There are some calculation costs for plant cultivation. One of them for potato, cost per ha is approximately 8.000 USD and 525 USD is spent for pesticide including insecticide, fungicide and herbicide. That is, 6.5% is spent for pesticide in total potato cultivation cost.
It depends on crop type/variety and season to come up with actual cost from total cost. For instance, if the farmer plant CG7 groundnuts and planted late, there is need of more pesticides to deal with Aphids than those planted the same crop early season. Therefore, this will trigger different calculations of the cost towards pesticides out of total cost.