• The seasonal conditions experienced during these trials had a profound impact on the trial results.
• During 2015 stubble treatments imposed late in fallow had no impact on N response.
• Similar to 2014, during 2015 generally farmers were unable to predict final yield before sowing when the season experienced extreme weather conditions.
• During 2015 split N applications did not improve yields and had only a very minor impact on grain quality.
• During 2015 split N applications was not a way to reduce financial risk as opposed to all N fertiliser upfront since crop outlook at Z30 was positive.

• SBU is the spread pattern of seed and fertiliser relative to row space, expressed as a percentage.
• Safe urea N rates in Canola are approximately half that of wheat at the same SBU %.
• When the SBU % is > 45%, safe N rates become less than half that of wheat.

For full assessment of plots and other results please see the attached trial report.

Nineteen experiments in the Mallee, over four years, have shown that mid-row banding does as well as top-dressing in obtaining yield and protein improvements over more conventional methods of nitrogen application at sowing (eg, broadcast, and incorporated at sowing).

The trial as a result of cockatoo damage experienced patchy emergence and has contributed to a higher LSD from the trial. While there is a larger LSD some conclusion can be drawn from the trial. It must also be noted that the price of the SRN has been assumed to be 1.5x greater than the cost of urea at $608/t. This assumption is only for comparison reasons only and is only an estimate.

This trial has demonstrated that SRN in leaching sands can be used as a banded product to  improve N efficiency and improve yields. From graph 1 the N efficiency of the applied nitrogen N applications has been calculated. As expected the banded urea had the poorest N efficiency ranging from between 1.6-<14%. SRN and urea mixes banded had an N efficiency improvement over the banded urea, with top-dressed urea at Z25 ranging from between 42 and 50% nitrogen efficiency.

SRN and top-dressed nitrogen had the best N efficiency ranging between 47 and 50%. In the WMG area this year the dry June while not welcome did help to improve N efficiency, with N efficiency >50% rarely heard of on the gravel matrix sand and deep sands in medium/high rainfall years. So while the area experienced a relatively low N leaching year the SRN has still enabled a greater $ROI/Ha for each plot.

• Soil acidification is a natural process accelerated by high crop yields and fertilizer use. It is an unseen cost of doing business.
• To maintain a good soil pH profile, producers should aim for a pHCa above 5.0 in the 0-10cm of topsoil or 5.5 if subsoil acidity issues are present. The target in the 10-30cm zone is greater than
  pHCa 4.8.
• Correct pH is paramount when growing legumes, especially if the decision to grow them is to increase soil nitrogen levels.
• Liming needs to be thought of as a farm input, like checking and changing the oil in the tractor (maintaining capital), rather than buying urea (dollars returned per dollar invested).

• Soil acidification is a natural process accelerated by high crop yields, fertilizer use and potentially direct drilling and stubble retention. It is an unseen cost of doing business.
• To maintain a good soil pH profile producers should aim for a pH(CaCl) above 5.0 in the 0-10cm of topsoil or 5.5 if subsoil acidity issues are present. The target in the 10-30cm zone is greater than pH (CaCl) 4.8.
• Retesting during 2015 of historic soil pH datasets confirms soil profiles continue to acidify.
• Left unmanaged sub soil acidification is likely to occur in most Central West NSW soils.
• Liming needs to be thought of as a farm input, like checking and changing the oil in the tractor, (maintaining capital) rather than buying urea (dollars returned per dollar invested).
• Cost in managing soil pH are easier to quantify than returns.

• Soil acidification is a natural process accelerated by high crop yields, fertilizer use and potentially direct drilling and stubble retention. It is an unseen cost of doing business.
• To maintain a good soil pH profile producers should aim for a pH(CaCl) above 5.0 in the 0-10cm of topsoil or 5.5 if subsoil acidity issues are present. The target in the 10-30cm zone is greater than pH (CaCl) 4.8.
• Retesting during 2015 of historic soil pH datasets confirms soil profiles continue to acidify.
• Left unmanaged sub soil acidification is likely to occur in most Central West NSW soils.
• Liming needs to be thought of as a farm input, like checking and changing the oil in the tractor, (maintaining capital) rather than buying urea (dollars returned per dollar invested).
• Cost in managing soil pH are easier to quantify than returns.

