it shouldn't interfere with the absorbsion of water. in fact when a peat based soil becomes compacted and hydrophobic a few drops of dish soap mixed in the water will encourage better water retention. if you'd still rather not use the dish soap, try a neem based insecticide.

The soap shouldn't affect the water absorbtion into the soil. It is a surfactant that can be used to improve water penetration into dry soil.

Thanks for the info....Ok, so what concentration of dishsoap should I use... is the 20ml/l that I heard correct?? I would like to use it to control cinch bugs and because they overwinter under my white Cedar and blue spruce, will the spray hurt these evergreens?
Also hopefully I will be able to use the soap to control earwigs...they are rampant in my flower beds and I simply cannot grow marigolds unless I spray Diazinon (just hate to do that!)every 10 days.
I will assume then that the same concentrations will work on courtland apples, niagara grapes, and a variety of roses?

Cody, What is a NEEM based insecticide? where does one get it?
Thanks for your super generous help!
Mat

neem oil is made from the neem tree. it's a natural insecticide and fungicide. safe to spray in the house even, although it has an odd smell. check at the walmart garden center for it.

Insect Control...Naturely. My favorite is Murthy's oil Soap mixed with water. This is plant based soap and cheap!

Here is a link that might be useful: Pest Control