Soil amelioration is a critical strategy for overcoming soil limitations to crop production in Western Australian farming systems. This project, spanning from 2018 to 2022, was completed in two phases; 2018-2020 focused on Soil Amelioration vs Soil Type and 2021-2022 focused on Effects of Early Post Emergent Ripping. The overall aim was to evaluate and demonstrate the benefits of soil amelioration across a diverse range of soil types common to the WA grain-growing region. The study involved a network of demonstration sites established across five port zones, with twenty-four sites set up in the 2018-2020 period by nine collaborating grower groups. The soil types tested ranged from sands to loamy soils, gravel and sand duplexes, forest gravels, and clay-based soils. The project also explored the effects of early post-emergent deep ripping as an alternative to traditional pre-seeding deep ripping.

• There were no significant differences between K sources or rates at this trial, despite soil test model predictions of high K response.
• Canola did not respond to high P application at this site in the absence of Nitrogen.
• The site was highly N responsive, although the N use efficiency suggests leaching was moderate. This may have been compounded by low pH and the presence of Aluminium in the subsoil.
• More K response may be seen in wheat in the 2010 season.

Crop establishment and nutrient supply had a greater effect on crop growth than soil water repellence at this site. Interestingly, grain yield showed a weak, slightly positive relationship with our measurements of water repellence e.g. grain yield was highest at points that had higher levels of water repellence (data not shown here). The positive relationship between soil water repellence reflects the role of soil water repellent organic matter and soil nitrogen supply. Our results suggest nitrogen supply was a major limitation to growth therefore it is reasonable that higher grain yields occurred where soil organic carbon (soil nitrogen supply) was high. Water repellence may have had a minor effect because it was not severe at this site; the MED values ranged from 0.1 (Low water repellence, King 1981) to 2.1 (Moderate water repellence) and the average was 1.0 (Moderate water repellence). However, the samples for MED measurement were taken in winter when the expression of soil water repellence is lowest.

Gamma thorium provided a reasonable prediction of shoot K concentration and gravel content and provides a feasible method for delineating K management zones on sandy gravels in the Badgingarra area. Figure 2 shows that high shoot K concentration is associated with gravel content and vice versa. The critical shoot K concentration for wheat at anthesis is 1.5%; based on the data shown in Figure 2 the areas where gamma Thorium is less than 40 ppm would be responsive to potassium fertilizer application.

The gravel measurements separated into 2 clusters; non-gravelly soil where the fraction of gravel was less than 15% by weight and gravel soil where the fraction was greater than 15%. The mean Colwell K 0 to 10 cm was 17 mg kg which is well below the critical range of 51 to 57 for high yield potential on deep grey sands. Based on current prices and a wheat yield potential of 2t/ha, the DAFWA K calculator shows profit would be maximized with 40 kg K/ha applied. However, the efficacy of topdressed K on this sand may be low. The mean Colwell K for the gravel soil was 24 mg / kg which is also well below critical levels but shoot K concentration was adequate. This suggests that the crop is accessing K from the subsoil and that tissue testing may be an important component of assessing nutrient supply from different parts of the sandy gravel landscape.

• Crop establishment was good for both sowing times due to good rainfall after seeding in 2011. Seed rates of 40 kg/ha achieved the target plant population of 100 plants/m2 on all sites. With each additional 40kg/ha of seed, plants numbers increased by approximately 50 plants/m2 at Badgingarra.   Ears/m2 increased from 219 to 320 with increasing seeding rate from 40 to 120kg/ha.   Averaged across all seeding rates, the ear numbers of Mace (227 ear/m2) were significantly lower than the other varieties (approx 275 ears/m2).
• At Badgingarra, increasing the seeding rate from 40 to 120 kg/ha increased the mean grain yield of King Rock, Mace, and Wyalkatchem at both sowing times. The mean yields of Fortune and Calingiri were not influenced by seeding rate at the May sowing time, but did increase from 40 to 120 kg/ha at the second sowing time in June (Fig. 1).   Magenta mean yields were higher at the 120 kg/ha than 40 kg/ha seeding rate at the second sowing time, but were highest with the 80 kg/ha seeding rate at the first sowing time in May.   Fungal staining of Mace and Wyalkatchem (data not presented) was greater than 5% at all seeding rates when sown on May 18th at Badgingarra.  

Seeding rate did not influence the level of screenings at Badgingarra of the varieties sown on May 18th.   The screenings of Magenta and Fortune declined when seeding was increased from 40 to 120 kg/ha at the June sowing (Figure 2).

Fungal staining of Magenta was greater than 5% for Magenta when sown at the second sowing time.  This influenced the gross income of this varieties (Table 2).   Lower yields and downgrading due to hectoliter weight (<74HLW) influenced the economic returns of Calingiri and Fortune in the first sowing time.

In a season like 2011 with good winter rainfall across all sites and stored moisture at seeding, higher seeding rates either improved maintained high grain yields when sown in May and June in a range of environments in Western Australia.   There was no evidence that increased seeding rate increased screenings risk in a season with good winter and spring rainfall.

These grower scale on-farm soil amelioration demonstrations have been managed by the growers according to standard practice. Both soil types are highly water repellent and in general the amelioration treatments have improved crop establishment, vigour and grain yield. Economic analysis indicates that the return on investment has been large as the benefits from the treatments have tended to last for at least 5-years or more at these sites. While it is possible to improve establishment, water and nutrient use efficiency and crop productivity using these techniques it is important to recognise that other constraints such as poor water and nutrient holding, soil acidity and compaction can still limit the yield potential of these soils and this needs to be considered when investing in amelioration. Liming to improve the soil pH and very deep ripping to remove compaction below 30-40 cm may well provide further yield gains beyond those achieved through amelioration of the top 10-30 cm only, and this may also help sustain the benefits of amelioration over a longer time.

These grower scale on-farm soil amelioration demonstrations have been managed by the growers according to standard practice. Both soil types were highly water repellent and the amelioration treatments have generally improved establishment but have probably had an even bigger impact on crop vigour. While it is possible to improve establishment, water and nutrient use efficiency and crop productivity using these techniques it is important to recognise that other constraints such as poor water and nutrient holding, soil acidity and compaction can still limit the yield potential of these soils. Pale sands which overly a clayey gravel or clay base within the top 1 m often have greater potential than the very deep sands.

• Over all there were no significant N responses despite a high yield potential and leaching rains.
• Tissue tests did indicate some differences in the timing of N uptake (later in the case of the coated urea), however none of these differences resulted in differences in N efficiency.

• Despite the lower yield of Tanjil compared to some other varieties Tanjil is still recommended in the high rainfall area because it is the variety with the best resistance to anthracnose.
• Mandelup performed well however it has lower tolerance to antracnose than Tanjil so should not be used in blue lupin areas.
• While Jenabillup has good resistance to black pod syndrome which is thought to be associated with bean yellow mosaic virus it only has moderate resistance to anthracnose and tolerance to metribuzin so should be used with caution if sowing in high rainfall blue lupin areas or in paddocks suspect of having large broadleaf weed seed banks.

• Jenabillup performed well across the state in 2009.
• This variety has good resistance to black pod syndrome which is thought to be associated with bean yellow mosaic virus.
• Jenabillup has only moderate resistance to anthracnose and tolerance to metribuzin so should be used with caution if sowing in high rainfall blue lupin areas or in paddocks suspect of having large broadleaf weed seed banks.
• This detracts from Jenabillup in the NAR as broadleaf weeds and blue lupins are the staple for many paddocks.

• The trial did re-iterate that early sowing provides more opportunity to ‘play the season’ and alter N management to significantly impact on crop yield outcomes compared with the late sown crops which, in the truncated 2010 season, provided little opportunity for changing N management.  This suggests that focusing on getting the N management of the earlier sown crops sown right for a given season is a good investment of time. Further testing will give a clearer picture as to whether Yield Prophet adds significant value to helping make these decisions. 
• Although the Farmer group were original concerned about the Yield Prophet N budget, tt appears that the model has utilized deep soil test data to reasonably assess the supply of soil N to plants and the movement of soil and applied N through the profile. From this point of view, with the addition of an accurately characterized soil profile, the model may allow growers to better account for and manage nitrogen supply and losses from below the 0-10cm zone.
• Although yields from the Farmer strategy tended to be higher than the Yield Prophet strategy (although not significant), returns per hectare (net of Nitrogen and application costs) were very similar due to the increased costs associated with the Farmer strategy. With further soil characterization and ‘ground proofing’ a tool such as Yield Prophet may be a useful way to reduce the risks and more accurately quantify the benefits associated with applying in-crop nitrogen.
• This trial will be repeated in 2011, and with a more accurate soil characterization it is expected that Yield Prophet will be more accurately assessed.

• Addition of clay-rich subsoil improved crop establishment at this site in 2010.
• There was a very dry finish to the growing season with <15 mm in total for September and October so those cultivation and claying treatments with increased biomass and higher yield potential would have been more prone to haying off.
• Poor incorporation of surface applied clay-rich subsoil can also hold more moisture near the surface which is then subject to evaporation and competes with the roots for water with small rainfall events.
• Despite these factors cultivation with or without the addition of clay-rich subsoil did increase grain yields from <700 kg/ha in the uncultivated situation to an average yield of 1.3 t/ha for the rotary hoe and rotary spaded treatments combined.
• Ongoing monitoring of this trial will be required to see the longer-term benefits of these cultivation and clay incorporation treatments on establishment and yield in seasons with a better finish.

• Non wetting soil resulted in poor weed germination pre seeding
• Pre seeding the total trial area received 2 knockdowns with 1.5 L/ha Sprayseed.
• The limitation and knowledge of the relative tolerance of the different perennial grasses to grass selective herbicides prevented removal of late germinating brome and ryegrass from the trial post seeding.
• Jaguar was sprayed on the 29/6/2011 and good broad leaf control was achieved.
• For further results please see the attached trial report.

• One of the fundamental problems of pale deep sands is their poor water and nutrient holding capacity. While cultivation techniques can overcome water repellence they do not necessarily greatly alter the lack of water holding capacity. Similarly addition of clay at rates of 100-150 t/ha can be used to overcome water repellence but will not greatly increase water holding capacity.
• Deep ripping or the soil loosening caused by rotary spading or mouldboard ploughing allows faster root growth and improved nutrient and water uptake and this appears to be one of the primary reasons for the improved yields. The advantage of the rotary spader and mouldboard plough over deep ripping alone is improved weed control and reduced water repellence although the longevity of this is unknown.
• Reduced water repellence may prove to be more significant in certain seasons and more sensitive crops. Sustained productivity benefits are likely to be required for these approaches to be economically viable.

• More moderate clay rich subsoil application rates of 100-150 t/ha are less costly to apply, can be easily incorporated, can still improve crop establishment and productivity and importantly can reduce some of the risks associated with crops haying off due to water shortage during grain filling in dry seasons.
• Clay spreading is likely to be more beneficial in higher rainfall, longer season environments and in wetter seasons where the risk of water shortage at grain fill and haying off is reduced.

FARMER COMMENTS

Usability of Yield Prophet

·         High input requirement to get detailed data out, but once it is setup the online format is easy to use and generates good reports.

·         Easy to use once you are familiar with the program.

Usefulness of Yield Prophet set-up process

·         Farmers commented that the exercise of opening up a deep soil pit was on one the most informative and useful aspects of the Yield Prophet process.

·         Good training with a consultant on how to use the tool was vital as well.

Yield Prophet reports

·         Farmers had mixed comments about the reports with each having their favorite report- one farmer chose to use only the crop report to make his decisions.

·         One farmer found the profit comparison report the most useful where as another found it the least useful report commenting ‘it is pretty obvious through the comparison report if the is likely to be a financial response, the seasonal risk is too great to compare nitrogen profitability to the last dollar.’

·         Farmers found the climate and weather aspects to the crop report of interest, specifically the breakdown of chances of certain weather characteristics influencing yield, however in reality this didn’t really clarify decision making.

·         The reports reference the Southern Oscillation Index (SOI) which is generally considered irrelevant to the Western Australia.

·         Growth stages of crops were very accurate for all sites.

Other aspects that limited yield

·         Three of the four sites experienced a three week dry spell that was accompanied by warm, weather at the beginning of September. The yield prophet crop reports at all three sites did not indicate that crop was experiencing moisture stress or heat shock. The three farmers commented separately that this dry spell had impacted the crop yield.

·         One of the potential issues is the assumption of root growth and rooting depth. If there is low soil nutrition at depth it is likely that the roots are "lazy" during the growing season and don't go as deep as the model suggests. This would then affect the modeling of water use down the profile and water stress on the plant.

·         One farmer generated a report on 26 September which indicated the crop was under moisture stress, however this did not convert to yield penalty in the crop report.

 

Future of Yield Prophet in West Midlands region

The low water holding capacity of sands in the West Midlands region means that the effect of short term dry spells has greater significance than total rainfall on production- this seems to be difficult to simulate in Yield Prophet.

Simulated yield on two out of the four sites was far from what would be considered an acceptable level of variation (1 t/ha for yellow sand and 1.85 t/ha for shallow loamy duplex). However the other two sites simulated yield very well.

Typical farm paddock of 60-70ha within the West Midlands region has multiple soil types present. At this stage Yield Prophet only allows the user to simulate one soil type per paddock. There is the ability to separately log each soil type however this requires a great deal of information input and the user has to pay a ‘paddock’ subscription for each soil type.

Unfortunately, there are very few soils classified in the West Midlands region, to WMG’s knowledge the five soils classified as part of this project are the only fully characterized soils in the West Midlands region. This project has estimated that the cost of fully classifying a soil is $3,000. When there is so few soil types classified in the West Midlands region coupled with farmers having multiple soil types (sometimes more than a dozen) on their farm this cost is the key barrier to adoption of this tool in the West Midlands region.

• The high ryegrass burden, particularly on the TOS1 plots impacted on the usefulness of the yield prophet tool for this time of sowing as it does not take into account other yield limiting factors.
• High rye grass burden on TOS1 had significant impact on yield (approx 1.2-1.3 t/ha).  As such we have learnt that site selection (most especially with herbicide resistant weeds) is critical in order to conduct meaningful trials.
• No difference in Yield Prophet forecasts between the two cultivars Mace and Bonnie Rock. This was also expressed in the harvest results, in direct contrast to the very dry, early finishing 2010 season, where Mace out yielded Bonnie Rock in all treatments.

• The ungrazed paddock yielded 1.2t/ha more than the grazed paddock.
•  The grazed paddock was grazed intensively to approximately 1-2 cm in height where only the white stems could be seen, the green foliage had all been removed. It was observed that after sheep were removed from the paddock, the barley crop re-grew rapidly and out competed the radish that was also recovering from the grazing.
• It was also observed in the demonstration that the grazing delayed the maturity of the cereal with the grazed paddock haying off later than the ungrazed paddock.
• The quality of the grain from both treatments has not been tested for quality but it has been observed that the grain from the grazed paddock is a better colour than the ungrazed paddock.

• The average yield response to TM21 for the three replications was 26%.
• Yield response from N application also recorded a significant yield increase between 7.5% and 35% but the cost benefit was significantly more for the TM21.
• The highest rate of N without TM21 gave a lower yield response than the TM21 without N. The above graph shows the comparative return from the treatments of urea and TM21. It should be noted that this paddock has a very soft history having only grown oats as a crop prior to this year’s wheat. It has rarely been treated with fungicides or harsh chemicals.
• Worm activity was obvious throughout the trial area with higher worm counts in the treated areas.

• Pale deep sand has inherently poor yield potential and given the high cost of the water repellence amelioration treatments it can be difficult to determine whether the investment is worthwhile.
• At this site the productivity gains have been sufficient to offset the costs and be profitable for each of the options tested.
• Claying despite being expensive does have the advantage of being long-lasting and reduces wind erosion risk. Shallower cultivation with offset discs or one-way ploughing can give profitable improvements but the example of the one-way plough demonstrated that the benefits can be reduced or even negated by wind erosion damage.
• It should be noted that other research indicates that improving the effectiveness of the seeding operation can give yield gains of similar magnitude or even greater than those measured for the offset discs without the erosion risk. Exploring this possibility is probably a first step for growers looking to manage repellence on these soils.

The trial was dogged by non-wetting and kangaroo grazing problems and so the bioassay of the residual effect of the original source of P treatments was poor..

Recoveries of applied phosphorus in the surface layers was poorest for the water soluble, plant available source superphosphate which had large leaching losses below 50 cm.  the less immediately available but citrate soluble source retained more P in the surface layers while the very insoluble C ore source produced poor growth but had only very low P leaching to depth.  The compromise in choice of source, between plant availability and leaching into the ground water and subsequently the waterways, is  well illustrated by this trial

As a rule, soil fertility factors (non-wetting, organic carbon, CEC, soil organic nitrogen, acidification etc were all more affected by length of pasture ley than by pasture composition and cumulated production.  Cross plot transfer of surface soil may well have affected this finding..

• Plant density counts were estimated on the 3rd August 2012 by counting 8 x 1 metre rows along each treatment.
• The treatment without Bio Char, there were counted 126 plants per square metre
• Where Bio Char was applied, there were 130 plants per square metre. 
• There were no replications of the treatment applied, so it is difficult to conclude if biochar application was beneficial in plant establishment.
• Subsequent visual observations and ratings were done on the 25th September 2012 with no difference noticeable.  The inherent variation across the site mad it difficult to gain adequate measurements at this site.
• We were not able to detect any difference in grain yield between untreated (nil) and the biochar plot.

The West Midlands site had an average yielding year for the Moora area. The Liebe Long Term Research Site had a good growing season in terms of rainfall and seasonal distribution. The average yield was about 50% higher than previous wheat trial years. This was similar to Forrestdale which also had good rainfall and seasonal distribution.

On average, all Bioprime treatments combined resulted in a 4% yield increase. Treatment 2 (foliar Bioprime and granular fertiliser) performed best, achieving a 10% yield increase averaged across the three sites). At the WMG site, five Bioprime treatments resulted in positive yield responses whereas this number was lower at the Liebe site (2 treatments). With data corrected for outliers, all Bioprime treatments resulted in a positive yield response. Given that the Liebe site, relative to the WMG site had a higher soil pH, and higher pre-seeding phosphate and exchangeable cations concentrations (Table 2), an average higher yield was expected and achieved here compared to the WMG (3.36 t/ha and 2.15 t/ha, respectively in unamended control treatments). Thus, the higher soil quality and soil health present at the Liebe site combined with the good 2016 season in terms of rainfall likely narrowed the yield gap.

