Musannaf Ibn Abi Shayba 28:186

Abu Usama narrated to us, from Sa'id, from Qatada, from Abu Mijlaz, who said: Umar sent Uthman ibn Hunayf to survey the land. He said: So Uthman imposed ten dirhams on a jarib of grapevines, eight dirhams on a jarib of date palms, six dirhams on a jarib of reeds—meaning alfalfa—four dirhams on a jarib of wheat, and two dirhams on a jarib of barley.