cashew wood and seaweed in hugelkultur beds?

I want to build a hugel bed on a site very close to the coast in Tanzania. I'm a complete novice.

The soil is almost pure sand, slightly saline, with an extremely high pH (8.4 - 10.5 in different places). But we have plenty of cashew trees that are need of serious pruning. Has anyone used this wood?

Being only a kilometre from the ocean we also have seaweed. I plan to incorporate this into the pile. Would this be a good idea?

Any other advice/comments for this? We have annual rainfall of around 1000mm in 2 main seasons and fairly strong winds most of the time.

Welcome to permies.com Cath.

Seaweed is an excellent source of many minerals. Kelp meal is one of the most expensive fertilizers here in the U.S.

It is also salty, and you stated that your soil was slightly saline to begin with. My suggestion for the seaweed would be to harvest it from the beach after a good solid rain. That should wash most of the surface salt off of it.

I am unfamiliar with cashew wood, but would imagine that it would be fine...using what is free and available is usually the best choice, unless there is some underlying fault that I don't know about. Does it rot naturally on the forest floor? Does it have chemicals which inhibit the growth of other plants?
Does it attract destructive pests?

I envy you...having your own source of cashews!

Thanks John. for the welcome and your tips.

There's little chance to see what happens to cashew wood when it falls as it's immediately taken - I think for firewood. But i'll search some out - there must be some somewhere. What little grows here does grow under the cashew so I don't think it has any inhibiting chemicals. Pests - not sure - will investigate.

No time to wait for the very infrequent rain to wash the seaweed but we have a borehole with nice tasting, unsalty water so I am washing it in that before adding it to compost.

The trees are old and not really productive so we will see if they improve with a good pruning. You're right, getting our own cashews would be a real treat.