As such any management options aiming to close the gap between actual and potential yield, would have had less scope to achieve this at the Liebe site in 2016. In contrast, the lower soil fertility at the WMG allowed Bioprime to more consistently improve crop production. The 2016 data suggest the opportunity to improve yield on a poor soil in a poor year is greater than on good soil in a good year.

Ongoing research will continue to further develop Bioprime technology as a tool to improve soil biology and maintain plant health and yield. There is a substantial database of microbiological and yield results which continues to expand with the expectation of understanding the links between root and plant colonization by beneficial bacteria and fungi with Bioprime application and growth improvements.

Prior to treatments being imposed aluminium toxicity was visually identified as a constraint by digging up plants and examining the roots. It was evident from the roots sideways growth that root pruning was occurring, affecting plant growth by limiting access to nutrients and water. Compaction was thought not to be an issue as it was possible to push a 1cm rod to a depth of 140cm by hand.

When the Grizzly treatments were being implemented it was difficult to have an even depth throughout the plot due to plot size. The discs were only achieving maximum depth (30-35cm) in the centre of the plot however; the average depth achieved within the plot was 25-30cm.

At seeding it was difficult to establish an even seed bed which led to uneven germination in both the Spaded treatments and the Grizzly treatments. This resulted in these treatments having lower plant establishment numbers over the no till (Control).

Throughout the season it was visually evident that the incorporation treatments had major effects on crop growth and health. The Grizzly and spaded treatments had better vigour and larger head sizes when compared to the control treatments. This is likely due to the lower plant numbers, leading to less competition for water and nutrients in the cultivated plots. Although this didn’t translate to significant yield increases in the first year, the second year of the trial is expected to show more as the seeding bed will have settled allowing for an even germination. 

• In 2016, the soil mixing (grizzly or spader) had a greater wheat yield than the control (0.27-0.42 t/ha), regardless of product applied. The incorporation treatments are still being paid off and therefore have not produced the greatest net margin.
• Limesand/No till returned the best net margin for the 2nd consecutive year due to the low yield increases from either application of product or mixing treatment.
• The lime or dolomite treatments had greater yields (0.22-0.5 t/ha) regardless of mixing treatment.
• Care must be taken in interpretation of results due to pH variation across the site.
•  

• Subsoil acidity, topsoil water repellance and herbicide resistance weeds are often found in combination on sandplain soils in Western Australian wheatbelt.
• One-off mouldboard ploughing is being investigated as a way to decimate herbicide resistant weed seed banks. bury water repellant top soil and incorporate lime into into acid subsoils.

• Intermittent prevailing dry conditions experienced through the growing season probably impacted negatively on the residual activity of Atradex WG and Intervix in the TT and CL canola systems respectively, while resistance to Group A and Group B Herbicides would also have been a contributing factor.
  • Final weed control ratings (out of 10):
  • Roundup Ready canola system – 9.9
  • Triazine Tolerant canola system – 7
  • Clearfield canola system – 7.5
• The trial was harvested 5th November (168 days after sowing). Yield data are shown below. The high yields and oil content probably reflect timely rain rather than a particularly good season. There is some discrepancy between the yields of the trial and the paddock average harvested by Andrew. The harvest contractor is confident that the figures reflect the true yield for the site and suggest that this area of the paddock was possibly a high yielding area compared to other areas of the paddock, or that the impact of small plot water harvesting may have played a role. The trial is more about relative performance than actual performance: on average the RR system yielded 38 percent higher than the TT system and 15 percent higher than the CL system.
• System specific input costs used in calculations in the table above provide a ball park summary of specific costs associated with each system. They are not hard and fast figures, to be disputed. It is appreciated that each and every item is subject to negotiation with suppliers so readers are encouraged to re-work the figures to suit their experience and anticipated costs for 2011.
• The trial demonstrates that in this instance growers would have on average an additional $500 per hectare to meet other costs when growing RR canola over TT canola (purchased seed) or an additional $465 per hectare over TT canola (using farmer saved seed – assuming that the same yields are obtained for these TT crops).
• Again in this instance growers would have on average an additional $225 per hectare to meet other costs when growing RR canola over CL canola (purchasing all seed) or an additional $190 per hectare over CL canola (using farmer saved seed).
• These additional earnings per hectare are even more attractive when one considers the fact that the level of weed control achieved by the RR system was significantly better than that achieved by the other two systems.

• There were no significant differences in yields between the varieties
• Quality information (admix and oil %) was not available at the time of printing.
• Due to the risk of spray drift onto sensitive crops, broadleaf control of the trial was not ideal. This may have had an impact on trial yields. • Jardee didn’t produce the expected yield advantage over the TT varieties that was expected. This may have been due to consecutive hot days in mid-October reducing the potential for later maturing varieties. This is supported by the highest yield in the trial being the earliest maturity variety (Tanami), although this was not a significant difference.

• Shorter season varieties Telfer and Tanami showed a higher trend in yield which may be due to a dry and early finish to the season.
• This may show there is less advantage in using hybrid varieties in a drier season.

• See attached trial report for Discussion of key messages.

A summary of the main results from the first season at the Moora trial are presented in Figures 1 and 2.  Due to technical issues, the trial was not seeded at the same time as the rest of the paddock, which was supposed to be used as an untreated control. For this reason, a comparison of the treatments to a control treatment without tillage and clay spreading is not available.  A statistically significant effect of tillage on early plant establishment was found when analysing the plant counts measured about four weeks after sowing (Figure 1, left). All the treatments with the off-set disc (in combination or not with clay spreading) had more plants per linear meter in comparison to the one-way plough treatments. This is likely due to uneven seeding depth following tillage with the one-way plough (deep tillage) compared to the shallower tillage with the off-set disc. Surprisingly, incorporation of subsoil clay at any given rate did not show any significant effect on early plant establishment although this result could be explained by the wetter than usual weather in April-May reducing the severity of soil water repellence.

Again, when looking at the tiller counts recorded 8 weeks after sowing (Figure 1, right) the addition of clay at different rates did not affect the number of tillers. However, the wheat growing in the one-way plough treatments overcame the initial delay in germination giving higher tiller number than those recorded in the treatments with the off-set disc (except for the treatment with 250 t/ha of clay). This trend continued at harvest, with the one-way plough treatments producing higher yields (4.5-4.6 t/ha on average) than the off-set disc treatments (4.1-4.3 t/ha on average) at any given rate of subsoil clay.

Due to the low rates of clay spreading and the low cost of the incorporation methods, all treatments provided a positive return of investments in the first year (ROI= ($/ha gain – $/ha total direct costs) / $/ha total direct costs), based on mean values in Table 1. Not surprisingly, the best ROI in the first year was obtained by the one-way plough treatment without clay spreading (1.42 $/ha), followed by the off-set disc without clay spreading (1.22 $/ha) and the treatments clay spread at 50 t/ha incorporated with one-way plough (1.17 $/ha). These estimates are indicative only, as indirect costs and interests on the initial capital investment are not included in the calculations. For more accurate estimates of ROI, yield results from multiple seasons and crops will be collected in the next 3 years.

 

A summary of the main results from the first season at the Moora trial are presented in Figures 1 and 2.  Due to technical issues, the trial was not seeded at the same time as the rest of the paddock, which was supposed to be used as an untreated control. For this reason, a comparison of the treatments to a control treatment without tillage and clay spreading is not available.  A statistically significant effect of tillage on early plant establishment was found when analysing the plant counts measured about four weeks after sowing (Figure 1, left). All the treatments with the off-set disc (in combination or not with clay spreading) had more plants per linear meter in comparison to the one-way plough treatments. This is likely due to uneven seeding depth following tillage with the one-way plough (deep tillage) compared to the shallower tillage with the off-set disc. Surprisingly, incorporation of subsoil clay at any given rate did not show any significant effect on early plant establishment although this result could be explained by the wetter than usual weather in April-May reducing the severity of soil water repellence.

Again, when looking at the tiller counts recorded 8 weeks after sowing (Figure 1, right) the addition of clay at different rates did not affect the number of tillers. However, the wheat growing in the one-way plough treatments overcame the initial delay in germination giving higher tiller number than those recorded in the treatments with the off-set disc (except for the treatment with 250 t/ha of clay). This trend continued at harvest, with the one-way plough treatments producing higher yields (4.5-4.6 t/ha on average) than the off-set disc treatments (4.1-4.3 t/ha on average) at any given rate of subsoil clay.

Due to the low rates of clay spreading and the low cost of the incorporation methods, all treatments provided a positive return of investments in the first year (ROI= ($/ha gain – $/ha total direct costs) / $/ha total direct costs), based on mean values in Table 1. Not surprisingly, the best ROI in the first year was obtained by the one-way plough treatment without clay spreading (1.42 $/ha), followed by the off-set disc without clay spreading (1.22 $/ha) and the treatments clay spread at 50 t/ha incorporated with one-way plough (1.17 $/ha). These estimates are indicative only, as indirect costs and interests on the initial capital investment are not included in the calculations. For more accurate estimates of ROI, yield results from multiple seasons and crops will be collected in the next 3 years.

The topsoil sand at Yanda was severely repellent (Figure 1, left), as measured by the molarity of ethanol droplet test (MED). Clay spreading and tillage (either combined or separated) significantly reduced the severity of water repellency. When the subsoil clay was not incorporated by tillage or was incorporated using an off-set disc, the soil water repellency generally decreased with an increasing amount of subsoil clay. However, low-repellency (MED<1) was obtained only at rates over 150 t/ha of subsoil.

