEY FINDINGS:

• Cereal variety choice can have a large impact on Pratylenchus thornei (Pt) population build-up within paddocks, which can then affect how following crops and/or varieties perform in the rotation.
• Significant differences were evident between varieties with an 8.9-fold difference in final Pt populations between the best (Commander) and worst (Mitch) entries.
• Very susceptible varieties should be avoided in paddocks with known root lesion nematode (RLN) populations as they can increase the population to high risk levels in one season (e.g. 19.1-fold increase with Mitch).
• There was no significant difference between varieties in crown rot inoculum level that developed during the season based on postharvest PreDicta B assessment.

Conclusions

Cereal variety choice can have a significant impact on the build-up of Pt populations within paddocks with an 8.9  fold difference in final populations between the best and worst variety at this site in 2015. Starting Pt populations of below 2.0 Pt/ g soil are considered low risk, populations between 2.0 and 15.0 Pt/g soil are considered medium risk and above 15.0 Pt/g soil are considered high risk for yield loss in intolerant crops or varieties in the northern region. This could have serious consequences for the production of following Pt intolerant crops and/or varieties within the rotation with all but two entries (Commander and Suntop) increasing the Pt population from a medium to a high risk level in one season or with one variety (Mitch) increasing the Pt population as high as 105.0 Pt/g soil at this site in 2015. Recent NSW DPI research has also demonstrated that significant yield loss still occurred in the moderately tolerant wheat variety EGA Gregory with high risk (>15.0 Pt/g)  populations in the top 30 cm of soil at sowing. Very susceptible varieties should be avoided in paddocks with known RLN populations as they can blowout the population to high risk levels in one season.

Although varieties appear to significantly differ in their yield in the presence of crown rot infection, differences in the levels of partial resistance, which limits the rate of spread of the crown rot fungus through the plant during the season, do not appear to result in significant variation in inoculum levels at harvest. Partial resistance does not actually prevent the plant from being infected but rather slows the rate of fungal growth in the plant arguably delaying expression of the disease which can translate into a yield and grain quality (reduced screenings) benefit. However, the crown rot fungus, while being a pathogen when the winter cereal plant is alive, is also an effective saprophyte once the plant matures and dies. This saprophytic colonisation of infected tillers late in the season as the crop matures is the likely reason why limited practical differences in residual inoculum levels are created between varieties and winter cereal crop types.

 

Further research across sites is required to confirm differences in resistance of barley and wheat varieties to Pt as this can have significant implications for the build-up of Pt populations within a paddock and hence following rotational choices. For instance, while it appears that Mitch has a useful level of tolerance to crown rot (average 0.54 t/ha higher yielding than EGA Gregory in 2015), its increased susceptibility to Pt resulted in it taking nematode populations from a medium risk level at sowing to an extremely high risk level by harvest at Macalister in 2015 (Figure 1). Hence, Mitch should only be considered for production in paddocks known to be free of Pt as its increased susceptibility to Pt is likely to override the yield gain in the presence of crown rot when considering the whole rotational sequence.

 

• Cereal variety choice can have a large impact on the build-up of Pratylenchus thornei (Pt) populations within paddocks which can then impact on the performance of following crops and/or varieties in the rotation.
• Significant differences were evident between varieties with a 22-fold difference in final Pt populations between the best (SuntopA) and worst (MitchA) variety.
• Very susceptible varieties should be avoided in paddocks with known Root Lesion Nematode (RLN) populations as they can increase the population to high risk levels in one season.
• There was no significant difference between varieties in the level of crown rot inoculum they developed during the season based on post-harvest PreDicta B assessment.

Birchip: The site was located in a paddock with moderate subsoil limitations (40 to 70cm layer had chloride reading of 1800ppm, and an EC of 0.6dS/m). The site had a previous legume history and was high in soil available N (prior to sowing the soil contained 230 kg available N/ha to 1m depth).

