When should zakah on crops and fruits be paid?
Question

How should zakah be given on foul (fava beans) and peas? Should it be straight after they are harvested, or should we wait until they have dried?
Praise be to Allah.Firstly:
Zakah on grains – which includes foul and peas – should be given after they have been shelled and any stalks removed, and they have been cleaned of any pebbles or dirt that may be on them. It is not valid to give zakah on them before that.
This is the view of most of the scholars of the different fiqhi madhhabs.
Ibn Jareer at-Tabari said: That is because all scholars are unanimously agreed, and there is no difference of opinion, that zakah on crops is not due until after threshing, cleaning and winnowing, and that the zakah on dates is not due until after they have dried.
End quote from Jaami‘ al-Bayaan (9/611).
Ibn Hazm az-Zaahiri said: There is no difference of opinion among the scholars that it is not permissible to pay zakah on the day of the harvest, but in the case of crops, it is to be paid after harvesting, threshing, winnowing and weighing, and in the case of dates, it is to be paid after drying, cleaning and weighing.
End quote from al-Muhalla bi’l-Athaar (4/20).
Al-Bahooti said: zakah must be paid on grains when the husk has been removed, and on dates when they have dried… Because that is when they reach peak quality and is the time when they could be picked, and is the time when zakah should be paid. If he does not do that, and gives zakah in the form of grain in the ear, fresh dates before they have dried and grapes, then that is not the right time to give zakah from these crops.
End quote from Kashshaaf al-Qinaa‘ (2/212).
In Fataawa al-Lajnah ad-Daa’imah (9/176) it says: zakah must be paid on grains when the husk has been removed and on dates when they have dried.
With regard to the time when zakah becomes due, it is when the produce ripens and it looks ready and is in sound condition, and that is when the grain has filled out and the dates have turned red. In this case, zakah becomes due from the farmer, because at that time the crop is in peak condition.
Ibn Qudaamah said: The time when zakah becomes due on grains is when they have filled out, and in the case of dates, it is when they look ready and are in sound condition. Al-Mughni (4/169).
Knowing when zakah becomes due is important for the following reasons:

The ruling on liability. If the crop is destroyed before the time when zakah becomes due, then no zakah is due at all, but if it is destroyed after zakah becomes due, zakah is not waived, unless it was destroyed by an “act of God” or by something over which the owner had no control.
If he sells it before it appears to be ripe and in sound condition, then no zakah is due from him; rather zakah is to be given by the purchaser. But if he sells it after it appears to be ripe and in sound condition, then zakah is due from the seller.
If he inherits the crop and fruit before it appears to be ripe and in sound condition, then he must pay zakah on it. If he inherits it after that, then no zakah is due from him.

In Fataawa al-Lajnah ad-Daa’imah (9/176), it says: When the grain has filled out and the dates appear to be ripe and in sound condition, then zakah becomes due. The obligation is not confirmed until he puts (the harvest) into containers. If it is destroyed before that, through no fault on his part, then zakah is waived. End quote.
For more information, please see the answer to question no. 99843.
Secondly:
What we mentioned above does not contradict the verse in which Allah, may He be exalted, says (interpretation of the meaning): “but give the dues (in charity) that are proper on the day that the harvest is gathered” [al-An‘aam 6:141]. This verse was revealed in Makkah, before zakah was made obligatory with its designated rates and thresholds.
What is meant by “the dues” in this verse is something other than zakah; it is due in the sense of being mustahabb (recommended); therefore it is recommended for the owner of the fruits and crops to give some of the yield on the day of harvest and picking to the poor and needy, as much as he feels comfortable giving.
Ibn Hazm said: It is something due other than zakah. What is meant is that the harvester gives at the time of harvesting whatever he feels comfortable giving; he must give something, and there is no set limit for it. This is the apparent meaning of the verse, and this is the view of a number of the salaf (early generations).
End quote from al-Muhalla bi’l-Athaar (4/21).
At-Tabari narrated in his tafseer that Ibn ‘Umar said: He should give something to the poor, other than what he gives of the one tenth and the half of one tenth [i.e., the prescribed zakah].
It was narrated that ‘Ataa’ said: He should give some of his harvest on the day thereof, whatever he wishes, and that is not zakah.
It was narrated that Mujaahid said: If the needy come (when you are harvesting), give them something, and if you move onto another process and you start to weigh and measure (the harvest), then give them a few handfuls of it. When you know how much you have, then set aside the zakah from it.  When you start to pick bunches of dates, throw some bunches to them, and when you start weighing them give them some handfuls, and when you know how much you have, set aside the zakah from it. See Tafseer at-Tabari (9/600-604).
Al-Qurtubi said: Some of the scholars said: The one who harvests grains or picks dates should give some of it to those present. This is the meaning of the verse (interpretation of the meaning): “but give the dues (in charity) that are proper on the day that the harvest is gathered” [al-An‘aam 6:141], and it refers to something other than zakah.
End quote from Tafseer al-Qurtubi (18/239).
Ibn Jizziy said: It was suggested that “the dues” here refers to zakah, but this view is weak for two reasons:

The verse is Makki (i.e., revealed before the Hijrah); zakah was enjoined in Madinah.
zakah is not given on the day of the harvest; rather it is given on the day when grains and dates are collected and put in containers.

And it was said that “the dues” refers to what is given to the poor on the day of the harvest, and that was obligatory, then it was abrogated when the one tenth (i.e., zakah on produce) was enjoined. And it was said that it refers to whatever grain falls on the ground, and the command here is to be understood as encouraging people to give.
End quote from at-Tas-heel li ‘Uloom at-Tanzeel (p. 474).