YES!
But some of the N stays in the leaves.
That fact & the fact that leave are plentiful is the reason that I use more leave then animal manures, when I compost.

The green you see is chlorofil, not Nitrogen. As those plant parts age some of the Nitrogen is lost and some is retained. How much N is in any particular plants leaves depends on many things, but the C:N ratio in leaves ranges from 40:1 to 80:1 depending on the age of those leaves.

Kimmsr wrote:
> The green you see is chlorofil, not Nitrogen.

There is Nitrogen in Chlorophyll, though :-)

Chlorophyll consists of Nitrogen, Magnesium, and the 3 usual cast of characters: Carbon, Hydrogen, and Oxygen.

Sidenote for the newbies like me:

Through use of chlorophyll in that process called photosynthesis, plants are able to make their own energy from light (Wow). We animals, however, don't have that ability, of course. We have to eat our energy by eating plants (or by eating animals that eat plants, or by eating animals that eat animals that eat plants). Ultimately, all animals rely on plants. Without them, we wouldn't be here--right.

The plants make animal life possible. So I guess we should never take our precious plants for granted :-)
In a sense, we are their children.

And of course, some children can treat their parents terribly. Many people think Roundup is hurting plant life, hurting the Earth, and ultimately hurting ourselves--but that's another story.

Anyway, for photosynthesis, water molecules are broken down to form Oxygen Gas and hydrogen. Of course, animals like us need Oxygen to breathe. Almost *all* the oxygen in our planet's atmosphere comes from the photosynthesis performed by organisms like the plants. That's another thing for which we owe the plants big-time, I guess.

And plants use Carbon Dioxide (CO2) to make sugars. Sugars are carbohydrates or "carboNhydrates" (Carbon, Hydrogen, and Oxygen): C-H-O.

(Refresher course for me: Water is H20, oxygen is O2 and hydrogen is H.)

God bless the plants. Have you hugged a plant today :-)

Forgot to add: So not only do the plants give us OXYGEN, they also give us CARBOHYDRATES. These things are amazing.

Oh yes, and they also give us proteins too, either directly when we eat them, or through the animals we eat that eat the plants.

Plants give us so much. I'm going to go out and hug a plant right now.

thanks everyone for the fascinating information.

soysiasod, i agree, plants are wonderful!

but my original questions remain unanswered.

i ask those questions because i've been thinking about cover crop. traditionally, cover crop is turned into the soil, but what would happen if i don't do that and the plant complete its life cycle. will the majority of nitrogen in the aerial parts of the plant go into the atmosphere, into the soil, or even into both (i.e., 50/50)?

and how about plants like say...a pear tree that sheds all its leaves every year? what happens to the nitrogen in the leaves (and other precious leaf nutrients)?

What are you planting as a cover crop?
If clover then the N will be higher on the root nodules, and in your soil, than in the plant material. If one of the grains, and you simply allow those to die off, most all of the N will be in the seeds, the grains, that will then germinate and grow again the next year.
All plant parts will have some Nitrogen in them, even after drying for quite some time. Tree leaves, the pear, have a C:N ratio of 40 to 80 to 1, depending on age and weathering. Some of the Nitrogen gasses off into the atmosphere, some is taken back by the tree to be stored for the next growing season, and some is retained in the leaves.

If you are considering a non-leguminous cover crop that will winter-kill before setting seed, most of the nitrogen will be in the vegetative portion of the plant, but as it desiccates, much of that will be lost to the atmosphere. What you gain is a bit of N and some increased porosity in the soil from the decomposing roots and a dense mulch on top, but not a high boost of N

kimmsr, i'm growing crimson clover as a cover crop.

thank you billme and kimmsr for the info; i now have a better understanding of cover crop.