What is Fertilizer?
Ask yourself: what does a plant need to survive? Odds are that you listed: sunlight, air, water, soil… but did you also list macro-nutrients, micro-nutrients, and trace elements? Plants, like people, need a balanced diet of elements (food!) in order to grow and thrive in their environment. Fertilizer is a mix of (or single) either man-made or all natural elements, that are added to the soil or land in an area to improve and increase plant growth. The easiest way to understand it is to think of an American style family dinner:
- The Main Dish (Macro-nutrients) is composed of Nitrogen, Phosphorus, and Potassium – these elements are found in most fertilizers.
- The Side Dishes (Micro-nutrients) are Sulfur, Calcium, and Magnesium. These elements are secondary nutrients that are needed in lesser amounts than the micro-nutrients.
- The Condiments (Trace Elements) are Boron, Cobalt, Copper, Iron, Manganese, Molybdenum, and Zinc. Trace elements are nutrients that are needed in very small amounts. Usually the plant can absorb all the trace elements needed from the surrounding soil without any additions from fertilizer.
The most important of these are the Macro-nutrients: Nitrogen (N), Phosphorus (P), and Potassium (K). Without them the plant cannot produce amino acids, cell membranes, or ATP (energy). So if any of these nutrients are missing or hard to get, it limits the plant’s ability to grow – like a car factory running out of steel!
The Fertilizer Cycle
In natural settings, plants are able to obtain all the nutrients they need from decaying plants that release these elements as they break down over time. This natural process is a slow one, providing a constant, relatively balanced diet. In man-made (landscape) settings, the normal transfer of elements from dead plants to living ones is disrupted because we regularly remove dead plant material to improve garden appeal. In short, we’re stealing all the food!
To offset this, people add organic or inorganic fertilizers. Organic fertilizers are made by mixing together natural ingredients that naturally have a lot of N, P, and K, or all three, and also contain trace elements. Commonly, people use chicken feces, bone meal, and fish extract. These naturally release nutrients slowly over a long period of time, improving soil quality and plant growth. However, they tend to be a bit more expensive because it takes more time and effort to produce them.
Inorganic fertilizers are man-made chemical fertilizers manufactured using pure minerals, and are available in many different forms to suit your purpose: Fast release, slow release, liquid, solid, combination – anything you can think of, there’s a variety somewhere!
One way to think of the difference between organic and inorganic fertilizers is through an analogy – it’s the difference between relying on a balanced diet OR over the counter vitamins to maintain your personal health – one is all natural, one is man-made, but both can get the job done if used properly. To determine which type you need to use, think about what you’d like to accomplish: Fast blooms? Long term health? Chemical free vegetables? Answering these simple questions will help you determine which products you do, or don’t, need.
Reading the Label
When using fertilizer in the USA, you’ll always see 3 numbers on the front of the bag, for example 12-8-10. These numbers stand for the percent of each element in the container. Numbers always represent the elements in the same order: N-P-K. So 12-8-10 fertilizers will have 12% Nitrogen, 8% Phosphorus, and 10% Potassium.
Much like people, plants need different amounts of the 3 nutrients depending on where they are in their life cycle. For example, if they’re in a rapid growth stage, plants may require more Phosphorus than Nitrogen or Potassium (because Phosphorous is used in building cell membranes) much in the same way you need more protein when you’ve been hitting the gym to build up muscle. Some plants have evolved to thrive in regions that say, have night levels of potassium but low nitrogen. In which case, they need a fertilizer that mimics their preferred growth conditions.
To find out what ‘food’ your plant needs, simply look it up by name online or visit your nearest nursery center. Happy Gardening!