I am making a new radiant layout and wanted to know do I need a way to shut off all of my loops with ball valves?  DO I put them on the start or return if I need them of each loop. 

You do not "need' to isolate each loop, but it will help when purging air on start-up. The best manifolds have isolation and flow meters built in.

Naturally you will perform a heat load, as no radiant floor heating system can be properly designed without one.

I am making a setup for a Utility room so I will get a manifold with them on it. On another setup I have about 200 feet going under a plant trough in a greenhouse to heat the water and it will only have one loop. I am using TACO smart valves so that will keep it from opening if I turn it off or turn it down. Then I could just get a ball valve right after the smart valve to repair it if I had too. I will use antifreeze because I am in the greenhouse. What do you mean by a heat load?

The heat load is the amount of heat lost while in outdoor design conditions (the coldest week of the year). If you don't know how much heat you will need to replace the heat lost on the coldest day, then the temperature will drop from the indoor design (where you set the thermostat).

Okay I had an engineer do a complete setup of everything. I know what I am needing and have all of the items figured out except for my isolation idea but if you saw I do not need them I should be okay. I am using a boiler set up and it will eliminate the air. Thanks

you don't understand. even with air elimination on a system, loop isolation is handy for the initial purging. Also if there is a problem later it can allow for servicing a loop without turning off the whole system.

You definitely want to be able to turn off a loop, but full isolation is not quite as critical... still helpful though.