{"disclaimer":"Always check with your agronomist before acting.","notice":"General information only. Prices are null unless verified from a public listing (indicative). Grain price default is an example, not a market quote. Loss ranges: see references.","inputs":{"soil":"loam","ph":6.5,"crop":"wheat","method":"surface","calcareous":false,"nRate":null,"area":null,"scenarioId":"auto","prices":{},"nRateUsedKgPerHa":50},"scenario":{"id":"incrop","label":"Australian average, in-crop top-dressing","lossPercent":{"low":0,"mid":8.1,"high":29},"basis":"GRDC/Schwenke 2021: in-crop mean 8.1%, range 0–29%.","referenceIds":["grdc-2021-schwenke"],"automatic":true,"reason":"Intermediate texture; using the Australian in-crop average range."},"calculator":{"assumptions":{"grainPriceIsExample":true,"note":"low = smallest loss (best case), high = largest loss"},"results":{"low":{"lossPct":0,"spendPerHa":50,"nAppliedKgHa":23,"nLostKgHa":0,"nDeliveredKgHa":23,"dollarsLostPerHa":0,"effectiveCostPerKgN":2.1739130434782608,"yieldGainKgHa":230,"grainRevenuePerHa":92,"totalCostPerHa":50,"netReturnPerHa":42,"returnPerDollar":1.84,"breakEvenResponse":5.434782608695651,"breakEvenGrainPricePerTonne":217.3913043478261,"breakEvenYieldGainKgHa":125},"mid":{"lossPct":8.1,"spendPerHa":50,"nAppliedKgHa":23,"nLostKgHa":1.8629999999999998,"nDeliveredKgHa":21.137,"dollarsLostPerHa":4.05,"effectiveCostPerKgN":2.3655201778871175,"yieldGainKgHa":211.37,"grainRevenuePerHa":84.548,"totalCostPerHa":50,"netReturnPerHa":34.548,"returnPerDollar":1.69096,"breakEvenResponse":5.913800444717793,"breakEvenGrainPricePerTonne":236.55201778871174,"breakEvenYieldGainKgHa":125},"high":{"lossPct":29,"spendPerHa":50,"nAppliedKgHa":23,"nLostKgHa":6.67,"nDeliveredKgHa":16.33,"dollarsLostPerHa":14.5,"effectiveCostPerKgN":3.0618493570116354,"yieldGainKgHa":163.29999999999998,"grainRevenuePerHa":65.32,"totalCostPerHa":50,"netReturnPerHa":15.319999999999993,"returnPerDollar":1.3063999999999998,"breakEvenResponse":7.654623392529087,"breakEvenGrainPricePerTonne":306.1849357011635,"breakEvenYieldGainKgHa":125}}},"rows":[{"slug":"granular-urea","name":"Granular Urea","brand":"Incitec Pivot Fertilisers","category":"Nitrogen","nPct":46,"nForm":"urea","multiNutrient":false,"pricePerTonne":820,"priceIndicative":true,"productKgPerHa":108.69565217391303,"nDeliveredKgPerHa":{"low":50,"mid":45.95,"high":35.5},"costPerHa":89.13043478260869,"costPerKgN":1.7826086956521738,"effectiveCostPerKgN":{"low":1.7826086956521738,"mid":1.939726545867436,"high":2.5107164727495404},"dollarsLostPerHa":{"low":0,"mid":7.219565217391303,"high":25.84782608695652},"lossPct":{"low":0,"mid":8.1,"high":29},"lossQuantified":true,"rating":"Caution","ratingNote":"Surface urea: scenario \"Australian average, in-crop top-dressing\" 0–29% (mid 8.1%).","rules":["Surface urea: scenario \"Australian average, in-crop top-dressing\" 0–29% (mid 8.1%).","Acidifying fertiliser (DPIRD 1994); monitor soil pH over time."],"totalCost":null,"totalProductTonnes":null},{"slug":"green-urea-nv","name":"Green Urea NV","brand":"Incitec Pivot Fertilisers","category":"Nitrogen","nPct":46,"nForm":"urea-nbpt","multiNutrient":false,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":108.69565217391303,"nDeliveredKgPerHa":{"low":50,"mid":47.975,"high":42.75},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":4.05,"high":14.5},"lossQuantified":true,"rating":"Fair","ratingNote":"Surface urea scenario \"Australian average, in-crop top-dressing\" × 0.5 (NBPT reduces loss by about half on average; field results vary).","rules":["Surface urea scenario \"Australian average, in-crop top-dressing\" × 0.5 (NBPT reduces loss by about half on average; field results vary).","Acidifying fertiliser (DPIRD 1994); monitor soil pH over time."],"totalCost":null,"totalProductTonnes":null},{"slug":"gran-am","name":"Gran-Am (ammonium sulphate)","brand":"Incitec Pivot