Complex sentence: In 1952, after privileges were introduced for collective farms, their number grew, and a year later, there were 7800 such farms, which occupied 6,7% of arable land in Poland.
Split into simpler sentences: In 1952, after special privileges were introduced for collective farms, their number grew. A year later there were 7800 such farms, which occupied 6.7% of arable land in Poland.