Price in the notified production clusters meets any one of the following conditions:
Prices fall below preceding 3 years’ average market price at the time of harvest;
Prices fall more than 15% compared to last year market price at the time of harvest;
Prices fall less than the benchmark price for procurement, if any, fixed by the State/Central Government for a specified period
Trigger price is higher of these three prices and it is the price at or below which the crops are being sold in that production clusters. The actual purchase price should be equal to or less than the trigger price for being eligible for subsidy. The list of eligible crop, production cluster and trigger price is available here.