I've switched to chemical fertiliser this year for my lawn. Reason
that I'm sick of being ripped off for increasingly expensive bags
chicken and cow manure. 4 euros now gives me enough fertiliser for
whole season for two lawns. I wonder if grass really minds where
N-P-K comes from. . .
No, of course grass doesn't mind where its NP and K come from (not
that those are the only nutrients a plant needs). The point of
organic methods is to take a whole-system view, mimicking or taking
advantage of natural processes, in order to set up long-term
sustainability, and reducing dependence on oil. There's quite a bit
about it in this group's FAQ, and there are many books. You might
like to look at HDRA and Soil Association on the Web.
(You may not need to feed your lawn all that much, anyhow.)