• Removing subsoil compaction is critical and for some soil types can dramatically improve access to deep soil moisture.
• Correctly ground-truthing the depth of the compaction layer can drive the success or failure of ripping outcomes.
• Yield increases at the Goomalling site were largely driven by very deep ripping, with either the very deep ripper or delver, with yield increases of 0.55-0.74 t/ha, an increase of 74-93%. The only other treatment to increase yield was mouldboard ploughing on its own with a 0.44 t/ha, 55% yield increase.

• Despite visual differences there is no major impact on soil structure, water holding capacity or water infiltration from grazing in summer or winter when soils are water logged.
• Grazing in the previous winter or summer does not affect the following crop establishment or grain yield.
• Any yield losses after winter grazing are the result of moisture stress in the period immediately after grazing through to flowering.
• Annual ryegrass and wild raddish populations did not increase because of grazing, although the sites only had low levels of infestation to being with. However, farmer observations do not support this and further work is needed.

• With the current climate trending to decreased seasonal rainfall, each 1% increase in productivity is important.
• Increases in productivity can come from increased yield, more efficient application of inputs, or more timely grain marketing.
• Knowledge on the soil water holding properties, the time when the crop is taking up the most water from the soil and the current yield estimation models allows growers to market grain with more confidence pre harvest.
• Tools such as Yield Prophet, iPaddock Yield, soil moisture Probes and water use efficiency models are all very useful in assisting to predict grain yields with a relatively high level of confidence when accurately set up.
• In this project “iPaddock Yield” provided the greatest level of accuracy in predicting final grain yield on July 31st 2015. The simple French & Shultz “Broken Stick” model was very close to the accuracy of the ipaddock Yield at 77% & 74% accuracy.
• When there is confidence in the early to mid-season yield prediction combined with accurate soil Nitrogen testing and modeling, there is a greater chance of maximizing profits from applied nitrogen.

Soil moisture retention granules did not influence wheat grain yield or quality at Hart in 2010.

Soil moisture retention granules did not influence wheat grain yield at Hart in 2009.

• This is the second season in which this trial has been run and the fallow has yielded higher than continuous cropping in both 2011 (0.4 t/ha) and 2012 (0.2 t/ha). Other research indicates that fallows produce yield benefits in dry seasons which are not the case in the crop in 2011, which received 231mm for the growing season. The yield difference in 2011 was therefore more likely to have been the result of extra nitrogen in the soil, or weed or disease control rather than soil water benefits, however, these were not measured.
• Farm economics need to be carefully considered before implementing a fallow, the opportunity cost of not producing a crop needs to be weighed up, and benefits of yield, extra N, weed control and disease breaks carefully factored into the decision. 
• In 2012 the yield benefit from fallow was 0.2 t/ha and likely to be due to extra nitrogen and water being present in the soil. However, this is an unreplicated demonstration and thus it is hard to tell whether yield differences are the result of fallow or random variation in the paddock. 

A network of soil moisture probes and Yield Prophet sites has been established across the Esperance, Albany, Kwinana East and Kwinana West port zones with the aim of providing public access to real-time soil moisture and weather data and periodic Yield Prophet reports to aid in-crop decision making, with particular reference to top-up nitrogen decisions.

Growers and agronomists have commented that the sites provided useful supporting information when making top-up nitrogen decisions, with the soil moisture probes providing additional confidence in the model’s output. Continuation of the Yield Prophet sites and soil moisture data recording and analysis will continue in 2015 across the Esperance/Albany and Kwinana East port zones, with the aim of further refining the sites to improve their accuracy and providing access to Yield Prophet and soil moisture information in a more user-friendly format.

• Wheat yield increased from 2.6 t/ha in controls to 3.2 t/ha in plots receiving the equivalent of summer rainfall decile 5 (50mm) or decile 9 (100mm) in a single event in February.
• Stubble treatments (bare ground control, standing 2 t stubble/ha, flat 2 t stubble/ha, flat 5 t stubble/ha) did not affect the dynamics of soil water nor grain yield.

