Very Low Yield On My Tray Of Wheatgrass

Booster Juice at 355 Wellington St. has very low yield on their Wheatgrass trays!

I bought a tray of Wheatgrass from them for $10 today and had it juiced right there. The yeild was 5oz but the clerk kindly added some from another tray so that I got 6oz.

She told me the owner does his own trays and he got different Wheat kernels and the yeild on the trays with the different kernels was way down. She told me typically they where getting 10oz from the 11″ x 21″ tray.

From the pictures below can anyone tell me what they did wrong.

Here Is The Tray Before Harvest:

Here Is The Tray After Harvest:

Here Is A Cross Section Of The Clump:

Here Is A Close Up Of Top Of The Sod: