I sometimes use a bit of artificial fertiliser in my garden, as well as my home-made compost. I don’t use much, so the pack bought one year may last for a couple of years.
If it is kept for a couple of years, the pack becomes wet. It is as if it were sprayed with water, so that the outside packaging is damp, and curls up. The contents are caked together and moist, like potter’s clay.
This is not due to the storage place. it is a large building which is well-built and watertight. Nothing else stored there shows any sign of damp - only the fertiliser. So, I believe that the dampness is not caused by a wet environment. The fertiliser becomes wet in some way, and that makes the package wet.
I assume it is some chemical reaction. The current batch of wet fertiliser is a normal NPK mix - with Nitrogen, Potassium and Phosphorus. (Please convert to the USAian term or spelling for those chemicals, if it causes confusion to Amerenglish speakers.)
Two queries -
- Why does this happen?
- i still use it on the assumption that it still has the same chemical composition - but am I poisoning my plants unwittingly?