Kooloonong: The site was located on a Mallee land system, on a flat to sloping rise with a sandy loam soil to a depth of 40cm and at greater depth a sandy clay loam to at least 130cm. The soil has no subsoil limitations but because it is light and sandy, leaching of nutrients can be a problem. 2010 had a growing season rainfall of 329mm (decile 10).

• Vegetable beetle and slater activity is correlated to high relative humidity, mild temperatures and time of day, and that these conditions overlap with other crop emergence pests such as conical snails.
• Vegetable beetles and slater movement was not correlated with soil moisture content, unlike conical snails.
• There may be a wider window of opportunity to apply chemical controls to target these pests pre-sowing especially in dry sowing situations. Whereas when baiting for snails, efficacy is improved when baits are applied immediately following rain when the soil surface is moist and there is high relative humidity overnight.

• Annual disc fallow provided no benefit this season and chemical fallow would be less profitable than whea ton wheat with 600mm row spacing.
• Wilder rows produced a less 'bulky' crop with less biomass/grain weight.

• Vetch grain and dry matter yields were very good at Minnipa in 2015, the grain trial mean was 1.4 t/ha with the top lines achieving 2.1 t/ha, mean dry matter yields were 4.1 t/ha with the top line achieving 4.3 t/ha.
• The Piednippie SAGIT trial was poor, suffering from moisture stress post emergence which stunted growth and limited the potential once the crop received rain in mid-June, the site mean was only 1.1 t/ha of dry matter.
• Early sowing (mid-April) can achieve good results but is heavily reliant on either good subsoil moisture or follow-up rain.
• The new varieties, Volga and Timok continue to out yield all existing varieties in both grain and hay production on the EP.
• Herbicide choices for vetch are very dependent on local conditions so talk to your local agronomist about the best options for your conditions.

• Vetch is a versatile crop that can be used for grain, pasture, hay/silage or green manure.
• Common vetches can be successfully grown in lower to mid rainfall areas of southern Australia where no other legume crops perform consistently well.
• It offers disease and weed breaks in rotation and also returns significant amounts of nitrogen to the soil.
• New vetch species are showing potential in very low rainfall areas, with trials to be conducted on Eyre Peninsula in 2012.

When vetch is establised in March and is terminated 'early' (three to four months later, in June, July), soil water will be conserved for the subsequent wheat crop; the risk of haying off due to high nitrogen will be lower than if the vetch were terminated 'later' (August, September),

Vetch biomass production of approximately 2t/ha is unlikely to cause a subsequent wheat crop to hay off given dry seasonal conditions. 

Residual nitrogen from vetch brown manure can carry over for two years and influence cereal crop growth, but the conservation of soil water is more critical in seasons of Decile 2 or lower. 

When vetch is establised in March and is terminated 'early' (three to four months later, in June, July), soil water will be conserved for the subsequent wheat crop; the risk of haying off due to high nitrogen will be lower than if the vetch were terminated 'later' (August, September),

Vetch biomass production of approximately 2t/ha is unlikely to cause a subsequent wheat crop to hay off given dry seasonal conditions. 

Residual nitrogen from vetch brown manure can carry over for two years and influence cereal crop growth, but the conservation of soil water is more critical in seasons of Decile 2 or lower. 

When vetch is establised in March and is terminated 'early' (three to four months later, in June, July), soil water will be conserved for the subsequent wheat crop; the risk of haying off due to high nitrogen will be lower than if the vetch were terminated 'later' (August, September),

Vetch biomass production of approximately 2t/ha is unlikely to cause a subsequent wheat crop to hay off given dry seasonal conditions. 

Residual nitrogen from vetch brown manure can carry over for two years and influence cereal crop growth, but the conservation of soil water is more critical in seasons of Decile 2 or lower. 

Nitrogen (N) fixation by vetch was closely related to dry matter (DM) production (26kg N fixed per tonne DM accumulated). The later the termination, the higher the calculated inputs of fixed N. Both soil water reserves and mineral N were highest at the end of the 2012 growing season following the earliest (June and July) termination timings. To establish the best time to terminate a vetch crop, weigh up the benefits being delivered by vetch (biomass accumulation and N fixation), the need to conserve moisture and time required for N to mineralise for the next crop.

