Good advice Jogee. I'd take the results of the soil samples to the local dealer for advice. Many of those old timers know more about your land than you do. The place I lease has been fertilized by the same old man for 30 years prior to me leasing it.
Weed killer also kills the good stuff. My own pasture is so full of clover varieties, vetch, and blue bonnets right now that I don't want to kill since they add N to the soil. Some of it is being grazed and some of it isn't. I am going to try and get my timing right with the mowing and then evaluate the unwanted stuff. Prolly just spot spray with some 24D