Not enough is being done when it comes to making the public aware of the differences in chemical Vs. organic fertilizers. The following frequently asked questions were compiled by Garden-Ville to assist gardeners in determining the proper fertilizer to use, and address the differences between chemical and organic fertilizers.
What Are the Different Types of Fertilizer?
There are several types of fertilizers. Most common are the general purpose lawn & garden fertilizers. They may be pelletized or granulated, and are usually formulated to address various plant, soil and climate zone requirements. They are sized to be used in a standard drop or cyclone spreader. Individual macronutrients, such as nitrogen, phosphate and potassium, are also available, as are micronutrients, usually in powder or granular form, but they should be used sparingly, and only when recommended as a result of a soil test, or to correct a specific plant or soil deficiency.
Most nutrients are also available in liquid form, and can be used as a drench or as an ingredient in foliar sprays. It is a little-known fact that plants feed as efficiently through their leaves as they do through their roots.
What is NPK?
The three primary plant nutrients: NPK (macronutrients) are nitrogen (N), phosphate (P) and potassium (K). NPK numbers are required by law to be printed on all fertilizer bags.
What Do the NPK Numbers Mean?
The NPK numbers on a bag of fertilizer represents the percentage of each nutrient in the bag. A 40 lb bag of 15-5-10 chemical (salt) fertilizer contains 15% nitrogen, 5% phosphate and 10% potassium for a total nutrient content of 30%. The other 70% consists of filler material, usually an inert material like clay.
Why the Difference in NPK Numbers on Chemical vs. Organic Fertilizer?
It is easy to become confused when the NPK numbers on a bag of organic fertilizer are smaller than on a bag of chemical fertilizer, when the organic product costs the same or more than the chemical product. To understand the difference, it is important to understand that plants use only as much food as they need for healthy growth. For the nutrients in chemical fertilizer to be available to plants, they must be soluble in water. To be soluble in water, they must be in the form of salt. The problem with salt (chemical) fertilizers is that once dissolved in water, they are subject to evaporation, gasification and runoff, resulting in a significant percentage of their nutrients ending up in underground water tables, streams, lakes and oceans. The NPK numbers on chemical fertilizers are higher to offset the losses to runoff, evaporation and gasification; the NPK on organic fertilizers reflect the actual nutrient content of the ingredients.
What Does "Slow Release" Mean?
To overcome the outcry about excess nutrients in our water tables, rivers, lakes and oceans, some salt fertilizer manufacturers brag about their products being "slow release". They accomplish this by coating the pellets with a specially formulated sulfur that dissolves slowly over time. When using an organic fertilizer, the natural digestive process takes time, making a naturally slow release fertilizer.
In What Other Ways Do Organic Fertilizers Differ From Salt Fertilizers?
As in nature, the nutrients in organic fertilizer are only made available to plants through the digestive processes of soil organisms. Nothing is lost. There is no filler material in a bag of organic fertilizer; everything in the bag is food for beneficial organisms in the soil.
What's the Advantage of Using an Organic Fertilizer?
As in nature, organic landscapes are self-sustaining, healthier, and cost less to maintain. Organic landscapes, once established, do not require as much fertilizer as chemically maintained landscapes because nutrients are constantly being made available to plants as the ongoing result of the digestion and decomposition of the organic matter in the soil.
How Often Should I Fertilize?
Garden-Ville organic fertilizers act as a food for the biomass in the soil, but the nutrients in it are not released until the soil organisms become active. It is important that the nutrients be available to the organisms once they become active. For that reason, a late winter or early spring application is advisable. With soils low in organic matter, fertilize at least four times for the first two years, in early spring, late spring, summer and early autumn. In the third through fifth years, a minimum of three applications per year are all that is required; early spring, summer and early autumn. In soils with good organic content, three times per year for the first five years is sufficient. Apply in early spring, summer and early autumn.