The nitrogen in the soil of the left garden is more plentiful than the right. People have probably already harvested the right which leaves less nitrogen in the soil which leads to weaker crops
An element is a pure substance. (Like gold) and A compound is a substance that contains two or more elements; Like Water and oil. They are together but they will not mix. The oil separates from the water and floats on top.
A is the sun or light energy
Groundwater is the largest available source of freshwater.