An encapsulated water soluble fertilizer which comprises a polymeric film of about 2 to about 100 micrometers coated on a surface of said fertilizer, said polymeric film comprising a sulfonated polymer having about 10 to about 200 meq of sulfonate groups per 100 grams of said sulfonated polymer, said sulfonate groups being neutralized with a polycaprolactone polymer being characterized by the formula ##STR1## wherein R.sub.1 or R.sub.2 is an alkyl, cycloalkyl or aryl group; R.sub.3, R.sub.4 and R.sub.5 are a hydrogen or alkyl, cycloalkyl, or aryl groups; m equals 1 to 20 and n equals 1 to 500.