Fertilizers replace lost nutrients that plants need for optimal growth and health. Fertilizers are generally divided into two types: chemical and organic. Chemical fertilizers are usually made from petroleum derivatives and can quickly enhance a soil that is not offering enough nutrition for plants or crops. Organic fertilizers are based on natural sources, and can include fish emulsions and meals, kelp emulsions and meals, bone meal, seed meal and compost.
Liquid fertilizers soak quickly down through the soil to reach plant roots. Liquid fertilizers are used to quickly raise nutrient levels in potted plants, gardens and crop fields. There are both chemical fertilizers in liquid form and organic fertilizers in liquid form. Specific application techniques and procedures will vary, depending on the type and brand of fertilizer. Some fertilizers are simply poured around a plant. Others are best sprayed on the ground.
Many fertilizers are powdered. Many chemical fertilizers are available in powdered form, with some organics also being sold as powdered fertilizers. Powdered fertilizers are usually spread over an area and "watered in" to encourage them to reach plant roots. However, exact application procedure can vary, so follow any instructions on the bag to ensure proper application.
Some fertilizers are sold as "plant food" stakes. By driving these stakes into a pot or next to a plant, the stake releases nutrients over time into the soil around the plant. Stakes are often chemical fertilizers, but some companies manufacture organic stakes. How long the stakes will last before needing to be replaced will depend on the brand. Follow the replacement schedule on the packaging.
Composts are organic fertilizers that result from the natural partial breakdown of organic components. Most home compost piles convert grass clippings and vegetative household waste into a black, soil-like fertilizer. Some composts are made using animal manures. Before composting, some manures can harm some plants. By allowing the manure to break down into compost, the harmful elements break down creating a spreadable organic fertilizer. Composts can either be spread on the surface of the soil or worked in during planting.