In this 2013 trial;

• Applying nitrogen 12 weeks after sowing had a similar effect as the same total nitrogen rates applied earlier.
• Nitrogen reduced on oil%, and late N reduced it more than early N.
• Applying more than 25 kg N/ha to ATR Stingray increased yield but was of little economic benefit. 
• Grain yield of Hyola 404RR responded to 150 kg/ha of applied nitrogen, but gross margin was highest at 75 kg N/ha.

In this 2015 trial;

• Economic response plateaued at 75 kg N/ha – lower than grain yield (125 kg N/ha)
• Nitrogen applications at 12 and 14 weeks produced similar canola responses to N applied earlier in the year – but no added benefit.
• OP TT and hybrid RR varieties had a similar response to nitrogen timing and rate.

 

This trial has demonstrated the impact poor nozzle selection and water rates can have on herbicide efficacy. Farmers generally only use one nozzle type for all post emergent herbicide applications and water rates tend to be lower than optimal. It was found that increasing the water rate and selecting a nozzle with a fine droplet pattern and good coverage gave best results for contact herbicides and those poorly translocated within the plant (Group A herbicides eg. Verdict 520). For herbicides that move readily through the plant, coverage is not as essential allowing larger droplet size nozzles to be used without losing efficacy. For smaller grass targets it is even more important to have the correct water rate and nozzle type. Understanding how herbicides work, modes of action and movement within the plant will allow for better water rate and nozzle selection leading to more cost effective weed control and less off target impact.

This trial has demonstrated the impact poor nozzle selection and water rates can have on herbicide efficacy. Farmers generally only use one nozzle type for all post emergent herbicide applications and water rates tend to be lower than optimal. It was found that increasing the water rate and selecting a nozzle with a fine droplet pattern and good coverage gave best results for contact herbicides and those poorly translocated within the plant (Group A herbicides eg. Verdict 520). For herbicides that move readily through the plant, coverage is not as essential allowing larger droplet size nozzles to be used without losing efficacy. For smaller grass targets it is even more important to have the correct water rate and nozzle type. Understanding how herbicides work, modes of action and movement within the plant will allow for better water rate and nozzle selection leading to more cost effective weed control and less off target impact.

Higher rates of Spray.Seed provided significantly greater levels of final ryegrass, radish, canola and lupin control.

The trials clearly showed that high levels of control of resistant radish populations could be achieved with a 2 spray program that used both old and new chemistries. The trials clearly showed that growers don’t need to use 2 applications of pyrasulfatole in one crop to achieve satisfactory control if small weeds are targeted with robust herbicide rates and good spray coverage.

Growers should be using a 2 spray regime on bad wild radish paddocks as a matter of course. Growers should be targeting radish as early as possible i.e. from the 2 leaf stage of the cereal crop and be coming back 3 - 4 weeks later with a second application using alternative modes of action to those used in the first spray. An example of this would be to use Velocity at 2 leaf stage of the crop and follow up with 24,D amine plus Ecopar as a second spray application.

The plan must address the target and the nature of the target. Is the target small or large, short or tall, fine or course, young or mature. Is the target stressed eg. heat, waterlogged, dry or frosted.

The use of cultivation, whether deep or shallow, in 2003, shows no advantage in increasing the grain yield. In fact there may be a penalty in the loss of soil water, particularly at the surface, if the cultivation is performed in a dry autumn, as was the case in 2003.

The data would suggest that Deep Ripping had an effect on increasing the total water content of the soil, thereby making more moisture available to the barley crop during the spring months at a time when the crop was filling the grain. This may have resulted in a higher grain yield for both Ripped and Ripped + Gypsum treatments by comparison to the Direct Drilled and Shallow Cultivation treatments (although yield difference not statistically significant). 

For further conclusions please see the attached trial report.

For results and discussion please see the attached trial report.

• The average yield for the spring wheat trial was 1.89 t/ha for the 2009 season.
• The shorter season varieties Derrimut and Beaufort were the highest yielding varieties with 2.78 and 2.38 t/ha respectively.
• The rapid finish to the season due to the unseasonal hot conditions in early November contributed to the shorter season varieties yielding better than the longer season varieties.
• The rapid finish also reduced grain quality where all varieties were downgraded on test weight and screenings.
• Time of sowing was also identified as a key outcome of this trial. Earlier sown Winter wheat and barley varietiy trials achieved greater yields and water use efficiencies.

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

Artificially applied nitrogen had no significant effect on crop establishment or on early growth as determined from NIR testing 

• For further conclusions please see the attached trial report.

Velocity®, Igran®, Precept® and Lexone® provided the most effective statice control in barley.

The use of, or addition, of Group G herbicides failed to improve control.

Group C herbicides had varied results. Products containing terbutryn and metribuzin achieved a high level of control, but products containing  diuron and bromoxynil did not.

Use of foliar fungicides applied prophylactically at the start of flowering (GS60) gave good control of a late stem rust infection in Yitpi, but were largely uneconomic in 2011.

• Fungicide application for stem rust control was more effective and economic where product application was made prior to visible infection in the crop.
• Where fungicide application was made at an early stage of grian fill (GS 71) disease control of stem rust was inferior to the same products applied at the same rate 16 days earlier at 50% ear emergence (GS 55).
• Higher rates of fungicide (label rates for stem rust control) need to be employed for this disease in order to give effective control; this is particularly the case with fungicides containing a single active ingredient such as tebucanazole (e.g. Folicur) or epoxiconazole (e.g. Optus).
• The strobilurin/triazole mixture of azoxystrobin/cyproconazole (Amistar Xtra) gave excellent stem rust control at its highest rate but its higher cost reduced its economic return.
• The performance of propiconazole (e.g. Tilt) against stem rest was poor in terms of disease control, relative to other products tested.

The project on the strategic use of tillage within no-till systems continued at the 4 sites in 2015: Harden, Daysdale (near Corowa), Thuddungra (near Young) and Berthong (near Cootamundra). Soil physical and chemical properties continued to be monitored throughout 2015. Establishment counts, dry matter and grain yields were also measured. The final harvest for the sites occurred in December 2015, except at the Daysdale site where we grew a vetch brown manure crop that was cut for dry matter in October. The final soil sampling at all sites will take place in autumn 2016. 

• Think of a fallow as a risk reducing investment for your property.
• Soil testing after chemical fallow is essential to determine the starting point of available nutrients in the soil.
• Good agronomic practices that maximise plant health and growth will allow crops to use water more effectively, improving yield potential.
• Weed free fallows mean increased moisture conservation leading to potentially higher yielding crops for the following year and more profitable rotations.
• The use of a residual herbicide to help suppress weeds over summer will be beneficial.
• If this trial was to be repeated, results will vary given different seasons and different soil types

• Maximise wheat WUE by ensuring as much crop flowers during the optimal period as possible – sow on time or early!
• Early sown, slow maturing varieties (winter and spring) yield as well as or better than faster maturing varieties sown later
• Including an early sown variety in a cropping program can greatly increase whole-farm yield

• Fertiliser nitrogen (N) rates should be tailored to suit paddock history and soil mineral N levels at sowing.
• Sorghum yields without N fertiliser, although high in a favourable season, were still well below those achieved using additional N fertiliser.
• At Tamworth, in-season rainfall ideally suited a split-N application strategy resulting in the highest yields.
• At Breeza, drier conditions meant that neither split N application nor slowrelease N products boosted grain yields above those reached using urea all applied at sowing.
• Gross margins for most alternative N strategies were greater than that achieved when no N was applied.
   