• The highest yielding treatments were the early high nitrogen rate (2.80t/ha) or the high nitrogen rate (2.91t/ha).
• Treatments imposed to manipulate crop growth were unable to save more soil moisture for grain fill

• Wheat dry matter production and total crop nitrogen was significantly lower in wider row spacing treatments.
• For the all the crops grain yield was significantly lower in the wider row spacing treatments.
• Treatments imposed to manipulate crop growth were unable to save more soil moisture for grain fill.

• Proximal sensing reflectance data predicts soil moisture with reasonable accuracy at depths (0-10, 10-30, 30-90 cm) on upper Eyre Peninsula in 2018.
• Reflectance data may also be useful for predicting the amount of soil nitrogen and crop macronutrients, including but not limited to nitrogen, phosphorus, potassium and sulphur.
• Further experimental data is required to use soil and crop reflectance as a means to predict nutrient content because environmental parameters can confound results.

• Crop water use and soil analysis values were very similar between the sites comparing long term reduced tillage and stubble retention.
• Reduced tillage and stubble retention has significantly contributed to increasing organic carbon levels at these sites.
• The grain yields of wheat were greatest at the sites with higher water use efficiency for each location.

• Crop water use and soil analysis values were very similar between the sites comparing long term reduced tillage and stubble retention.
• Reduced tillage and stubble retention has significantly contributed to increasing organic carbon levels at these sites.
• The grain yields of wheat were greatest at the sites with higher water use efficiency for each location.

• Crop water use and soil analysis values were very similar between the sites comparing long term reduced tillage and stubble retention.
• Reduced tillage and stubble retention has significantly contributed to increasing organic carbon levels at these sites.
• The grain yields of wheat were greatest at the sites with higher water use efficiency for each location.

Light to moderate grazing of sheep on no-till stubbles in autumn is unlikely to have detrimental impacts on crop growth in the following season.

• Electromagnetic (EM) zoning was strongly related to differences in pH at 10–30cm depth in two out of three paddocks.
• All three paddocks showed variability in chemical properties, with the EM zoning showing good separation of chemical properties between zones. This provides confidence that the zoning was suitable.
• Variability in plant growth needs to be examined ‘holistically’ rather than just focussing on one variable. While a paddock may show variation in plant available water (PAW), it may be that sodicity or subsoil acidity is the key limiter in plant performance, not water availability per se.
• Existing precision agriculture (PA) datasets, in conjunction with selected chemistry sampling, can be used to indicate relative change in PAW across paddocks, but not the actual volume of water storage.

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.

Late sown Mitre (July 4) produced yields in the range of 0.6 – 2.16 t/ha following Canola stubble. With soil nitrogen reserves of approximately 30kg/ha N (0-10cm) recorded pre sowing, applied nitrogen was detrimental in this trial, with 50 kg/ha N reducing yield by 0.09t/ha and 100kg/ha N reducing yield by 0.23 t/ha. These figures disguise more detrimental yield reductions with seedbed nitrogen applications and no effect from stem elongation timings applied at GS31-39.

Late sown Mitre (July 4) produced yields in the range of 0.6 – 2.16 t/ha following Canola stubble. With soil nitrogen reserves of approximately 30kg/ha N (0-10cm) recorded pre sowing, applied nitrogen was detrimental in this trial, with 50 kg/ha N reducing yield by 0.09t/ha and 100kg/ha N reducing yield by 0.23 t/ha. These figures disguise more detrimental yield reductions with seedbed nitrogen applications and no effect from stem elongation timings applied at GS31-39.

The complex nature of these trials has generated a vast array of information. To best extract meaningful results it is necessary to pry apart the data to generate answers addressing the key facets of the hypothesis: see attached report for full details and discusison.

