Mulch in pot for releasing water slowly

An alternate method of making a self watering pot is by using a material which absorbs a lot of water and releases it slowly. Different kinds of scrap material are being used as mulch

However testing this method can be very time consuming, especially if equipment for measuring the moisture content, is not easily available, for the broke domain investor. Any suggestions on a suitable method will be greatly appreciated.

The squirrels, birds and rats are also eating many test materials.