In contrast, spading (either at standard speed of the tractor or at half speed) was the most effective method for the alleviation of soil water repellency. In these treatments, the MED values were completely reduced to zero (non-repellent soil) and, most importantly, this was achieved independently from the presence, or not, of clay-rich subsoil. The significant reduction of the soil water repellency however did not convert to better plant establishment measured five weeks after sowing (Figure 1, Right).  This result could be explained by the wetter than usual weather recorded during April-May 2016 that reduced the impact of the soil water repellency on plant establishment. Nevertheless, tiller counts collected five weeks after plant counts showed a significant effect of tillage on the number of tillers. In particular, the spader treatments (standard and ½ speed) had the most tillers while the control had the fewest.

This trend was repeated with the barley grain yields at harvest time (Figure 2). Both tillage and rate of clay spreading, significantly improved grain yield in comparison to the control treatments (no clay and no tillage). The lowest yield were recorded in the control treatments and in the off-set tillage only (no clay) with an average of 1.41 t/ha and 1.36 t/ha respectively. The shallow tillage (or incorporation) using off-set discs did not yield significantly differently from the treatments with no incorporation at any given rate of subsoil clay. Clay spreading at 250 t/ha followed by spading at standard speed produced the highest yield on average (2.93 t/ha). Nonetheless, all treatments with spading (standard and ½ speed) were able to yield over 2.5 t/ha, even without the addition of subsoil clay (Figure 2). 

Field observations showed that the trial was also affected by frost, which explained the lower than expected yields. Head samples were collected in early November 2016 from all the treatments (except spading at ½ speed) for the assessment of frost induced sterility (FIS= number of sterile florets / total number of florets) and the results are shown in Figure 3.

The results on FIS showed that frost damage might be one of the main reasons of low yields and responsible of the large yield differences between treatments. The control treatments and the off-set treatment (no clay) had over 60% frost induced sterility. Even though increasing amounts of subsoil clay significantly reduced FIS (Figure 3c), the treatments with no incorporation or with incorporation by off-set discs still recorded FIS values above 50%. Spading was the most effective treatment to significantly reduce frost damage to below 40%, regardless of the presence or not of subsoil clay (Figure 3a and b).

Spading was the most successful treatment in this first year of the trial at Yanda. Most importantly, spading was able to produce the highest yields and significantly reduce the frost damage regardless of the addition subsoil clay. This was particularly evident when estimating the simple return of investments on the first year of the trial (ROI= ($/ha gain – $/ha total direct costs) / $/ha total direct costs), based on the mean values presented in Table 3. Because of the high crop-specific costs with barley at Yanda (500 $/ha) and the yield reduction due to frost, spading alone at standard speed was the only treatment that gave a positive ROI on the first year (+0.4 $/ha) followed by negative ROI with spading at ½ speed (-0.18 $/ha) and the control (-0.35 $/ha). These estimates are indicative only, as indirect costs and interests on the initial capital investment are not included in the calculations. For more accurate estimates of ROI, yield results from multiple seasons and crops will be collected in the next 3 years.

 

• This trial clearly demonstrates the importance of matching clay application rate and incorporation method when clay spreading for water repellence. For subsoils with a clay content of about 30% using a rate of 100-150 t subsoil/ha incorporated with offsets to a depth of 120-150 mm was sufficient to overcome the repellence and given wheat yield increases of 11-18%.
• Alternatively subsoil application rates of 250-350 t/ha are probably required if the clay is to be incorporated to 250-300 mm with a rotary spader and this gave similar yield increases of 11-14% on what is a better soil type with higher inherent yield potential.
• The main benefit of higher clay application rates and deeper incorporation seemed to be in the canola year, although more seasons with canola need to be assessed to confirm the validity of this finding.

• The trial results from 2009 demonstrate there may be a number of options for companion annual legumes for perennial grass based pastures.
• The results need to be verified over a number of years with different seasonal conditions.

• The trial results from 2009 demonstrate there may be a number of options for companion annual legumes for perennial grass based pastures.
• The results need to be verified over a number of years with different seasonal conditions.

• Incorporation of the lower subsoil application rates (50 and 100 t/ha) with offset discs resulted in increased canola plant establishment compared with the offset disc control plots without subsoil. However, at the higher subsoil application rates (360 and 450 t/ha) establishment was reduced due to inadequate clay incorporation (Fig. 1). Visually it was clear that the high rates of subsoil application resulted in surface sealing due to the poor incorporation by offset discs and this sealing was sufficient to reduce canola establishment. Incorporation of 50t subsoil/ha using a spader appears to have resulted in a reduction in canola establishment (Fig. 1) but there is no apparent reason why this should the case. Apart from this anomaly there is a trend towards improved plant establishment when higher rates of applied subsoil are spaded (Fig. 1).
• Comparing grain yields between subsoil incorporation using offset disc and rotary spader is not valid on this trial as the offset disc treatments are situated on pale deep sand which has less water holding capacity and lower potential than the sandy gravel on which the spaded treatments are situated. Canola grain yields in 2010 showed trends not dissimilar to those obtained for wheat on this trial in 2009. For the offset disc treatment there was no impact of the lower subsoil application rates on yield but a trend towards lower yields at the high application rates (Fig. 1) again most likely due to inadequate subsoil incorporation. For the rotary spader there was a trend towards higher yields as the subsoil application rate increased (Fig. 1), indicative of the capacity for the spader to achieve good subsoil incorporation. Overall canola yields were increased by more than 300 kg/ha when either 360 or 450 t/ha spread subsoil was incorporated using a spader (Fig. 1).
•  In both the 2009 and 2010 seasons the trends in crop establishment and grain yield have demonstrated the principle that when claying the subsoil application rate needs to be ‘matched’ to incorporation method that will be used to incorporate the clay. The results suggest that offset discs are only likely to be successful at incorporating lower subsoil application rates, probably of the order of 150 t/ha or less while rotary spaders are more appropriate for incorporating higher subsoil application rates of 250 t/ha or more.

Using the highest label rate of either Aviator Xpro or Prosaro in the first application for sclerotinia lowered the level of sclerotinia infection and recorded a higher $ROI/ha in this trial. Increasing the rate of fungicide increases early activity on active disease but will also increase the length of protection from reinfection. 

The use of higher rates under high sclerotinia disease pressure is recommended not only in a single spray application to extend the window of protection but as recorded in this trial it can provide benefits to a two spray strategy. Improvements in length and strength of sclerotinia control from the use of a higher rate in the first application have been recorded across multiple commercial trials conducted by Bayer Crop Science across Australia in the 2016 season.

• Average yield for the trial was 3.47 t/ha with a range from 3 – 4 t/ha.  Most of the lines since Tanjil, which was released in 1998 ranked in the top 10 with the exception of Jenabillup.  Jenabillup is only recommended for the southern and low rainfall areas due to its low tolerance of metribuzin and moderate susceptibility to anthracnose.  
• The best performing lines were those with superior anthracnose resistance with the new variety PBA Gunyidi, whose anthracnose resistance is between Mandelup and Tanjil, being 109 and 114% better than Mandelup and Tanjil. 
• The stand out for yield performance was WALAN2325 which yielded 113% and 118% of Mandelup and Tanjil. 
• In addition, the breeding program has been concentrating on producing an anthracnose resistant, metribuzin tolerant variety specifically to replace all varieties in the coastal West Midlands.  

Over all four trials both Sakura treatments maintained a positive $ROI/ha with Sakura + trifluralin ($78.50) slightly ahead on average $ROI/ha to the standalone Sakura ($73.48)

Sakura 118 g/ha recorded a $55.08 increase in $ROI/ha over Boxer Gold across the four trials. Boxer Gold $ROI was generally in line with that of the prosulfocarb treatments in three of the sites, except from Waddy Forest where prosulfocarb 2.5 L/ha recorded a higher yield. Why this occurred is not clear as results were cross checked back with the contractor to ensure there was not a transcription error.

Trifluralin, due to its poor weed control, especially at Cunderdin, returned a slight positive $ROI/ha ($7.20) across the four trials.

All four sites to some extent were affected by frost which may have affected yield outcomes.

Getting weed control right is the key to ensuring the longevity of any herbicide but it also allows the crop it’s best possible chance of achieving its yield potential. Using a program of effective knockdowns and a product with a long residual activity like Sakura can deliver higher yields and returns across a variety of soil types and locations as seen across the four trials conducted during the 2016 season.

• All three seeders have resulted in successful establishment of sub-tropical grasses at the paddock scale.  This reinforces that successful establishment can be achieved with a range of seeding machinery providing the basic principles are followed: i.e. furrow sowing, press wheels, precise shallow seeding together with wide row spacing.
• The disc seeder appeared to have the least soil disturbance, with less loose soil on the soil surface after seeding, but had slightly more sand infill.  This may be due to steep side walls and a relatively narrow furrow, while the seeders with tynes created larger – wider furrows, so sand moving into the furrow was spread over a wider base.  The Case-International combine with a single point had the lowest sand infill.
• The disc seeder resulted in the highest establishment of panic grass, but in late October many of these plants were still small seedlings and subsequently many died over summer.  As number of plants, size and health of plants need to be taken into account, the disc machine may not provide an overall advantage as the proportion of healthy plants was much less. Visually, the Case-International combine appeared to produce a thicker stand; this was most likely due to the higher number of medium to large sized plants when compared to the other machines. 
• The knockdown did not completely kill the brome grass which subsequently recovered and competed with the emerging perennial grass seedlings in early spring.  Combined with dry conditions in October (5 mm) the perennial grass seedlings were struggling in late October.  More favorable seasonal conditions in November and December enabled the grasses to establish.  The scalping points on the John Shearer were able to reduce the impact of brome grass more successfully than the other seeders.
• Persistence will be measured over late summer until the break of the season.  This machinery demonstration trial will be the focus of an extension video which features the producers describing the modifications to their seeders.

