The corn crops demand for N up to the first 3 true leaves is minimal.Once the crop hits the 4th true leaf stage as shown in the photo above, N demand begins.

This is usually about 28 days after planting.Its best to try to have all your corn sidedressed before it reaches the 6 True leaf stage.Corn begins its grand flurry of growth after 6 true leaves and N demand picks up markedly every day through to tasselling.The

OMAFRA Corn N Calculator can be a useful tool in providing you some guidance on rate

application

Sidedressing N is the most efficient way of feeding the corn crop.Less total N is required to produce a crop as you reduce the possible losses of N through leaching and denitrification that can be caused by heavy early season rains.