A friend gave me a 50lb. bag of Scott's Turf Builder for free. It was a ripped open bag and would not close completey, but I kept it in my shed so it stayed dry. I applied it to my St. Augustine lawn about 2 weeks ago, watered as recommended, but everything is still brownish yellow and nasty looking. My question is - since it was exposed to air, does this reduce its potency in any way? Its humid around here, so I'm pretty sure a little moisture got in there. Does this matter and if so, should I refertilize?