NEW YORK (AP) — Legions of apartment dwellers will soon be asked — and may eventually be forced — to start collecting food scraps for composting, under Mayor Michael Bloomberg's latest bid to make the Big Apple greener. After launching a test program recently in 3,500 Staten Island homes and some Manhattan apartment buildings, city officials said Monday they planned to expand it to 100,000 houses and high-rise apartments in all five boroughs this fall. The initiative would be voluntary for now, but officials aim to make it mandatory citywide in a few years.