Early termination of vetch resulted in higher soil N and soil water at sowing the following year compared with later termination timings of vetch. Wheat yield in the year following vetch was highest for the earlier termination timings of the vetch. Brown manure vetch had higher soil N and soil water compared to vetch taken through to harvest.

All sites in this trial suffered from severe moisture stress and the effects of rust.

Narrow disc seeding system resulted 72% and 87% more biomass than wide row knifepoint and paired row systems across all varieties. Timok yielded 1.5 t/ha of biomass when averaged across all harvesting dates, which was 13% and 25% higher than Studenica and Morava.

Establishment and plant growth: The different seeding systems had a large effect on plant establishment with greater number of plants emerging in the disc sown treatments. As the trial was dry sown, the discs were not able to penetrate as deep as the tine-based systems (Root Boot and PSS) and therefore it is possible that the shallower sowing has resulted in an establishment advantage. However, the seed bed was noticeably more cloddy following seeding with the tine-based systems, which may also have had a negative effect on the establishment, as seed-soil contact was likely to be poorer.

Biomass: The disc seeding system resulted in 99 – 166% more biomass than the tine systems at each harvest date. By the final September harvest data, the narrow row disc system with the highest SBU resulted in over 1 t/ha (117 – 166%) more biomass than the other seeding systems.

Field pea and vetch hay was most economical due to strong hay prices this year. Field peas were the best performing grain crop (Table 1). Early sowing maximised biomass (hay) and grain yield.

Field pea and vetch hay was most economical due to strong hay prices this year. Field peas were the best performing grain crop (Table 1). Early sowing maximised biomass (hay) and grain yield. Table 1. Potential gross margins from the highest yielding varieties and treatments selected from these trials.

• Most drainage treatments did not cause a yield penalty in 2007 when waterlogging was not a constraint to cropping.
• The gravel slot treatment had the lowest yield in 2007, drained the most water, and was the most expensive to install.
• We now have a site established to evaluate a range of drainage treatments for their effect on crop yield and the amount and quality of water draining from the paddock.

• In a year where waterlogging caused yield penalties all treatments resulted in a yield increase compared to the control.
• The raised beds increased yield by almost 200% followed by gravel moles, gravel slots and conventional moles.
• On flat waterlogged land, raised beds provided the best yield result but they did have some management issues.
• Gravel slots and gravel moles also worked extremely well but the slots were too expensive to install to consider for broadacre use. No commercial scale gravel mole is available at present.
• Conventional moles are prone to collapse with Kangaroo Island’s sodic clays.

• In a year where waterlogging caused severe yield penalties, all treatments resulted in a yield increase compared to the control.
• On flat waterlogged land, raised beds provided the best yield result but they do have some
• management issues .
• The delved treatment drained a considerable amount of water, yielded equal to the other treatments (but less than the raised beds) and was more cost effective to install with fewer management issues.
• Gravel slots and gravel moles also worked extremely well but the slots were too expensive to install to consider for broadacre use. No commercial scale gravel mole is available at present.
• Conventional moles are prone to collapse with Kangaroo Island’s sodic clays.

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits.

• Several varieties including Mitre, Yitpi, and Annuello yielded well at this site.
• Of the highest yielding varieties Yitpi received the best price per tonne and return per hectare, under AWB’s Golden Rewards, due to higher protein than the other high yielding varieties.
• H45 was one of the lowest yielding varieties at this site and was also the most affected by stripe rust. However screenings were below 5% in all varieties indicating that stripe rust had a greater impact on yield than grain size.
• Wyalkatchem and AGHW 001 also yielded lower than the other varieties despite much lower stripe rust infection – in fact AGHW 001 remained free of disease all season indicating that moisture may have been a greater yield limiting factor at this site.

