多年来人们一直在使沙漠变良田，融化高山的冰川来灌溉庄稼。(turn into)

多年来人们一直在使沙漠变良田，融化高山的冰川来灌溉庄稼。(turn into)

For years people have been trying to turn deserts into fertile lands and to melt mountain glaciers to irrigate crops.