Allah (s.w.t.) tests all his subjects in this world, he gives some of his subjects worldly riches and withholds material things from some. Hence what falls upon the poor believer is to seek his livelihood and be content with what he has. The rich believer has to share this extra wealth given to him with people in need and to supply their needs.
The zakat (obligatory alms) and oshur (Islamic tithe) ordered by our Creator Allah (s.w.t.) emphasizes to us how important it is to share and cooperate in Islam. Zakat means to increase, purification and abundance in the dictionary. In the dictionary of Islamic Law, zakat refers to the share taken from the property of the Muslims who meet the religious nisab (threshold) in wealth, to be distributed to the Muslims who are considered poor.
The meaning of oshur (Islamic tithe) in the dictionary is one tenth, and in Islamic Law, it means zakat given from agricultural products. Allah (s.w.t.) has stated the oshur in the Quran:
"O believers! Donate from the best of what you have earned and of what We have produced for you from the earth. Do not pick out worthless things for donation, which you yourselves would only accept with closed eyes. " (Bakara, 2/267)
We can see from the hadiths of our Prophet (pbuh) and our Islamic jurisprudence books which agricultural products’ oshur should be given, how to give it and to whom.
As a result, all agricultural products that are grown by man and have economic value are subject to one-tenth or one-twentieth donation. The Prophet (pbuh) states the following in a hadith regarding the issue:
“One tenth of the soil products irrigated by rain and river waters, and one-twentieth for those irrigated with a bucket is required.” (Bukhari, Zakat, 55)
For the resulting crops, if the water cost is incurred, 1/20 is to be donated, if no irrigation is done and the crop is watered by rain, 1/10 oshur is to be donated. Also, there is no requirement to complete a full year as in zakat. When the crop is harvested, the oshur will need to be donated. If there is more than one harvest during the year, for each of these harvests, the oshur will need to be calculated and donated.