• Fertiliser nitrogen (N) rates tailored to suit paddock history/ soil mineral N levels optimised N2O emissions.
• At Tamworth, withholding N fertiliser on a high mineral N soil reduced N2O emissions, but did not optimise grain yield.
• At Breeza, most strategies of urea + nitrification inhibitor, polymer-coated urea and split N application substantially reduced N2O emissions. Most alternatives produced similar grain yields to the current practice of urea all applied at sowing, so the N2O emissions intensity per tonne of grain produced was also reduced.
• A 1:3 blend of urea + polymer-coated urea all applied at sowing, increased N2O emissions compared with the urea all at sowing treatment. The treatment also reduced grain yield, so potential slow-release treatments need to be carefully evaluated from both an N2O emissions and grain production point of view.

• Fertiliser nitrogen (N) rates tailored to suit paddock history/ soil mineral N levels optimised N2O emissions.
• At Tamworth, withholding N fertiliser on a high mineral N soil reduced N2O emissions, but did not optimise grain yield.
• At Breeza, most strategies of urea + nitrification inhibitor, polymer-coated urea and split N application substantially reduced N2O emissions. Most alternatives produced similar grain yields to the current practice of urea all applied at sowing, so the N2O emissions intensity per tonne of grain produced was also reduced.
• A 1:3 blend of urea + polymer-coated urea all applied at sowing, increased N2O emissions compared with the urea all at sowing treatment. The treatment also reduced grain yield, so potential slow-release treatments need to be carefully evaluated from both an N2O emissions and grain production point of view.

• Fertiliser nitrogen (N) rates tailored to suit paddock history/ soil mineral N levels optimised N2O emissions.
• At Tamworth, withholding N fertiliser on a high mineral N soil reduced N2O emissions, but did not optimise grain yield.
• At Breeza, most strategies of urea + nitrification inhibitor, polymer-coated urea and split N application substantially reduced N2O emissions. Most alternatives produced similar grain yields to the current practice of urea all applied at sowing, so the N2O emissions intensity per tonne of grain produced was also reduced.
• A 1:3 blend of urea + polymer-coated urea all applied at sowing, increased N2O emissions compared with the urea all at sowing treatment. The treatment also reduced grain yield, so potential slow-release treatments need to be carefully evaluated from both an N2O emissions and grain production point of view.

• Very dry conditions during the 2013−14 summer meant that much of the nitrogen (N) fertiliser applied was not taken up by the sorghum crop, especially if it had been applied in-crop at booting. Between 46–65% of the applied N remained in the soil at harvest in 2013−14.
• A following crop of unfertilised sorghum accessed the remaining N for crop growth and, at rates of 100 kg N/ha and above in the 2013−14 crop, increased grain yield and protein above the control. Late N application by topdressing in the 2013−14 crop gave similar crop production results to treatments where N was sidebanded at sowing.
• Two-year gross margins showed a significant benefit from N application as urea either at sowing or incrop.
   

• For three seasons, we applied isotope-labelled urea (15N) to sorghum in small (0.75–1.0 m2) plots, then calculated nitrogen (N) recovery by comparing the amount applied with the total 15N found in grain, crop residues and soil.
• Between 55–85% of the N fertiliser applied was recovered at harvest, meaning a 15–45% loss, presumably during wet soil conditions when nitrate denitrification led to N2 and N2O gaseous losses.
• In very wet conditions, little of the applied N remained in the soil at harvest, while in a dry season there was more of the applied N found in the soil at harvest than in the plant.

• Be vigilant and monitor every paddock – they can be very different ƒ
• Do not spray after head emergence – the damage has been done ƒ
• Use early season treatments in the Wimmera and be prepared to apply one spray in crop if it is required. ƒ Stripe rust is a permanent fixture in our environment
• We must all be prepared to control the disease WHEN (not IF) it occurs in 2006.

Grow varieties with the highest SR resistance.

Use a seed dressing on all varieties to protect against SR and smuts.

SR treatments prior to Z39 are unlikely to have a direct yield or income benefit.

• Treatment 1, Nil grazed, moderate stubble yielded the highest, (2.18 t/ha).
• No significant difference in Total Plant Available Water, majority of stored water was below the 50 cm depth.
• There was a significant difference between the eight treatments when comparing available soil nitrogen.
• There was a significant difference in grain quality attributes between the eight stubble treatments.

No real conclusions can be drawn from 2005 data, although the use of scratch tillage at the Inverleigh and Mingay sites showed some promise, but did come at a financial cost if implemented on raised-beds. 

• In 2016, a Decile 10 season, stubble load had no effect on soil mineral nitrogen or soil water.
• The presence of stubble resulted in higher soil mineral nitrogen over the summer fallow period.
• Wheat yields were higher following peas or fallow than they were after wheat or canola in 2016.

• The combination of stubble burning and post-emergent use of a Group A herbicide has effectively controlled ryegrass in plots continuously cropped for 21 years at Condobolin.
• This combination worked well in both cultivated and direct drilled systems.

• Subsoil manuring resulted in consistent grain yield increases across the network of sites in the HRZ of Victoria. In years with drier finishes, the yield of the commercial control crop was constrained due to water deficits during grain filling, while the subsoil manured crops were able to access additional subsoil water. Thus, these crops were not constrained and significantly higher yields were achieved.
• Please see attached trial report for further comments.

• Subsoil manuring resulted in consistent grain yield increases across the network of sites in the HRZ of Victoria. In years with drier finishes, the yield of the commercial control crop was constrained due to water deficits during grain filling, while the subsoil manured crops were able to access additional subsoil water. Thus, these crops were not constrained and significantly higher yields were achieved.
• For further results and discussion please see the attached trial report.

• When superphosphate was the commonly used cropping fertiliser, adequate sulphur nutrition was assured. With the move to high analysis fertiliser such as MAP and DAP sulphur deficiencies have become more common. Of all winter crops canola is most prone to show sulphur deficiency. Canola has high requirements for sulphur.
• It is twice that of pulses and five times greater than wheat for the same yield. At Sea Lake in 1999, a product or group of products that supplied a balanced level of phosphorus, nitrogen and sulphur produced the highest yields, however DAP proved the most economic

Sulfurs and zinc fertiliser increased wheat yields by 120 and 300kg/ha above MAP + urea.

• Durum quality wheat was produced at Lubeck, although high soil N levels pushed protein levels above the maximum for noodle wheat. Milling wheat grown at the same site achieved H2 quality. There was no yield response to N fertiliser at sowing. This demonstration highlights the importance of careful paddock selection when producing specialty wheat.
• While it has been demonstrated that durum wheat can be produced in this part of the Wimmera, durum is a high risk option. A basic economic comparison highlighted the high penalty when downgraded to feed quality if durum specifications are not met.

