Musannaf Ibn Abi Shaybah

Hazrat Ibn Jurayj says that I asked Hazrat Ata: If a piece of land is irrigated for some time with running (spring, etc.) water, then there arises a need to irrigate a part of it with well water, and then another part is irrigated again with spring water, how should its zakat be calculated? He replied: Ushr (one-tenth) is due. He said that the ruling will follow the method by which it was irrigated for the longer period; that is, if it was irrigated for a longer time with spring water rather than with buckets, then ushr is due on it. And if it was irrigated for a longer time with buckets rather than with spring water, then half-ushr is due on it. I asked: If some land is irrigated for some time with camels (i.e., by animal power) and rainwater, and then there arises a need to irrigate it with well water, is the ruling the same? He replied: Yes. Abu Zubair, the narrator, says that I also heard Ibn Umair saying the same, then I asked Salim ibn Abdullah about it, and he answered like Ubaid.