I've benefitted an enormous amount from the USDA soybean research. They run soybase.org, a repository of all things data around soybean cultivars. In my experience, no other crop has a database as complete as soybase. Perhaps it's a political phenomenon? The US pumps a lot of money into soybean so other countries are not that interested in soybean research, while for example rice databases are splintered across China, Japan, the Philippines etc..