  Key findings:

Yield in the presence of crown rot was generally barley > bread wheat > durum across both sowing times, but significant differences were evident between varieties.

• Barley, bread wheat and durum varieties differ in their extent of yield loss from crown rot and their actual yield and grain quality (screenings) in the presence of this disease.
• However, all varieties are susceptible to crown rot infection and will not significantly reduce inoculum levels for subsequent crops. Variety choice is not a sole solution to crown rot.

Conclusions

• Sowing date and variety maturity choice is a balance between frost risk and terminal heat stress in the northern grain region. Both can have a significant impact on grain yield. No frost damage was evident at this site in 2014 with either sowing time but terminal heat stress did occur which was more severe during grain filling with the second sowing time. A three week delay in sowing time resulted in an average 24% reduction in yield across the winter cereal entries.  Later sowing pushed grain-fill too far into hotter conditions. This can reduce yield by itself but if there is also an underlying issue with crown rot then delayed sowing significantly exacerbates the expression of this disease with negative impacts on both yield and grain quality.

  Varieties do differ in their extent of yield loss from crown rot and in their relative yield in the presence of high levels of infection, which is often referred to as tolerance. This is a function of a varieties level of partial resistance to infection but appears to also interact with its environmental adaptation and maturity relative to the timing of stress (moisture and heat) which exacerbates the expression of crown rot. Generally quicker maturing barley, durum and bread wheat entries were higher yielding in the presence of crown rot infection in this trial. This does not necessarily mean that these varieties have improved levels of resistance to crown rot infection but rather their quicker maturity allowed them to minimize stress during grain filling relative to longer season entries, reducing the expression of crown rot.

  If forced into planting a cereal crop in a high crown rot risk situation then some barley varieties may provide a yield advantage over bread wheat in that season, as long as early stress does not occur. Some of the newer bread wheat varieties do appear to be closing this gap to some extent. Barley tends to yield better in the presence of crown rot infection due to its earlier maturity relative to bread wheat, providing an escape mechanism which reduces its exposure to moisture stress during the critical grain filling stage. However, a key message is that this decision is only potentially maximising profit in the current season. Growing barley over bread wheat will not assist with the reduction of crown rot inoculum levels as barley is very susceptible to infection. Significant yield loss is still occurring in the best of the barley and bread wheat varieties in the presence of high crown rot infection. Variety selection can improve yield in the presence of crown rot, though all varieties still suffer yield loss, which can maximise profit in the current season but this will not reduce inoculum levels for subsequent crops. Winter cereal crop and variety choice is therefore not the sole solution to crown rot but rather just one element of an integrated management strategy to limit losses from this disease.

• Soil moisture: Surface soil moisture contents were measured using a soil moisture probe on 19 May 2011- after all treatments had been applied. There had been 14mm of rain at this site in the week prior to measurement. Results ranged from 10.5-12% however there was no significant difference between treatments. The texture of the top soil (loamy sand) indicates that field capacity is typically around 14%.
• Emergence, crop vigour and biomass: Table 2 lists the in-season measurements taken at the ‘Wathingarra’ yellow sand site on the plots sown with the DBS bar. No assessment of any treatment indicated a response to Lure application. Assessments were also taken of the plots sown with the Morris bar and the rolled DBS plots however there was no significant difference for any of the seeding systems.
• Yield and grain quality: There was no significant difference in yield between the treatments in either the DBS, DBS + Rolled or the ribbon seeded plots.

 

• The value of stored soil moisture at seeding in the Northern Agricultural Region of WA is not well understood.
• In trials so far, value of stored soil moisture at seeding has varied depending on season and soil type.
• In 2013, additional water at seeding increased yield by about 500 kg/ha at the sand site, and by 1000-2000 t/ha at the loam site.
• Trials such as these will help to unravel the value of stored soil moisture so that it can better be used as a predictor of crop performance and nutritional requirements.
• Available water at sowing is a poor predictor of expected yield and cannot be used as a simple tool for adjusting input levels. We need to develop an ability to understand when and why the water will be of benefit. 

