Nitrogen (N) management for processing sweet corn in Wisconsin has proven to be a complex issue. Sweet corn has a relatively large N demand and, to ensure complete kernel development, requires maintaining plant available N in the soil profile throughout the growing season, which can be a challenge on sandy soils. Current N guidelines for sweet corn in the University of Wisconsin Extension Publication A2809 (Nutrient Application Guidelines for Field, Vegetable and Fruit Crops in Wisconsin) suggest 150 lb/ac of N for soils with less than 2% soil organic matter and 130 lb/ac of N for soils with 2 to 10% soil organic matter, based on a yield range of 2 to 10 ton/ac. The guidelines also suggest split-applications or sidedress applications of N on coarse-textured (sandy) soils. Most, if not all, sweet corn production in the Central Sands is on coarse-textured soil with less than 2% soil organic matter and grown with split-applications of N. To evaluate the current A2809 guidelines for N application, on-farm N rate trials were conducted in 2009, 2010, and 2011, on four fields per year, for a total of twelve site-years. All fields were located in Adams County, WI. All plots had 60 lb/ac of N applied before V4 and 45 lb/ac of N applied as fertigation at tassel (VT stage). Six different N rates were then added as sidedress at V6-V8: 0, 25, 50, 75, 100, and 125 lb/ac of N, resulting in total N applications of 105, 130, 155, 180, 205, and 230 lb/ac of N.
Soil Science Extension
University of Wisconsin Madison