Soil & Fertility
Sweet corn can be grown in most Utah soil types that are suitable for growing other vegetable crops. Soil electrical conductivity (EC; measure of salinity) should be below 1.7 ds/m. Yields become detrimentally affected above this point.
Soil should be plowed deeply, free of clods and other debris, but not over-worked. Before planting, the soil surface should be smooth and even. These steps will ensure even plant emergence, proper irrigation, and consistent maturity across the entire stand.
Profitable sweet corn production requires maintaining adequate soil nutrition to maximize ear size, encourage dark green husks, and optimize tip fill. Keep records of previous crops grown in the field and of previous nutrient applications to determine future applications. Regular soil testing will minimize costs and maximize profits by allowing for customized nutrient applications. For more information about soil testing visit the Utah State University Analytical Laboratory website at: www.usual.usu.edu.
Both urea and ammonium sulfate are acceptable nitrogen (N) sources. Incorporate the fertilizer into the soil to minimize N volatilization and leaching. Sweet corn requires 125 to 150 units of N per acre per season. Several small applications will maintain a more constant amount of available N for the crop and minimize leaching. Apply and disk into the soil around 50 pounds N at the preplant stage. Another option is to band the fertilizer (apply a line of fertilizer 2 inches to the side and 2 inches below the seed furrow) when seeding using the same application rate. Do not use banding if applying more than 80 pounds of N per acre or if potassium (K) is also being applied. High N and K applications can potentially reduce emergence and damage young seedlings. Apply the remainder of the N in two side dressings when plants are in the 5th and 10th leaf stages. Nitrogen leaching is greater in sandy or sandy-loam soils so split applications are important in these soil types. (See Fig. 10.1 for symptoms of nitrogen deficiency.)
Fig 10.1. Nitrogen deficiency
Phosphorus and Potassium
Applications of the commonly used forms of phosphorus (P) and potassium (K) using P205 and K2O sources may not be needed in Utah soils. Conduct soil testing before planting and follow test recommendations. Rates may vary from 0 to 150 units per acre depending on soil test results. If needed, band P and K at the recommended amount at planting. Phosphorus is fairly immobile in the soil, and later applications may be ineffective. (See Fig. 10.2 for symptoms of phosphorous deficiency.)
Fig 10.2. Phosphorus deficiency