Impacts of Nitrogen Sources and Rates on Soil Chemical Attributes and Potato Nutrition and Yield in a Subtropical Environment

The nutritional status, the soil chemical attributes prior to vine killing, and the classified yield of tubers may characterise soil–plant interactions with nitrogen (N) sidedressing for potato cultivars. Two experiments with potato cultivars Agata and Atlantic were carried out with the aim of evaluating the effects of N sources (urea, ammonium sulfate, and calcium nitrate) and N application rates (70, 140, and 210 kg ha−1) as sidedressing, plus a zero-N control treatment, in southern Brazil. Discrete variations in nutrients in diagnostic leaves and in soil chemical attributes in the Agata experiment were not reflected in the maximum average increase of 69.0