Chicken Manure additive for Sunflower crop

We are relatively new to farming.  Soil testing says we need phosphorus and potassium for sunflower crop.

We found a source for chicken manure.

Questions are:

1)  Is chicken manure a good additive to improve the soil?

2)  How much do we add for a 15 acre field?  How many yards?

3)  Source is selling at $10/yard picked up.  Is that a good price for eastern ontario?