Zinc should be applied as 1 to 2 qt/acre of Zn chelate or complex or 6 to 12 lbs/acre of zinc sulfate as starter or in a band. When applying any form of Zn in direct contact with the seed, check with the supplier to ensure that the application will not be toxic to the seed and negatively impact germination.
Pulses and Soybeans
Corn following pulses (dried peas, edible beans, lentils, and chickpeas) or soybeans is an ideal rotation scheme because there is minimal residue, which allows the soil to warm quickly in the spring and the corn crop can capture the residual nitrogen (N) left behind. Corn insect and disease risk is reduced following pulses or soybeans.
Corn planted following small grains faces a more challenging environment for growth of young corn plants. The large amount of residue left behind slows the warm-up of the soil in the spring because the brightly colored stalks reflect the sun’s rays instead of allowing the soil to absorb them. Small grain residue is high in carbon and therefore competes with the small corn plants for free nitrogen in the spring. Corn following a small grain crop requires additional N compared to corn following a pulse, canola, or sunflower crop. Small grain stubble is also an ideal host for soil-borne insects (wireworms, seed corn maggots, and grubs) that can attack germinating seeds and young corn plants. Use a high-quality insecticide seed treatment for control of these insects. Small grains planted prior to corn may increase the risk of some fungal diseases in corn such as Fusarium or Gibberella stalk rots.
Flax fields rotated to corn can pose a challenge due to the highly durable residue that does not break down easily and competes for free nitrogen. Fertility needs will be similar to those of corn following small grains.
Sunflower to corn rotation is a good option as there is limited residue associated with sunflower production, which allows soils to warm up more quickly in the spring. Sunflower, like pulses, alfalfa, and other non-grass crops, breaks the lifecycles of insects and diseases, which is beneficial for corn production.
Corn after corn grain rotations can be very successful but will generally require more management than rotation following other crops (excluding sugarbeets). This rotation scheme requires more nitrogen (similar to rotating after small grains), increases the risk of insect and disease pressure, and limits options for rotation of herbicide mode of action. Large amounts of corn residue can slow the warm-up of the soil in the spring, harbor disease pathogens, provide shelter for overwintering insects, and can be a challenge to plant into. Yield reductions in stress years in corn after corn production systems are often higher than corn following soybeans. Hybrid selection is critical in this rotation scheme as good disease tolerance, strong early growth, good early season stress tolerance, and above average drought tolerance are all needed.