Canola yields in low and medium rainfall regions of south-western Australia are inherently low and variable.  We have shown that although N fertilisation increases the yield of canola, the yield increases are often relatively low.  Nitrogen also reduces the concentration of oil in the seed of canola and the rate of decrease can be rapid in low rainfall areas. 

The combined effect of N on yield and oil, along with the current payment structure for high oil canola, results in uncertain economic returns from N fertilisation in low to medium rainfall areas. 

We found that 90% of maximum gross margin was achieved at an average nitrogen rate of 17 kg N/ha, and the first 10 kg N/ha gave a return on investment in N greater than $1.50 per $1 in 80% of occurrences (experiments x variety combinations).  The next 20 kg N/ha applied gave a return on investment in N of $1.25 for every $1 spent on N in 80% of occurrences, and further increases were most likely to breakeven. 

We have shown that while farmers should continue to plan to apply N onto canola within the first eight weeks, delaying top-up N until 12 weeks after sowing – when the canola crop is near flowering, is a viable second option which provides some level of risk management for canola growers in low and medium rainfall areas in south-western Australia.

1. Summer cover crops can be very profitable; improving ground cover and increasing fallow water storage in long fallows to improve grain yields and boost returns in northern farming systems.
2. A later spray-out produced additional levels of a cover that is more resilient and stored more water in the longer fallow. Delaying spray-out too long reduced fallow water storage considerably.
3. Using a summer cover crop saved two fallow herbicide sprays and dramatically improved establishment of the subsequent wheat crop.
4. Yields and returns were increased by the cover crops, and yields were well in excess of those expected from the increased soil water storage alone.

The growing season rainfall in 2019 was below average at Perillup, and the summer cropping demonstration did not suffer from water-logging.

Grain growers in this region believe that the soil drying effects from growing summer crops has the greatest potential benefit to winter cropping yields.

In 2019, there was a 770kg/ha barley yield increase above the control from the plots where cowpea was grown in the summer.

There was a 470kg/ha decline in winter barley yield in the plot that was planted to canola between January 30 and May 9, 2019.

Nutritional requirements of summer crops need to be considered when selecting species. Cowpeas fixed useful nitrogen in the 90 growing days.

2019 Demonstration Key Messages

• The growing season rainfall in 2019 was below average at Perillup, and the summer cropping demonstration did not suffer from water-logging.
• Grain growers in this region believe that the soil drying effects from growing summer crops has the greatest potential benefit to winter cropping yields.
• In 2019, there was a 770kg/ha barley yield increase above the control from the plots where cowpea was grown in the summer.
• There was a 470kg/ha decline in winter barley yield in the plot that was planted to canola between January 30 and May 9, 2019.
• Nutritional requirements of summer crops need to be considered when selecting species. Cowpeas fixed useful nitrogen in the 90 growing days.
• The growing season rainfall in 2019 was above average in Williams, and the summer cropping demonstration site was severely water-logged.
• Buster Radish could also be a perfect non-machinery deep ripping tool with its great root system.

2018 Demonstration Key Messages

• The summer cropping demonstration sites were sown at two different timings. The Ryansbrook trial, 35km south west of Kojonup, was sown 4th October 2018 into moisture and the Woodgenellup trial was dry sown on the 30th January 2019 prior to a predicted rainfall event.
• According to our producer rainfall records, since 2003, every 4 out of 5 years they have had summer rainfall events in January and February. Unfortunately, in the 2018/19 summer there was minimal summer rainfall and the summer crops at the Ryansbrook site failed. The C4 grasses (millet and sorghum) persisted better with little to no moisture in the soil profile compared to the broadleaf crop types (canola and cowpea).
• At the Woodgenellup site germination was patchy however, plants have developed reasonable biomass.
• Winter season in-crop measurements will be taken at the Woogenellup site to determine the effect of the summer crop on water logging. Due to the failure of the summer crop at the Ryansbrook site, no further measurements will be taken at this

Forage sorghum and millets achieved the highest yields during the summer forage trial. Lab lab was the most promising forage legume although DM yields were low. Other legumes along with t eh brassicas and winter cereals either failed to emerge or achieved only sparse plant numbers.

• The presence of stubble did not increase stored soil moisture, regardless of the size and number of irrigation events.
• In 2010 additional soil moisture at sowing did not generally increase final grain yield.
• Additional soil moisture can increase crop demand and response to nitrogen.

• Traditionally, forage legumes are sown after the main cropping program is completed and require the application of a pre-sowing knockdown herbicide to control established weeds.  This treatment seriously reduces early winter pasture production which is then compounded by the slow growth rate of legumes under the cold winter conditions. 
• Summer sowing offers early winter grazing in a mixed enterprise farm. The technique has the ability to lift the legume component in a pasture which has degraded through a range of factors such as drought and/or intensive cropping. On a farm without grazing animals, summer sowing can be used to produce a green fallow with a high legume content that can be brown manured to provide  high nitrogen residues  and maximise the organic matter for the benefit of subsequent crops.
• Summer sowing reduces establishment cost by firstly, minimising seed processing particularly in the case of serradella where seed extraction is difficult and expensive and secondly, sowing does not require a pre-sowing application of herbicide.
• The requirement to sow hard-seeded cultivars in summer or early autumn does lose some of the flexibility to tactically respond to seasonal conditions and this needs to be balanced against the clear productivity advantages demonstrated.

• Traditionally, forage legumes are sown after the main cropping program is completed and require the application of a pre-sowing knockdown herbicide to control established weeds.  This treatment seriously reduces early winter pasture production which is then compounded by the slow growth rate of legumes under the cold winter conditions. 
• Summer sowing offers early winter grazing in a mixed enterprise farm. The technique has the ability to lift the legume component in a pasture which has degraded through a range of factors such as drought and/or intensive cropping. On a farm without grazing animals, summer sowing can be used to produce a green fallow with a high legume content that can be brown manured to provide  high nitrogen residues  and maximise the organic matter for the benefit of subsequent crops.
• Summer sowing reduces establishment cost by firstly, minimising seed processing particularly in the case of serradella where seed extraction is difficult and expensive and secondly, sowing does not require a pre-sowing application of herbicide.
• The requirement to sow hard-seeded cultivars in summer or early autumn does lose some of the flexibility to tactically respond to seasonal conditions and this needs to be balanced against the clear productivity advantages demonstrated.

• The results for summer sowing into an established perennial grass pasture were encouraging in a season with minimal spring rainfall. The results were negatively impacted by the low rainfall in spring. Drilling pod was more successful than broadcasting pod and then using animals to trample it into the soil.
• This was the first summer sowing trial into perennial grasses in WA so it is too early to develop recommendations, but it appears that you need to use 20 to 40 kg pod/ha to achieve a good seedbank. The mid-March sowing time is at the end of the ‘sowing window’ for summer sowing. Sowing in early February is desirable to maximize the time for hardseed breakdown.
• With summer sowing using pod rather than seed there is no need for de-hulling, so there is a cost saving per kilogram, but higher sowing rates are required as the seedlings need to compete with annual grasses, broadleaf weeds as well as the perennial grasses. The summer sowing method requires relatively high sowing rates and the concept relies to a large extent on farmers producing hard-seeded serradella pod on-farm at a low cost.After these promising results in 2010, similar trials will be undertaken in 2011 with local producers.

