I know what this method is and i know that it works. But i need facts. So i what i want to know is what kind of tests i should conduct to get those facts.[/quote]
A bunch of scientific articles on pitcher irrigation were found on Google with a simple query. (You will find even more if you search on Google Scholar.) The top five are described below.
Pitcher irrigation: a water saving technique
This page provides a basic overview of the technique and lays out its various advantages.
Performance of Pitcher Irrigation System [PDF]
This paper looks at determining the optimum pitcher size and argues that use of small sized (cheaper) pitchers with high hydraulic conductivity is comparable with using large sized (more expensive) pitchers although such the former would need to be refilled more frequently.
Development and Revision of Design Criteria for Pitcher Irrigation Systems [PDF]
This is a summary of a longer paper that determined that there are three important design factors that influence movement of water from the pitcher. These are a) hydraulic conductivity of the pitcher (most important), b) surface area of the pitcher and c) wall thickness of pitcher.
The auto-regulative capability of pitcher irrigation system [PDF]
This paper discusses the strong auto-regulative capacity of pitcher irrigation system looking at how evaporation influences movement of water from the pitcher.