Fertilisers","category":"Nitrogen + Sulphur","nPct":20.2,"nForm":"ammonium-sulphate","multiNutrient":true,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":247.52475247524754,"nDeliveredKgPerHa":{"low":50,"mid":47.975,"high":42.75},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":4.05,"high":14.5},"lossQuantified":true,"rating":"Fair","ratingNote":"Surface ammonium sulphate on non-calcareous soil: less than half the loss of urea (GRDC 2021); modelled as 0.5 × urea, an upper-bound simplification.","rules":["Surface ammonium sulphate on non-calcareous soil: less than half the loss of urea (GRDC 2021); modelled as 0.5 × urea, an upper-bound simplification.","Acidifying fertiliser (DPIRD 1994); monitor soil pH over time."],"totalCost":null,"totalProductTonnes":null},{"slug":"cal-am","name":"Cal-Am (calcium ammonium nitrate)","brand":"Incitec Pivot Fertilisers","category":"Nitrogen + Calcium","nPct":27,"nForm":"ammonium-nitrate","multiNutrient":true,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":185.18518518518516,"nDeliveredKgPerHa":{"low":50,"mid":50,"high":50},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":0,"high":0},"lossQuantified":true,"rating":"Good","ratingNote":"Nitrate/ammonium nitrate: no gaseous loss expected except on highly calcareous soils (DPIRD 1994).","rules":["Nitrate/ammonium nitrate: no gaseous loss expected except on highly calcareous soils (DPIRD 1994)."],"totalCost":null,"totalProductTonnes":null},{"slug":"easy-n","name":"Easy N (liquid nitrogen)","brand":"Incitec Pivot Fertilisers","category":"Nitrogen","nPct":42.5,"nForm":"uan","multiNutrient":false,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":117.64705882352942,"nDeliveredKgPerHa":{"low":50,"mid":46.9625,"high":39.125},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":6.074999999999999,"high":21.75},"lossQuantified":true,"rating":"Caution","ratingNote":"UAN-type liquid sits between urea and ammonium sulphate (Turner et al. 2012: urea > UAN > AS). Modelled as 0.75 × urea. UNVERIFIED: the factor is our assumption.","rules":["UAN-type liquid sits between urea and ammonium sulphate (Turner et al. 2012: urea > UAN > AS). Modelled as 0.75 × urea. UNVERIFIED: the factor is our assumption."],"totalCost":null,"totalProductTonnes":null},{"slug":"big-n","name":"Big N (anhydrous ammonia)","brand":"Incitec Pivot Fertilisers","category":"Nitrogen","nPct":82,"nForm":"anhydrous","multiNutrient":false,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":60.97560975609756,"nDeliveredKgPerHa":{"low":50,"mid":50,"high":50},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":0,"high":0},"lossQuantified":true,"rating":"Good","ratingNote":"Anhydrous ammonia: loss is small if slots are covered immediately and soil moisture is right (GRDC 2022); not quantified here, modelled as 0. Specialist equipment and training required.","rules":["Anhydrous ammonia: loss is small if slots are covered immediately and soil moisture is right (GRDC 2022); not quantified here, modelled as 0. Specialist equipment and training required."],"totalCost":null,"totalProductTonnes":null},{"slug":"dap","name":"DAP (diammonium phosphate)","brand":"Incitec Pivot Fertilisers","category":"Phosphorus","nPct":18,"nForm":"ammonium-phosphate","multiNutrient":true,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":277.77777777777777,"nDeliveredKgPerHa":{"low":50,"mid":50,"high":50},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":0,"high":0},"lossQuantified":true,"rating":"Good","ratingNote":"Ammonium fertiliser on acidic/neutral soil: volatilisation not expected (GRDC 2022).","rules":["Ammonium fertiliser on acidic/neutral soil: volatilisation not expected (GRDC 2022)."],"totalCost":null,"totalProductTonnes":null},{"slug":"map","name":"MAP (monoammonium phosphate)","brand":"Incitec Pivot