• The results for summer sowing into an established perennial grass pasture were encouraging in a season with minimal spring rainfall.  The results were negatively impacted by the low rainfall in spring.
• Drilling pod was more successful than broadcasting pod and then using animals to trample it into the soil.  This was the first summer sowing trial into perennial grasses in WA so it is too early to develop recommendations, but it appears that you need to use 20 to 40 kg pod/ha to achieve a good seedbank.  The mid-March sowing time is at the end of the ‘sowing window’ for summer sowing.  Sowing in early February is desirable to maximize the time for hardseed breakdown.
• With summer sowing using pod rather than seed there is no need for de-hulling, so there is a cost saving per kilogram, but higher sowing rates are required as the seedlings need to compete with annual grasses, broadleaf weeds as well as the perennial grasses.  The summer sowing method requires relatively high sowing rates and the concept relies to a large extent on farmers producing hard-seeded serradella pod on-farm at a low cost.
• After these promising results in 2010, similar trials will be undertaken in 2011 with local producers.

Results from a demonstration in December of 2012 suggest weed control had an impact on stored soil moisture and consequent yield in 2013 across a range of soil types at seven locations across the Eastern Wheatbelt. Another factor that could have been quantified in this work, was the effect of weed control on nitrogen status (and consequent effect of N on yield). Opening values were collected at the beginning of the trial but no closing N values were measured. Removing summer weeds has an impact on the nitrogen levels in the soil, and this will be further quantified with more field work in 2014.

• Controlling summer weeds improves crop yield.
• Summer weeds like Heliotrope use large amounts of stored soil water and nitrogen, which is then not available to the following crop.

• The crop reached 100% efficiency rating according to WUE principles.
• In years with low rainfall agronomic practices aimed at optimising produciton are unlikely to have any special benefits.
• It is only in years with average to above average rain that limiting factors can start to be identified.

During 2006 and 2007, a field trial designed to quantify the effect of two different surface drainage strategies of pasture (hump & hollow and raised beds) on farm productivity, profitability and sustainability was conducted on a commercial farm near Derrinallum. Under the rainfall conditions experienced for the two years of the trial, it is concluded that the use of raised beds for the growing of pastures for grazing has little to offer the sheep industry. On the basis of the data obtained in this trial, it is recommended that the hump & hollow system is the preferred method of surface drainage for sheep grazing systems in this environment and should be promoted in the region. Major findings included:

• In both years, total annual pasture dry matter (DM) yields from the raised bed treatment were substantially less than for the undrained and the hump & hollow treatments.
• In the drought year of 2006 the raised bed treatment grew 37% (2.8 t DM/ha) less while the hump & hollow treatment grew only 7% (0.6 t DM/ha) less than the undrained (total of 7.6 t DM/ha).
• In the higher rainfall 2007 year the raised bed treatment produced 15% (1.6 t DM/ha) less pasture than the undrained. In contrast, the hump & hollow grew 10% (1.1 t DM/ha) more than the undrained (total of 10.7 t DM/ha) in 2007.
• The reasons for the lower than expected pasture yields on the raised beds are speculated to be a combination of low yields in the furrows, poorer plant establishment and density on the beds, and a reduction in the water holding capacity of the soil relative to the other treatments.
• Soil physical health was however considerably better on the raised beds than the other treatments. Aeration porosities at field capacity in November 2007 were a very healthy 16.3% in the raised beds, a moderate 11.8% for the hump & hollow and a poor 7.0% for the undrained.
• No significant differences in ewe or lamb weights at weaning were found between treatments in either year. This was most likely due to the set stocked sheep having pasture on offer in excess of requirements for most of the spring. In 2006 however, the raised beds were stocked at around 1 ewe/ha less due to the lower pasture growth rates.
• From a catchment and general environmental health perspective, the water run‐off results raise some concerns about the environmental impact of growing and grazing pastures on raised beds.
• The raised beds proved to be very effective in removing excess water from the pasture. Over 2007, the raised bed treatment (47.1 mm) had 170% more runoff water than the undrained (17.4 mm) while the hump & hollow (26.7 mm) had 53% more runoff.
• Both drainage treatments had considerably higher concentrations of, and total loads of phosphorus (P) and nitrogen (N) in runoff water. Of particular concern were the losses of 0.5 and 0.4 kg P/ha for the raised bed and hump & hollow treatments respectively compared to 0.1 kg P/ha for the undrained in 2007. For N, corresponding losses were 6.3, 2.1 and 0.9 kg N/ha for the raised beds, hump & hollow and undrained respectively.
• It is recommended that if raised beds are to be used for grazed pastures, then the best practice recommendations developed for raised bed cropping also be applied to pasture.

Both invertebrate pests and beneficials are found in association with chaff in paddocks. However, the species composition depends on the location of the paddock. Paddocks located in the Albany port zone are more likely to have higher densities of pests associated with chaff, whereas paddocks located in the Kwinana East port zone had the least pest densities and highest numbers of seed-harvesting ants associated with chaff.

The most abundant beneficials were weed seed harvesting ants which were found in close association with chaff. As these ants predate on weed seeds and live in holes in the ground, it is unlikely they are using chaff as a refuge, it is more probable that they are foraging in the chaff. This trend presents an opportunity to investigate in greater detail whether seed-harvesting ants provide an economic benefit to growers by consuming weed seeds from HWSC systems left to rot-in-situ.

Pitfall trapping was able to capture a higher diversity of invertebrate species than direct sampling of chaff. As pitfall trapping did not rely on samplers locating an invertebrate, it is more likely to be a more accurate representation of species presence and diversity in a paddock. However, this technique does rely on invertebrates moving and falling into a pitfall trap.

Leaving chaff to rot-in-situ does not affect abundances of pests such as desiantha weevil. However, other pests do use chaff as refuges. For instance, pest beetles, Rutherglen bugs, European earwigs were found in association with chaff. It is unlikely these species are feeding on chaff, but rather are using chaff as a refuge. This survey was not able to determine if long term retention of chaff will increase abundances of these pests.

In 2001 the Rankins Springs CWFS plan to sow lupins across all treatments with the exception of organic treatment, which is considering vetch. The original plan was for barley in 2001, but at the last meeting a motion was passed for lupins to be sown this year to aid soil nitrogen levels.

The Sustainable Land Management Demonstration Sites in the Mallee have been established to demonstrate improved farming practices through a better understanding of crop management and water use to reduce groundwater recharge and soil erosion.

• For this trial, the N-calculator prediction optimised yield and gross margin in Mace wheat.
• In Season N Calculator model predictions were
• Getting mid-season N decisions right can have a significant impact on profitability since optimal top up N rates indicatively increased yields by 480 kg per hectare and net returns by $70 per hectare.
• The value of split N applications was shown and the trial provides more weight to the building confidence that the N calculator can provide real and robust N recommendations that are not in excess of crop requirement and produce maximum or near maximum margin returns from mid-season N applications.