• Biodegradable polymer films retain soil moisture and increase soil temperature.
• Polymers allow crops to be grown out of season and expand the planting window.
• Sorghum and millet successfully germinated under the film failed to germinate in the absence of the film.

High machinery loads and working when soil moisture is not optimal can cause topsoil and subsoil compaction.

• Cooler spring temperatures and excellent plant available soil moisture, favoured the yield potential of longer season and mid maturing wheat varieties in 2016.
• The mid–late and mid-season bread wheat varieties SuntimeA, LRPB FlankerA, SuntopA, BeckomA, MitchA and EGA GregoryA all performed well from an April 27 sowing date (SD1) with yields >6.5 t/ha. The new long-season spring type SunmaxA, likewise achieved ~6.5 t/ha.
• The longer season bread wheat varieties LRPB KittyhawkA and SunlambA also demonstrated their yield potential, achieving yields >6 t/ha for SD1.
• Varieties that performed well across the three sowing dates included EGA GregoryA, MitchA, LRPB FlankerA, SuntopA and BeckomA.
• The new mid-fast season variety LRPB ReliantA yielded well from a main season and delayed sowing date.
• Warm autumn temperatures resulted in many spring wheat entries, particularly the more temperature responsive cultivars, reaching anthesis faster (days from effective SD to anthesis) for SD1 compared with SD2. LRPB LancerA for example was ~9 days faster to reach anthesis for SD1 vs SD2.
• The advanced durum line AGT D043 performed well, achieving yields comparable to the best performing durum DBA AuroraA and bread wheats from a main season sowing date.

The early break to the 2014 season meant soil moisture and rainfall conditions were similar between ToS 1 and 2 and there was little variation in annual ryegrass control among pre-emergent herbicides tested. Grain yield and quality were not affected by pre-emergent herbicide however, there was a 1.22 t/ha yield penalty for the later ToS

• The early break to the 2015 season meant soil moisture and rainfall conditions were similar between ToS 1 and 2 and there was little variation in annual ryegrass control among preemergent herbicides tested.
• Grain yield and quality were not affected by pre-emergent herbicide; however, there was a 0.7 t/ha yield penalty for the later ToS.
• Over two seasons of research ryegrass seed set was greater when sowing was delayed.

• 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.

• In 2015 the drier start to the season and low soil moisture resulted in lower herbicide efficacy and less chemical damage than expected.
• In different stubble management systems the activity and resulting weed control of specific herbicides will be influenced by the solubility index (movement through the soil profile with rainfall events) of that herbicide. Soil texture and soil chemical properties can affect chemical movement and availability in the soil profile.
• Herbicide performance will vary seasonally due to soil moisture levels, rainfall pattern post application, timing of weed germination, position and number of weed seeds in the profile, etc. Understanding how the various herbicides work can reduce the likelihood of failures.
• Herbicides are only one tool for weed control – always adopt an integrated weed control package that includes non-chemical control, and where possible, consecutive seasons of total weed control.
• Consider the whole farming system when making chemical decisions as the impact may last for several seasons (eg. effects on medic germination and medic seed bank).

• Crop establishment increased with on row sowing. Stubble from the previous season helps soil moisture infiltrate into non-wetting sands and into a position closer to the seed.
• Initial germination of brome grass weeds was higher with inter row sowing.
• Late brome grass weed numbers was also greatest with inter row sowing. Sowing on row may also increase crop and weed competition as will a higher seeding rate.

Adequate crop nutrition following summer crop is essential for optimised winter grain yield. Soils moisture was not limiting this season, therefore wheat responses were driven by crop nutrition.

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

• The benefit of summer weed control can vary across soil types and conditions.
• Conserving summer soil moisture is generally money in the bank and can prove invaluable when there is a dry finish, although the benefits seem to differ according to soil type.
• Higher glyphosate prices meansthat growers need to become more efficient when controlling weeds. Targeting weeds while they are young and fresh will help with reducing glyphosate rates. The addition of residual herbicides, such as Ally, will reduce the need for follow-up spraying.

