WordNet
nitrogen balance
n. the balance between the amount of nitrogen taken in (to the soil or the body) and the amount given off (lost or excreted)
Wikipedia
Nitrogen balance
Nitrogen balance is a measure of nitrogen input minus nitrogen output.
Nitrogen Balance = Nitrogen intake - Nitrogen loss
Sources of nitrogen intake include meat, dairy, eggs, nuts and legumes, and grains and cereals. Examples of nitrogen losses include urine, feces, sweat, hair, and skin.
Blood urea nitrogen can be used in estimating nitrogen balance, as can the urea concentration in urine.
Usage examples of "nitrogen balance".
Let them into a place and they were mentally hanging curtains and planting flowers before you even had a decent oxygen-nitrogen balance established.