• N Calculator recommendation was accurate for 9 weeks after sowing (WAS) application with additional nitrogen not increasing yeild. The recommendation was slightly below optimumfor 7 WAS.
• Achieving close to the target 10.5% protein indicates that recommended N rates were utilised to optimise growth and yeild and application of N was not deficient or excessive.
• This provides confidence to incorporate the use of N Gauges and the N-calculator to assist in making N application decisions to wheat crops during the season based on the growth status of the crop.
• Summit will continue further testing of the N Calculator under differedt seasonal consitions in the noerthern Wheatbelt and the effect if timining of NVDI assessment and N-Calculator recommendations on yield response to in season N applications.  

• Nuseed Diamond achieved 5 t/ha grain yield from early sowing (watered for germination on 12 April).
• The high yield of Nuseed Diamond was due to its high biomass accumulation and high harvest index. ATR BonitoA was the lowest yielding variety, largely because it accumulated less biomass than hybrid non-TT varieties.
• Split nitrogen application resulted in higher grain yield than all nitrogen applied at sowing or all nitrogen
delayed to the 8-leaf stage.

• Pioneer® 45Y88 (CL) was the highest yielding variety, averaging over 4 t/ha, with Nuseed Diamond and Pioneer® 45Y25 (RR) also achieving high yields.
• Sowing on 5 April resulted in higher grain yield, reduced lodging and lower oil content compared with sowing on 26 April.
• A plant population of 35–56 plants/m2 resulted in higher grain yields than populations of 18 plants/m2 or 68 plants/m2.
• Applying 200 kg N/ha resulted in higher grain yields than 150 kg N/ha when the soil available nitrogen (N) at sowing was 64 kg/ha. Nitrogen rates above 200 kg N/ha resulted in no extra yield.
• Increasing N application rates above 200 kg N/ha reduced oil concentration.
• Crop lodging increased with plant populations above 35 plants/m2 and N rates above 150 kg N/ha.

• Correct varietal selection and optimal agronomic management can result in irrigated wheat yields of over 10 t/ha.
• LongReach CobraA, LongReach TrojanA and BeckomA were the highest yielding varieties.
• Delaying nitrogen fertiliser application by applying the greatest amount at booting was shown to improve grain protein concentration and reduce lodging compared with applying more nitrogen at sowing.
• A plant population of 120 plants/m2 was shown to yield more than higher plant populations whilst also minimising lodging.

In this trial we observed no response to the non-nitrogen test products, either on the low or high fertilizer at seeding treatments.  However we cannot say that they will not work under other site, season and management conditions.  Unfortunately the promoters can rightly say that we did not give their product the best opportunity to perform and so it was an invalid test.

Such a reply has implications for the promoters rather than the testers. The promoters have an obligation to state under what conditions they expect their product to work and those conditions  have to be readily recognized by potential local users. It is not good enough to list a range of processes which the product “improves” or even to quote circumstances from elsewhere where the product has worked. Any new product (and agronomic practice for that matter) has to be  extensively tested under local conditions so that the promoters can say what the chances of success are if used by local growers.

We, the testers are able to state that the product did not work under our conditions and in the Popper sense of “falsification” have disproved any statement about how generally useful the product might be. That is, 100% of our observations say it does not work, but that is hardly useful. We could have had a drought year and nothing would have worked. We could have been wiped out by      frost or we may have chosen a site with the wrong levels of fertility. We did not test across a full range of conditions and so have too limited information for invalidating the all claims made for the products. This problem is equally true for validation by the product developers.

Products MUST be tested across a wide range of local conditions before it can be promoted with confidence to the broader agricultural community.

In short, any new product (or agronomic practice) requires a major investment in validation trials which are ranged across the full set of management, site and season conditions experienced in the new environment. Otherwise, general promotion of those products should not be believed until such work has been done.

• From the 10% challenge came a feast of ideas, usually with one or two key focus points considered valuable to the farming operation, with farmers agreeing with or discussing other ideas as they were shared within the groups.
• The information arising from these sessions has been presented at farmer meetings for local groups to discuss in relation to their own farming systems. Further development and extension of this work and ‘rules of thumb’ will be investigated with the discussion
• groups and delivered at local farmer meetings.

There are substantial benefits from GM herbicide tolerant canola when compared with alternative non-GM weed control systems. These include more effective weed control, reduced pesticide use, reducted use of cultivation, improved yields, reduced risk of herbicide resistance and a reduction in the environmental 'footprint'.

Topdressing pulses with nitrogen does not pay; inoculation does. Nitrogen topdressing of pulses resulted in little or no net growth or yield benefit. Inoculating pulses is most effective if the soil is moist and if residual soil nitrogen and soil rhizobia populations are low. The current study indicated that a return on investment of up to $60 can be achieved from the inoculation of chickpeas in the absence of soil rhizobia.

The results of this study suggests:

• Whilst the streaming of UAN modestly reduced annual ryegrass N percentage in the tissue, no difference in annual ryegrass biomass or seed production was evident.
• Nitrogen placement did not affect Wheat biomass accumulation (NDVI results), however modest differences in Canopy closure percentage existed. UAN rate and timing however had a greater effect on wheat biomass (NDVI results and wheat biomass cut) and percent canopy closure.
• UAN rate, UAN timing (plus interaction of UAN timing and placement) were found to have significantly affected Radiation interception of the crop in the absence of weeds.
• Nitrogen placement affected the yield and protein content of the grain produced.

Whilst the streaming of UAN modestly reduced annual ryegrass (ARG) N percentage in the tissue, no difference in annual ryegrass seed production was evident. Due to the dry conditions in 2019, the application of supplementary UAN did not significantly increase wheat canopy closure or yield. Interestingly, UAN placement did affect the total nitrogen uptake in the ryegrass population, potentially increasing ARG competitiveness. Banding UAN to the crop row was found to increase ARG N uptake. As seeding systems provide herbicide free bands on otherwise herbicide treated soil for safe wheat establishment it was found that the majority of ARG emerged from these crop rows. Concentrating N applications to these regions may have inadvertently increased the N uptake in ARG. This study was conducted in York over the 2018 and 2019 seasons. A multi- environment trial analysis for the combined data to be completed.

•  Use the tools – they are easy to use and real eye opener on what acidity can be costing you.
• Significant yield improvements have been seen when cropped paddocks are limed.
• Make liming a part of your annual program. 
   

A harvest-time knockdown to kill summer weeds has been shown to conserve significant soil moisture prior to seeding in a series of trials across the eastern wheatbelt this year.

• Wider row spacings (300mm vs 200mm) significantly reduced yield when averaged across three wheat varieties and two nitrogen timings. Wider rows reduced crop income in excess of $100/ha.
• The cultivar (variety) grown was just as important as row spacing in determining yield. When averaged across the different row spacings and nitrogen timing treatments, Kellalac yielded 4.61t/ha, Bolac 5.12t/ha and Beaufort 5.72t/ha.
• Tiller counts were significantly less when moving to the wider row spacing widths. At the 200 mm row width, Beaufort had significantly fewer tillers/m2 than Kellalac, which in turn had significantly fewer tillers than Bolac. When the row spacing increased to 300mm, both Kellalac and Bolac had a significant reduction in tillers, while counts for Beaufort did not drop significantly. Kellalac had the fewest number of tillers at the wider row spacing.
• Row widths of 200mm with nitrogen applied at GS00 & GS31, tended to give higher yields (5.30t/ha & 5.33t/ha respectively) when compared to a row spacing of 300mm with nitrogen applied at GS00 (5.09t/ha) & GS31 (4.88t/ha).