• This trial demonstrates that a good establishment result is possible using a range of different seeding configurations, provided the key steps to establishment are followed.
• These factors include:
  • scalping of non-wetting sand and weeds away from drill runs;
  • row spacing of 50-60 cm;
  • sowing into furrows to harvest rainfall (especially important in dry springs); minimizing furrow collapse;
  • ensuring sowing depth is 5-10 mm; and - using press wheels for good soil contact with seed.

The trial establishment was variable early due to some non-wetting soil and the crop was sown too deeply due to furrow fill from significant rain after sowing. Early crop vigour as a result was low with blackleg further reducing plant establishment; this coupled with high levels of Vegetable beetle damage also reduced the evenness of the plots.

According to the DAFWA sporacle model spore maturity occurred on approximately the 22nd May which meant this trial was at very high risk of significant disease risk as emergence coincided with high spore levels being released from last year’s stubble.

• A Predicta B sample taken from the site indicated a medium risk of rhizoctonia although patches did not express during the season.
• Early establishment across the site was severely impacted by non-wetting affected all plots across the trial with the worst of it commencing around plot 215 and increasing in severity throughout replicate 3.  Early dry conditions further staggered the crop emergence.
• Good rains through late July and into early August ensured the crop was growing well albeit patchy across the trial with high levels of disease present at both the Z31 and Z39 applications. Only 48.9 mm of rain fell from the second Z39 application to the end of October reducing the benefits to yield of the different fungicide treatments.
•  Increasing variability in the trial due to the sub-soil issues from plot 215 into replicate 3 was a significant factor. Yield data should be treated with caution due to the variability of the site with disease control is the most accurate assessment of treatment efficacy.

• Soil pH results after liming and tillage treatments were applied was found to be quite variable and more sampling needs to be done before pH results can be quoted. Soil loosening indicates that only the deep tillage techniques were likely to incorporate lime into the deeper 20-30 cm acidic layer.
• This trial highlights the importance of measuring subsoil pH levels and applying sufficient rates of lime to prevent and correct subsoil acidification. Where tillage treatments are used to incorporate lime it is important to understand to what depth lime will be incorporated and which subsoil layers need correction. It is intended to monitor this trial for the next few years to further assess the benefits of correcting subsoil acidification. Yield response to lime incorporation can increase over time as the untreated soil continues to acidify further and as lime has more opportunity to react and neutralize the acidity that is present.

• The trial area was seeded in June 2015 to wheat by Peter Negus, while he was seeding the surrounding paddock.  Unfortunately, the seeder ran out of seed as the trial was being sown.  The result was that there were large unseeded strips running through the trial. 
• Rainfall at the site was very poor in September and October 2015; approximately 70% below average for that period.  As a result, cereal crops on soils with low water holding capacity were badly affected, with yields well below average.
• Analysis of the harvest results (excluding plots affected at seeding) showed no significant differences, leading us to conclude that either (a) the tillage and lime treatment effects have ‘worn out’ at the site, or that (b) poor rainfall in September and October severely reduced yields, obscuring any other effects.  We believe that (b) is more likely.
• This trial will be sown to lupins in 2016.

The pH results from this trial show some interesting trends. 

The treatments with greater disturbance at depth (spade, deep rip + spade, mouldboard) tend to decrease surface pH.  This is of concern if the ‘new’ topsoil pH is acidic enough to inhibit root development. 

The treatments with greater disturbance at depth (spade, deep rip + spade, mouldboard) tend to increase midsoil pH most rapidly.  This is the effect hoped for.  The differences between treatments are generally not significant, but more intensive sampling may tease out differences.

The treatments with greater disturbance at depth (spade, deep rip + spade, mouldboard) tend to increase subsoil pH most rapidly.  This is the effect hoped for.  The differences between treatments are generally not significant, but more intensive sampling may tease out differences.

Deep cultivation strips on growers’ properties did not show much in the way of early responses and so did not excite much grower interest as a direct diagnostic of the hardpan conditions in their paddocks. However, at responsive sites, there was a lot of grower interest to the level where it might be worth funding another year of this direct diagnostic approach in the hope that early season conditions are conducive to major nitrogen growth responses.

• 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.

 

• With a disease like rhizoctonia crop rotation away from cereals is important to reduce inoculum levels. In high risk rotations or in paddocks known to have high disease levels EverGol Prime will be a useful new option for growers based on Australia wide trial experience.
• EverGol Prime has demonstrated excellent control of smut diseases (including bunt) with work conducted in Western Australia on loose smut this year confirming it as an excellent new tool for grower’s to target this hard- to- control disease.

While incidence of root rot was high (83-95%), the disease severity was low on the trial site ranging from 14.3 to 19.5% for treatment averages; many plants had a low level of root disease. Distinct patches were not evident in the trial.

Despite low levels of disease severity observed in the trial and only minor treatment effects on root rot, two in-furrow treatments were found to significantly improve the yield by more than 0.24 t/ha compared to the Untreated control. These were the granular fertiliser treated with Uniform® and the split application of Uniform® above and below the furrow.

In a site with a moderate rhizoctonia disease risk, as indicated by PreDicta B, the majority of plants had root rot however severity was low and patch development did not occur. Under low disease pressure, the Uniform treatments as a whole were able to provide a small reduction in disease incidence which subsequently resulted in yield increase from two treatments. Under higher disease pressure these products can be included as part of an integrated management approach for rhizoctonia.

Yield differences of 2*st. dev. are significant. Within plot variability was large (st. dev. about 0.3 to 0.4 t/ha) but there is an apparent response to ripping, but not to depth of ripping.  More information is needed to interpret these results. 

All cultivation treatments reduced crop establishment significantly below “Nil” cultivation. 

Poor rainfall in September and October 2015 meant that the trial yielded very poorly (~0.5 T/ha), with no significant differences between treatments.

Soil test results are not yet available.

The Long Bottom Boots functioned reasonably well at first, but tended to plug with soil from underneath after multiple passes and on finer textured soil to the south of the trial area.

We think that a design that was wider at the back (60 – 80 mm) and therefore more open would improve soil flow down the boot, and reduce the risk of plugging.

• Our results suggest shifting investment from nutrients to lime and cultivation and maintaining profit in the first year for the 2 sites we ran is a feasible proposition.  However, this is dependent on the soil constraints and existing soil fertility.  In this trial, it appears that the cultivation response was driven by an increase in the mineralisation rate of organic matter. The incorporation of lime did not provide any yield benefit; while the rotary spader provided adequate mixing of the lime this had no impact on growth because soil pH was already above target levels.  The yield benefit from cultivation was enough to offset the cost of the cultivation and most of the lime application, and the net margin in the year of application could be improved by reducing fertiliser rates.
•  

Our results so far suggest that there is an important interaction between year (timing and distribution of rainfall) and soil and nutrient management. There were no significant treatment effects on grain yield in 2013 and 2015, but there were in 2014 and this may be related to autumn rainfall. At the end of March, 75 and 57 mm had fallen in 2013 and 2015 respectively (Figure 3), however, only 16 mm had fallen at this time in 2014. In 2014, soil water repellence as measured in a laboratory test was significantly higher in the no-till control treatments compared to the rotary spader treatments. Seedling density in 2014 was highest in treatments that had the highest soil water repellence, however, this effect did not carry through to grain yield which was lowest in the no-till control. This trial will continue for at least one more year.

 

• 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 early growth of the sub-tropical grasses (panic grass, Rhodes grass) was slow and they appeared to have cold stress.  The seedlings were cold stress with all three TOS and they took a while to recover.
• An interesting observation was that the surrounding paddock was sown to a sub-tropical grass mix (Gatton panic and Rhodes grass) just before the 3rd time of sowing, however the early growth of the perennial seedlings in the paddock was superior to the small plot trials.  Gatton panic is apomictic (i.e. all plants are essentially clones), so any difference must be due to the environment.  In this case, the markedly stronger early growth and less cold damage maybe due to the improved nutrition from the fertilizer applied at seeding. 
• To evaluate whether there was a nutrient deficiency an application of fertilizer - 150 kg/ha of DAP plus 100 kg/ha of MOP was applied to half of each rep in mid-December in a split plot design.  Subsequently there has been little rainfall, so no opportunity to measure a response.
• By mid-February there was not a substantial difference between the three times of sowing for Rhodes grass and Gatton panic which makes sense as in effect the sub-tropical grasses all emerged in early to mid-September for all three TOS.  The only species to emerge in any numbers before the third TOS was perennial veldt grass. However, by mid-February about 35-40% of the veldt grass plants had died and many more plants were highly stressed and may die over summer –autumn.  Sowing veldt grass in late winter – early spring with the sub-tropical grasses may not work in that persistence over summer may be poor.  Perennial veldt grass is a C3 so does not have the same soil temperature requirements as the sub-tropical grasses (C4).  An autumn sowing may be more successful for veldt grass.
• The results from the TOS at Eneabba in 2012 suggest little or no advantage in early sowing of sub-tropical grasses in early August.  The optimum sowing window appears to be late August with more flexibility with Rhodes grass than Gatton panic for early sowing. 