Fertilisers","category":"Phosphorus","nPct":10,"nForm":"ammonium-phosphate","multiNutrient":true,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":500,"nDeliveredKgPerHa":{"low":50,"mid":50,"high":50},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":0,"high":0},"lossQuantified":true,"rating":"Good","ratingNote":"Ammonium fertiliser on acidic/neutral soil: volatilisation not expected (GRDC 2022).","rules":["Ammonium fertiliser on acidic/neutral soil: volatilisation not expected (GRDC 2022)."],"totalCost":null,"totalProductTonnes":null},{"slug":"yaraliva-calcinit","name":"YaraLiva Calcinit (calcium nitrate)","brand":"Yara","category":"Nitrogen + Calcium","nPct":15.5,"nForm":"nitrate","multiNutrient":true,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":322.5806451612903,"nDeliveredKgPerHa":{"low":50,"mid":50,"high":50},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":0,"high":0},"lossQuantified":true,"rating":"Good","ratingNote":"Nitrate/ammonium nitrate: no gaseous loss expected except on highly calcareous soils (DPIRD 1994).","rules":["Nitrate/ammonium nitrate: no gaseous loss expected except on highly calcareous soils (DPIRD 1994)."],"totalCost":null,"totalProductTonnes":null},{"slug":"yaraliva-nitrabor","name":"YaraLiva Nitrabor","brand":"Yara","category":"Nitrogen + Calcium + Boron","nPct":15.4,"nForm":"nitrate","multiNutrient":true,"pricePerTonne":null,"priceIndicative":false,"productKgPerHa":324.6753246753247,"nDeliveredKgPerHa":{"low":50,"mid":50,"high":50},"costPerHa":null,"costPerKgN":null,"effectiveCostPerKgN":null,"dollarsLostPerHa":null,"lossPct":{"low":0,"mid":0,"high":0},"lossQuantified":true,"rating":"Good","ratingNote":"Nitrate/ammonium nitrate: no gaseous loss expected except on highly calcareous soils (DPIRD 1994).","rules":["Nitrate/ammonium nitrate: no gaseous loss expected except on highly calcareous soils (DPIRD 1994)."],"totalCost":null,"totalProductTonnes":null}],"references":[{"id":"grdc-2021-schwenke","title":"Nitrogen loss pathways. How much N is lost when urea is not mechanically incorporated after application?","authors":"Schwenke G (NSW DPI)","publisher":"GRDC Update Papers","year":2021,"type":"Grower research summary","url":"https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2021/02/nitrogen-loss-pathways.-how-much-n-is-lost-when-urea-is-not-mechanically-incorporated-after-application","verification":{"status":"verified","checkedOn":"2026-10-17","note":"Full text fetched and read (curl is blocked by GRDC with HTTP 403; page loads via the fetch tool)."},"claims":[{"text":"Field-measured ammonia loss from broadcast urea on Australian cropping soils averaged 11.7% of applied N on fallow (range 5.4–27%) and 8.1% in-crop (range 0–29%). Measurements are described as sparse and sporadic.","verified":true},{"text":"Loss is low when urea is broadcast on dry clay soil in non-humid, non-windy conditions with sufficient rain within a few days; higher on wet soil followed by dry, windy weather with little rain.","verified":true},{"text":"Soils with CEC above about 25–30 cmol+/kg have vastly reduced volatilisation losses in many studies; low-buffered soils show greater pH rise around urea.","verified":true},{"text":"Ammonium sulfate lost less than half as much N as urea on non-calcareous soils in the northern NSW study, but 19–34% on fallow soils with more than 10% calcium carbonate (higher than urea).","verified":true},{"text":"Urea coated with NBPT reduces ammonia loss by around half on average globally compared with uncoated urea.","verified":true}]},{"id":"grdc-2022-schwenke","title":"Nitrogen loss pathways – how much do we lose and in what form under different situations","authors":"Schwenke G (NSW DPI)","publisher":"GRDC Update Papers","year":2022,"type":"Grower research summary","url":"https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2022/06/nitrogen-loss-pathways-how-much-do-we-lose-and-in-what-form-under-different-situations","verification":{"status":"verified","checkedOn":"2026-10-17","note":"Full text fetched and read."