Adding fertilizer to a garden is like a person taking vitamin pills. If there is no nutritional deficiency then, at best, the pill is wasted. If the vitamin pill leads to an excess of certain vitamins, it may actually harm the health of the person. Before adding any fertilizer the soil should be checked with a monitoring kit available at any garden store to see specifically what the needs are. Focus on adding only what is needed in the amount that is needed. Otherwise, any normally "safe" fertilizer may do more damage than good.
Burning the Plants
All fertilizer are chemical salts and they attract moisture. An imbalance between the fertilizer and the garden plants will draw the moisture from the plants and roots, drying them out. Following the manufacturer's instructions or understanding how a specific organic fertilizer works helps prevent burning. The main problem to avoid is overfeeding fertilizer.
Inorganic fertilizers are created from non-living materials that have been converted into chemical compounds that plants can use. Organic fertilizers come from previously living organisms. Either is perfectly safe to use on the garden when used properly, but the organic fertilizer has the advantage of also amending the soil to make it more attractive to the necessary micro-fauna that are important to plant growth.
The "Big Three" of fertilizers--nitrogen, phosphorus and potassium (NPK)--are brought together in various percentages with inorganic fertilizers. Whether in bags, bottles or shakers, the percentage for each will be prominently listed with three consecutive numbers similar to 00 (N) 00 (P) 00 (K). This allows the consumer to pick which compound will best meet the garden's needs. Inorganic fertilizer often includes a slow release form of nitrogen, helping to prevent burning from a sudden release of salt.
Gardeners can purchase ready-made organic fertilizer in product lines similar to inorganic ones, with the same NPK percentages listed. The cost runs a little higher for organic. Organic fertilizer almost always naturally slow-releases the stored nitrogen, which prevents burning. If too much is put on the garden, though, the release of an excessive amount when the soil warns is a potential danger.
Gardeners can buy and mix their own fertilizer, giving them complete control over what goes into their garden. Popular plant by-products include alfalfa, soy and cotton seed meal, seaweed and used coffee grounds. Animal by-products include bone meal, dried blood, fish extractions, manure and urea.
Plant material from the yard, garden and kitchen that has purposefully been mixed and allowed to decompose is labeled compost. Depending on the ingredients, compost can provide a valuable source of long-term fertilizers to the soil and plants. Although usually low in NPK, the compost feeds the micro-fauna over several years, which provides the plants with the basic chemical compounds that are completely safe. A continuous replenishment of compost into the soil ensures the plants always have access to a steady source of safe nutrients.