• High operational speed reduced sowing depth of both disc and tyne openers.
• Counts of unsprayed (nil) annual ryegrass were greater for the tyne machine than the disc seeder at 8km/h and 14km/h.
• Within the applied herbicide treatments herbicide efficacy was fairly high. 
• all standing stubble and poor seed placement at 8km/h and 10km/h by the tyne machine severely affected crop establishment.
• At 14km/h the discs ability to penetrate the soil was greatly reduced, impacting sowing depth.
• Barley yields were higher for the disc sown treatments than the tyne sown treatments.

• Establishment and growth to date have been good.
• Low survival rates for some species appear to be consistent with that seen at other trial sites.
• Monitoring will continue, and information on responses to grazing will be available in due course.

• All treatments met Hindmarsh food grade parameters although loose smut was not tested for, which may have excluded the untreated from delivery due to its levels of infection.
• There was no significant difference in yield between treatments.

• This and other research demonstrates that it is possible to improve crop establishment and productivity on water repellent soils using modified furrow sowing techniques.
• Banded wetting agents are helpful with early dry or partially dry sowing before opening rains but show less benefit later in the sowing program when there has already been rain and the soil has started to wet up more (see Banded wetting agent paper WMG 2012 research annual). In very erodible conditions with high wind erosion risk the use of this strategy may be safer than the options with winged points or boots due to less soil disturbance and release of root anchorage for existing plant cover. Optimal wetting agents for WMG areas still need identification.
• Winged points and winged-paired row systems perform better than knife points under certain soil conditions but the benefits are variable and in some sowing conditions may provide little benefit. Further research is required. Winged points look most attractive when shallow moist soil can be ‘delved’ to the seed zone to provide early establishment (as in the winged knife point on the gravelly sand with shallow moisture).
• Simple approaches like sowing next to or at a shallow angle across the previous year’s crop row and broadcast spreading a portion of the seed in front of the seeding tynes are relatively simple approaches that can provide establishment benefits.
•  

• There is still a lot of work to be done but it appears crops can be sown successfully into perennial pastures in some situations.
• Agronomic results from the Moora focus site appear to support the view that Marginal or problem soils are a potential fit for pasture cropping systems. However, it is important to note that the extra green feed produced over summer-autumn needs to be converted into wool or meat in order to offset any grain yield losses.
• Further research is required across different sites and seasons as the yield penalty on better soil classes may well be greater than on deep pale sands which have limited capacity to store moisture from summer rainfall for crop production. The viability of pasture cropping systems based on other sub tropical grass species, native grasses. lucerne and bluebush are also worth evaluating.

Many wheat varieties grown in WA already have the major gene for acid soil tolerance. In this trial several other acid tolerance traits are being assessed under field conditions to determine if they confer growth and yield advantages in addition to the major gene. If the traits do prove useful they can then be back-crossed into current well-adapted WA wheat varieties and ultimately become available for growers to use. In addition to these field trials, the project aims to identify molecular markers to facilitate the breeding process. The traits are likely to be beneficial in situations where soils are being limed to correct soil acidity but are not likely to help in highly Al toxic soils in the absence of liming. This trial and others like it will help determine under what soil acidity levels the traits are likely to be beneficial.

Acid soil tolerance in wheat is not a stand-alone solution for managing acid soils, rather it complements a liming program to ameliorate subsoil acidity. Subsoil at the site is acidic to a depth of at least 40 cm as demonstrated by the indicative site soil pH (CaCl2): 0-10 cm = 5.4; 10-20 cm =  4.2; 20-30 cm = 4.3; 30-40 cm = 4.3. Prior to the site being seeded 1.5 t/ha limesand was spread and this has lifted the topsoil pH to ~5.4 on average. More lime will need to be applied to the site to lift the low subsoil pH values.

At the time of first visit (30th May), plants were at ~3 leaf stage and no foliar disease was evident.  Seedling establishment showed no spatial differences, with average emergence of >100 plants / m2 in all treatments except those with triadimenol seed treatment where >20% reduction in emergence was noted.

Minimal foliar disease was evident at 7th July (~Z31) assessment, minor levels of Stagonospora nodorum (septoria nodorum blotch) (SNB) were evident in the lower canopy but severity was too low for fungicide differences to be assessed.  

Trace levels of powdery mildew (PM) were evident on stems and lowest canopy leaves of untreated plots at booting (27th July) when the second foliar spray was applied. Development of PM was slow and on 15th September (~Z69) average severity in untreated controls was <1% leaf area affected on top 3 leaves, with infection primarily restricted to Flag-2 (Table 1).

PM was also present on heads and stems at low severity at this time, however the distribution of disease, particularly on heads, was patchy across the trial making differentiating between treatments difficult. At this time only the booting foliar spray provided consistent significant reduction in incidence of powdery mildew on stems and leaves.

SNB was present at low levels throughout the season, assessments at head emergence (23rd August) showed a small but significant effect of foliar treatments (Z31 and Z45) and flutriafol and Uniform in-furrow on necrotic leaf area. Assessments 3 weeks later at Z69 indicated that flutriafol in-furrow, triadimenol seed dressing and both foliar spray timings were providing a small reduction (~8-15% leaf area) in necrosis associated with SNB infection (Table 1).

With late and patchy onset of PM, yield responses to fungicides were 0-320kg/ha, with only the flutriafol in-furrow treatment having significantly greater yield than the untreated control, this response is likely due to the reduction of SNB rather than any effect on powdery mildew. Neither foliar spray timing gave significant yield response. Reduced emergence in triadimenol treated plots resulted in a 15% yield reduction (Table 2).

At two other sites (Geraldton, Dalwallinu), where powdery mildew infection commenced during stem elongation, all tested seed dressing and in-furrow fungicides had significant impact on disease severity and incidence. At the one site (Geraldton) where powdery mildew was yield limiting, in-furrow and foliar fungicide treatments gave a significant yield response.

• Fungicide seed treatment or in-furrow did not affect germination or emergence.
• Root disease levels were too low for fungicide responses to be evident.
• Foliar assessments at Z25 & Z30 indicate low levels of necrotrophic disease, both yellow spot (YS) and Stagonospora nodorum (SNB) present with SNB dominant, with no significant impact of at-seeding fungicides on disease expression.
• Foliar fungicide applications at Z31 and Z39 significantly reduced foliar disease severity (YS and SNB) at flag leaf and head emergence.
• Warm dry spring conditions limited fungicide response to late fungicide (Z55) application.
• Yield and quality results were not available.

One way ploughing slightly improved establishment, head numbers, biomass production and yield but is not a viable long term solution for the severe non wetting on this soil type.

Deep ripping and spading improved head numbers by over 60% and biomass production by 87% compared to the control.

Grain yields were improved by over a 1 t/ha and gross margin by about $200/ha when treatment costs were amortized over 5 years in the combined ripping and spading treatments.

Canola provided significant grazing value during the growing season as well as during summer.The varieties tested showed minimal yield penalties from grazing with some varieties showing a positive yield advantage from the grazing operation.Grazing canola crops were able to provide good weed control and will allow the following wheat crop to benefit from this.Grazing canola and cereal crops allows farmers to alter their stocking rate quickly and easily as they progress through the season. This practise will mean in better seasons a much smaller proportion of paddocks will need to be left for stock and more paddocks can be taken through to harvest which will result in a significant increase in farm profitability. In poor seasons there will be less paddocks taken though to harvest which will result in a reduction in grain income, higher sheep grazing losses and lower farm profitability. The overall profitability of grazing cereal crops will depend on the frequency of dry years and good years.Don Nairn finds that grazing cereal crops takes the stress out of running sheep as there is always an option for the farmer when feed runs short (ie he can simply graze another crop). Hopefully this trial gives farmers a better appreciation of where the dollars fall when crops are grazed.

• There was no yield penalty from grazing in 2011. 
• This was probably due to removal of the sheep at closer to the ideal (i.e. Z31) crop stage and possibly the reduced grazing density as well as a favourable finish to the season. 
• This resulted in a profit of $29.89 in 2011 for the grazed treatment compared to -$29.74 for the grazed in 2010.

• Grazing crops can offer the ability to spell pastures, however careful management needs to be practised to ensure there are no grain yield losses. Grain yield losses can very easily result in a negative profit from grazing crops.
• In this case I suggest that the paddock was grazed heavily in the days leading up to removal of the paddock and this resulted in poor recovery of the crop from grazing.  In hindsight I feel that fewer yield losses would have resulted if there was more bulk left leading into stem elongation.
• On the 17th August the Grain & Graze II trial site was visited by the Northern Agri Group (NAG) field day.  During the day we had over 100 growers discuss the pros and cons of grazing crops.  Both Don Nairn and I addressed the field day and had good feedback about the system.