• Sowing at 5 km/hr gave significantly higher seedling establishment densities than sowing at 10 km/hr and 15 km/h.
• It was most noticeable that the 15 km/h plots had the most soil disturbance.

• The farming systems containing a perennial pasture phase contained 140-180 mm less soil water in the top 300 cm than the continuous cropping system.
• Soil under the two lucerne-wheat cropping rotations and the perennial pasture system were considerably drier below 90 cm, presumably due to water extraction by lucerne in previous years.
• At sowing, June 2004 and June 2005, the continuous cropping system contained 60 and 30 mm respectively more plant available water in the top 1 m than the lucerne-wheat cropping rotations. This resulted in 50% and 35% higher yields in 2004 and 2005 repectively.
• Rooting depth in 2004-5 appeared limited to the top 70-90 cm for wheat, 50-70 cm for peas and 210 cm for perennial pasture.
• Modelling indicates potential drainage of 19 mm annually under annual crops, thus a 2-3 year lucerne phase is capable of providing 7-9 years of buffering at average rainfall

• No significant yield difference between treatments in WL trial in first year.
• Redox potential affects availability of nutrients and was dependent on soil moisture.
• Redox potential higher for the lime treatment which should mean better conditions for plant growth.
• Commercial varieties used showed little variation in waterlogging tolerance.

Engineering solutions:

• On flat waterlogged land, raised beds provided the best yield result but they do have some management issues.
• Gravel slots and moles also worked well but the slots are expensive for broad acre use.
• Conventional moles are prone to collapse with Kangaroo Island’s sodic clays.
• The nature of many of our clays (sodic and poor draining) results in poor water movement from the soil into a slotted agricultural pipe.

Agronomic solutions:

• The adverse effects of waterlogging are primarily due to anoxic conditions in the soil, rather than element toxicities or deficiencies, except perhaps for aluminium.
• Liming acidic soils will reduce al toxicity.
• In waterlogged soils the application of poultry manure doesn’t appear to improve yields. But the application of lime may increase yield.
• Waterlogging may cause nitrogen (N) deficiency but high rates of N will not turn a waterlogged crop into a good crop.
• There may be some potential for varietal difference to waterlogging in wheat.
• Broad beans: improve nodulation through a combination of liming and application of molybdenum. Liming will also reduce inherent nutritional problems of low soil pH. Early tissue testing and nutrient correction with foliar applications help overcome some soil ph deficiencies

• Although chickpea yields were higher than previous years, the rapid finish to the season
  favoured earlier flowering and maturing varieties such as GenesisTM079 and Sonali.
• Ryegrass competition at 31 and 86 plants/m2 reduced chickpea grain yield by 31% and 56%, respectively. Similarly, at Turretfield ryegrass at 41 plants/m2 corresponded to 33% yield loss, and 62% at 123 plants/m2.
• Similarities between moisture stresses caused by lack of finishing rainfall in 2009 and from
  competition with ryegrass meant that the same varieties yielded well with or without  ryegrass competition eg GenesisTM079.
• Breeder’s line “Chickpea 4” recorded the lowest yield loss from ryegrass competition at both
  sites (9% at the low ryegrass density at Hart), and also displayed 35% better tiller suppression than other varieties at Hart.
• Early vigour appeared an important trait in chickpea for improved competivness with ryegrass, plant height was a disadvantage, but further work is required on a larger set of
  phenotypes and in a more favourable growing season.
• Some ambiguous results in 2009 (eg PBA Slasher and Chickpea 2) may be due to the
  unfavourable seasonal conditions for chickpea production which prevailed in SA last year.
  However they do indicate the need for more work in a more favourable growing season, and
  potentially on a larger set of phenotypes.

• In the past four (dry) years on this demonstration farm the fallow/wheat/oats/lucerne (Phase farming) and wheat/fallow rotations have proved the most financially rewarding, probably due to the moisture storing benefits of fallow.
• Urea seems both less risky and more reliable than the pulse or ley in increasing wheat yield.
• The extreme dryness has caused problems with weed control (chemicals not effective) and with growth of pulse crops and subclover leys.