},"claims":[{"text":"Volatilisation from banded or incorporated N fertiliser should be negligible in most cases.","verified":true},{"text":"Reported ammonia loss from N applied to Australian cropping soils ranged 0.1–34% (median 6.7%) (Barton et al. 2022).","verified":true},{"text":"Ammonium fertilisers volatilise ammonia only if soil pH is already alkaline, except ammonium sulfate on calcareous soil or with lime.","verified":true},{"text":"Losses typically occur over 1–2 weeks after application; low-clay, low-organic-matter soils have poor pH buffering and are at greater risk.","verified":true}]},{"id":"grdc-2026-adhikari","title":"How much urea N is lost as volatilisation","authors":"Adhikari K, Luo Z, Armstrong R, Wilhelm N, Schwenke G","publisher":"GRDC Update Papers","year":2026,"type":"Field trial report","url":"https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2026/02/how-much-urea-n-is-lost-as-volatilisation","verification":{"status":"verified","checkedOn":"2026-10-17","note":"HTTP 200 and full text read."},"claims":[{"text":"Horsham Vertosol (45% clay, CEC 34.5): 8.2% and 9.2% of applied N lost over two seasons. Minnipa Calcarosol (sandy loam, 18% clay, CEC 8.3, free lime): 19.6% and 13.7%.","verified":true},{"text":"Previous southern-region studies reported 9.5–26% loss from surface-applied urea.","verified":true},{"text":"Most loss occurs within two weeks; light rain on the day of application followed by wind increased loss; splitting applications or urease inhibitors may help on sandy, low-clay Calcarosols.","verified":true}]},{"id":"grdc-2022-hunt-wallace","title":"A systems approach to nitrogen management","authors":"Hunt J, Wallace A","publisher":"GRDC Update Papers","year":2022,"type":"Grower research summary","url":"https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2022/02/a-systems-approach-to-nitrogen-management","verification":{"status":"verified","checkedOn":"2026-10-17","note":"Full text fetched and read."},"claims":[{"text":"In a long-term Curyo (NW Vic) experiment, profitability declined above a marginal NUE of about 20 kg grain per kg fertiliser N; gross margins were highest at a neutral to slightly positive N balance (costs were 2022 prices incl. urea at $1,400/t).","verified":true},{"text":"Crops typically use only 30–50% of applied fertiliser N in the year of application; unused N is not necessarily lost.","verified":true},{"text":"Median ammonia loss from in-crop surface-applied urea of 8.1% (range 0–29%) (Schwenke 2021); urease-inhibitor-treated urea can reduce volatilisation risk when N is applied in dry conditions; use depends on an economic response offsetting the price premium.","verified":true}]},{"id":"ipf-2024-laycock","title":"Planning nitrogen applications and rethinking potential urea nitrogen volatilisation losses","authors":"Laycock J (Incitec Pivot Fertilisers)","publisher":"Incitec Pivot Fertilisers (manufacturer; commercial interest in Green Urea NV)","year":2024,"type":"Manufacturer technical article","url":"https://www.incitecpivotfertilisers.com.au/resources/agronomic-insights/planning-nitrogen-applications-and-rethinking-potential-urea-nitrogen-volatilisation-losses/","verification":{"status":"verified","checkedOn":"2026-10-17","note":"Full text fetched and read. Manufacturer source: treat product-performance statements with that in mind."