Considering how much is overused and washes into rivers and oceans and creates dead zones. This is a really good thing. We over produce as is.
A lot of it used to be caused by manure runoff from large animal operations. But twenty or more years ago laws were changed and regulators focused their attention on correcting this problem. There are always exceptions but mostly this problem is fixed. Farmers have to file plans on which lands gets manure, complete with soil tests showing they're not overdoing it.
I helped farmers in the late nineties fill out these reports in my former career as an agronomist. Back then some larger farmers were either moving to composting or using the manure to power plants creating electricity.
So where is it coming from now? Lawn fertilizer! People over fertilizing their lawns.
Long answer: You need to break down the organic matter in the leaves through composting. To speed up composting you want the right proportions of both brown (carbon - your leaves) and green (nitrogen) matter, the right moisture levels, and access to oxygen, usually in a large pile to create the perfect environment for the microorganisms that break down the matter. Your leaves are a great base for your compost, I always use mine, but you will probably need to put a little sweat equity into it, as well as kitchen scraps, lawn cuttings, etc. to get the right proportion of greens.
Lawn fertilizer!? I didn't even know that was a thing! Why would you fertilize a lawn. Won't that just make it grow faster and therefore require you to mow it more often?
So why does there exist a massive waste problem from nets being dumped in the ocean? The answer lies in large scale fishing fleets which is an industry that is not a a low margin business. For them the cost of repairing or properly disposing nets is a cost compared to just dumping them into the ocean, and even if they get fined the cost would be less than the savings.
Small farmers are in a low margin business, and yes, if they use too much nitrogen they make less money. They would also get fined by local government, risk loosing farming rights and so on. Large scale farming and factory farming is not a low margin business, and sometimes the cost of violating regulations can be seen as the cheaper alternative. There is always the option to let a sub company go bankrupt, and route the profits away from the costs. Those are options not available to a small farm.