in order to get tartan you must ship a product then after that you must visit takakura's house when his inside after that you will see tartan...
in order to get the "great field" you must have tartan and the hybridize option after that you must talk to takakura about clearing the forest on your farm (the field with useless tall tress) and the last step go to your ledger and the the "gread field" must be in your extension option (20,000g)
FEEL FREE TO ASK ME SOME QUESTIONS....