Alternative Benchmarks for Economically Optimal Rates of Nitrogen Fertilization for Corn

Kyveryga, Peter; Blackmer, A. M.; Morris, Thomas F.

doi:10.2134/agronj2006.0340

Cited by 35 publications

(38 citation statements)

References 21 publications

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“…For this fertilizer, the quadratic and quadratic‐plus‐plateau models provide a slightly better fit ( r 2 = 87%) but the optimum N applications are considerably higher (data not shown). The linear‐plateau model, which is independent of fertilizer‐to‐corn price ratio (Cerrato and Blackmer, 1990; Kyveryga et al, 2007), could be related to soil properties and N management practice. McSwiney and Robertson (2005), using 28% UAN or granular urea in corn post‐seeding, report a linear increase at lower N applications with an asymptote at ∼101 kg N ha −1 followed by a plateau, regardless of years and climate variations.…”

Section: Resultsmentioning

confidence: 99%

Grain Corn and Soil Nitrogen Responses to Sidedress Nitrogen Sources and Applications

Gagnon

Ziadi

2010

Agronomy Journal

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Th e effi ciency of synthetic N fertilization can be improved by selecting the fertilizer source and application that best matches the soil N supply and crop demand. A fi eld experiment was conducted for 3 yr (2004-2006) on a clay soil near Québec City, QC, Canada, to evaluate the eff ects of N fertilizer source and application on corn (Zea mays L.) yield, plant N accumulation, and residual soil inorganic N. Treatments consisted of an unfertilized control (0 N) and three sources of N fertilizer (urea ammonium nitrate 32% [UAN], calcium ammonium nitrate [CAN], and aqua ammonia [AA]) applied at three diff erent concentrations (100, 150, and 200 kg N ha -1 ). Nitrogen fertilizers were banded 5 cm below the soil surface between corn rows at the six-leaf stage every year. Fertilizer source aff ected grain corn with the highest mean yields (8.9 Mg ha -1 ) and total plant N accumulation achieved with UAN at any application. For all fertilizer sources, the linear-plus-plateau model best described the corn response to N application with optimum rate at 100, 124, and 128 kg N ha -1 for UAN, CAN, and AA, respectively. At harvest each year, the concentration of residual soil inorganic N increased in the upper layer. Under the cool and humid climatic prevailing conditions, UAN was the most effi cient synthetic N fertilizer when banded into the soil at sidedress.

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Section: Resultsmentioning

confidence: 99%

Grain Corn and Soil Nitrogen Responses to Sidedress Nitrogen Sources and Applications

Gagnon

Ziadi

2010

Agronomy Journal

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“…1 are statistically significant ( P < 0.05). Increases in the number of observations, especially within the range of interest, should be considered an effective way to reduce uncertainty in the values determined for slopes (Kyveryga et al, 2007).…”

Section: Resultsmentioning

confidence: 99%

Sensitivity of Chlorophyll Meters for Diagnosing Nitrogen Deficiencies of Corn in Production Agriculture

Zhang

Blackmer

Ellsworth³

et al. 2008

Agronomy Journal

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A gronomy J our n al • Volume 10 0 , I s sue 3 • 2 0 0 8 543 ABSTRACT Chlorophyll meters have been widely used to diagnose N defi ciencies in research trials and to help refi ne N fertilizer recommendations in production agriculture. Th e diagnoses are based on the assumption that chlorophyll meters can detect a wide range of N defi ciencies under fi eld conditions according to relationships between chlorophyll meter readings (CMRs) and yield responses to N fertilization that are established from small-plot trials. We conducted a fi eld-scale study to evaluate the sensitivity of chlorophyll meters when they are used to detect N defi ciencies in corn (Zea mays L.) production. Th e multiple year-location data were gathered in three cornfi elds where N fertilizer was applied at diff erent rates in strips that crossed several soil map units. Grain yields were related to CMRs taken on corn leaves in June, July, and August of 1998-1999. Results showed that the chlorophyll meters could detect severe N defi ciencies early in the season, but small and moderate defi ciencies of N could not be diagnosed with reasonable certainty until it was too late to make in-season fertilization. Two types of discontinuity are discussed in this paper as likely causes for the limited sensitivity of the chlorophyll meters. Our study suggests that problems associated with the use of chlorophyll meters to diagnose defi ciencies of N in production agriculture are much greater than their use to help interpret results of well-controlled research trials where yields are also measured.

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“…The inefficacy of the choices when using the EONR stems from using inappropriate models (response curves) fitted to corn yield data and from the fact that these response curves are usually relatively flat in the near‐optimum range of fertilization (Cerrato and Blackmer, 1990). The uncertainty in estimated model parameters can be partially addressed by calculating confidence intervals for the EONR for individual trials (Bachmaier and Gandorfer, 2009; Hernandez and Mulla, 2008; Jaynes, 2011) or by estimating additional benchmarks for the EONR when pooling data from many trials (Kyveryga et al, 2007; Sawyer et al, 2006). The challenge, however, consists in determining how to use a given EONR value (or range of values) to make reliable predictions of corn N needs for another field, another farm, or the next growing season.…”

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Predicting Risk from Reducing Nitrogen Fertilization Using Hierarchical Models and On‐Farm Data

et al. 2013

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Current systems for developing N recommendations for corn (Zea mays L.) lack methods to quantify the effects of factors influencing yield responses to N and quantify the uncertainty in N recommendations. We utilized hierarchical modeling and Bayesian analysis to quantify the risk from reducing N to corn using on‐farm observations. Across Iowa, farmers conducted 34 trials in 2006 and 22 trials in 2007. Each trial had a farmer’s normal N rate alternating with a reduced rate (by about 30% less) in three or more replications. Yield losses (YLs) from reduced N were calculated at 35‐m intervals. Posterior distributions were used to identify across‐field and within‐field factors affecting YL and to quantify the risk of economic YL (>0.31 Mg ha−1) from reducing N in unobserved fields. In 2006 (dry May and June), the economic YL for corn after soybean (C‐S) was predicted to be 20% larger than that for corn after corn. Also in 2006, C‐S fields with above‐normal June rainfall had economic YLs 35% larger than those with below‐normal June rainfall, and sidedress applications were about 20% riskier than spring applications. In 2007 for C‐S, N reductions with above‐normal spring rainfall were riskier than with below‐normal spring rainfall. Areas with higher soil organic matter (SOM) had economic YLs about 20% smaller than those with lower SOM. Many on‐farm trials can be conducted across the state and the use of the proposed statistical methodology can improve decisions on where to reduce N applications across and within fields.

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Alternative Benchmarks for Economically Optimal Rates of Nitrogen Fertilization for Corn

Cited by 35 publications

References 21 publications

Grain Corn and Soil Nitrogen Responses to Sidedress Nitrogen Sources and Applications

Grain Corn and Soil Nitrogen Responses to Sidedress Nitrogen Sources and Applications

Sensitivity of Chlorophyll Meters for Diagnosing Nitrogen Deficiencies of Corn in Production Agriculture

Predicting Risk from Reducing Nitrogen Fertilization Using Hierarchical Models and On‐Farm Data

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