Landfill sites are engineered to be stable and low in moisture. In Australia, landfills are so dry and compact they tend to "mummify" their contents. As a result, nothing much breaks down in landfill - even newspapers, which are 100% degradable, remain intact and legible for decades. This means a biodegradable nappy in landfill is normally not given the chance to biodegrade.
(Virtually all nappies you put in your garbage bin end up in landfill).
We understand you may still be concerned about the volume of your disposable nappies going to landfill (see Nappies make up around 1% of landfill). That's why we have focused on a real issue in landfill management and reduced the volume, or bulk, of our nappies, to reduce the space they take up in landfill. We have significantly lessened the bulk of Snugglers nappies over the past 10 years. This reduction has largely been achieved by substituting fibre with additional super-absorbent material and more effective product design.