Sowing cereals in early April on a soil profile full of water is possible if:

• long season varieties are planted to ensure that the crop does not flower before the high-risk frost period has passed,
• the topsoil is moist at seeding to ensure that the crop germinates and allows for early root growth down into the stored water in the subsoil, and
• weeds can be controlled.

• Soil acidity cost $170/ha to $228/ha alone in yield penalties in 2015
• Keeping pH at good levels by liming prevents yield penalties
• Increasing soil aluminium levels caused by pH falling below 4.8, provides a good guide to the likely yield penalties incurred 

Of the paddocks investigated in the Southern Mallee, water was severely limiting in 1994, and the amount of water that could be supplied to crop from the soil was very small.

• Sowing date combined with appropriate variety selection and adequate nitrogen supply was key to increasing grain yields.
• Nitrogen fertiliser decision needs to consider the maximum attainable yield and be adjusted for the seasonal conditions and initial available soil nitrogen.

• The 1999 season was fairly average with a dry spring reducing potential yields.
• Nitrogen responses were marginal due to already high levels of nitrogen in the soil.
• Topdressing nitrogen on wheat increased yields at all sites to some extent.

• If you are a productive farmer, you will be acidifying your soils.
• Use the tools – they are easy to use and provide valuable information on what is driving acidity and what it is costing you and your property.
• Liming will save you money – it’s cheaper to lime than wear the cost of lost production . 
   

May 4th sown Mackellar wheat produced yields in the range of 4.74 – 5.99 t/ha following canola stubble. With high soil nitrogen reserves (176 kg/ha N, 0‐90cm) recorded 2 days pre sowing, there was a small but significant response to applied nitrogen (0.43 t/ha at 50kg/ha N & 0.58 t/ha at 100kg/ha N). There was a significant advantage to nitrogen timed during stem elongation (GS30‐39) over nitrogen applied in the seedbed. This advantage was evident in both single and split applications between which there was
no difference.

• This trial showed that under the extremely dry conditions of 2006, wheat yield at this site was largely determined by water supply because major diseases were absent and the soil had abundant nutrients in reserve for the small demands of such a low yielding crop.

Funded by DAFWA and GRDC through DAW00204 ‘Delivering agronomic strategies for water repellent soils in WA’ and DAW00218 ‘Wheat agronomy systems profitability’. Thanks to LivingFarm for management of sites at Wickepin and Cranbrook. The provision of sites and support of growers Ray Falconer, Kyle Carson, David Stacey, and Kim Oliver is greatly appreciated. Thanks to Trevor Bell, Anne Smith, Stephanie Boyce, Paul Bartlett, Virginia Smee and Greg Brown for technical support. Thanks to West Midlands Group, Northern Agri Group, Facey Group, Gillami Centre and the soil wetter product manufacturers for ongoing support.

• Seeding rate had a bigger impact on wheat establishment than soil wetting agents
• High seeding rates on soils with low yield potential were sometimes a disadvantage; optimal seeding rates would need to account for yield potential as well as the degree of soil water repellence.
• Delaying sowing providing an opportunity to get a knockdown of weeds was important on water repellent soils where staggered weed germination, and reduced herbicide activity, reduces efficacy of in-crop and pre-emergent applications.
• In these trials soil wetting agents did not consistently improve wheat establishment and despite some evidence of benefits to vegetative growth this generally did not translate into a grain yield benefit.

• Despite high levels of available soil nitrogen at the start of the season (113 kg/ha N, 0 – 100 cm), there was a significant yield response to applied nitrogen. There was no yield advantage of 100kg/ha N over 50kg/ha N.
• At 50kg/ha N, there was a significant yield advantage (0.47t/ha) from application at GS33 (third node) compared to application pre-sowing.
• At 100kg/ha N, there was a significant yield advantage (0.55t/ha) from application at GS30 above seedbed application. Differences at 50kg/ha were not significant.

