The latest research indicated there are 20 essential chemical elements (plant nutrients) known to be required for plant growth. This number is different from the 17 nutrients that I learned about in college. All of these elements can be supplied by either organic or commercial inorganic fertilizers.
Strangely, the three most heavily utilized nutrients are not purchased or applied. The three most utilized nutrients are carbon, hydrogen, and oxygen. These big three come from just the air and water that exist naturally around plants.
The next ‘big three’ are what knowledgeable gardeners and agriculturalists would have thought of first: nitrogen, phosphorous, and potassium.
The final 14 essential elements are iron, calcium, copper, sulfur, magnesium, manganese, zinc, boron, chlorine, molybdenum, cobalt, sodium, silicon and vanadium. With the exception of nitrogen and phosphorus, most alkaline, clay type soils usually contain enough of these elements for vegetable production. In acid sandy soils, nitrogen, phosphorus, potassium, calcium, magnesium and, at times, sulfur and boron may need to be added for successful crop production. The last three are the newest to be discovered by science: cobalt, silicon, and vanadium. And these three have only been proven essential for a few plants.
Most every fertilizer bag is labeled with at least three numbers. These numbers list the percentage, by weight, of nitrogen (N), available phosphate (as P2O5) and soluble potash (as K2O). These numbers represent nitrogen, phosphorous and potassium, commonly referred to as N-P-K. For example, if we have a 100-pounds of fertilizer labeled 10-10-10, it contains 10 pounds of N, 10 pounds of P2O5, and 10 pounds of K2O.
Working our way thru these nutrients of the coming weeks. Let us start with nitrogen. Chemically, nitrogen is a very mobile nutrient. If nitrogen had a personality, I’d call it fickle and flighty – unable to hold a job or stay in any long-term relationship. Honestly, nitrogen’s natural state is as a gas. It wants to be free and, well, be a gas. We simply want it to stay in the soil in a form that a plant can absorb it.
Nitrogen is a major nutrient of all plant life and, of all the elements required for plants to grow, nitrogen is given the most credit for making plants green and vegetative. Without nitrogen, plants will appear yellow and will produce less vegetative growth.
Elemental nitrogen is a mostly an inert gas that is colorless, odorless, tasteless, and, constitutes about 78% of the volume of Earth’s atmosphere. Think about it: almost 80% of every breath you take is nitrogen. Yet, this is a nutrient often lacking in the soil.
Nitrogen gas in the atmosphere is the starting material of all commercial nitrogen fertilizer. Nitrogen is reacted with hydrogen under great pressure and heat to produce gaseous ammonia (82% nitrogen). In the United States the hydrogen gas is obtained almost entirely from the reforming of natural gas. A fertilizer plant requires about 35,000 to 40,000 cubic feet of natural gas to produce a ton of anhydrous ammonia which is finally formulized into a nitrogen fertilizer.
The three most commonly used nitrogen fertilizers used in our area are ammonium nitrate (34-0-0), urea (46-0-0), and ammonium sulfate (21-0-0).
The complex process of making nitrogen fertilizer roughly outlined above results in the fertilizer we use to make a lawn lush and green. Without the nitrogen component in vegetable gardens, tomatoes, okra, corn and others wouldn’t produce to their fullest amount.
But adding too much can result in unwanted results. A tomato plant giving copious amounts of nitrogen fertilizer and not having enough of the others will result in beautiful tall, green tomato plants that bear little fruit. Too much of this one nutrient on a lawn will encourage disease problems as fungus. So nitrogen is abundant in the atmosphere, often lacking in your soil, and is one of the most important nutrients for green, leafy growth. Next, we will look at some of the other major nutrients.
