Hugelkultur as a method was developed by Sepp Holzer in a very humid alpine climate. My experience is that burying wood can be an effective means of building soil, but only with an abundance of moisture, and ONLY with lots of mulch in top of the system.
Where I live in Africa the method works in the rainy season when it rains several times a week. But in dry season it's a liability for the reason stated: it's difficult to keep the whole thing hydrated. It's often sold as a method of regulating soil moisture by absorbing excess and releasing it during dry periods, but actually wood mulch on the surface does this even better because it also protects the surface of the soil from evaporation and erosion both. Makes sense: that's the way nature integrates dead wood.
Of you bury wood, then you have to baby sit it: keep it mulched and make sure it has enough moisture. If you lay the wood on top of the soil as mulch it's working for you for years to come. I make wood core garden beds because it's hard to mulch an annual garden with logs, and because I keep it irrigated.
Hugelkultur is basically a way to slow compost LOADS of excess wood in a high humidity environment, while growing stuff at the same time. If those aren't your parameters then just forget about it. Mulch mulch mulch.
