Hooray for lowly mulch. It really is magical stuff to gardeners. Actually, vegetable mulch makes humus of the highest quality due to some other lowly organisms, such as earthworms and bacteria. In a hot climate mulch turns into humus year around, unlike up north where the frozen ground puts things on hold for several months of the year. Take advantage of it's quickness to rot, and don't seek out cypress chips or other non-rotting materials like gravel to use as mulch. To work it's magic for you, it needs to rot and make humus - lovely, fluffy, black soil that makes plants thrive like you thrive on vegetables and fruit.
My father-in-law liked to garden. He moved to a hilltop in Kentucky where the soil was only inches in depth before you hit bedrock. Undeterred, he built raised beds several feet high, bought a wood chipper, and made a rotating barrel in which to create humus. Then he went to work. He filled his barrel half full with his wood chips, vegetable trash, and leaves and wet it all down. Then he would rotate the barrel several turns a day. When the material had semi-rotted he put it into wire cages and the earthworms happily ate it. He would stir this all around and turn it over once a week. Soon bacteria and earthworms in the mulch turned it into black humus with which he filled his beds. There was enough vegetables that grew in these beds to freeze, can, and give away! And such lovely vegetables and flowers he grew!
Mulch holds water like a sponge, and just as importantly for gardeners in Texas, it keeps the ground temperature lower which in turn lowers the heat stress on plants tremendously. Mulch binds to nitrogen so water won't rinse it away as quickly. It also holds onto phosphorous, and potassium. I made the mistake of putting the same amount of fertilizer on heavily mulched plants that I was used to putting on the bare ground. The plants quickly got burned by it. I actually had to add lime to neutralize the mulch, and this was in an area with alkaline pH soil! Humus is not necessarily high in nitrogen and you will have to add that nutrient to it unless you have used a legume such as clover or peas as your base. If you use this as your mulch you'll have to watch out for nematodes and therefore I avoid using it.
Be careful if you use commercial fertilizer or you will use too much like I once did, for the plants wont show immediate improvement, and it will take several weeks of watering before the humus will slowly begin to release the nitrogen. It could take several months before the plants becomes green and loses their chlorosis, (yellow leaves). But then the good result will last and last. I have found that I usually wont have to add more nitrogen for a whole year. It is a good thing in the long run for mulch to act this way, for plants need nitrogen, potassium, and phosphorous to be released slowly over a long time, and that is what humus will do. Think of it as slow release vitamins.
Humus has a neutral pH, and if you use a lot of it, it will help neutralize the pH in your garden. Most plants do best with a pH of around 7.2. If you have hard alkaline water, constant watering will not only rinse out the nitrogen but will leave behind lime salts. Unfortunately in Texas, constant watering is a necessity. When my plants show some chlorosis, I carefully sprinkle some ammonium sulfate around them, water it in often, and wait.
Mulch won't become humus overnight, unless you work at it like my father-in-law did. If you just keep a mulch pile for kitchen and garden refuse, you'll have humus in a year on the bottom of the pile. You can turn it over and wet it down sometimes to encourage the earthworms and bacteria's activity, and oxygen will quicken the transformation. I'm too lazy for all of that. I learned my method from a book titled "Gardening Without Work" by Ruth Stout. She was an old lady in the 70's whose method of gardening was to use lots of straw and hay as her mulch. This mulch soon became humus and she just kept adding more straw and hay until the humus became very deep. She kept at this method of gardening until she died at the age of 91. By then, she had wonderful dirt. How lucky for the homeowners who bought her property!
People are often leery of using hay as mulch because they are afraid of weed and grass seeds. Weed and grass seeds will germinate and die in old hay, and so seek out the oldest hay you can find to use as mulch. Farmers will happily sell it to you at a cheaper price for they can't use it as animal feed by then. I buy hay that is at least two years old. Also, if you pile it on almost a foot thick, weeds blown by the wind can't reach the soil to sprout. The old hay will completely rot and become humus naturally without any effort on your part, and so when it becomes thin, just add more! Over time in this way, old hay will become great topsoil! Add some nitrogen, some water, and you will have magic dirt that will grow most anything. If you have acidic, sandy soil, it will not only neutralize your soil, but help hold the water that used to rinse right through it.
Mulch really is magical for everybody. For those with alkaline soil, acidic sandy soil, heavy clay soil, or rocky thin soil, mulch is your answer. Hooray for mulch!