Updated at: 23-06-2022 - By: Sienna Lewis

In addition to knowing how to measure fertilizer, you should also be able to calculate the rate of liquid fertilizer using formulas. Remember that fertilizers can only do their work effectively if you utilize them correctly in your garden and plants. Fertilizer application can only be considered optimal if the precise rate and measurement are utilized.

Proper fertilizer management, on the other hand, has a significant impact on the surrounding environment and wildlife. Those who need to use liquid fertilizer can use simple math to figure out how much to apply. As you become more familiar with the ideas, rate computations become practically second nature to you.

Comprehensive Guide On How To Calculate Liquid Fertilizer Rates

Step #1. Understand the formula

Understanding the formula is the first step in determining liquid fertilizer rates. The technique may look complicated at first glance, but it’s actually rather simple. You’ll get used to inserting the values over time. Your fertilizer’s N-P2O5-K2O content, for example, can be found on the label.

How To Calculate Nitrogen in Liquid Fertilizer - YouTube

Additionally, you’ll need to conduct a soil test prior to using fertilizers. Using this information, you may determine your ideal fertilization rate and choose a product that meets your plants’ demands. The total area of the area where the fertilizer will be used is the final component of the formula, and this is self-explanatory.

Finally, the density or weight of the substance is what sets liquid fertilizer rates apart from other rates. For liquid fertilizers, this only applies. Understanding these four numbers will make it easier for you to apply the formula and calculate it accurately.

Step #2. Apply the formula

Example #1.

We’ll use a crop like corn as an example to demonstrate how to calculate the liquid nitrogen fertilizer rate. N application rate in gallons per acre and the amount needed to put 160 pounds of N on the area can be found using the formula. For 500 acres of corn, you’ll require 30 percent UAN liquid N fertilizer, which means you should be aware of this fact.

A gallon of fertilizer containing 10.86 pounds of nitrogen contains 30% nitrogen, resulting in 0.30 pounds of nitrogen per pound of fertilizer. The pound of N per gallon of fertilizer can be calculated by multiplying 10.86 pounds per gallon by 0.30 pounds of nitrogen per pound of fertilizer.

The gallon of UAN per acre can be calculated by dividing 160 by the previous amount. For 500 acres, you can calculate the tonnage using the results from the preceding two calculations. Liquid fertilizer rates are calculated in the same way as dry fertilizer rates.

However, the weight of the liquid fertilizer is also taken into consideration when determining the amount of nutrients it contains.

Example #2.

Using the calculation can be complicated, thus a shortcut is to multiply the required nutrient application rate by 100 and divide the result by the fertilizer’s nutritional percentage multiplied by its weight in pounds. How much nitrogen may be applied using a liquid fertilizer with 30% nitrogen per weight and a gallon of UAN weighs 10.86 pounds?… It’s not clear how you can apply the formula.

After multiplying 15 by 100 and dividing 30 times, you’ll receive the fertilizer rate, which is 15 divided by 100. After that, you’ll have 50 pounds, which you may then calculate by multiplying by 10.86. 4.6 litres of liquid fertilizer will be required.

How To Calculate Nutrient Requirements

Calculating nutrient requirements is just as important as knowing how much liquid fertilizer to use. Remember that if you don’t know the crop’s nutritional needs, you won’t know how much fertilizer to apply. To ensure that your garden’s production is met, conduct a soil test first.

Keep in mind that soil nutrients diminish with time. Some nutrients need to be added once a year, while others need to be added more frequently. Phosphorus and potassium should be applied every year, while nitrogen may need to be applied more frequently.

Because fertilizer recommendations are often made for vast areas, you’ll need to adjust the amounts if you’re growing in a greenhouse. In order to avoid over- or underfertilizing, it’s best not to make any educated guesses about how much to use. The recommended weight per 1000 square feet multiplied by the square footage divided by 1000 square feet is a straightforward equation to utilize.

Applying Liquid Fertilizer // First MOW AND THROW of 2020 - YouTube

Preparing for Your Calculations

I’ll use Foliar Pak 11-0-11 as an example. Let’s begin by determining the product’s weight per gallon first. In most cases, this number can be located on or near the product’s container or on the container’s label. Weight per container is another way of expressing it. Count the number of gallons in the container if it’s given in this manner. Foliar Pak 11-0-11 has a gallon weight of 10.4 pounds.

