Download the nitrogen cycle: what a gas

THE NITROGEN CYCLE: WHAT A GAS!!
Although nitrogen gas makes up 79% of the Earth’s ___________________,
it cannot be used in that form. Nitrogen is needed so cells can make
____________________ and genetic material like ____________________.
For this to happen, the nitrogen gas must first be converted into
____________________, which plants can use. This process is known as
____________________ and can be performed by bacteria in the soil or by
____________________. The bacteria in the soil are found in lumps on
roots called ____________________, in a special group of plants called
____________________, one example being ____________________.
Denitrifying bacteria can break nitrates into ____________________ and
then back into nitrogen gas. This process is known as
____________________ and removes the nitrogen from the soil. The
bacteria that do this are called anaerobic because ____________________
will kill them. This is why people put holes in their lawns (a process called
____________________) which allows oxygen in to kill this bad bacteria.
If a farmer continues to grow the same crop of corn in a field for too long,
all the nutrients will get used up. As a result, he will leave a field empty
(called ____________________) and allow clover or some other useful
plant to grow, returning the nitrogen to the soil. If the soil is poor, he may
add manure or some chemical fertilizer to return the
____________________ back to the soil, so that more crops can be grown.
Word List:
nitrates
nodules
denitrification
protein
DNA
nitrites
nutrients
atmosphere
lightning
fallow
soybeans
nitrogen fixation
oxygen
aeration
legumes