And finally, I bring you the 4th, least-known and most-recently added, R, Rot.
Rot: Vegetation that can be Rotted in compost bins to enter the Carbon cycle and emerge as rich, moist, dense, 'nutritious' fertilizer.
Rot: Reducing what we put into our landfills by Reusing food scraps and plant clippings as fertilizer, a process facilitated by Recycling these nutrients back into the Carbon cycle via the process of Rotting, which utilizer microbes, worms, and other decomposers.
In traditional composting, you layer brown and green layers, so one layer of grass clippings or fallen leaves and the such, then one layer of foodstuffs, then another layer of grass clippings or fallen leaves or branches, etc. You need a critical mass of material for this to work, you also need to turn it every now and then to aerate [oxygen is critical to this process! I think. Either oxygen or carbon dioxide, but either way, you definitely need to let fresh air circulate in]. The microbes, worms, and other materials will slowly eat away these layers and produce rich fertilizer.
An alternative is composting with worms [called "red wigglers," you can find them in fishing stores, 1 pound of worms is enough for 1 family], which is what I do, or rather, what my dad currently does as I have left my worm bin with him, but once my doppelganger helps me put together my own worm bin, I rather think I shall steal away half the worms and start up the process up here.
The process is quite simple. You lay down a 'bed' for your worms, a couple cups of soil and loosely packed layers of moist newspaper strips about 1" thick. Give your worms about a week to adjust to their environment [they can eat the newspaper strips] before you start feeding them. Important - don't feed them anything with dairy, meat, oil, fat in it if you don't want the bin to smell [my friend kept her bin in her closet ... it can be done!].
Of course you can also keep them outside. If you are afraid of them freezing you can insulate the bins by putting a towel or two on the lid, keeping it close to your house [the heat that leaks out means the area immediately surrounding your house is a couple degrees warmer], keeping it in the garage, etc.
Scraps from the fresh produce that you eat, moldy bits of old apples ... they eat it all. Its great because it isn't even stuff that you yourself were going to consume anyways. You can store the food scraps in a little tub and bring them out a couple times a week. Just dig down a bit into the newspapers and bury the food, and you're good to go! If you want you can rotate where you put down the foodstuffs.
At this time its also a good idea to plump up the newspapers strips a bit to make sure that fresh air is getting down there ... and if this seems icky to you, you can improvise with a small garden tool or two as my dad's been known to do. This is also a good time to check how much food your worms are eating, and make adjustments accordingly. It may take awhile to get enough worms to eat every bit of food scraps that you produce, or you might find you already have the perfect number of worms. It's a fluid ecosystem - the worm population will adjust to the amount of food that is provided.
Worms also create this great super-nutritious liquid that can be collected [depending on the type of bin that you have] and used on plants, while you are waiting for them to turn out enough compost to make harvest it worthwhile.
And since worms can eat up to their own weight of food daily AND reproduce every 3 weeks, you can bet this can get pretty efficient.
I highly recommend. Keeps food out of dumpsters and brings it back into the earth, increasing your ability to garden organically, maintaining the nutrient cycles that have existed on this planet for millions of years, and heck, its science that you can SEE.