You sound like me. I have used QB since 1997 but I use Excel to make invoices.

I buy everything together at wholesale and bill them after applied. Fertilizer gets weighted off the truck. I attach a copy of the invoice for each load they receive part of with the scale tickets. Chemical invoices get copied and attached to a spreadsheet that shows the amounts used and price per unit.

I have different spreadsheets for fertilizer, chemicals and seed. I've saved a copy of each bill that I have sent for ever. I wouldn't even try to use QB for invoicing.