Big spreads of decoys are one way to go. But, I've met a few guys up in Sask, who hunt over 5 or 6 full body decoys with much sucess.

In fields that have a lot of pressure, the bigger spreads can spook birds who've been shot at. Smaller spreads, when tucked into a corner can entice spooky geese. It's all about showing the birds something different. Check the field for old droppings or muddy feathers. They may indicate that the birds have already fed or been in the field.

Most important thing though, is that you wrote that they fly around the field. If they're not landing in the field, there's a reason. You may have some luck calling in singles or pairs, but the local flock may be tough to convince.

Try to find where they're landing. If you can get permission there, you've got half the battle won.