• With very low levels of available soil nitrogen and rooting limitations due to salinity at 70cm, there was a significant response to applied nitrogen over the zero N control, but was statistically significant only in treatments that received nitrogen in the seedbed.
• Where nitrogen was applied in-crop at GS31 (14 August) and GS39 (14 September), there was no significant yield response above the control (a result attributed to limited uptake 3.25mm of rain in August, 8.5mm in September).
• While grain protein content increased after seedbed nitrogen applications, there was no protein response to in-crop applications, confirming a lack of nitrogen uptake as a result of limited follow up rainfall.

• In this water-limited scenario, with 70 kg/ha N available in the soil at the start of the season, in-crop nitrogen application served to significantly reduce yield relative to the zero N control.
• Yield depression was strongly significant (p=0.001) when nitrogen was applied at GS30 (start of stem elongation) but was less evident when applied at GS37 (flag leaf first visible).
• Unusually, the yield reduction from GS30 nitrogen timing was associated with higher grain protein than the later flag leaf first visible (GS37) timing. This result looks likely to have been influenced by protein concentration effect accompanying the stronger yield reduction at GS30.

• It was a relatively low yielding site, perhaps reflecting the fact that the site was in cereal in 2001 and the soil nitrogen status at planting was very low. Protein figures certainly indicate the fact that soil nitrogen was low 
• All varieties performed equally, although the winter wheat types had slightly lower grain protein than the spring wheat types. 
• The season tended to favour the earlier maturity types such as Chara, although given this, the performance of MacKellar and Brennan was quite acceptable. 

• Pre-sowing: dry seeded some moisture below seeding depth.
• Early season and pre-harvest: dry and hot days caused tipping.

• Previous crop (legume, oaten hay, cereal or fallow) had no effect on wheat grain yield in 2014.
• Grain protein values were lower following a cereal where there was less available soil N at the start of the season.

• There was significatn rain in early April.
• Main weed problem was radish.

Pre sowing comment: good moisture. Small amount of capeweed and lupins.

Early season comment: dry period after emergence. Some lupins present and a small amount of radish.

Mid season comment: dry periods after frost.

Pre harvest comment: severe frosts during grain fill effected earlier maturing lines.

• Wheat responded to up to 12 kilograms per hectare of phrosphorus (P) without added nitrogen (N) and to 6kg/ha of phosphorus with added nitrogen.
• Higher fertiliser rates did not improve yield or tiller numbers.

• Both N and K have influenced wheat growth at the site, to varying degrees.
• Summit’s complex soil test interpretation model recommended 90 kg N for a 3 T/ha wheat crop based on the soil sample analyses at this site. With a growing season rainfall of 300 mm and the responses in this trial, an N recommendation of 80 kg/ha appears appropriate.
• Potassium recommendations from the Summit model were 20 kg K for a 3 T/ha wheat crop. Potassium recommendations will be much more dependent on soil characteristics and laboratory test results, but even on the duplex soil at the site, 10 to 20 kg K/ha looks to be of benefit in helping plants to maximise the potential growth benefits from top-up nitrogen applications.
• Mace wheat utilises N nutrition for yield, on the whole, but protein does increase somewhat with increasing N application and targeting higher delivery grades is possible if desired.

Despite weed competition, less-than-ideal winter weather and soil conditions, wheat responded to both P and N application at this site. Grower returns on fertilizer investment were best with P applied at 8 to 16 kg/ha and N applied at 40 kg/ha. Greater response and returns from increased fertilizer application may be expected with improved early-to-mid season moisture conditions and less weed competition.

Two years of trials at Forbes on low Zn soils show no indication of wheat response to Zn fertiliser. There is some evidence that Zn deficiency in wheat can be intensified by SU herbicides. However, the critical soil Zn levels needed to justify Zn fertiliser use in wheat grown on lower pH soils treated with SU herbicides is unknown. Fertiliser test strips over a number of years have an important role to play in determining potential Zn responsiveness.

