Mixing NPKs - Ask Extension
When mixing fertilizers with different NPK values, how do I calculate the final result?
Example; 1Tbsp 12-0-0 + 1Tbsp 3-12-0 + 1Tbsp 0-0-21.
Would ...
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Mixing NPKs #877059
Asked July 13, 2024, 9:30 AM EDT
When mixing fertilizers with different NPK values, how do I calculate the final result?
Example; 1Tbsp 12-0-0 + 1Tbsp 3-12-0 + 1Tbsp 0-0-21.
Would the resulting 3Tbsp be 15-12-21 or 5-4-7 or something else?
Jackson County Oregon
Expert Response
Dear Eric,
Thank you for contacting us about fertilizers. In your example, the result would be 15-12-21. This is 3-times stronger than an N-P-K of 5-4-7 even though they both have the same ratio of nutrients. This is one of the reasons that it is important to follow the directions and precautions on each package label.
Fertilizer is helpful only if your soil is deficient in nutrients, and only a laboratory soil test can determine this.
Using too much of a nutrient (or when it's not needed) not only wastes money but can damage your plants as well as the environment. Too much N encourages a lot of new foliage at the expense of fruit and flowers. Too much P can runoff the soil in rain, polluting our waterways and creating algae blooms. Too much K can reduce the plant's ability to take up calcium and nitrogen.
I hope this information is helpful. Please write again anytime you have a gardening question.
Thank you for contacting us about fertilizers. In your example, the result would be 15-12-21. This is 3-times stronger than an N-P-K of 5-4-7 even though they both have the same ratio of nutrients. This is one of the reasons that it is important to follow the directions and precautions on each package label.
Fertilizer is helpful only if your soil is deficient in nutrients, and only a laboratory soil test can determine this.
Using too much of a nutrient (or when it's not needed) not only wastes money but can damage your plants as well as the environment. Too much N encourages a lot of new foliage at the expense of fruit and flowers. Too much P can runoff the soil in rain, polluting our waterways and creating algae blooms. Too much K can reduce the plant's ability to take up calcium and nitrogen.
I hope this information is helpful. Please write again anytime you have a gardening question.