• N2O emissions at the Gunnedah site were approximately 10 times higher than at the Emerald site, due to the wet soil conditions and high pre-season rainfall at Gunnedah which led to denitrification of N from pre-season anhydrous ammonia application.
• Two nitrification inhibitors, DMPS (“Big N-sure”, Incitec Pivot Fertilisers) and nitrapyrin (“N-serve”, Dow AgroSciences) directly injected into anhydrous ammonia during pre-plant N application delayed the conversion of applied ammonium in the soil to nitrate for a period of 2–3 months.
• At the Gunnedah site, cumulative N2O emitted was reduced by 86% (DMPS) and 65% (nitrapyrin), compared to untreated ammonia.

Conclusions: 

In a season such as that experienced at the Emerald 2016–17 site, there were only minor environmental benefits from using a nitrification inhibitor in conjunction with anhydrous ammonia. However, these experimental conditions may not be typical as pre-plant fertiliser is usually applied earlier in the year at Emerald than it was at this site. A longer period of time between pre-plant application and plant establishment would provide greater opportunity for N2 O losses to occur, although the potential for heavy winter rainfall tends to be low in the Emerald region. While both inhibitor products clearly reduced emissions during the first two measurement periods, it was apparent that the effectiveness of these products had dissipated by the time of the second irrigation. The additional inhibitor application with the side-dressed urea boosted the N2 O reduction period for the DMPP treatment, while the application of untreated urea to the other treatments allowed further losses matching those of the untreated control after the initial pre-plant N application. The 2016–17 Gunnedah experiment provided the perfect testing conditions for nitrification inhibitors as the soil was very wet at application, and received frequent heavy rainfall during the next 3 months. These inhibitors were designed to retain mineral N from applied N fertiliser in the soil during periods of excessive rainfall that may otherwise lead to large losses of nitrate N through denitrification and leaching. Leaching occurs through downward movement of nitrate with water in the soil, but we found no evidence of this having occurred in the soil core samples we took just prior to sowing. For heavy clay soils such as this one at Gunnedah, denitrification of soil nitrate during periods of anaerobic soil conditions is the most likely major N loss pathway. The results of the gas sampling campaigns highlighted the almost complete mitigation of N2 O emissions during this period by adding nitrification inhibitors. The Big N-sure® inhibitor appeared to remain active for longer in the soil than the N-serve®.

Averaged across all sampling locations, protein levels increased by 0.6% in the 50kg/ha of urea treatment and by 1% in the 100kg/ha of urea treatment relative to the nil in-crop fertiliser strip. This increase in protein was enough to improve grain quality from Australian Standard White (ASW) to Australian Premium White (APW) at four of the six sampling locations. On the day of harvest at the nearest grain receiver site (Yelta), the ASW silo cash price was $127/t and APW was $158/t. At a urea cost of $620/t, the application of 50 kg/ha of urea costs $31/ha (fertiliser cost only). Therefore, at the four sites where grain quality was improved, a small profit was made (15 – 55 $/ha) with the application of 50 kg/ha of fertiliser. However, at one third of the protein sampling sites, a loss of $31/ha was incurred as there was no difference in grain quality between the treatments.

While all soil types responded to nitrogen, the response and profitability of nitrogen application varied between soil zones. Using the Urea/SOA treatment as an example, for the loam and swale soil types, the additional profit compared to no in-season N was approximately $50/ha. However, applying additional fertiliser to the dune soil was twice as profitable (approximately $100/ha). As input costs were standard across all soil types (i.e. an N Rich strip with the equivalent rate of N was used for all treatments), profitability was driven by the increase in yield. As fertiliser efficiency was below its potential for the loam and swale soils (and at potential for the dune soil), it is possible that the same yield response could have been achieved with less fertiliser, therefore these two soil zones could have been more profitable if less nitrogen was applied.

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

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

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

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

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

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

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

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

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

• Soil applied fertiliser was and better than liquid urea or UAN applied with standard spray nozzles to the crops leaves.
• Both urea and UAN are equally as effective when applied to the soil.
• Growers should select the nitrogen product that most suits their farming system in terms of logistics and cost.

Tor top dressing to be effective on canola the following points are required:

• It needs to be applied to a crop with marginal soil N levels that has the potential to respond.It must be applied before the crop suffers an unreasonable yield potential loss due to N deficiency.
• This will usually mean top dressing before stem elongation.
• The crop also needs good growth conditions after top dressing so that it has potential to provide an economic response.

