Answer to Question 1The presence of algae, especially in large numbers, would tend to suggest that the
soil was holding a large amount of water that was not draining well from the site.
Answer to Question 2Soils that have high quantities of organic material, such as mulch or crop residue,
would have larger numbers of soil bacteria and fungi. The soil bacteria and fungi
are responsible for decomposing the organic material and releasing the nutrients
from the organic material into the soil. Soils with large amounts of water would
have a higher concentration of soil algae. Algae also require light for
photosynthesis; they will tend to be concentrated at or near the soil surface. Fields
with surface irrigation or irrigation canals may have greater concentrations of soil
algae near the irrigation source. Phosphorus tends to be a limiting nutrient for algal
growth. The addition of high phosphorus fertilizers to saturated soils could result in
a large population of soil algae. Some nitrogen-fixing bacteria are associated with
the roots of leguminous plants. Soils surrounding plants in the bean family may
have higher numbers of these bacteria.