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Using the reasoned nitrogen (N) fertilization method in potato crops (Solanum tuberosum L.) requires the validation of its parameters under the probable conditions of crop response. A field experiment in an Andisol was established to assess the parameters of this method and the nitrogen utilization efficiency of the crop. To describe the crop N response, five statistical models were used. Dry matter production and nutrient concentration were measured in tubers, leaves, fruits and roots. At both the beginning and the end of the experiment soil samples were collected to evaluate the mineral N. The quadratic-potential model was the most appropriate to describe the positive response of the potato crop to available nitrogen, from an initial level of nitrogen (the control, zero application ) to a maximum application of 200 kg N ha -1 . The relationship between the N doses and the potato yield reached a physical optimal of productivity at a rate of 228 kg N ha -1 . Higher rates (300 kg N ha -1 ) resulted in a decrease in yield, generating phytotoxicity for cultivation. This variation allowed us to evaluate the reasoned application method under different nitrogen availabilities (deficiency, optimal and above-optimal) in addition to the variation of the parameters generated.

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