Dent corn or "Field corn" is grown for both livestock and human consumption. A wide range of pre/post-emergent herbicides are used to maximize crop yields. As a earlier poster stated, many corn crops are now genetically modified "Roundup ready" meaning they are designed to be resistant or, to be totally impervious to the herbicide Glyphosate. This product is non-selective and will kill your plants. While it is not persistent in the soil-profile, it is commonly applied over-the-top to Roundup ready crops until it is no longer practical for the farmer to apply due to the height of the crops. Tall dent corn also greatly competes for sunlight and can grow to 12' in ideal conditions. This, coupled with the fact that any corn crop(dent, sweet or even popcorn) have earlier harvest times than your cannabis makes a corn field a poor choice for a grow site. Rethink your grow site.