Nitrogen management for corn after corn and corn after soybean

Meese, B. G.

doi:10.31274/rtd-180813-11240

Cited by 7 publications

(7 citation statements)

References 13 publications

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“…We analyzed data collected in 54 response trials (Fig. 1) described elsewhere (Binford et al, 1990, 1992; Meese, 1993). Each trial included seven rates of N (0, 56, 112, 168, 224, 280, 336 kg N ha −1 ) that were applied to plots (12.2 by 4.6 m) in a randomized complete block design with three replications.…”

Section: Methodsmentioning

confidence: 99%

Disaggregating Model Bias and Variability when Calculating Economic Optimum Rates of Nitrogen Fertilization for Corn

2007

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Efforts to calculate economic optimum rates (EORs) of N fertilization for corn (Zea mays L.) have been hampered by a lack of methods for disaggregating problems caused by model bias and variability in crop responses to N. We illustrate how the concepts of ex post and ex ante analyses can be used in a multistep procedure to disaggregate these problems when calculating ex post EORs when large amounts of data are available. Five models were used to describe yield responses from a collection of 54 small-plot trials that included seven rates of N. The multistep procedure included steps to reduce model bias and steps to reduce unexplained variability by forming categories based on information available at the time of fertilization. The concepts of ex post and ex ante analyses were used to clarify what information is important at each stage of the procedure and to ensure that information generated in early steps is used effectively in later steps. Analyses illustrate that calculated values for EORs should be expected to vary with the amounts of information available and that the new procedure can be described as a systematic search for the best EOR that can be calculated with existing information. Although this procedure may have little practical use when data are collected in traditional small-plot trials, illustration of this method by using data collected in such trials revealed the problems of model bias and variability in yield response as well as the potential for solving these problems in production systems where advances in technology make it practical to collect unprecedented amounts of data.Abbreviations: EOR, economic optimum rate; EXP, exponential model; LRP, linear response and plateau model; QRP, quadratic response and plateau model; QUAD, quadratic model; SR, square root model.

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Section: Methodsmentioning

confidence: 99%

Disaggregating Model Bias and Variability when Calculating Economic Optimum Rates of Nitrogen Fertilization for Corn

2007

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“…We utilized datasets of yield response data presented elsewhere (Binford et al, 1990, 1992; Meese, 1993). The data analyzed were collected in 54 response trials with seven rates of N (0, 56, 112, 168, 224, 280, and 336 kg N ha −1 ) that were applied just before planting to plots (12.2 by 4.6 m) of corn in a randomized complete block design with three replications.…”

Section: Methodsmentioning

confidence: 99%

Alternative Benchmarks for Economically Optimal Rates of Nitrogen Fertilization for Corn

2007

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Discussions of N fertilizer needs for corn (Zea mays L.) usually are based on the assumption that economic optimum rates (EORs) of N provide the best benchmark to indicate the rates most likely to maximize profits for producers. We describe methods for calculating some additional benchmarks and illustrate how efforts to improve N management could be advanced by recognizing several alternative benchmarks simultaneously. We analyzed data from 54 small-plot trials with a new procedure that disaggregates problems associated with systematic model bias and variability in crop yield responses to fertilizer N. We compared the commonly used method for calculating EORs to a method that is described as discrete marginal analysis at near-optimal rates of N fertilization. We described methods for calculating the incremental break-even rate, the incremental rate that gives no crop response, and the incremental rate of N that gives the desired level of profit. Discussions of the relative merits of each benchmark suggest that problems associated with calculating and using the concept of EORs can be avoided by presenting the alternative benchmarks as proposed in this paper. P.M. Kyveryga, Iowa Soybean Assoc., 4554 114th St., Urbandale, IA 50322; A.M. Blackmer, Abbreviations: EOR, economic optimum rate; EXP, exponential model; IRBE, incremental break-even rate; IRDP, incremental rate that gives the desired level of profit; IRNR, incremental rate that gives no yield response; LRP, linear response and plateau model; QRP, quadratic response and plateau model; QUAD, quadratic model; SR, square root model.

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“…A commonly mentioned non-N rotation effect is soybean induced interruption of pest cycles. Meese (40) and Maloney et al (38) found a greater incidence of rootworm damage, borer damage, root pruning, and barren stalks in continuous corn than for corn after soybean.…”

Section: Underlying Causes Of Differences In Soybean Nfrvsmentioning

confidence: 99%