• Only 31 per cent of the applied urea nitrogen (N) was taken up by the wheat crop in 2014. This low fertiliser use efficiency may be partly related to the season; unused N in the soil can benefit the following crop.
• In a decile 1 season, different stubble retention practices had no effect on microbial biomass and N supply potential (avg. 58kg N/ha).
• Labelling a wheat crop with 15N allows researchers to quantify the fertiliser use efficiency and trace the N from stubble to the subsequent crop.

• The trial was designed to test the capacity of TwinN to enable reductions in nitrogen fertiliser applications.
• The control treatments showed no statistical difference in yield between 0 and 50 kg/ha urea but a difference was seen between 50 kg and 100 kg/ha ureas.
• Yield from TwinN plus 75 kg/ha urea was not statistically differenent from that from the 100 kg/ha urea.
• No treatment effects were found in protein% or screenings%.

Following this year's trials results we are confident that UAN can have a role as an in-crop N fertiliser.

• Agntain was found to provide little benefit for increasing canola yield. Agritain may have a role in reducing urea toxicity to germinating seeds, when crop seeds are sown close to pre-applied urea (especially when large amounts of N are used).
• This warrants further investigation.

• Agntain was found to provide little benefit for increasing canola yield. Agritain may have a role in reducing urea toxicity to germinating seeds, when crop seeds are sown close to pre-applied urea (especially when large amounts of N are used).
• This warrants further investigation.

CAN gave a significant yield result at both timings and over both rates of urea (Table 1). The site responded to topdressed N markedly with a yield increase of 0.81 t/ha (90 Urea) to 0.93 t/ha (132 CAN) at the first timing. The second timing showed a 0.6 t/ha (132 Urea) to 0.82 t/ha (132 CAN) yield response. Both CAN responses were significantly different to Urea. The first timing gave a higher yield response with both products. There was little site variation with both controls not significantly different.

• Liquid P applications must be considered a viable option in these farming areas considering these results. It should also be pointed out that this is only one set of trial data in one year for this area. These results indicate that more trial work on LMAP needs to be conducted in the future. 
• Based on previous trials from other areas, the above results indicate that soils in these areas are able to tie up P and that the use of the liquid form of P as LMAP is a viable option for broadacre cropping where this occurs. 
• Finally this trial indicates that a positive yield response can be gained from additional use of N fertilisers, as seen in treatment 5, which was a combination of urea and MAP granules. 

• There is an opportunity to use locally available amendments in place of inorganic fertiliser.
• High rates of surface-applied chicken litter tend to have a better yield response than either surface-applied compost or inorganic N fertiliser.
• Stability of these organic products may provide a less risky option for managing inputs with no need for top dressed urea in the first two years.

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

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

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

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

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

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

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

• Our standard package of 100 kg 18:20/ha at seeding under the seed row (to avoid fertiliser toxicity), Jockey-treated seed, endosulfan and simazine pre-seeding, a follow up spray of atrazine and a grass herbicide mid-season, and two top-ups of nitrogen during the season (50 kg N/ha as broadcast urea each time) gave us a clean, high yielding and good quality crop with no pests or diseases.
• There was no evidence that extra management options provided any further benefits to canola performance (ie a fungicide spray, B fertiliser or use of a growth regulant) under the conditions of last year’s trial.
• However, it would appear that we may have been a bit generous with our N and P inputs in the standard package because we could halve the mid-season N rate and not suffer any yield or quality loss. Additionally, leaving out P altogether had little impact so a rate lower than 20 kg P/ha may have been the best compromise last year.
• There seems little reason to change from a management strategy of plenty of N at seeding (providing you can avoid seedling toxicity by separating the N and the seed) followed up by an early season top-up. Delayed aapplications of N produced yields or quality no better than our standard.

Under the 2013 growing season conditions, there was no advantage to wheat growth and grain yield in the use of a polymer-coated urea product.

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

• Trojan apparently responded better to 3 Nitrogen applications at GS 31, 33 & 37.
• Revenue yielded most will nil extra Nitrogen, but not significantly better than with 100kg applied urea.
• Higher Nitrogen late increased grain protein across all varieties as expected • Revenue expressed reduced yields at Urea application rates higher than 200kg/Ha.