You need to talk to farmers in the area, and also talk to your local extension agent. Putting nitrogen on this time of year is a loser, because it will evaporate or run off before the spring growing season. If the pasture is well developed with clover and grasses, applying nitrogen will cause the grass to overcompete the clover and kill off the natural nitrogen fixing. You can badly damage a pasture with fertilizer. If your pasture is all grass, this is the time of year to pug seed ladino clover for cows or subterranean clover for horses or sheep.
Phosphates can be soluble or insoluble depending on the chemicals you buy. You could apply insoluble phosphate this time of year, but wait until spring before you apply soluble phosphate. Potash is always soluble, so spring is the only time to apply it. Before you put anything on you need a soil analysis. It's very doubtful that a triple 16 is appropriate for your pasture. Your aim should be to balance nutrients without paying for runoff that buys you nothing.