bass,
your figs look great. good pictures. i have grown vegetables under plastic for years. it works really good to control weeds, thus eliminating the trees competition for nutrients and moisture. the way we do it we first work in fertilizer in the soil, then we lay drip tape irrigation, then plastic, then set our plants. later in the growing season we use a flowable fertilizer and run it through our irrigation drip tape which is near the plant and under the plastic. it is very easy and requires very little labor after u set it up. i grew a 187 pound watermelon last year that won first place at our fair last year. that method works well for us and i hope it does for you, but DO NOT FORGET WATER UNDER THAT PLASTIC.