Complex sentence: James Machen took over Walney after his father's death and after the war, the farm had been transformed from growing crops to a dairy farm and by 1880, James was producing 3000 pounds of butter a year.
Split into simpler sentences: James Machen took over Walney after his father's death and after the war, and transformed the farm from growing crops to a dairy farm. By 1880, James was producing 3000 pounds of butter a year.