If you are looking for a natural alternative to spot removal carpet cleaning then try hydrogen peroxide. I found a great natural carpet cleaning trick on a carpet cleaners website. You can make a homemade solution of carpet cleaner that works well with stains and odors.
Fill a spray bottle with two-thirds water and one-third water. If you want a refreshing fragrance add a drop or two of essential oil such as lemon, or cedarwood. Hydrogen peroxide breaks down the chemical structure of the odors by ripping them apart. For a troubled area, you may want to let the solution sit a while to do it’s job before blotting up the solution.
For recent spill or a difficult area spray the solution of hydrogen peroxide then add generous amounts of baking soda to the stain allowing the baking soda to absorb the spill on the carpet. Vacuum up the baking soda and blot the stain with a paper towel.