I know that Longman dictionary gives "in" as a correct preposition to use after "trade". But I am confused by a number of examples from British corpus and Google Search where they say "trade of", such as "increasing number of local taxes on the trade of goods", and "these people enjoyed a peaceful existence, engaging in the trade of nuts, apples and rice with India".
Does it depend on the context?
The most important part of the question: I need to translate the qualifications that will be written on a diploma, bachelor of International grain trade. It seems to me that if I place "grain" after "trade" it sounds more profound. What preposition is better to use in this context? It is appropriate to say "international trade of grain"?