the Messenger of Allah ﷺ said: “For crops that are irrigated by the sky (i.e. rain) and springs, one-tenth. For those that are irrigated by watering, one half of one-tenth.” (Using translation from Ibn Mājah 1816)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ فِيمَا سَقَتِ السَّمَاءُ وَالْعُيُونُ الْعُشْرُ وَفِيمَا سَقَتِ السَّانِيَةُ نِصْفُ الْعُشْرِ