Ibn Majah

1599. Commentary:
➊ The Messenger of Allah (sallallahu alayhi wa sallam) said that the produce of land irrigated by rainwater or natural springs is subject to ‘ushr (one-tenth). And for land irrigated by water-lifting devices, etc., the obligation is nisf al-‘ushr (one-twentieth, i.e., five percent). [صحیح بخاری، الزکاة، باب العشر فیما یسقیٰ من ماء السماء و لماء الجاري۔ حدیث: 1483]
From the Qur’anic verse and the hadith of the Messenger (sallallahu alayhi wa sallam), it is clear that zakat is due on everything produced from the land, except for vegetables, because there is explicit mention in the hadith that zakat is not taken from them. However, there is a condition that the produce must reach five wasq or more. Thus, the nisab (minimum threshold) for grains and cereals is five wasq. If the produce is less than this, zakat is not obligatory. One wasq equals sixty sa‘. In this way, five wasq equals three hundred sa‘, which, according to Pakistani measurement, is approximately 20 maunds. Therefore, whoever’s produce is 20 maunds or more must pay zakat; otherwise, it is not obligatory. The zakat (‘ushr) on agricultural produce is to be paid at the time of harvest. If there are two harvests in a year, then ‘ushr must be paid twice, because the passing of a year is not a condition for this zakat; rather, the existence of a crop is the condition, whenever and whatever it may be. If the land is barani (rain-fed), i.e., irrigated by rain or natural springs, and there is no expenditure on irrigation, then one-tenth (‘ushr) of the produce is to be paid. If the land is not barani (i.e., irrigated by wells or canals, for which expenses such as water charges are incurred, or irrigated by tube wells), then nisf al-‘ushr (one-twentieth) is to be paid. This is based on the hadith mentioned earlier, in which the Messenger of Allah (sallallahu alayhi wa sallam) said: “On what is irrigated by the sky (rain) and springs, or is naturally moist, the ‘ushr (one-tenth) is due; and on what is irrigated by water-lifting devices, half of the ‘ushr (one-twentieth) is due.” [صحيح البخاري، الزکوة، العشر فیما یسقی من ماء السماء والما ء الجاري، حدیث: 1483]
For produce irrigated by the sky (rain) or (natural) springs, or if the land is naturally moist (due to proximity to a river or canal so that it does not require additional watering), the obligation is ‘ushr (one-tenth). And for what is irrigated by buckets (or water-lifting devices), the obligation is nisf al-‘ushr (one-twentieth, i.e., five percent). Zakat is only due on produce that can be stored, such as wheat, rice, maize, barley, etc. Therefore, there is no zakat on vegetables, because they cannot be stored for long periods.

➋ What the Imam (rahimahullah) has said regarding cucumber and citron (orange) is an indication towards the blessings of zakat and charity—that Allah Ta‘ala places immense blessing in wealth through them.