We also need to know the percentage of nutrients in the food. Foliar Pak 11-0-11 would have nitrogen (11%) and potassium (K20) as the main ingredients (11 percent ). When we do the calculations, we’ll find that we need to move the decimal point two places because they are percentages. For N and K, the value would be 0.11 in this case.

Third, we need to choose the rate at which the product will be applied. In general, a dose of 6 oz/1000 per 14 days is suggested for Foliar Pak 11-0-11. The 6 ounce rate will be used in this example. Let’s do the math now that we have the three figures we need to figure out our nutrient delivery.

Calculating the Nutrient Delivery

Finding out how much of a particular nutrient there is in a gallon is the first step in figuring out the nutrient delivery rate. Example: We’ll take our nutrient concentration and divide it by the weight of a gallon of product (10.4 pounds) (both N and K are 11 percent or 0.11). Foliar Pak 11-0-11 contains 10.4 pounds x 0.11 = 1.14 lbs of each N and K in a gallon.

My preferred method of doing so is to divide the number by 128. We know how much nutrition is in an ounce since there are 128 oz in a gallon. If I know how much nutrient is in an ounce, I’ll be able to make adjustments to my application rate if I decide to increase or decrease it. For this example, we’ll use the following: Foliar Pak 11-0-11 contains.0089 pounds of N (and K) per ounce, based on the following calculations: 1.14 pounds of N (and K) per gallon / 128 ounces per gallon.

Once again, knowing how many pounds of nutrition are in each ounce allows us to modify a pace on the fly. Using the.0089 pounds N (and K) per ounce formula, we would simply multiply the rate at which we intended to apply the product by that formula. Foliar Pak 11-0-11 has an oz/1000 rate of 3-12. 6 oz/1000 is what we’re utilizing in this case. An ounce of N (and K) weighs.0089 lbs, therefore we multiply that by 6 oz (per 1000):.0534. We’ve completed our task! Foliar Pak 11-0-11 is applied at a rate of 6 oz/1000, which means we’re applying 0.0534 lb. of N and K per 1000 square feet.

I receive a lot of inquiries about calculations while I’m on the road, so I hope this serves as a reminder on liquid fertilizer nutrition delivery. When working with your plants, it’s critical to have a firm grasp of the math involved.


Potassium and phosphorus are other important plant nutrients. Nitrogen is one of the three main plant nutrients. Aside from limiting agricultural yields, it is the most common nutrient to deplete. Because nitrogen is so easily eroded from the soil, fertilizers frequently include a considerable amount of it because plants need a large amount of it for optimum development and output. Deficiency of nitrogen, which contributes to chlorophyll’s green hue in plants, can be seen in light-green or yellow leaves.

Amounts of Nitrogen

Nitrogen demands can vary greatly depending on soil conditions, crop selections, and gardening methods. It is difficult to develop firm recommendations for nitrogen treatments. Nitrogen levels in the soil can fluctuate based on soil temperature, organic matter decomposition, and rainfall, hence many soil tests don’t assess this nutrient because it isn’t stable in the environment. If considerable amounts of nitrogen are not supplied by leguminous cover crops or manure applications, the average garden requires roughly 1 pound of elemental nitrogen per 1,000 square feet.

Fertilizer Applicator - YouTube

Content of Nitrogen in Fertilizers

The percentages of nitrogen, phosphate, and potash in each fertilizer are listed on the label. The first figure on the analysis label reveals the percentage of nitrogen, which is known as the N-P-K analysis. Simply divide the N % by 100 and multiply this decimal by the entire weight of the fertilizer solution to get the actual nitrogen weight in that volume of fertilizer solution. It’s necessary to convert the volume of your fertilizer to a weight, then multiply it by the same number.


To avoid over- and under-fertilizing, it’s critical to understand and calculate fertilizer rates. Understanding the formula and applying the values will teach you how to determine liquid fertilizer rates. As intimidating as the formula may appear at first glance, it’s simple.

One way to simplify it is to divide by the percent nutrient in fertilizer weight multiplied by 100 the required nutrient application rate. Consider its weight as a factor when determining how much liquid fertilizer you’ll need for your plants. Make careful to include a soil test in your calculations to ensure that your plants are getting the correct amount of fertilizer.

In order to accurately determine the rate of your liquid fertilizer, it is essential that you grasp the numbers and the formula. Check out university extensions for more examples.