When your soil needs amending or your plants need a nutritional boost, your choices of fertilizer can be overwhelming. Although I am not a professional, I can give you some basic information on organic and inorganic fertilizers so you can decide which type to use and when.
Organic fertilizers come from living things, while inorganic fertilizers come from non-living material such as minerals. Both types of fertilizer will feed your plants the main nutrients of nitrogen, phosphorus, and potassium – commonly known as NPK – but each type varies in how the plant can utilize it and what affect it has on the soil.
Organic fertilizers are more expensive to use than inorganic fertilizers, but they may increase the quality of the soil as well as increase how well plants can utilize the nutrients. Organic fertilizers must be broken down in the soil by micro-organisms, so they are “slow release.” This means you can’t over feed your plants. However, it also means the nutrients are not immediately available for your plants.
If your soil is deficient or your plants are showing immediate need for nutrients, you may want to use an inorganic fertilizer. They are inexpensive, and the nutrients are immediately available for the plant to use. However, there is a danger of over feeding your plants and causing plant “burn” or death. Also, inorganic fertilizers easily leach out of the soil with rain and watering.
There are several types of organic fertilizer you can use. Sources that contain good portions of NPK together are composted cow and chicken manures, bat guano, and compost tea. Of these, composted chicken manure has the highest levels of NPK. (Note: Never use fresh/uncomposted manure in your soil unless you plan to let it decompose at least three months before planting, else you risk e. coli contamination of your food.) Blood meal is mostly nitrogen, while bone meal is mostly phosphorus and calcium. Fish emulsion is high in nitrogen and phosphorus and also contains trace elements. Seaweed contains an abundance of micronutrients.
If you plan to use inorganic fertilizer, it’s best to choose one that has a balance of NPK. Miracle Gro is one such balanced type. If your soil needs a major boost of one nutrient over the others, you can purchase bags of nitrogen, phosphorus, or potash (potassium) at your local feed and seed store. But if you are inexperienced in using these chemicals, please talk to a professional at your local college cooperative for advice.