},"claims":[{"text":"N budget guide: 40 kg N per tonne of grain for wheat and 80 kg N per tonne for canola.","verified":true},{"text":"Volatilisation risk rises with higher soil pH, low buffering capacity, low CEC, residue holding granules off the soil, temperatures above 18°C, wind, light rain, and moist soil that dries down.","verified":true},{"text":"Swapping urea for ammonium sulphate is not advised where soil has free lime (>2% CaCO3).","verified":true},{"text":"NBPT (Green Urea NV) inhibits urease for up to 14 days (manufacturer statement).","verified":true}]},{"id":"hearn-2023-soil-research","title":"Ammonia volatilisation losses from urea applied to acidic cropping soils is regulated by pH buffering capacity","authors":"Hearn LO, Barton L, Schwenke GD, Murphy DV","publisher":"Soil Research 61(7), 685–696 (peer-reviewed)","year":2023,"type":"Peer-reviewed paper","url":"https://doi.org/10.1071/sr23044","verification":{"status":"partial","checkedOn":"2026-10-17","note":"DOI link is correct (full citation appears on the fetched Incitec Pivot article) but the publisher blocks automated checks (HTTP 403). The abstract was read via search results, not the full paper."},"claims":[{"text":"Laboratory incubation of urea on moistened acidic/neutral cropping soils: 0.9–25% of applied N volatilised; loss strongly related to pH buffering capacity (R² = 0.77). Highest (25%) on a Badgingarra WA sandy soil, comparable to a 27% field measurement.","verified":true},{"text":"Grain production on sandy, acidic soils with low pHBC could lose substantial NH3 if urea is broadcast.","verified":true}]},{"id":"turner-2012-nutr-cycl","title":"Ammonia volatilization from nitrogen fertilizers applied to cereals in two cropping areas of southern Australia","authors":"Turner DA, Edis RB, Chen D, Freney JR, Denmead OT","publisher":"Nutrient Cycling in Agroecosystems 93, 113–126 (peer-reviewed)","year":2012,"type":"Peer-reviewed paper","url":"https://doi.org/10.1007/s10705-012-9504-2","verification":{"status":"partial","checkedOn":"2026-10-17","note":"DOI resolves (HTTP 302 to Springer; publisher blocks automated follow-up). Abstract read from the CGIAR repository copy."},"claims":[{"text":"Ammonia loss varied with fertiliser type (urea > UAN > ammonium sulfate) and location, from 1.8 to 23% of N applied, versus the IPCC (2007) emission factor of 10%.","verified":true},{"text":"Variation was attributed to soil texture, soil moisture when applied and rainfall after application.","verified":true}]},{"id":"turner-2010-agee","title":"Determination and mitigation of ammonia loss from urea applied to winter wheat with N-(n-butyl) thiophosphorictriamide","authors":"Turner DA, Edis RB, Chen D, Freney JR, Denmead OT, Christie R","publisher":"Agriculture, Ecosystems & Environment 137, 261–266 (peer-reviewed)","year":2010,"type":"Peer-reviewed paper","url":"https://doi.org/10.1016/j.agee.2010.02.011","verification":{"status":"partial","checkedOn":"2026-10-17","note":"DOI loads (HTTP 200). Only the title and citation were confirmed; the abstract was not read. Used here only as the primary reference behind the 26% figure quoted in the Incitec Pivot article and the 9.5–26% range in GRDC 2026."},"claims":[{"text":"Primary source for NBPT-treated urea trials on winter wheat in SE Australia (details not independently read).","verified":false}]},{"id":"nbpt-review-2018","title":"Agronomic efficiency of NBPT as a urease inhibitor: A review","authors":"See article","publisher":"Journal of Advanced Research (PubMed Central)","year":2018,"type":"Peer-reviewed review","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC6077139/","verification":{"status":"partial","checkedOn":"2026-10-17","note":"HTTP 200. Abstract read via search results; full text not read."},"claims":[{"text":"NBPT-treated urea reduces NH3 loss by around 53% compared with urea (worldwide data); yield gain from NBPT averaged about 6%, varying from −0.8 to 10.2% by crop.","verified":true}]},{"id":"dpird-bulletin-4283","title":"Bulletin 4283 – Nitrogen fertilisers for cereal production","authors":"Mason MG (Department of Agriculture Western Australia)","publisher":"DPIRD Digital Library","year":1994,"type":"State agency bulletin (historic; prices and rates are dated)","url":"https://library.dpird.wa.gov.au/cgi/viewcontent.cgi?article=1341&context=bulletins","verification":{"status":"verified","checkedOn":"2026-10-17","note":"Full text fetched and read. 1994 publication; use for principles only, not prices."