• In 2015, two spring irrigations produced the highest wheat grain yield (7.61 t/ha), but one irrigation provided the highest water use efficiency (1.7 t/ML).
• Ponding irrigation water for 48 hours to induce waterlogging did not reduce grain yield in this experiment, but increased water use and reduced water use efficiency by 25%.
• If the number of spring irrigations is limited, it is important to find a balance between irrigating before significant moisture stress occurs and ensuring adequate moisture is available during flowering.
   

• Suntop was the highest yielding variety (4.48 t/ha).
• Lancer achieved high protein, high test weight and low screenings at all nitrogen application rates.
• Grain yield increased as nitrogen application rates increased, but there was no significant increase in yield above 20 kg N/ha applied nitrogen.
• Applying 160 kg N/ha resulted in a yield decrease.

For results and discussion please see the attached trial report.

Rhizobium inoculation improved faba bean yields by 9-30% above uninoculated plants. Higher rates of rhizobium inoculum show a trend to further increase yield though this was not significant. Rhizobium inoculation should be considered as cheap insurance against conditions not favourable to nitrogen supply, particularly during winter.

• Early sown (9 April) Pioneer 45Y88 (CL) yielded similarly to later sown (20 April) Pioneer 45Y88 (CL) and Hyola 575CL.
• The irrigation treatment that stored 20mm plant available water did not increase grain yield or oil concentration.
• The maturity biomass was higher from the later sowing date, but the harvest index was slightly higher from the early sowing date.

 

• Variety phenology and sowing date need to match to avoid plants flowering and podding during periods of severe frost. The highest yield in 2017 came from the 6 April sowing of the long season varieties Archer and ATR WahooA that flowered in early August.

• ATR Stingray and Nuseed® Diamond flowered earlier than the optimum start of flowering (OSF) date (28 July) from both the 6 April and 20 April sowing dates with significant frost damage incurred at both sowing dates.

• Canola varieties have the ability to recover from severe frost damage where soil water is not limited.

• Cereal stubble should be thought of as a source of C for microbes, not as a source of N for crops. In the Mallee under no-till systems, only 1-2% of the N requirement of wheat crops is derived from the previous wheat stubble.
• N tie-up in cropping soils is only a temporary constraint as the immobilised N will be released through microbial turnover, generally later in the crop season in spring.
• N tie-up by cereal residue is not just a problem following incorporation – it also occurs in surface-retained and standing-stubble systems.
• Management of tie-up is reasonably straightforward – supply more N (5 kg N for each t/ha of cereal residue) and supply it early to avoid impacts of N tie-up on crop yield and protein.
• Deep-banding N can improve the N uptake, yield and protein of crops, especially in stubble-retained systems.

• Varietal selection again proved to be the major factor in achieving higher wheat yields in the second year of experiments in irrigated wheat production at Leeton.
• CobraA was the highest yielding variety in this experiment but CorackA, SuntopA and the durum breeding line 280913 also performed very well.
• Correct nitrogen timing significantly increased grain yield, grain protein and significantly reduced lodging.
• Managing plant population also significantly reduced lodging

The practical implications of harvest weed seed control are a more resilient farming system with some insurance against further resistance evolution. The combination of effective herbicide use, plus harvest weed seed control techniques has been shown to reduce and maintain weed populations at very low densities. In cropping systems, low weed densities, regardless of their herbicide resistance status, allows flexibility in crop choice, seeding time and herbicide use. This flexibility provides growers with the capacity to readily adjust farming practices in tune with seasonal and market considerations.

• A series of field experiments was conducted on the Eyre Peninsula to examine the effects of herbicides on the nutrition of treated crops.
• Experiments investigating the effect of metsulfuron-methyl and chlorsulfuron on crop performance are reported here.
• The parameters measured were shoot growth, tissue nutrient concentration and grain yield.
• Application of metsulfuron-methyl to manganese-deficient barley and chlorsulfuron to zinc-deficient wheat crops caused yield penalties by intensifying the respective deficiencies.
• Yields were not affected when the herbicides were applied to plots which were trace element adequate.
• The consequences are that if adequate fertiliser regimes are not employed in the field, yield benefits due to weed control may be eroded by losses due to aggravated micronutrient deficiencies.

1. Most farming systems extract more nutrients than are supplied by common fertilisation strategies.
2. Increasing the frequency of legumes doesn’t necessarily reduce nitrogen inputs required across the crop sequence and increases export of potassium.
3. Higher fertiliser application has maintained higher soil mineral nitrogen levels but rarely increased grain yield or total system nitrogen use.

The results suggest using nitrogen and/or increasing sowing rates will increase drymatter available for grazing at late tillering but if grazed these treatments will have a positive impact on grain yield.

• Increasing siphon pipe diameter used for flood irrigation, from 42 mm to 63 mm halved irrigation time, reduced the amount of water applied per irrigation, and increased cotton lint yield and lint quality.
• The longer irrigation time increased soil water content for up to a week post irrigation, and likely led to waterlogging effects on cotton plant growth.
• The maximum daily nitrous oxide (N2O) emissions occurred in response to the first irrigation event after pre-plant nitrogen (N) application and continued for more than a week after irrigation.
• The highest N2O emissions in each plot came from the non-irrigated side of the plant bed where surface soil nitrate concentrations were also highest – despite pre-plant N fertiliser being applied evenly to both sides of the plant bed.
• Postharvest, excess soil nitrate was found to depth in the non-irrigated side of the plant bed, indicating that nitrate moved both sideways and downwards during the season.
   

• The high input pasture treatment provided the opportunity to carry 8 DSE/ha with an estimated gross margin of $240/ha, however it was unable to utilise plant available water above 50% of potential water use efficiency (WUE).

• It appears that once disease suppression is achieved in low rainfall farming systems of upper EP and inoculum levels are low, it is quite robust and will be maintained despite systems with substantially different amounts of mineral N.
• Fallow, Medic/Fallow and Peas all lowered rhizoctonia inoculum levels in 2010, and Fallow and Peas lowered levels in 2009.
• Continuous cereals produced the highest inoculum levels but all levels were low at this site.
• Even high mineral N (118 kg N/ha) in the top 60 cm (measured in April after spraytopped medic) did not increase Rhizoctonia patches in 2010.
• Trichoderma fungus and the beneficial PEM microbes are present in the MAC N12 system.

• Soil mineral nitrogen (N) values were low across all sites, which was indicative of the wet seasonal conditions and high nitrogen losses.
• There were no significant differences in mineral nitrogen values between the stubble treatments due to high variability (likely due to transient waterlogging across the sites).
• The project has been extended to enable the research to be repeated during 2017.