• Ripping below the hard pan (greater than 500mm) in pale sands, yellow sands and yellow loams in wheat or canola increases yield.
• Soil moisture probes show ripping deeper (below 500mm) allows more plant roots to access moisture deeper in the profile for longer in the season. Water infiltration also increase with depth of ripping.
• Leaving a firm even seed bed after deeper ripping is important to reduce seeding establishment issues.
• A negative yield response to deeper ripping in lupins on yellow sand was measured at Binnu in 2016.
• Crop yield response to ripping does vary depending on seasonal conditions and crop type therefore the economics of ripping must be considered over multiple seasons and timing of ripping in the rotation.

• In dry regions, summer fallowing is not just about controlling weeds but mainly about conserving moisture!
• Cultivation conserved the most amount of soil moisture over the summer period. ƒ
• The three treatments which controlled summer weeds: (i) cultivation every three weeks; (ii) cultivation when required; and (iii) knockdown when required, had a significantly higher yield (0.4 to 0.7 t/ha) compared to the treatments where there was no or poor summer weed control. ƒ
• Greater than 80mm of available moisture was lost under heavy heliotrope and melon populations

Effective control of summer weeds before cropping can increase both grain yield and quality. The key to increased yield potential lies in additional sub-soil moisture available to the crop during the subsequent growing season. Summer weeds also deplete mineralised N reserves. Provided there are no limitations preventing crop roots from accessing the subsoil, the additional soil moisture can be seen in higher grain yields and generally grain protein and test weight.

• In a drier season, early-mid maturing Mace wheat provided better feed and grain value than mid-late maturing Trojan.
• Make variety choice based on the stored soil moisture, the potential time of sowing and the seasonal outlook.
• Variety differences exist between Mace and Trojan and their response to grazing.

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

 

• The highest recorded water use efficiency (WUE) was observed at Spalding where 26.6 kg of wheat was produced per hectare for every mm of growing season rainfall.
• Growing season rainfall was below average meaning that stored summer soil moisture was very valuable in 2011.
• The WUE at Hart has been 14 kg/mm/ha or 70% calculated since 2001.

• Canola and peas only produced half the yield of wheat, but barley performed very well.
• Ryegrass is becoming a problem in wheat on wheat plots.
• Pastures performed well where seed reserves had been increased in 2011.
• All options had good soil moisture (40mm) at the start of the season.

The simulation study suggests that the rate of root extension into the subsoil was dramatically slower in the presence of subsoil constraints. However, in the 2001 season, wheat yield was not limited by this factor, which reduced the use of soil moisture early in the season and thus delayed the onset of water stress during the dry grainfilling period.

Mackellar wheat was cut at early‐mid stem elongation (GS32‐33), considered too late to be grazed without affecting grain yield, to determine effects under irrigation. Dry matter production was 22% higher compared with an earlier cut at GS30‐31 (start of elongation). With adequate soil moisture the late cut plots recovered well and grain yield was only 3% lower and not significantly different to the
earlier cut plots. Extended grazing of dual purpose wheat coupled with capacity to irrigate therefore provides increased economic and management flexibility.

• The application of lime and gypsum to a sodic soil has produced improvements in soil structure observable to visitors of the trial site.
•  Improvement in soil structure have been associated with variable responses in grain yield and quality across years, apparently in response to varying available soil moisture over the last 5 crop years (2000 to 2004).
• Yield increases with soil amelioration are associated with years where crop growing conditions were conducive to high yield and/or reasonable levels of sub soil moisture were available to the crop (years 2001 and 2002).
• In contrast, barley yield declines of 40% - 80% and quality downgrades have occurred in the last two very dry years (2003 and 2004). This is thought to be due to the soil amelioration treatments promoting additional early season vegetative growth but being followed by severe spring conditions leading to the crop "haying off”.
• The trial has sown no economic benefit of soil amelioration in 5 years.

