Musannaf Ibn Abi Shaybah

Hasan says that when wheat or barley comes out of the earth and each of them is less than five wasq (a specific measure), but when both are combined, they amount to five wasq or more, then zakat is due on both because each of them is a crop. And if it is wheat and raisins and they do not amount to five wasq, then nothing is due on them until each of them reaches the amount of five wasq. When they reach five wasq, then ‘ushr (one-tenth) is due on them.