Introduction
Nitrogen is essential to the growth and development of plants and other
organisms in the environment (Argonne
National Laboratory, 2005).
However this colorless, odorless gas cannot be used by plants or any other
complex life in its neutral form (
Killpack and Buchholz, 1993).
Specialized soil bacteria add H20
to the nitrogen, converting it into ammonia (NH3)
in a process called nitrogen fixation. Other soil bacteria then convert the
ammonia into nitrites (N02) which
nitrites are then transformed into nitrates (N03)
in a process called Nitrification. The plants soak up the nitrate into
their roots to create amino acids and nucleic acids, the vital building blocks
of all life and these chemicals then move through the food chain where they are
recycled through decomposition and the process repeats itself
(Brewer,
Kelley-Brown, Moats, and Wiltgen, n.d).
Hence the nitrogen cycle is critical to the well-being of plants and soil.
The
flow of the nitrogen cycle is greatly influenced by bacteria. The efficacy of
bacteria significantly depends on the behavior of protozoa. Protozoa are the
natural predators of bacteria, and have an inverse relationship, meaning that as
protozoa numbers increase the amount of bacteria decreases (Valentino
and Ingham, 2011).
Furthermore the amount of water in the soil affects the relationship between
protozoa and bacteria (Ingham,
2011). Since more water
in the soil increases protozoa mobility, the protozoa can hunt the bacteria much
faster. As the protozoa consume the bacteria they also force them to reproduce
much faster (Ingham,
2011). Water therefore
significantly changes the levels of bacteria and protozoa which in turn
influence the amount of fixed nitrogen available to all organisms in the
ecosystem. Since Water influences the productivity in the bacteria in the soil,
it indirectly affects many other elements including nitrogen. By changing the
amount of water in the soil, the nitrogen levels and bacteria and protozoa
density change as well.