Comparison of Three Statistical Models Describing Potato Yield Response to Nitrogen Fertilizer
Gilles Bélangera,
John R. Walshb,
John E. Richardsc,
Paul H. Milburnd and
Noura Ziadia
a Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, 2560 Hochelaga Blvd., Sainte-Foy, Québec, Canada, G1V 2J3
b McCain Foods Limited, Florenceville, New Brunswick, Canada, E7L 3G6
c Atlantic Cool Climate Crop Research Centre, Agriculture and Agri-Food Canada, 308 Brookfield Road, P.O. Box 39088, St. John's, Newfoundland, Canada A1E 5Y7
d Potato Research Centre, Agriculture and Agri-Food Canada, P.O. Box 20280, Fredericton, New Brunswick, Canada E3B 4Z7
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Fig. 1 Example of potato yield response to N fertilization, indicating how each model fits the data. The data correspond to total yield under irrigation at S2. Arrows indicate the Nop values for each model
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Fig. 2 Regression residues (measured yield – calculated yield) when models were fitted to data from individual sites for total yield without irrigation with the (a) quadratic model, (b) exponential model, and (c) square root model. Each point represents one N rate at one site
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Fig. 3 Regression residues (measured yield – calculated yield) when models were fitted to data from individual sites for total yield without irrigation with the (a) quadratic model, (b) exponential model, and (c) square root model. Points from each site and N rate are positioned relative to calculated economic optimum rates of fertilization, which are located in the centers of the figures
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Copyright © 2000 by the American Society of Agronomy.
