My take on hugelculture is that it depends upon a lot of different factors....
... How the
hugel is physically constructed.
... What sort of components are used.
... What the
local environmental factors are.
... What sort of plants are planted on the hugel.
On my own farm I've only constructed hugel pits. A mound would dry out rapidly due to the wind and sun regardless of how much wood was incorporated. Thus hugel mounds would be failures here and discourage people from using the concept. But constructed as pits, they work great in my situation. My first hugelpit pit has been functioning without irrigation for 4-5 years and growing bananas. It has functioned well even during the year where I only got 13" of rain. Because of the good results, I've been expanding the pit in order to double its size. I plan to build others as I have material to use.
I did not record the construction phase. Nor am I interested in conducting controlled experiments. I have a subsistence homestead, so as long as I get positive results, I use the method. But that being said, I do have plenty of other clumps of bananas not growing atop hugelpits. While they all live, even during drought years, they do not produce much in dry years. The hugelpit bananas constantly produce well.