Complex sentence: Ala can spread out herself over a field and thwart the ripening of the crops, but even worse than that is her consuming of the field's fertility--the very life force that causes the plants to grow and bear their fruits.
Split into simpler sentences: Ala can spread out herself over a field; in this way she thwarts the ripening of the crops. But even worse than that is her consuming of the field's fertility--the very life force that causes the plants to grow and bear their fruits.