Ah, springtime is approaching quickly. You and I both know you’re getting anxious to get out into your gardens to grow your plants. I’m not faulting you, far from it. You’ll find that your local Extension agents want your garden to succeed as much as you do. Because we all want you to have a bountiful harvest, we need to have a conversation about fertility in your lawns and gardens.
Definitions
Before we get too deep into this topic, let’s define nutrition. You may hear some refer to fertilizers as “plant food.” While this is a common phrase concerning fertilizers, it is not factually accurate. Food is associated with energy creation within an organism. Plants are autotrophs, meaning they convert sunlight into energy. So, under this premise, sunlight is plant food, whereas plant nutrition is the building blocks of tissues or catalysts of metabolic processes.
The 17 elements designated as plant essential nutrients are categorized based on the quantity needed for healthy growth. All are important to have in your soil; as per the “Law of the Minimum,” your plant’s development will be limited based on the most deficient element.
UF/IFAS Photo
Macros
Those elements with the largest demand within the plant are known as macronutrients. The three most critical of these are very often absent in fertilizer conversations as they cannot be added to soil in granule form. These are carbon, hydrogen, and oxygen, and their presence in your garden results from your cultural practices. You get them from air and water in the pore spaces of your soil. Appropriate tillage and irrigation are the only ways to provide these elements to your plants. They are critical for proper photosynthesis and fluid balance in the plant.
The most discussed elements are so vital that they make up the three numbers on every bag of fertilizer. These are nitrogen (N), phosphorous (P), and potassium (K), all of which may be added to soil to overcome deficiencies (N often being the limiting factor). These elements are crucial for protein creation, photosynthesis, and fluid movement.
Secondary Nutrition
UF/IFAS Photo: J. Criss
The next set of nutrients have less demand than NPK. They are sulfur (S), magnesium (Mg), and calcium (Ca). Ca is essential for cell structure but is often abundant in our soils. S is frequently rained out of the atmosphere (though you may still need to add some) and facilitates enzymatic processes in plant cells. Mg needs the most attention in this category as it has a lot of mythology among gardeners. You’ve likely heard you should add this element to “green up” your plants. While it is true that Mg is critical to chlorophyll, adding it without testing for deficiencies first is a recipe for poor plant growth.
Micros
Our final category of fertilizer is micronutrients. These are iron (Fe), manganese (Mn), boron (B), chlorine (Cl), zinc (Z), copper (Cu), molybdenum (Mo), and nickel (Ni). These serve various functions in the plant, mainly in metabolic processes.
To Sum Up
Plant fertilization is critical for lawns and gardens. It behooves gardeners to understand these elements and their role in plant growth. Once you do, you’ll understand the importance of applying the correct version of the element in the proper amount at a time and location to maximize use efficiency. You can learn more about what they do and how they react in the soil here. For more information, contact your local extension office.
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