Planting on septic leach field?

There is a sizeable area of my lawn that is dedicated to the leach field for my septic system. Right now there is just grass and weeds growing there but I imagine it would be pretty fertile for growing. Not too keen on eating stuff fertilized with human waste (I know lots do, but I'm just not open to it right now) but I think it would be perfect to grow stuff for my chickens and ducks.

So my questions are;
Have any of you grown anything on a leach field?
What can I grow that I don't have to worry about damaging the system (no deep roots).
What can I grow that doesn't get too tall. It's already on a hill and it's right next to my patio. I would like it to look somewhat neat.
And what can withstand trampling by ducks feet and scratching from the chickens? I would probably put a temporary fence up until it get's established but then let the critters help themselves to whatever is growing there.

I am having one of these systems installed on my property right now and have been wondering the same thing. Apparently the flexible "pipes" that snake along under the ground - on contour - are buried about a foot deep and will not in any way be damaged by what grows above it. The guy who is doing the install said to plant whatever I want but that the ground does need to get some sun, wind, etc. to function properly. He said the system will put out fair amounts of nitrogen and phosphorous.

It sounds like I may be more open to edibles in this area than you but am not yet sure what would be best. Will keep an eye on your post for some ideas.