},"claims":[{"text":"Ammonia loss from urea broadcast on sandy soils is greatest on a moist surface left uncovered with no following rain, and is greatly reduced if incorporated or washed in soon after application.","verified":true},{"text":"Ammonium nitrate has no gaseous losses after application except on highly calcareous soils; nitrate is readily leached; calcium ammonium nitrate costs more per unit N than urea or sulphate of ammonia.","verified":true},{"text":"Sulphate of ammonia (21% N) is strongly acidifying; urea and ammonium nitrate also acidify.","verified":true},{"text":"Barley and oats need larger grain-yield increases than wheat to give the same profit at the same N rate (example: 120 kg/ha wheat vs 150 kg/ha barley vs 180 kg/ha oats for 25 kg N/ha, depending on relative prices).","verified":true},{"text":"Cost:price method: cost of a tonne of N on farm vs net grain price; expected yield increases should cover fertiliser and application cost.","verified":true}]},{"id":"dpird-mason-1969","title":"Ammonium Nitrate Vs Urea","authors":"Mason MG","publisher":"DPIRD (WA) Digital Library","year":1969,"type":"State agency report (historic)","url":"https://library.dpird.wa.gov.au/rqmsplant/10/","verification":{"status":"verified","checkedOn":"2026-10-17","note":"HTTP 200; abstract read. Historic document: principles only."},"claims":[{"text":"Urea left uncovered on the surface loses N by ammonia volatilisation; loss can be largely avoided by covering with soil or by heavy rain washing it in soon after.","verified":true}]},{"id":"farmtender-2026-10","title":"Farm Inputs (Farm Tender) fertiliser listings: Urea ex Geelong, Brisbane, Port Kembla, Newcastle; SOA ex Geelong","authors":"Farm Inputs / The Farm Trader Australia Pty Ltd","publisher":"Farm Tender (commercial listing page)","year":2026,"type":"Retail listing (price data, not research)","url":"https://www.farmtender.com.au/prime-ag-centre","verification":{"status":"verified","checkedOn":"2026-10-17","note":"HTTP 200; listing prices read on 17 Oct 2026. Listing dates are not shown on the page; prices are ex-GST asking prices and may change at any time."},"claims":[{"text":"Urea ex Geelong $820/t + GST; ex Brisbane $800/t; ex Port Kembla $845/t; ex Newcastle $800/t; SOA 44 t ex Geelong $540/t + GST.","verified":true}]},{"id":"grdc-2024-hunt","title":"Back to nitrogen basics – soil testing and nitrogen budgeting fundamentals","authors":"Hunt J (The University of Melbourne)","publisher":"GRDC Update Papers","year":2024,"type":"Grower research summary","url":"https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2024/02/back-to-nitrogen-basics-soil-testing-and-nitrogen-budgeting-fundamentals","verification":{"status":"verified","checkedOn":"2026-10-17","note":"Full text fetched and read. The paper says it simplifies complex topics and is a starting point for southern Australian farming systems."},"claims":[{"text":"A robust rule of thumb for wheat and barley is 40 kg/ha of N (soil mineral N plus fertiliser) per 1 t/ha of economic yield; canola needs about 80 kg/ha of N supply per 1 t/ha of grain yield.","verified":true},{"text":"Economic yield is estimated as 80% of water-limited potential yield. Fertiliser N requirement = crop N demand minus soil N supply; a urea rate is that figure divided by 0.46.","verified":true},{"text":"Worked example: 5.5 t/ha economic yield x 40 = 220 kg N/ha demand; soil mineral N 69 kg/ha plus 8 kg N/ha already applied as MAP = 77; requirement 143 kg N/ha = 311 kg/ha urea.","verified":true},{"text":"Crops take 55–70% of their N from the soil; fertiliser usually supplies 30–45% of plant N uptake at most.","verified":true},{"text":"Soil tests are best taken in the month or so before sowing and before fertiliser N is applied; 6–8 cores