Plant leaves

[zackish]

When some of my plant leaves are like half brown, like the upper part of them, does this mean their definitely dead?
Also, are those leaves contributing to nitrites because they are dieing so should I cut them off?

[cocoa_pleco]

some of the time its natural. my java fern has a few brown leaves. they do produce some nitrate but i leave them. however, if you have yellow or black spots on the leafs youre screwed, especially yellow

[zackish]

I don't care about nitrates, I care about nitrites.
And what do yellow and black spots mean?

[hungryhound]

Yellow and black leaves are a sign of nutrient deficiencies. I am not sure of your set-up and what you are running. If you have a heavily planted tank you can use the following reference to diagnosis your deficiencies:

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Personally if the leaves are brown and dying I remove them. The only time I do not do this is if the plant has very few leaves and it needs the extra photosynthetic space to help produce new growth.

[dev]

I completely agree with hungryhound. These are all often connected to nutrient deficiencies or poor lighting.

Decomposing leaves will contribute to the nitrogen cycle in the normal way, ultimately ending up as nitrates.