I grew up with so many trees around me it's surprising I didn't end up a hippie. My dad was a farmer and we often spent time a lot of time planting stuff (duh). It was a nice way to grow up. I don't remember a time when I thought that earthworms were gross and that pig poo was such a terrible thing. Smelly, yes, but plant anything near a sty's drainage canal and you'll see how wonderfully they'll grow. But anyway, growing up with trees obviously means that I grew up with a lot of fallen leaves that I had to clean up.
Anybody who's taken care of a plant or a tree knows that fallen leaves are useful. Yes, they might be unsightly at times and having too many at the wrong time might mean that something's wrong with your plant. However, when it's just the normal amount, you can put those fallen leaves to work by turning them into mulch. All you have to do is shred them up with a mulcher or, when they're dry and brittle enough, you can actually pulverize the whole thing and you'd end up with something like very light soil.
Leaves become mulch through a natural process of decay but shredding them artificially quickens the process. It also makes it easier to handle and use in gardening. Sooner or later, the nutrients from leaf mulch would go into the soil and into whatever's planted there. Mulch also helps lessen the rate of dehydration in soil. Though it doesn't retain water better than normal soil, it does form as a sort of barrier between the sun's rays and the water on the ground.
However, as good as leaf mulch is, you can end up with too much of it. In farming communities or where there are vast spaces of land, it's not really a problem. You can just share it with your neighbor or spread it out on a field as a form of fertilizer. From my experience in farms, you can almost never have too much mulch (unless you're growing something that requires a special kind of soil).
It becomes more of a problem with woody backyards and parks in neighborhoods. Leaving the leaves just lying around might be unsightly. Worse, leaving them on a grassy lawn might result in the uneven growth of the grass. What you can do if you have this problem is you can simply put them in the garbage. Some neighborhoods have common processing plants that turn biodegradable material into useful products. If your neighborhood doesn't have one then you can make a compost pit of your own.
This simply means that you dig a hole and dump all the excess mulch you don't need there. After that, you can sell it to garden shops as organic fertilizer. You're literally making money out of dirt!
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