Blood meal or fall time cover crop such as clover
Blood meal and urine are both nitrogen-rich additives.
Decayed plants and animals
Cake
The fact that nitrogen will be added to the nitrogen deficient soil is the advantage of adding fertilizer. Nitrogen, phosphorus, and potassium are the major nutrients that plants and soils need. Commercial, conventional, standard, synthetic fertilizers also are called NPK fertilizers. The initials come from the first letters of the scientific names for precisely these three nutrients. Additionally, nitrogen is present in such organic fertilizers as compost. So whether by the inorganic or the organic route, the soil gets nitrogen when it gets a fertilizer treatment.
Adding phosphorus to soil that needs more, promotes root growth, winter hardiness, and can hasten maturity in the plants grown there. Nitrogen helps plants to grow and helps them to feed themselves.
I think you may need to rethink this question.
draining of nutrients from the soil
adding leaves to the soil
The disposing of sewage into water is one way humans interfere with the nitrogen cycle. Humans are also responsible for releasing large amounts of NOx gasses into the atmosphere, which interferes with the nitrogen cycle as well.
I believe you determine Organic Nitrogen by subtracting Ammonia Nitrogen from Total Kjeldahl Nitrogen.
adding chemical fertilizers to the soil
It means that you are feeding the soil so that the soil will feed the plant
Nitrogen is an element on the periodic table of element, but when adding the "s" it means a multiple of that element.
the nitrogen is only used to clean out the lines prior to adding the refrigerant