Broad cast fert or row fert

New year raising 30 acres of roundup ready corn 30" rows. What are the advantages of using a planter with dry fertilizer vs broad casting the entire field? We have always broad casted.

Row placement with planter will result in "more bang for the buck" because you'll be placing the fertilizer closer to where the plant is going to need it. Particularly important in the case of phosphorus because P doesn't move around in the soil. The plant roots have to find it. Bottom line will be less $$$ need to be spent on fertilizer when applied by planter.

we used to put an actual 18-46-30 on with the planter and side dress the N, pretty hard to get it all down with the planter, too many pounds and alot of N will attract moisture

Probably the primary nutrients you would be putting on with the planter are P and K (and some N). Like was said before you will get more efficient use of your fertilizer. The P and K are banded creating a zone of fertilizer that is less likely to get "tied up" in the soil chemistry. Also, it is closer and more readily available sooner. Some experts say you can cut the soil test recommendation by 1/2 if you band. First, do you need P and K?? Have you taken a soil test?? You might not need any. I don't know where you are located, but the Land Grant College in your state generally has a soil test lab and can do the P, K and Ph test for a reasonable cost. Most people that are putting on P and K with the planter are also putting on some nitrogen. The early roots can readily get to this N which helps it grow rapidly and have a dark green color. Like was said before it would be hard to get all of the nitrogen on with the planter attachment. Appling N, P and K with the planter was commonly called "starter fertilizer" or "pop up fertilization". Normally applied no closer than 2" deeper and 2 " sideways. Some people do apply SMALL amounts of liquid fertilizers directly in the seed zone. You have to be careful as the fertilizers have a "salting" effect which is harmful to young plants if too much is applied or if it is applied too close. I no-till everything. So, I apply all of my P and K with the planter. I soil test, but typically apply a minimum of 100 # of 11-52-0 and 100 # of 0-0-60 per acre on the corn ground. The fertilizer plant blends the two and I apply 200 # per acre. That would give the corn 11 # of nitrogen, 52 # of phosphorus, and 60 # of potassium. This year I also added about 7 # of sulfur and 10 # of calcium. That is less than the plant takes off, but keep in mind the efficient usage. My soils tend to be medium (some places high) in P and K so I am trying to supplement what the corn removes every year and also fertilize the soybean crop the next year. By putting it on with the planter I am getting it in the ground rather than leaving it on top in a no-till situation. I use large dry fertilizer openers (like a Yetter) and put the fertilizer 3.5 inches to the side and about 4 inches down. I have put up to 300 # of dry fertilizer per acre without any problems. If my soil gets behind I have broadcast, but rarely. On one farm I have only used the planter for fertilizer application for 15 years and the soil tests are still very good with very good yields. I primarily apply ammonia in the spring for the nitrogen (160# per acre), but have used 32% liquid nitrogen as well in a side dress situation. If I do side dress 32% I cut back the nitrogen to about 120 # since it is applied a little later in the season. I spike the dry fertilizer blend with more N (15 - 20#) if I am planning on side dressing 32% the second week June as I don't want the corn to get short on N. It all boils down to what works for you. What equipment you have. How many acres you are fussing with for the cost and time. For me it works and I like the efficient fertilizer use. I plant with an 8 row planter and can carry 6000 pounds of dry fertilizer. I know exactly what sprockets will deliver 150, 200, 250, 300 lbs. of product. Buy the way you have to check the # per acre each year as the granular size (density) of the fertilizer may change.