This wheat crop provided significant grazing value, however the paddock was in late in the sowing program which reduced the ability to graze the crop early in the season. This may also have affected how well the crop recovered from grazing due to the delay in maturity of the crop.There was an 11% reduction in yield in this demonstration. Sheep grazed the trial past the Z31 stage which would have meant grain heads would have been vulnerable to the damage from grazing. Smaller yield reductions would have been possible if sheep were removed from the paddock a few days earlier.When the grazing value of the sheep was taken into account there was a $29.74 reduction in profitability from grazing the paddock.Grazing cereal crops allows farmers to alter their stocking rate quickly and easily as they progress through the season. This practise will mean in better seasons a much smaller proportion of paddocks will need to be left for stock and more paddocks can be taken through to harvest which will result in a significant increase in farm profitability. In poor seasons there will be less paddocks taken though to harvest will result in a reduction in grain income, higher sheep grazing losses and lower farm profitability. The overall profitability of grazing cereal crops will depend on the frequency of dry years and good years,Don Nairn finds that grazing cereal crops takes the stress out of running sheep as there is always an option for the farmer when feed runs short (ie he can simply graze another crop). Hopefully this trial gives farmers a better appreciation of where the dollars fall when crops are grazed.

These on-farm trials once again demonstrate that it is possible to graze crops in winter and maintain grain yield.  However, the frequency that yield penalties occurred (when grazing crops) increased when compared to the same set of trials in 2011.  Yield penalties (i.e. greater than 5% yield reduction) occurred in seven out of eleven (64%) trials in 2012 compared to two out of seven (29%) trials in 2011.  There are three possible reasons for this increase.  Firstly, growing season rainfall was significantly less in 2012 with most sites receiving only decile 1 or 2 rainfall.  Moisture stress may reduce the ability of crops to recover from grazing.  Secondly, a number of the 2012 trial sites were located in the low rainfall zone where the short seasons are less suited to crop grazing.  And finally, the timing and intensity of grazing may have increased the frequency of yield penalties experienced.  Four out of the eleven crops were grazed later than recommended and seven out of eleven crops were grazed heavily.  It is quite likely these three factors interact, and that a dry year or location exacerbates the negative impacts of late and/or heavy grazing.

The average amount of grazing value provided by crops was significantly less in 2012 compared to 2011 (214 vs 307 DSE grazing days per hectare).  This was mainly due to the late start and the cold and very dry July experienced in 2012.  The amount of grazing value provided by the crop is important when considering the economic implications of crop grazing.  In a year such as 2012, when grain prices were high, a small yield penalty caused by crop grazing can have a large impact on grain income per hectare.  At the current relatively low livestock prices, a lot of grazing value is needed to make up for any grain yield penalty.

• Quadrat cuts at the end of July showed that each of the crops produced about 0.5 t/ha dry matter. There were no significant differences between the crops (P< 0.05).
• Crop yields were generally between 3 and 4 t/ha. Once again, there were no significant differences between varieties and there was no significant effect of grazing on yield (P < 0.05).
• The ungrazed Baudin was badly affected by mildew.

• Total seasonal biomass production from all of the annual pasture legumes was relatively poor as a result of the poor start. It begs the question, should Serradella, given its useful tolerance to the Imidazolinone group of herbicides, be sown with a fast growing Imidazolinone tolerant cereal such as Scope CL barley to improve early season feed production? If the season is good, the cereal could be grazed early and then sprayed out with a grass selective herbicide to stop it out-competing the Serradella later on. If the season is poor, the cereal could be left to provide valuable winter and spring feed.
• Residues of Imidazolinone group herbicides can affect the performance of the following year’s crops and pastures, so be aware and plan ahead. 

• This trial demonstrated the attributes of true forage varieties in comparison to grain varieties.
• The practices adopted through graze and grain techniques have been invaluable to WA farmers and the products used in the trial can be adopted to increase production in mixed areas where livestock play an important part in farming systems through increased stocking rates and maintaining existing cropping rates.

Overall the site experienced low starting rainfall with staggered plant emergence and then with further rainfall plot populations were within 75 to 85% of targeted plants/m2. All pests and diseases were controlled to an acceptably high level.

• The trial was sown into dry soil on the 11th May. This trial was indicative of many lupin crops within the West Midlands region in 2010, with establishment and weed control issues. Establishment was inconsistent across the trial site with seasonal conditions, non-wetting soil and rhizoctonia root rot contributing to uneven plant numbers and poor growth within some plots. Herbicide management of weeds, particularly ryegrass, was less effective than expected, resulting in high weed burdens, especially in plots with poor lupin establishment.
• Anthracnose was introduced into plots 4 weeks after sowing but warm dry weather following introduction of infection and long dry spells during the growing season reduced disease development.
• Disease assessments at crop maturity indicated that despite high levels of inoculum being introduced only low levels of disease were present within the trial and differences between varieties were not statistically significant. Approximately 10% of the moderately susceptible Jenabillup plants suffered stem infection, the resistant variety Tanjil and resistant breeding lines had between 2-4% of plants with stem infection. Pod infection levels were low across the trial due to dry weather during podding.
• Due to uneven establishment, variable soil moisture, root disease and weed burden, individual plot yields varied from 0.5 t/ha to 2 t/ha across the site (average 1.4 t/ha), however neither variety nor anthracnose infection significantly affected yield.
• In seasons with good rainfall, anthracnose can be a yield constraint for lupin production in the high-medium rainfall regions of the northern agricultural region (particularly in areas with abundant blue lupins); the anthracnose resistance in current advanced breeding lines will reduce disease development and yield loss.

• In the first two seasons, 2009 and 2010, there was a strong and consistent yield increase in response to mouldboard ploughing. 
• In 2011 the mouldboard plough plots on average yielded 300 kg/ha (13%) less than the unploughed plots.
• This trial is an unreplicated demonstration so it’s hard to tell if the negative response is real or not. 
• For further results please see attached trial report.

Grower adoption of rotary spading and mouldboard ploughing in the West Midlands has been steadily increasing.

• This trial demonstrates the productivity and financial benefits that can arise from implementing rotary spading and indicates that the practice of deep ripping prior to spading appears to be worthwhile as not only does it remove obstacles and make spading easier it also appears to be a benefit to crop growth and productivity particularly in times of drought.
• Soil compaction was a significant constraint on this site and deep ripping alone has shown an advantage. Ideally controlled traffic system should be implemented after deep tillage to prevent re-compaction and loss of these benefits.

• Our results from the first year of the study show that the method used to manage soil water repellence had little impact on soil nutrient supply with the exception of phosphorus. The lack of grain yield response to applied P in the mouldboard and spading treatments suggest that soil phosphorus is more available in these soils, though is not clear whether this is due to the removal of the non-wetting constraint or mineralisation following tillage.
• The lower grain yield and harvest index in the spading treatment suggests that there was less soil water available late in the growing season. Further research is required to determine how these management practices, in particular inversion and rotary spading, changes fertiliser advice. The results of this work will be used to develop guidelines on if or how nutrition should be managed for crops sown on soils treated for water repellence.

• In general for the bulk of the paddock in the wetter 2011 season there was little obvious difference in establishment between the knife point and winged point with paired rows seeder. However there were a several water repellent patches where establishment was poor for the knife point seeder but was much improved for the winged point-paired row seeder.
• Plant counts in these areas revealed that establishment was more than doubled from <100 plants/m2 to >200 plants/m2 through use of the winged point-paired row system in both the sandy gravel and pale deep sand soil types
• The advantage of improved furrow sowing as a tool to manage water repellent soils is it can be applied over all the repellent cropping areas, potentially for relatively low cost if only points and press wheels need changing on an existing seeder.
• For further results please see the attached trial report.

A trial was established west of Moora in 2016 to investigate in season potassium response in barley. The main objective was to compare Lokomotive, a liquid potassium product, to the more commonly used granular muriate of potash (MoP).  Both soil and plant sample analysis showed the site to be marginal/deficient in potassium. Treatments were applied at GS 32. This timing was chosen as potassium deficiency is most commonly identified late in the growing season, when visual symptoms appear, and confidence in an economic response to applications of MoP in the current season is diminishing. At the time of application there were typical potassium leaf deficiency symptoms on the lower leaves. 

Good growing conditions were experienced in Moora in 2016 and resulted in high barley yields of 4.17 to 4.39 t/ha. There was a small yield response (1.7% to 5.3%) from both Lokomotive and MoP however this was not significantly different to the untreated control. The small response to potassium in 2016 may be attributed to the wet spring conditions that would have made potassium in the soil more available to the crop. Further evaluation of in season potassium application is required when spring conditions aren’t as favorable as 2016.  

 

 

Prior to seeding the trial in 2015, the site was extensively soil sampled to a 60 cm depth by Precision SoilTech.  An area with the capacity to accommodate the treatments with minimal variation in soil pH between plots was identified, however due to the nature of this site and the layout of the treatments (designed to be practical for the landowner to implement and maintain), there are inconsistencies within the trial which need to be carefully considered when assessing treatment effects. There were no systematic differences between the lime treatments in crop establishment and harvest yield, seemingly as a result of variability in soil pH and other characteristics between plots, complicated further by the layout of the trial, rather than a treatment effect.

It was observed that incorporation by both offset discs and one way plough did not reduced or cause uneven germination compared to knife-point at seeding, and during the season it was not visually evident that incorporation treatments had a major effect on crop growth and health compared to the control treatment.

