Here are a few points worth considering:

1. We would consider phosphate to be the most important nutrient to be in the liquid form since it is the most critical nutrient in early growth above and below the ground. Cold dry soils in the spring are where a seed placed plant available liquid phosphate fertilizer really shines. Compared to a dry granular phosphorus that can still be in granular form in June when soil moisture is limited.
2. Greater amounts of Nitrogen are needed later in the season and should be placed away from the seed to insure there is no seed burn from the nitrogen. We recommend the seed placed liquid ALPINE phosphorus and a side banded nitrogen program –this gives the farmer the best of both worlds – early plant growth from the seed placed phosphorus and no burn from the side banded Nitrogen
3. Placement of phosphate is extremely critical to maximize early growth and root development. Endless amounts of research point to the only place to put phosphate is with the seed. A lot of guys using a complete liquid program are mixing the phosphorus with the nitrogen and placing the blend away from the seed which reduces the efficiency of the phos.
4. One big reason our customers like switching their phosphorus program to liquid is that it frees up that much more space in their air carts for more dry nitrogen and since we find only 3-4 gals of a plant available phosphorus with the seed of most crops is enough the farmer does not a very big liquid tank added to the cart. A 500 gal tank @ 3 gals/acre will cover a quarter section.
5. Most of our customers use dry nitrogen since 46% urea is much more concentrated than 28% UAN. Although some customers will opt for a complete liquid system for the overall convenience.
6. If your soils require micronutrients adding say 1 litre of  Zn or Mn to 3-4 gals of ALPINE liquid phosphorus will evenly disperse the micro across every ft of every row compared to trying to add a micronutrient into your dry blend. We have seen excellent results adding micros into the seed placed ALPINE at planting time where the soil is deficient in that micro..
7. Our same seed placed liquid phosphorus product can also be used as a great foliar product and since the farmer has in on farm in bulk it is much cheaper than any packaged foliar product on the market. We really like following up our starter phosphorus program with 1-2 litres of our product foliar at crop spray time. It gets more nutrients into the plant at a time when environmental and chemical stresses can be going against the crop.
8. Quality of raw materials must always be considered. One problem with the fertilizer industry as a whole is the NPK analysis is the only thing that needs to be guaranteed. The level of impurities and the raw materials used to make the product are never considered. We have found a very wide range of impurity levels in liquid fertilizers. There are what is known as “Spent Acids” that make their way into the fertilizer industry from the bright dipping car part industry. These are very cheap raw materials but can cause problems with germinating seeds due to the high levels of impurities like aluminum. Dry phosphorus can even have as much as 10,000 ppm of Aluminum where our product will run closer to 1500 ppm. Aluminum at high levels can be toxic to root growth – not a good idea for a seed placed fertilizer.
9. When applying phosphorus we look at a concentration per ft of row. We will recommend more product on narrower rows because you have more liner ft of row per acre in a 7” row vs a 10” row. Phosphorus is your starter part of your program and concentration per ft of row needs to be considered.
10. Cost per pound of plant food is always an issue with liquids vs dry. With nitrogen I am not convinced there is enough advantage with liquid N over dry N to cover the added cost per lb. but with phosphorus there is no doubt that a small amount of very plant available liquid phosphorus seed placed on crops will perform better than larger amounts of dry phos. So the cost per acre with ALPINE is usually similar to a dry phosphorus program since we normally recommend less lbs of phosphorus per acre than is normally used in a dry phosphorus program. We recommend 8-10 lbs of actual phosphorus as ALPINE where most dry programs are 20-30 lbs actual phos.