Understanding the Primary Nutrients: NPK

Understanding the Primary Nutrients: NPK

The recipe to create healthy soils, strong stands and bin-busting yields involves a long list of ingredients called essential nutrients. Some of these ingredients are needed in small quantities, less than a pound per acre, and are called micronutrients. But three of the ingredients – N, P, and K – are called macronutrients because plants use large quantities of each, several pounds per acre. All states require that concentrations for these three macronutrients are listed on every bag of fertilizer.

For instance, a fertilizer labeled as 24-8-10 is 24% nitrogen (N), 8% phosphorus (P), and 10% potassium (K).

In short, N, P and K are the A, B and Cs for providing the nutrition that plants need to survive. Knowing how each of these effects plant growth and knowing the NPK content in their soils give farmers much of the information they need to improve crop production and increase yield.

Why NPK are so Important for Plant Health and High Yields

Nitrogen (N) is a critical component of proteins and chlorophyl. Plants require large amounts of N, and they can only take it up through their roots, as either ammonium or nitrate. The most readily plant-available nitrogen fertilizers are anhydrous ammonia, urea or a solution made of urea and ammonium nitrate (UAN). A common symptom of nitrogen deficiency is a yellowing of the lower leaves because the production of chlorophyl is restricted.

PRO-TIP: Surface-applied nitrogen can be quickly lost as a gas; incorporating fertilizer into the soil at a depth of two inches helps prevent this loss.

Phosphorus (P) plays an important part in early root growth and cell growth throughout the growing season. It’s the base element of two compounds (ATP and ADP) that drive many of the processes of living cells including plant respiration. Phosphorus deficiency in corn can be seen in older leaves, which exhibit a purplish color before turning the margins of the leaves brown.

PRO-TIP: Fertilizers containing phosphorus are completely unavailable to plants when soil pH is less than 5 or above 7.

Potassium (K) is a key ingredient to establishing strong roots and stalks. Strong roots improve the plant’s ability to take up other nutrients and increase its resistance to drought, insects and disease. Stalk strength is dependent on the amount of lignin in the cell walls and potassium is the key component of lignin. Corn plants deficient of potassium will often lodge or break, making a real mess at harvest.

PRO-TIP: Plants use similar amounts of potassium and nitrogen, so a good rule of thumb is to balance the applied nitrogen with a similar amount of potassium.

Managing the Nutrients in Your Soil

Management of all plant nutrients begins with a soil test. The soil test results are an estimate of the pounds per acre of plant-available nutrients in the rooting zone. The test report will show if the soil has a sufficient or deficient amount of each nutrient. If deficient, the report makes a fertilizer recommendation to bring the soil back to the sufficient range. Because N is so mobile in the soil it is very difficult to sample and test. A nitrogen recommendation is based on several factors including the soil organic matter reported on the soil test, the crop being grown, yield goal, and the price of nitrogen.

How Agnition Can Help

That challenge with Nitrogen is that only 5% of it is in a plant available form at any given time. The key to unlocking nitrogen for your crop is found in your soil microbes. Generate® is a biostimulant that uses patented Microbial Catalyst® technology to stimulate existing soil microbes to unlock enzymes for more efficient nutrient utilization. Research using Generate shows a 7.6% increase in water extractable nitrogen. Meaning, more nitrogen is available for plants to use for growth.