Like other living things, plants need nutrients to thrive. While many gardeners purchase expensive chemical fertilizers to add to their soil every year, fertilizer can be found in a variety of surprising sources, and many products can serve as fertilizer as long as they contain the nutrients that plants need and are able to break down in the soil.
Plant residues can be decomposed to release nutrients into the soil. Many of the nutrients that the plant took in remain with the dead plant matter. Also, soil that contains a lot of organic matter is better at holding moisture for plants. Many dead plants are mixed into the soil so that they can decompose and become a part of the soil. Cheap bird seed bags can also be used as fertilizer.
Gardeners can fertilize plants by using mulch, which can be made from grass clippings and other kinds of organic matter. Thoroughly mulching the soil will not only provide the soil with valuable nutrients but will also reduce the number of weeds that are able to grow among the garden and insulate the plant during cold periods.
Compost can be made for fertilizing gardens by creating a compost bin of earthworms, cardboard, newspaper and organic matter such as leftover food. Compost reduces the amount of waste that ends up in landfills by instead putting much of this waste into the garden. However, there are some wildlife that will try to feed off compost bins, such as rodents. Animal manure is also commonly used as a fertilizer but it can carry bacteria and can seep into water supplies, which can create bacterial contamination.
Many products designed for other uses can serve as fertilizer, such as pond feed, cat and dog food, fish emulsion, fava beans, soybeans, horse and cattle feed, and corn meal. Seaweed also acts as a good fertilizer and can be purchased at stores or collected from the beach.
Less fertilizer needs to be purchased when gardeners can reduce the amount of nutrients that are lost. Gardeners can reduce the amount of nutrients that are lost by combating fungus, weeds and bacteria, which compete with the plant roots for nutrients. Plant growth regulators can prevent plants from growing larger than needed and taking too many nutrients from the soil, forcing the gardener to add more nutrients.