A to Z of Crop Nutrients – The Basics

This is the first of a series of blogs focused on crop nutrients. The first part of the series will deal with the actual nutrients themselves and then we will dive into concepts such as CEC, pH, liming, soil structure and other concepts.

There are seventeen known chemical elements that are critical for plant growth and development. These nutrients are divided into two separate categories; mineral and non-mineral. Quick, before reading on, test yourself and see how many you can name.

The non-mineral elements are found in the atmosphere and are part of the photosynthesis process. They are, of course, carbon, hydrogen and oxygen. If you think back to your high school biology class, you’ll remember that the photosynthesis process looks like this:

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The mineral elements are the ones we think about most often. They are divided into three different categories, classified by the quantity used by the plant. However, this does not mean that a primary nutrient is necessarily more important for plant growth only that more of it is required.

1) Primary: nitrogen (N), phosphorus (P), potassium (K). Because the plant uses a larger quantity of the primary nutrients, we see deficiencies of these nutrients show up more frequently.

2) Secondary: calcium (Ca), magnesium (Mg), sulfur (S). The crop uses more secondary nutrient than micronutrients, but less than the primary nutrients. The three secondary nutrients are calcium (Ca), magnesium (Mg) and sulfur (S). We rarely see deficiencies in Calcium and don’t often see Magnesium deficiencies but Sulfur deficiencies have become much more common as we have reduced SO2 emissions from power plants.

3) Micronutrients: boron (B), chloride (Cl), copper (Cu), iron (FE), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn). Micronutrients are used in smaller amounts, but we do see deficiencies occurring from year-to-year. Because micronutrients are found in such small amounts in the soil, tissue testing in conjunction with soil testing can be a solid practice to help detect deficiencies. Also because many of the nutrient’s availability is affected by soil pH, presence of the nutrient in the soil does not mean they are getting to the plant. Except for potassium, these nutrients must be mineralized from organic matter, and mineralization occurs at different rates every year and is driven by various environmental factors.

There are four additional nutrients that can be classified as essential in some crops but are rarely deficient in most soils. Those nutrients are sodium (Na), cobalt (Co), vanadium (V) and silicon (Si).

So let’s dig in and examine these nutrients, what they do in the plant, how they get there and other things that are handy to understand as it relates to your crop. Join us over the next few months as we discuss the nutrients and your soils.