Answer:
Monocropping is the practice of growing the same crop on the same plot of land, year after year. This practice depletes the soil of nutrients (making the soil less productive over time), reduces organic matter in soil and can cause significant erosion which can most probably cause drought.
Primary sources can be described as those sources that are closest to the origin of the information. They contain raw information and thus, must be interpreted by researchers. Secondary sources are closely related to primary sources and often interpret them.
Around 400 million years old
There military strength, there economy must be stable, and they must have a strong government