• The harvest results show the gains to be made from the banded application of phosphorus and nitrogen to wheat crops grown in the southern Mallee.
• Carefully assess soil fertility prior to sowing of cereals and canola to ensure dollars spent on the most profitable nutrient combination for each paddock.
• Plan on balanced nutrition of crops to optimise farm 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.

• Axe, Wyalkatchem and Gladius appear to be the wheat varieties that use added P efficiently.
• Scout is able to maintain yield when no P is added.

• There was no yield response to increased P rates in any variety tested suggesting that adequate available soil P masked any purported difference in P use efficiency between varieties.
• However, there was a trend in that the grain yield of the variety Axe increased in response to higher levels of P in both the replicated and broad acre studies.

• There was little difference in the root growth of wheat and canola.
• There was evidence of restricted root development in the 20-40cm soil layer.
• Wheat yield increased with increasing nitrogen but grain size was reduced slightly.
• There was no evidence of declining yield with high nitrogen in this experiment.

• Despite the late sowing, wheat yields were reasonable. The hightest yield was for wheat after canola with ripping. With 80kg N/ha, this was 3.1t/ha.
• The benefit of ripping had decreased markedly from the previous season.
• The canola rotation increased wheat yield by about 0.5t/ha. It was greater with ripping.
• The main conclusion from this experiment is that on this soil type, potential yields can be obtained with management tools already available to growers.

Nitrogen use has resulted in great improvements in crop yield in favourable seasons.
In dry seasons too much applied nitrogen can result in haying-off and lower yields.
Good guidelines are now available for nitrogen use to reduce the risk of crop failure resulting from applying too much fertiliser nitrogen.
The critical factors are:
• Stored soil water (control summer weeds)
• Measure how much nitrogen is in the soil prior to sowing
• Calculate nitrogen requirement from the target yield
• Do not pre-drill more than 60 kg/ha of urea in the 350mm rainfall zone (100kg/ha in the 450mm zone)
• Split applications are safer
• Topdress with urea if the soil test indicates a need, the crop is healthy, and the outlook is for an average to wet season

30 years after application, water soluble P leaches to depth on grey sands but is still effective for the growth of deep rooted blue lupins.  On the one-hand, the citrate-soluble P in C-500 releases more slowly through time and so has a longer term residual effect than water soluble P. On the other hand, higher rates of C-500 are required than superphosphate to reach maximum yield when soil P levels are low.  It is less likely to leach and so pollute ground waters. If cheap enough, C-500 could be used as a maintenance P fertiliser.  Much work is still to be done on this trial site.

Vetch is a multi-purpose crop; its versatility allows decisions about its end-use to be made during the year (grain, hay/silage or green manure/grazing) and also can be used as a management tool against resistant weed development. Vetch can improve soil fertility by returning organic matter to the soil, increase yield in the following crop by means of nitrogen fixation and reduce disease and insect risk for the following crop. Two new varieties; SA-34823 and SA-35103 are set for release in spring 2013.

Andrew’s management of water repellence demonstrates that a strategy of affordable progressive amelioration and better sowing methods for the rest of the crop can be a successful and profitable approach for managing soil water repellence. On-farm testing of water repellence management options can help confirm which strategies are likely to be successful and profitable on particular soils and landscapes. The use of winged paired-row systems, winged points, banded-wetting agents, on-row seeding or broadcast spreading a proportion of the seed ahead of the bar can all potentially improve the effectiveness of sowing on water repellent soils and this is the subject of ongoing research.

• The Whole Farm Soil Mapping Project addresses the Caring for our Country and the South West Regional Natural Resource Management Strategy (2012 - 2020) targets to reduce the fertilizer and nutrient run off in to water ways through implementation of best practice fertilizer management on farms, as recommended in the Peel - Harvey Water Quality Improvement Plans (WQIP).