• Grain yields of wheat were higher when additional nitrogen was applied at sowing compared to when applied at GS31.
• Timing of nitrogen application is essential to maximise plant growth and achieve yield potential.
• Grain protein was only higher when delayed nitrogen application was applied, which resulted in reduced wheat yield.
• Starting soil moisture, paddock rotation history and potential yield of crop are important factors to consider when deciding amount of nitrogen to apply and timing.
   

• The wild radish population was consistent and of high density (303 /m2) across the site. Spray coverage was affected due to the high weed density and with 65% of the wild radish 4 leaf or larger across the site at application shading was also an influence.
• This trial was applied immediately after rainfall so soil moisture was good but the weeds had just endured a fortnight of frosts with very dry conditions and were still highly stressed.
• Coverage issues and the seasonal conditions prior to application coupled with ongoing dry and stressed conditions following application have contributed to lower than expected wild radish control from all treatments in this trial.

 

• Deep ripping to 500-600mm in coarse textured sandy soils increased yield by 21-66% compared to 6-24% with ripping to 300mm in wheat and canola in 2016 and 2017 in the Geraldton port zone.
• There was only a small yield response to ripping the red loam in 2016 and no difference in 2017.
• Soil moisture measurements and visual observations of plant root growth indicated deeper ripping allowed the plant roots to access more water from deeper down the soil profile. This is particularly beneficial in sandy soils that have a low plant available water capacity(PAWC) per 10cm down the profile therefore roots need access deeper into the soil profile to gain the same amount of water as heavier textured soils that have a higher PAWC per 10cm.
• Economic analysis found the higher cost of deeper ripping gave a positive return on investment up to $5/ha for every dollar invested at 3 sandy sites but not on the red loam where the return on investment was negative with a return of $0.63/Ha for every dollar invested. On the sand at Ogilvie there was a yield penalty in lupins in 2016, resulting in a negative return on investment which could not be recouped in the following dry season of 2017.
• If ripping below 400mm, consideration must be given to crop selection in year one (lupins are higher risk); leaving an even seed bed post ripping to reduce bogging and plant establishment issues; and managing weeds as due to poor competition and better access to water and nutrients can increase the weed burden as these factors can have a negative impact on yield reducing the return on investment.

• In the 2012 wheat after canola trial, moving from a narrow row spacing (22.5cm) to a 30cm spacing reduced yield by 9%.  Moving from 22.5cm to the widest (37.5cm) row spacing reduced yield by 11%.
• In a season where yields averaged about 3t/ ha overall (based on a GSR of 196mm plus 85mm stored soil moisture), increasing row spacing beyond 22.5cm significantly reduced yield.
• During 2009, in the same rotation position on the same trial site, there was no difference in yield between the 22.5cm and 30cm row spacings (based on 2.5t/ha average yields), although the 37.5cm row spacing still yielded significantly less. 

• The moisture results indicate that canola uses more water at a greater depth than wheat. There is less water remaining in the soil profile below 40cm under canola sown at 1 and 6 kg/ha than for the same depth under wheat. There will be less moisture accessible to a wheat crop in 2012 on the canola plots than on the fallow plots.
• The use of fallow for moisture storage alone is unlikely given the volume of stored soil moisture at the beginning of May 2011. Indications for the use of a break crop were positive from early April. Summer rainfall had refilled the soil profile, fol-lowing the wheat of 2010, giving some surety to crop yield. Only a small rainfall event was required to break the season and join the soil moisture fronts.
• Season length and consistent rainfall has favoured yield of canola regardless of its plant density. A very plastic species as the yield from 22 plants/m2 is only 200 kg/ha less than that from 68 plants/m2. The canola plots received all required inputs as a result was a more expensive crop to grow than either the wheat or fallow.