Miscellaneous issues regarding zakat and other matters]

Answer—and Allah is the Granter of success and aid:
Stall-fed sheep have no zakat due—unless they are for trade, in which case one quarter of one-tenth (2.5%) is due. As for a crop intended for fodder, zakat is due upon its owner—one-tenth (10%) or half of one-tenth (5%). Regarding sheep that are sometimes pastured and sometimes stall-fed, consideration is given to whichever predominates: if pasturing predominates, zakat is obligatory; if stall-feeding predominates, no zakat is due; if the two are equal, then Êno zakat.
As for sheep that graze among quḍub (bersim/clover), the implication of the jurists’ words in the madhhab—as in the marginalia of Sharḥ al-Azhār—is that zakat is obligatory. They said: if a man purchases a place for pasturing, the settled ruling is that [his animals] are considered Êsāʾimah (pasturing). And if they eat another’s crop with his permission, then zakat is due—though he has sinned by what he did—because pasturing has in fact taken place.
As for using “carbon” so that the green color of oranges turns to the familiar orange color—there is no impediment. In some regions, such as al-Jawf and Maʾrib, the orange ripens and is good while its peel is still green, and it does not take on the orange color except by means of this substance.
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1