Does Guano go bad or expire?

I know it sounds like a pointless thing since guano lays on the cave or ground where ever its collected but I really dont know for sure. I have read that EWC can go south as they age. I try to buy fresh EWC from a place on Ebay direct from a midwest producer that has a fresh supply. But I dont use as many pounds in a year as bigger growers so I can live with the small added expense.
After further review it seems not. Never mind.

Not really any such thing as "old" guano. The high phos bat guano comes from fossilized deposits, the high nitro more from Peruvian seabird guano and is much more "fresh". Too fresh and it burns the plants, and (as I understand it) the nitrogen in the PSG diminishes over time. But both are pretty much like worm castings which means that even when old they pack quite a nutrient punch.

I've been using the same bag of N guano and the same bag of P guano for about 12 years. Keep it dry and you are fine.


VG

It came out of some animals ass. It was as bad as it was gonna get at the moment the bat or bird took a dump. Once it's shit, that's it. Keep it dry.