using inventory goods during production

[ario <..hidden..>]

Hello,

for a farm there is fertiliser in stock, purchased some time  ago and
recorded through 'vendor invoice', hence recorded as inventory in stock.
Now the farmer is spreading some of this stocked fertiliser on the soil,
but he is not selling any, nor does he know how much produced end-goods
(kg produce) will result from his current farming operations.
How is the consumption of this fertiliser to be recorded and moved out
of the inventory and charged to that particular 'department' (specific
area) and project (cropping type and date) of the farm without selling
any to a third party?
I'm quite stuck with this as the only possible way I see to move this
used fertiliser out of the inventory is through selling.

Thanks
ario