per production zone, bulked, gives about an 80% chance of being within 20 kg/ha N of the true mean; sample to 0.6–1.0 m, segmenting layers; keep samples cool and get them to the lab quickly.","verified":true},{"text":"Mineral N (kg/ha) = (nitrate mg/kg + ammonium mg/kg) x bulk density x depth increment in decimetres. Soil tests can easily be out by 20–40 kg/ha N or more; in wet springs in-crop mineralisation can supply more than 80 kg/ha N on high organic matter soils.","verified":true},{"text":"Wheat or barley with protein below 11.5% is likely to have been N deficient. About 20 kg N/ha per 1 t/ha of cereal grain (40 kg/ha per 1 t/ha of canola or legume) is removed from the paddock in grain.","verified":true}]},{"id":"grdc-2026-silburn","title":"Volatilisation of surface-applied urea on Queensland Vertosols: how much nitrogen is lost and what drives it?","authors":"Silburn C, Lester D, Schwenke G, Macpherson I, Bell M","publisher":"GRDC Update Papers","year":2026,"type":"Grower research summary","url":"https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2026/07/volatilisation-of-surface-applied-urea-on-queensland-vertosols-how-much-nitrogen-is-lost-and-what-drives-it","verification":{"status":"verified","checkedOn":"2026-10-17","note":"Full text fetched and read. Trials were on one grey Vertosol at Goondiwindi; the national figures are quoted from the national GRDC project the paper summarises."},"claims":[{"text":"Across the national GRDC project (21 sites) median loss from surface urea was 8% of applied N (range 0–48%); highest losses were where urea was spread onto wet, low-CEC soil with no significant follow-up rain; sites with CEC above 25 cmol/kg consistently lost less than 10%.","verified":true},{"text":"At Goondiwindi (100 kg N/ha as urea) spread urea lost 1–10 kg N/ha depending on weather; drilling urea 5 cm deep kept loss to 1 kg N/ha or less (about 90% lower in one trial).","verified":true},{"text":"More than 10 mm of rain within a week of spreading was enough to wash urea in; humidity, dew or light rain can dissolve urea at the surface without moving it into soil, and loss can continue for weeks.","verified":true},{"text":"NBPT-coated urea only gave a benefit when rain was delayed; with timely rain there was no difference to standard urea.","verified":true},{"text":"For Vertosols, budgeting 10% of applied N for volatilisation when spreading urea is described as a defensible planning figure.","verified":true}]},{"id":"agvic-soil-tests","title":"Understanding soil tests for pastures","authors":"Agriculture Victoria","publisher":"Agriculture Victoria","year":2026,"type":"Government guidance (pastures)","url":"https://agriculture.vic.gov.au/farm-management/soil/understanding-soil-tests-for-pastures","verification":{"status":"verified","checkedOn":"2026-10-17","note":"Page read in full (page last updated 25 Jun 2026). Targets are for Victorian pasture soils sampled to 10 cm; they are not cropping targets."},"claims":[{"text":"pH (CaCl2) values are usually 0.5 to 1.1 units lower than pH (water); the page suggests keeping pH above 5.3 (water) or 4.5 (CaCl2) for pastures.","verified":true},{"text":"Olsen P for Victorian pasture soils: below 9 mg/kg low, 9–14 marginal, 14–20 adequate, 20–27 elevated, above 27 very high.","verified":true},{"text":"Sulphur is considered adequate above 8 mg/kg on the KCl 40 (Blair) test.","verified":true},{"text":"PBI classes: below 15 extremely low; 15–35 very very low; 36–70 very low; 71–140 low; 141–280 moderate; 281–840 high; above 840 very high. A soil with a high PBI needs more phosphorus fertiliser than one with a low PBI.","verified":true},{"text":"Colwell K / exchangeable K targets depend on soil type (e.g. ideal 101–150 mg/kg on sands, 161–250 on clay loams); ideal soil salinity is below 0.2 dS/m (EC); exchangeable aluminium of 10% or more of CEC calls for lime.","verified":true}]}]}