Fertilizer Nonsense #1: Balanced Fertilizer

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Robert Pavlis

This is the first in a series of posts on fertilizer nonsense. I’ll look at some traditional fertilizer myths and explain why some recommendations for commercial fertilizers do not make much sense.

Fertilizer Nonsense #1 Balanced Fertilizer
Fertilizer Nonsense #1: Balanced Fertilizer

Balanced Fertilizer Myth

Before commercial fertilizer was invented, people just put manure on their garden and things grew fairly well. Keep in mind manure was easy to come by–this is before the invention of the car.

Along came the ability to put fertilizer in a bag which presented manufacturers with a problem. What formulation should they use? The answer was found in the marketing department, which created the concept of a “Balanced Fertilizer”. This seemed to make a lot of sense. It was known that plants need N, P and K (nitrogen, phosphorus and potassium) so why not give it to plants in equal amounts, ie a balanced fertilizer.

Fertilizer bags labeled with fertilizer numbers 5-5-5 or 10-10-10 became very popular with home gardeners. You could not go wrong since you were providing all three of the main nutrients plants need.

Soil Science for Gardeners book by Robert Pavlis

Reality

After many years competitive companies wanted to get in on the action and they needed a different marketing plan. They asked the question, “do plants really need the nutrients in equal amounts?”

In an attempt to answer this question scientists measured the nutrient content of plants. Turns out that plants don’t contain equal amounts of N, P and K. It became obvious that using a balanced fertilizer did not make sense. Unfortunately, it is still recommended a lot of the time.

Is it a good idea to match fertilizers to plants? Find in in my next post Fertilizer Nonsense #2 – Match Fertilizer to Plants.

References:

1) Photo Source: No Dig Gardener

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

2 thoughts on “Fertilizer Nonsense #1: Balanced Fertilizer”

  1. Saying “Turns out that plants don’t contain equal amounts of N, P and K. It became obvious that using a balanced fertilizer did not make sense.” is complete non-sense. A balanced fertilizer does exactly what its name implies, and each plant efficiently uses whatever it needs from it.

    Firstly, it’s important to understand that the use of ‘balanced fertilizer’ isn’t just about the N, P, and K ratios but also involves providing a full suite of macro and micronutrients. These include sulfur, magnesium, calcium, and trace minerals such as iron, boron, manganese, zinc, molybdenum, copper, and cobalt, among others. All these nutrients, including N, P, and K, work in synergy, and their adequate presence is necessary for the balanced growth of plants.

    Moreover, the “balanced” in balanced fertilizers doesn’t necessarily mean that plants uptake these nutrients in equal amounts, but rather that the fertilizer provides a broad spectrum of nutrients that plants can draw upon as needed. Different plants, and even the same plant at different stages of growth, can require different ratios of nutrients.

    Yes, it is true that plants do not require equal amounts of N, P, and K. The optimal ratio often depends on the type of plant, soil conditions, the plant’s growth stage, and environmental factors. However, using a balanced fertilizer does not mean that these nutrients are forced upon plants in equal amounts. Plants are capable of selectively absorbing the nutrients they need from the soil. Therefore, while a balanced fertilizer provides an equal amount of each nutrient, this does not mean plants will uptake these in equal amounts.

    Note that a balanced fertilizer like a 10-10-10 is generally meant to be a ‘one size fits all’ solution for average home gardeners who may not have the knowledge or resources to customize their nutrient ratios for different plants or growth stages (something that actually isn’t needed much because each plant takes what it needs if fed right, except the cases of overfeeding).

    Reply
    • “balanced fertilizer’ isn’t just about the N, P, and K ratios but also involves providing a full suite of macro and micronutrients” – not true. Most such products have no micronutrients.
      “Yes, it is true that plants do not require equal amounts of N, P, and K. The optimal ratio often depends on the type of plant, soil conditions, the plant’s growth stage, and environmental factors” – also not true. The amounts that a plant uses is mostly determined by genetics.

      No plant uses a balanced NPK – it is a dumb product being sold to people who do not understand the needs of their plants.

      Reply

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