• While significant differences in mineral nitrogen (N) values were measured between stubble treatments, these differences were small and unlikely to elicit a plant growth response.
• No consistent trends were observed between trial sites.
• Delayed plant growth and development under no-till stubble retained (NTSR) systems in the Riverine Plains region is unlikely to be due to decreased mineral nitrogen availability as a result of immobilisation.

The data from this trial supports the theory that an early sowing date will increase DM and total N fixation in Percy and Morava.

• Summer weeds use significatn amounts of stored soil water.
• The long-term impact of summer weeds amounts to a loss in production of 1t/ha in cereal yield in the southern Mallee.
• In a changed climate scenario, where our region is likely to receive more summer rain at the expense of spring rain, the impact of summer weeds on potential crop yield is likely to increase.

• Nitrogen fertiliser management influences crop nitrogen uptake at defoliation and cotton lint yield
• Irrigation management did not influence crop nitrogen uptake at defoliation, but significantly influenced cotton lint yield.
• The apparent nitrogen fertiliser recovery was 46% where the optimum fertiliser nitrogen rate was applied
• Seed nitrogen concentration and nitrogen removal was influenced by nitrogen fertiliser application rate, but the effect was not consistent with rate.

• For a wheat crop with an average yield of 4.5–5t/ha, increasing the rate of nitrogen (N) applied (40 and 80 extra kilograms of nitrogen per hectare above the farm standard) significantly increased dry matter (DM) accumulation, crop height and final yield of first wheat following canola.
• Applying a plant growth regulator (PGR) (Moddus + chlormequat) reduced crop height by 3cm and significantly decreased DM production.
• A small, non-significant yield reduction was measured with PGR application, which was similar to that observed during 2014, when yields were in the 5–6t/ha range. Conversely, during 2015, there was a positive yield effect of 0.1t/ha, when average crop yield was approximately 3t/ha.
• Although differences were small, the PGR application significantly increased screenings and decreased test weight, results that are not in line with the effects observed during 2015.
• After three years of trials there is no evidence to suggest PGR application has delivered any positive yield effects or consistent quality effects.
• In all three years of trials, PGR application showed a trend to reduce DM, which was significant in 2016.

• In two first-wheat trials yielding 4.5-5.0t/ha, the application of a plant growth regulator (PGR) delivered no benefits in terms of yield or grain quality.
• The PGR application did not interact with additional nitrogen applied in terms of yield or quality.
• The impact of PGR application on crop height was greater than the impact of nitrogen timing; however, the differences in height were small.
• The grower-applied nitrogen at Redlands, at a rate of 75kg N/ha, and at Yarrawongs at a rat eof 100kg N/ha, were shown to be optimum in terms of yield and quality, with no extra yield or protein resulting from the higher nitrogen application rates with Corack and Wedgetail.

• With an average yield of almost 3t/ha, increasing the rate of nitrogen applied (40 and 80 extra kg N/ha) did not affect dry matter (DM) accumulation, crop height or fianl yield of first wheat following canola.
• Applying a plant growth regulator (PGR) decreased crop height, but did not influence DM or grain yield.
• Although differences were small, PGR application significantly decreased screenings and increased test weight.
• Applying the PGR also decreased crop reflectance, measured as normalised difference vegetation index (NDVI) during stem elongation (GS39); a result also observed during 2013 and 2014.
• The lower NDVI readings suggest PGR altered greeness of the crop canopy or the orientation of the leaves, decreasing crop reflectance.

• While machinery ownership and management has its complexities, being aware of some of the aspects that directly impact upon its economic efficiency is a step in the right direction. Consideration of work rate efficiency and timeliness versus over-capitalisation and ultimate returns achieved by the system is very important.
• The Farming Systems Project has identified that the cost profile of the different farming systems from most to least costly is, Fuel Burner, Hungry Sheep, Reduced Till and Zero Till.

• Select crops best adapted to the soil and climatic conditions of your region; faba bean is the pulse crop best adapted to soils prone to waterlogging.
• Avoid soils with acidic subsurface layers and/or shallow topsoil that limit root development and impermeable subsoil that restrict drainage.
• Test soil pH at 5cm intervals to a depth of 20 cm, to detect subsurface acidity.
• Select paddocks at least two years before sowing acid-sensitive crops to allow time for applied lime to react and increase soil pH, if required.
• Sow early in the recommended sowing window for your location, to encourage effective nodulation, early vigour and biomass accumulation before the onset of cold, wet conditions.

Executive summary

Recently interest in the role of renovation cropping in the farming systems of the Western Australian wheatbelt has increased.  It has been proposed as a means of addressing the apparent decline in soil quality in some intensively cropped areas and the increased incidence of herbicide resistance. 

Renovation cropping involves either turning a crop into the soil at flowering or cutting the crop and leaving it on the soil surface.   This is done to maximise the amount of organic matter added to the soil and to control weeds most effectively.  In the Western Australian wheatbelt the focus has been on using pulses, although a range of crops can be used.  The pulse phase of a rotation is favoured as pulses improve the nitrogen status of the soil. In addition the returns to pulses are lower relative to cereals and canola, so the forgone profit in the year of renovation cropping is lowest.

Renovation cropping leads to changes in soil conditions that persist for at least the following season.  It reduces weed numbers in the following crop by reducing seed set, increases the availability of nutrients and may improve soil structure.  Lower weed numbers reduce the carry-over of root diseases thus providing a disease break for the following cereal crop.  Recent trials have shown likely yield increases of 20-30% above those after a pulse crop and increased grain protein levels in the following cereal.

The main cost of green manuring is the income lost by sacrificing grain production.  The loss in income plus any additional costs associated with soil renovation need to be recouped in the following season(s).  Therefore the income from the yield increase(s) in the subsequent year(s) needs to be equal to or greater than the total costs of renovation, including the income forgone.

Despite the increase in interest in renovation cropping, no comprehensive economic analysis has been undertaken to determine its role in Western Australian farming systems.  This study investigates circumstances under which renovation cropping is likely to be profitable and estimates the needed increase in farm profit, given the variability of yields that result from seasonal influences.

To investigate the consequence of risky yields historical rainfall data was used to generate yield distributions for different rainfall zones, soil types and crops.  The yield distributions were used as input to a simulation model to determine the distribution of income, resulting from renovation cropping, in a lupin:wheat:wheat rotation.  The mean yield boost resulting from renovation cropping was estimated to be 3% based on trial results (F. Hoyle, pers. comm.). 

The results of the analysis showed that there is a 30-40% chance of increasing profit if yield is increased by 30% on average.  However, the results were very sensitive to the average increase in yield.  The probability that profit will be increased was halved when yield boost was reduced to 20%. 

The yield increase required to make renovation cropping profitable can vary between 100% under the worst case and below 10% under the best case.  The variability depends on grain prices, grain yield in the renovation phase (if a commercial crop had been was harvested), and the cost of renovation and grain yields in the following crop phase.

The likelihood that profit will be increased depends largely on minimising income forgone relative to the increase in income in the following years.  Therefore green manuring will be most profitable when done in years when the grain yield of the pulse crop is low, and/or when the following cereal yield is very high. 

