Impact of long-term nitrogen fertilization for corn on soil properties and soil productivity
Nitrogen (N) fertilization can increase crop productivity and residue carbon (C) additions. Previous studies have found positive, negative, and neutral responses of soil organic carbon (SOC) and soil properties to long-term N fertilization for corn. A ten-year N rate (2009 – 2018) experiment was established in Elora, Ontario to investigate the impact of long-term nitrogen fertilization at six rates ranging from 30 to 260 kg N ha-1 in corn (Zea mays L.) on soil properties. This study found no change in either SOC or total soil N across N rate treatments after ten years despite large differences in residue C additions. Further, wet and dry aggregate stability were unaffected by N rate, and the quantity of mineralizable N, measured in an incubation experiment, only showed minor differences. In a sub-experiment within the long-term trial where N was limited, long-term N rate increased yields in only one of three growing seasons.