I used black plastic one year and put hay over it. I made some places for water to run down under it when I noticed it was keeping the rain away from my plants. I used it for sweet potatoes which I had made hills for, so there were depressions between the hills, which I lined with newspapers to absorb the moisture and keep it in.. I set the sweet potatoes down in slits in the plastic. This worked very well for me. I also put pie pans and bits of aluminum foil around to reflect the sky and confuse the bugs. I had a really great crop of sweet potatoes, the best I ever had.(posted 9007 days ago)However, when I tried black plastic on level areas in my raised, boxed garden beds, without the other precautions, my poor plants didn't get enough water and dried up. A neighbor, observing what i was doing, came to me very unhappy and told me that he had seen someone else use black plastic which they left in place for three years and that the earth turned sour and all the plants (perrenials) died. I didn't see that for myself, so I don't know if it is true.
I have the book Lasagna Gardening and it's a great book.
I got my black plastic by scrounging. It had come off a new mobile home and the owners were delighted I took it away. I have also experimented with old carpeting in the rows between my raised beds. It lets the water and air in and makes a wonderful place for earthworms to gather. It does not entirely suppress weeds. They grow through it and eventually it biodegrades but the price is right and I use every scrap I can get my hands on. I used clear plastic, also scrounged, after wetting down my soil good to "sterilize" my soil and kill weeds, but i pulled it up when it was time to plant. The best thing I have used in my garden to keep down weeds is heavy cardboard from boxes. This cuts off the light and suppresses weeds, but the earthworms LOVE it! They like to eat the glue in the corrugations, I believe, and the cardboard, too, so it keeps the weeds down and also feeds my garden.
I have tried hay and straw and they biodegrade well but generally have seeds which sprout -- don't let them take hold or they have really deep roots and are hard to pull out! I pull up the sprouts and put them in my compost. Weeds do come up through the straw and hay but are easy to pull out if you get them while they are young.
Each material has its advantages and disadvantages but to me, price or cost is a major disadvantage! However, if I had unlimited funds and was going to buy either black plastic or landscape fabric -- the original question here -- based on my own experience, I would opt for the landscape fabric so the earth could breathe and water could get through to my plants' roots. I would not buy black plastic. In fact, there is a third option you can purchase which is paper mulch which supposedly keeps down the weeds, lets water thrugh, and biodegrades. If I were going to buy a weed-suppressant mulch, I would buy the paper mulch.