Weather forecasts are not yet sufficiently developed to predict potentially good years over 12 months ahead, so renovation needs to be undertaken in poor years to maximise the chances of increasing profit.

Identifying poor yielding years prior to renovation does present some difficulty although weather forecasts may improve the chances of undertaking renovation in the 'right' year.  .  Also yield potential is determined directly by biomass of the crop, so this may be used as an early indicator of yield.  Where waterlogging or disease has caused low vegetative growth, resistant weeds are widespread in a paddock, or where frost has damaged the crop green manuring is more likely to be a profitable option. 

This suggests a role for tactical use of renovation cropping so that it is undertaken in years where the forgone income is minimised (i.e. it is done in poor yielding years).  The results of the analysis show that only small yield increases in the following cereal crop are necessary to break even in these circumstances. 

The analysis highlighted gaps in the knowledge of the impact of renovation cropping that may be important for more comprehensive economic analysis, or information that may improve the grower’s ability to undertake the practice profitably.  Further research into green manuring could include:

• Determining whether the profitability of green manuring can be increased using long term weather forecasts.  Improving the estimates of the probability of achieving different yields may allow farmers to renovate soils in years that have lower risk.
• More information on the effects of green manuring on yield and protein for different crops under different conditions is required to better assess the economic advantages of green manuring
• The profitability of green manuring relative to other methods of improving sustainability of cropping also needs to be addressed.

 

Executive summary

Recently interest in the role of renovation cropping in the farming systems of the Western Australian wheatbelt has increased.  It has been proposed as a means of addressing the apparent decline in soil quality in some intensively cropped areas and the increased incidence of herbicide resistance. 

Renovation cropping involves either turning a crop into the soil at flowering or cutting the crop and leaving it on the soil surface.   This is done to maximise the amount of organic matter added to the soil and to control weeds most effectively.  In the Western Australian wheatbelt the focus has been on using pulses, although a range of crops can be used.  The pulse phase of a rotation is favoured as pulses improve the nitrogen status of the soil. In addition the returns to pulses are lower relative to cereals and canola, so the forgone profit in the year of renovation cropping is lowest.

Renovation cropping leads to changes in soil conditions that persist for at least the following season.  It reduces weed numbers in the following crop by reducing seed set, increases the availability of nutrients and may improve soil structure.  Lower weed numbers reduce the carry-over of root diseases thus providing a disease break for the following cereal crop.  Recent trials have shown likely yield increases of 20-30% above those after a pulse crop and increased grain protein levels in the following cereal.

The main cost of green manuring is the income lost by sacrificing grain production.  The loss in income plus any additional costs associated with soil renovation need to be recouped in the following season(s).  Therefore the income from the yield increase(s) in the subsequent year(s) needs to be equal to or greater than the total costs of renovation, including the income forgone.

Despite the increase in interest in renovation cropping, no comprehensive economic analysis has been undertaken to determine its role in Western Australian farming systems.  This study investigates circumstances under which renovation cropping is likely to be profitable and estimates the needed increase in farm profit, given the variability of yields that result from seasonal influences.

To investigate the consequence of risky yields historical rainfall data was used to generate yield distributions for different rainfall zones, soil types and crops.  The yield distributions were used as input to a simulation model to determine the distribution of income, resulting from renovation cropping, in a lupin:wheat:wheat rotation.  The mean yield boost resulting from renovation cropping was estimated to be 3% based on trial results (F. Hoyle, pers. comm.). 

The results of the analysis showed that there is a 30-40% chance of increasing profit if yield is increased by 30% on average.  However, the results were very sensitive to the average increase in yield.  The probability that profit will be increased was halved when yield boost was reduced to 20%. 

The yield increase required to make renovation cropping profitable can vary between 100% under the worst case and below 10% under the best case.  The variability depends on grain prices, grain yield in the renovation phase (if a commercial crop had been was harvested), and the cost of renovation and grain yields in the following crop phase.

The likelihood that profit will be increased depends largely on minimising income forgone relative to the increase in income in the following years.  Therefore green manuring will be most profitable when done in years when the grain yield of the pulse crop is low, and/or when the following cereal yield is very high. 

Weather forecasts are not yet sufficiently developed to predict potentially good years over 12 months ahead, so renovation needs to be undertaken in poor years to maximise the chances of increasing profit.

Identifying poor yielding years prior to renovation does present some difficulty although weather forecasts may improve the chances of undertaking renovation in the 'right' year.  .  Also yield potential is determined directly by biomass of the crop, so this may be used as an early indicator of yield.  Where waterlogging or disease has caused low vegetative growth, resistant weeds are widespread in a paddock, or where frost has damaged the crop green manuring is more likely to be a profitable option. 

This suggests a role for tactical use of renovation cropping so that it is undertaken in years where the forgone income is minimised (i.e. it is done in poor yielding years).  The results of the analysis show that only small yield increases in the following cereal crop are necessary to break even in these circumstances. 

The analysis highlighted gaps in the knowledge of the impact of renovation cropping that may be important for more comprehensive economic analysis, or information that may improve the grower’s ability to undertake the practice profitably.  Further research into green manuring could include:

• Determining whether the profitability of green manuring can be increased using long term weather forecasts.  Improving the estimates of the probability of achieving different yields may allow farmers to renovate soils in years that have lower risk.
• More information on the effects of green manuring on yield and protein for different crops under different conditions is required to better assess the economic advantages of green manuring
• The profitability of green manuring relative to other methods of improving sustainability of cropping also needs to be addressed.

 

There was a significant response to all nitrogen applications.

In an irrigated trial on Mackellar (feed wheat) at Hagley, Tasmania, plot yields ranged from 6.6 – 9.4 t/ha depending on the level of nitrogen and fungicide input. There was a significant response to nitrogen application, with an optimum that varied from 60 ‐120 kg/ha depending on whether fungicide was applied. There was a significant yield interaction (P=0.003) between the amount of applied nitrogen and the level of fungicide input, whereby the higher the level of applied nitrogen the greater was the need for fungicide input. Without fungicide application at stem elongation the optimum nitrogen input for the crop was 60 kg/ha N; however with fungicide application it was at least 90 kg/ha N. There was a significant increase in grain protein associated with increasing nitrogen level in the range of 60 ‐120 kg/ha N and a significant increase in protein associated with fungicide application.

Six varieties of canola were tested to compare their responsiveness to urea. The varieties selected had different growth patterns, and the slow growing varieties such as the TT types showed a similar response in growth to the other more vigorous types. In this experiment, urea did not increase yield of any of the varieties tested, but oil contents fell for five of the six varieties with added urea, with ATR Hyden the exception. Given the poor yield response, little can be directly interpreted from these results, although it is reasonable to conclude that higher urea rates are less profitable with lower yielding types or on sites with low yield potential.

The SOI phase signal for April-May (available on the last day of May) and subsequent monthly phases can provide useful information on the likelihood for rainfall for the rest of the season. It can be a very useful tool for assessing the risk of topdressing nitrogen fertiliser (especially if it is used in combination with other indicators such as potential of the crop; decile trend and stored soil moisture).