There is a lot of research online how to plant and fertilized field corn but not as much on sweet corn. Research data for sweet corn vs field corn is identical. Doing Google search for, How to Plant & Fertilize corn lots of pages come up with lots of good research information. Read several pages they are mostly all the same but some have extra information other pages do not have. You need to read several different research studies to get the full picture.
Farmers alternate planting, beans, corn, beans, corn, beans year after year. Beans puts nitrogen in the soil for the corn crop that will be planted next spring. Most of of the nitrogen from the bean crop will be gone by the time corn is ready to plant this is good because corn seed can be damaged by too much nitrogen in the soil this can give you a very poor seed germination. The home gardener should fertilize in fall with 16-16-8 fertilizer for next years corn crop and good root growth.
Farmers plant seeds 4" apart between rains in soil that is 55 degrees or warmer. Seeds need to be down in the moisture area of the soil then covered with 1 1/2 inches of soft dry soil. Seeds will germinate then plants will have no trouble pushing up through the soft soil. If it rains before plants reach the surface soil can dry to a hard crust making it hard for corn to reach the surface giving the farmer a poor crop. You need 5 to 7 days between rains to plant seeds. Home gardener should plant seeds about 6" apart if full sun.
Fertilizer information online is about the economics of the correct amount of fertilizer. If a farmer spends $5000 too much on his 2000 acre corn crop his profit will be $5000 less. Fertilizer is directly related to crop size and profit. If farmer don't use enough fertilizer he gets a smaller crop and smaller profit. If farmer uses too much fertilizer he gets a larger crop but not large enough to make up for the extra cost of fertilizer. For the home gardener if we use $2 too much fertilizer so what all we care about is a large crop of good tasting corn.
Plant your seeds corn when weather is right using no fertilizer. Keep an eye on your corn crop plants will tell you if they need more nitrogen or already have enough or too much nitrogen. When corn is 2 ft tall side dress each row with 46-0-0 slow release Urea fertilizer 1 lb per 100 sq ft that is a plot 10'x10' square. Side dressing should be 6" both sides of each corn row. Fertilizer needs to be under the soil, not on top of the soil. Fertilizer that lays on the surface looses 10% of its nitrogen every day it continues to lay on the surface. The home gardener can side dress with 46-0-0 on the surface then water the fertilizer until it dissolves into the soil.
Keep an eye on your corn what it does will depend on how much nitrogen was already in the soil and did you side dress with enough or too much fertilizer. If the bottom 3 leaves on each corn stalk turns brown and dies fertilizer is just about perfect nitrogen. If the bottom 5 leaves on each corn stalk turns brown and dies corn is a little bit low in nitrogen. It is not practical for a farmer to spend, time, money, extra fuel, adding a tiny bit more nitrogen to his corn extra profit will just about equal his fuel costs and not add to his profit. But the home garden can add a tiny bit more nitrogen as needed with out much trouble or cost. If the home gardener adds a little bit too much nitrogen it is not a problem for the corn plants.
Keep a close watch on your corn first signs ears are making silks fertilizes with nitrogen again 1 lb per every 100 sq ft = 10'x10' square. Side dress corn with 46-0-0 Urea fertilizer 6" both sides of each row. Home gardener can water the fertilizer to make it dissolve into the soil.
Corn produces the largest harvest when it make ears in full sun, 85 degree weather and lots of rain. Know your own weather condition try to plant at the correct time so your corn matures in 85 degree weather. The State of Wisconsin is known to have more rain during corn maturing season than other States so Wisconsin continues to produce about 10% more corn than other States year after year. If the home gardener waters his corn when ears are developing they will have a larger harvest.
When ears develop large soft sweet kernels of corn it is harvest time for the home gardener.