Im and agronomist and I can help you out. Just email me with any questions anyone might have. 12-12-12 is triple super phosphate. It is a pretty good general purpose fertilizer. To lower your pH to make your soil more acidic you need to apply Elemental Sulfur. When it rains it turns the sulfur into an acid which bonds to soil. To raise your pH you need to use Lime not postassium. Very little nitrogen should be used when planting legumes. The create their own nitrogen through nitrogen fixing cyanobacter. By adding more nitrogen fertilizer you are primarily pouring your money on the ground. Feel free to ask me any questions.