What is the nisab for Zakat on agricultural produce, does it differ between rain-fed and machine-irrigated cultivation, and what is the obligatory amount to be given from dates and grains?

The nisab (threshold) for grains and fruits is five awsuq, which is equivalent to three hundred sa's according to the sa' of the Prophet (peace be upon him). The measure of one sa' is four average, full double-handfuls. In terms of weight, one sa' is 480 mithqals, and the nisab is approximately 612 kg. If irrigated by rain or rivers, one-tenth is due. If irrigated by machines or irrigation canals, then half of one-tenth is due.