• In the dry season of 2001, lentils, field peas and canola yielded poorly whereas whet and barley yielded well.
• Hostile subsoil conditions limited the rooting depth of pulses and canola, while wheat and barley were more tolerant and able to extract moisture down to a dep of 1m.
• Pulses and canola will always struggle to perform in dry springs unless they are grown on soils where their roots can extrac soil water deeper than 50cm.

• The only way to accurately know your soil pH is to send a sample for a laboratory test (soil testing kits are available from the PIRSA Office in Kingscote).
• Have a look at the on-line acidity tools . They are easy to use and extremely helpful in guiding liming decisions.
• Liming will pay for itself, often in the first year. 
   

• The main difference in yield may have been due to poor tillage in the 500mm spaced crop.
• The entire crop was reliant on the soil nutrition from the pasutre as no fertiliser was applied to the paddock prior to and following seeding.
• Later sowing of the trial may have jeopardised the wide row's yield capacity therefore it would be encouraged that when considering sowing in wide rows early seeding is preferable.
• It may be noted that if nutrition was not a limiting factor for the 500mm crop, the water supply from the wide row may have increased yield to similar or better than that of the 250mm crop.

The results, even after relatively good spring rains, support the idea of conserving soil moisture between wide rows and reducing drought effects.

Stubble height can have a significant impact on wind speed close to the soil surface. This can increase soil erosion in vunerable environments (sand hills).

1. Winter cover crops can improve ground cover, increase plant available water and improve subsequent cotton yields in pivot-irrigated systems.
2. The early spray-out treatment was the best cover crop for storing water over the short fallow in this study where cover did not have to last very long. However, the extra cover in the mid-terminated cover treatment continued to boost infiltration in the cotton’s
early growth stages.
3. All cover crop treatments improved the yields of cotton by approximately 3 bales/ha; well in excess of any gains expected from the increased fallow soil water storage.

• Scout and Mace continue to out-yield the rest of the pack at Witera.
• Oxford and Fathom (WI4483) break 3 t/ha under severe leaf rust pressure at Witera.
• Espada and Scout top Elliston yields in 2011.

Take Home Messages

• Near perfect growing season for canola, provided ideal opportunity to assess the residual N feeding effect of the legumes.

• All legumes sown in 2016 – peas, lupins, sub clover and faba beans had similar starting soil N levels and soil water nitrate readings throughout the year which was reflected in similar grain yields inferring that all legume species were equal in terms of their N fixing capabilities.

• The average amount of N fixed by the legumes was calculated as ~86kg/ha.

• Growing adequately nodulated legumes can give rise to a ~1t/ha canola yield advantage compared with a non-legume.

• Linseed used more moisture, from a greater depth, than the faba beans in 2016. Resultantly more moisture was extracted by the canola crop sown on the faba bean stubble in 2017, and yet there is still more  residual moisture left.

• Pasture cropping systems can provide grain (and out of season fodder) on deep sandy soils and reduce the likelihood of groundwater recharge.
• Potential yield penalties associated with pasture cropping across perennials on deep sandy soils in the west midlands appear to be less than 20%.
• Pastures started competing with the crop for soil water during grain filling, but impacts on soil water and grain yield were generally small given average rainfall in spring.
• During the crop growing season, there was little difference in soil water under annual crop, perennial pasture, and pasture-cropped plots.
• Soil water contents were much lower under pasture and pasture-cropped plots during summer and autumn.

• Yield Prophet® in 2005 had many new features and capabilities and was delivered to 338 paddocks that were subscribed Australia-wide. From 5 April to 1 December, 6813 reports of various types were generated by subscribers, with most around time of top-dressing.
• Final simulated yields for wheat crops, using appropriately measured soil characterisation and initial soil data, fitted observed yields comparable to previous seasons (R2=0.74, 67% of simulated yields within 0.5 t/ha of observed, 98 % within 1.0 t/ha).
• Yield Prophet simulates yield more accurately than it does grain protein content.
• However, overall accuracy for all subscribed crops was lower due to expansion into new regions with less soil characterisation data available.