If the soil is low in P & K, broadcasting will promote the growth of innoculated legumes over grasses - If a soil test has not been done, there is no good way to know existing P&K levels, or the ability for plants to uptake these ions in the soil due to the acidity (Ph) of the soil.

Generally, broadcasting P&K alone will help - but when speread with lime according to a soil test, the outcome is a little more clear.