I am about to create a number of raised planter-boxes where i can't separate the wood and soil with plastic. So, in order to create something that will last for as long as possible I have been trying to collect information about which wood species will last the longest with direct soil contact.
I have found a fair amount information about Robinie, oak and some hardwoods like Cumaru, Jatoba and Ipe as wood species which will last a long while with direct soil contact.
But I expect that someone must have made some structures comparisons and tests, that I just have been unable to find. Can someone either tell me which species of wood will last the longest in direct soil contact. Or, even better, provide some structured study that I can take a look at?