Switch out the soil with more fertile soil
Answer: Petroleum, Electricity and Steel
Explanation: The second industrial revolution is a period between the late 19th to the early 20th century which is characterized by massive growth and expansion of industrialization. The second industrial revolution is also known as the technological revolution most notable for steel production, expansion in electrification which was previously limited to very few cities and development of Petroleum and gas supply.
According to Albert Barnes, their mistake was that they didn't speak against slavery. Although many of them believed that slavery was against god and against the idea that god made everyone equal, they didn't do much against it out of many reasons, either they thought it was a necessary evil or they were afraid of the public reaction.
Answer:
Invasive species, including communicable diseases, etc..