While it may not be expected that shallow incorporation of lime would result in significant differences between lime treatments on a forest gravel soil type in the first year of a trial, it is imperative going forward into the next two seasons that a professional statistician helps analyse current and future data to ensure that subsequent interpretations can be improved, given the apparent impacts of site variability, and as treatment effects may become more pronounced.  It is expected that the ongoing plot soil testing conducted prior seeding each season will be the primary indicator used to determine whether incorporation of lime using either offset discs or one way plough can reduce soil acidity on a forest gravel at depth more quickly than the district practice of top-dressing, while yield responses will determine any economic benefits.

EverCrop research reported in this and previous Crop Updates (2010-2014) has built up a sound knowledge base on the viability, performance and economics of pasture cropping and companion annual legume based systems for fragile soils in the Northern Agricultural Region that are marginal for continuous cropping. Collectively, trials at Mingenew and Dandaragan over the past two seasons (2013 & 2014) have demonstrated that subtropical perennial grass pastures lift the overall productivity of deep sandy soils, extend the period of available green feed, convert summer rainfall into feed, reduce the winter and summer weed burden, and increase ground cover.

• It was found that incorporating canola or fallow, followed by an early-sown high value legume (chickpea, lentil) was a profitable crop sequence that increased grain yield of the following cereal crop.

• Chickpea were a consistent performer at most sites on a range of soil types (deep sands, sandy loams) as well as clay soils.

• The area suitable for chickpea production may now be greater following successful amelioration of soil constraints in the Wheatbelt.

• The inclusion of chickpeas or lentils in the crop sequence did lead to an increase in weed populations. However, this did not cause any management issues in the following cereal crop.

• Crop yields declined by an average of 31 kg/ha/day when sowing was delayed from the 20th May to the 2nd June.
• Delaying seeding from 2nd June to the 15th June resulted in an average yields decline of 45 kg/ha/day.
• There were not any significant interactions between varieties in their response to delayed sowing time from 20th May to the 15th June. -
• The top performing AH/APW varieties were Carnamah, EGA Bonnie Rock, Espada, Katana, King Rock, Mace, Scout, Wyalkatchem and Zippy. Screenings of these varieties was less than 5% at each sowing time.
• The varieties Binnu, EGA Bonnie Rock, Espada, Fang, Lincoln and Yandanooka produced screenings greater than 5% when sown in mid June.

• The negative effect of water repellence management at this site is at odds with other work in this project. In both years we have observed a lower grain yield in the banded wetter, mouldboard ploughing and spading treatments than in the control at this site.
• However, the average yield response to mouldboard ploughing and spading was 550 to 600 kg/ha over 28 sites.
• For further details please see the attached trial report.

The success of break crops to increase wheat production in the Eastern Wheatbelt is dependent on firstly addressing any physical and chemical soil constraints to crop production and where the previous land use is a chemical fallow. In this situation, the grain yield of lupin, chickpea, lentil and field pea was 0.97-1.42 t/ha 0.67-1.1 t/ha, 0.3-0.97 t/ha, and 1.2 t/ha respectively in a below average season. The yield of wheat following legume break crops tended to be higher than either canola or wheat planted in the remaining paddock area. The profitability of double break-crop sequences was negative in many of the sequences evaluated in this study compared to a positive profit for continuous wheat. The profitability of double break-crop sequences can be improved by the inclusion of high value legumes as the second break-crop, but further work is required to lower the risk of growing these species of crops.The yield of wheat following legume break crops tended to be higher than either canola or wheat planted in the remaining paddock area. The profitability of double break-crop sequences was negative in many of the sequences evaluated in this study compared to a positive profit for continuous wheat. The profitability of double break-crop sequences can be improved by the inclusion of high value legumes as the second break-crop, but further work is required to lower the risk of growing these species of crops.

• The results presented in this report are from the first year of a three-year study that investigates the effect of break-crop sequences on wheat grain yield. The site was selected due to its high background levels of ryegrass control, and crop rotation treatments have been designed around weed control as the main rotational factor.
• Grain yield was relatively low compared to the growing season rainfall of 253 mm. Grain yield was affected by severe frost that occurred during grain fill.
• This project will continue with the second crop in rotation for the 2017 season, followed by wheat across all plots in 2018 to assess the benefit of a stacked rotation for subsequent wheat grain yield.

The trial will be going into its 3rd year in 2018 and all trial plots will be sown into wheat. The aim is to determine the difference in grain yield for wheat following a range of single or double break crop rotations, compared to continuous wheat. The site was established in 2016 on a paddock that had very high level of ryegrass that was affecting crop production. This area around this trial has been in pasture for 2017 as the comparison farmer solution for the issue.

• Establishment densities were higher at both sites following the double knockdown treatment.
• Sand infill was less with the single knockdown treatment, but these differences were not statistically significant.

• The one-off 2010 mouldboard ploughing treatment has resulted in yield increases of 1.0 t/ha or more for the past 4 seasons.
• The measured yield increases were partly a result of overcoming the water repellence by soil inversion and improving crop establishment.
• For further details please see attached trial report.

• These results showed that field pea was much better suited to the deep sand than lentil, albus lupin and chickpea.
• This is consistent with results of the previous study undertaken in 2005. 

• There were no significant differences between cultivation treatments at the Martin site.  There was a significant effect from lime applied, as expected. There is an interesting trend of increasing pH over the 3 years in the limed treatments, suggesting that the lime applied in 2013 is still acting to reduce soil acidity after three years. 
• There were no significant differences between cultivation treatments at any depth in either year at the Brown site. 
• There were no significant differences between cultivation treatments at any depth at the McAlpine site. 

It is critically important to sample soil pH to depth prior to investing large sums in lime application and incorporation. Typically it has been found that on sandplain soils the yield benefit of one-off deep cultivation or deep ripping is large enough to cover the cost of the tillage in the first year so the subsequent productivity benefits associated with more rapidly fixing the soil pH by incorporating lime can be realised sooner. Other factors such as water repellence, herbicide resistant weeds, subsoil compaction, wind erosion risk and soil type will impact on the choice of incorporation implement used.

This first year study has shown that the adoption of a strategic tillage practice (one-way plough) provided a significant improvement in terms of crop establishment and grain yields on a moderately repellent sandy gravel. The adoption of other agronomic options, such as paired-row sowing or wetters, in this instance did not provide any noticeable improvement in comparison to the control treatments. In fact, in one case (wetter 1), the cost of the treatment was not covered by the yield increase.

Without doubt, the tillage proved to be the most effective treatment for reducing SWR but at this stage it is not possible to evaluate the extent to which this improvement alone contributed to the significant increase in yields.

With this long term experiment, we expect the following seasons to give us more information to better understand what changes drive the yield increase and possibly the potential longevity of these improvements.

In the first growing season, the one-off tillage treatments showed to reduced significantly the water repellency of the soil. Significantly better plant establishment and grain yield were obtained in all the tillage treatments. In terms of grain yield, better results were achieved with the tillage treatments that mixed the soil more efficiently, such as the “Deep ripping + Spading” and the “Mouldboard plough” treatments. The “Deep ripping” treatment, which effectively targeted only subsoil compaction, provided the lowest improvements in terms SWR and the lowest grain yield.

The greatest profit in the first growing year was achieved using the “Modified one-way plough” thanks to its low capital cost which reduces its operating cost. Nonetheless, further growing season will be necessary to establish its long term profitability in comparison to the “Deep ripping + Spading” and the “Mouldboard plough” treatments.

Changes in the soil pH profile were also observed after the tillage treatments, with increased acidity in the topsoil. That was particularly the case with the “Mouldboard plough” treatment and the management of soil pH with addition of lime after the tillage needs to be considered.

We expect the next four growing seasons to give us more information to better understand the long term effects of these soil modifications on soil productivity.

 

Longer-season wheat with later flowering time produced higher yield than early flowering wheat. However, the high correlation between the time to anthesis and the time to terminal spikelet initiation makes it difficult to evaluate the relationship between yield and CPD independently. Increasing biomass from longer-season wheat is probably more promising trait than lengthening CPD to achieve higher yield in the high rainfall area.

The results from this trial show the importance of ripping below the hard pan with deeper ripping. The hard pan at this site measured to a depth of 400mm prior to the ripping treatments going in. Ripping to 300mm, without spading, has not improved yield in either of the first two seasons as plant roots are slowed through the hard pan. For return on the dollars spent deep ripping it is important to understand where the hardpan is in your paddock before starting the program.

It is likely that the topsoil slotting plates are impacting the inter-row soil strength during the ripping process. Therefore the design needs investigation. It may be that additional shatter is required through winged points allowing the plates to pass through with less impact.

Monitoring of this trial continues during 2017 and 2018 seasons.

• Analysis of the results has not been conducted. The analysis will be distributed to the WMG membership when it is completed.
• Despite this, it is apparent that the data for the WMG trial does not show any trend to an improvement in pod numbers or yield for any treatment over the ‘Nil’ treatment.
• Of the other 2 sites, only the Mingenew trial showed a significant trend to increased pod numbers using ‘Lupin Bud‘ at the 6 leaf stage. Secondary pod numbers were also higher for all treatments compared to the Nil. This trial was not harvested.
• This trial should be repeated in 2014 to see if any conclusive claim can be made for the efficacy of ‘Lupin Bud’.

• A number of plots were impacted by water erosion from a cloud burst after sowing, an erosion channel running through a section of the trial.
• Yield of these plots was impacted. As a result yield outliers were removed during analysis of the trial.