 Switched to liquid fertilizer--is my math correct?

# Thread: Switched to liquid fertilizer--is my math correct?

1. ## Switched to liquid fertilizer--is my math correct?

I recently bought a 3 point sprayer because I was tired of trying to schedule fertilizing before it rained. I had my soil tested as I am trying to correct the soil which seems more like clay the soil. This year the analysis said for me to apply 30-0-5 twice in the fall at 3 lbs per 1000 sq ft. I know how to do that with the spreader but just want to make sure that my liquid fertilizer math is good.

For example, one product is 20-0-0 and I could mix half add in potassium per application. I want to make two passes like I do using dry fertilizer, going east-west with a half mix and then mix another half and go north-south to make sure I get even coverage. The product has 2.1 lbs of Nitrogen per gallon which is about 5.25 lbs per 2.5 gallon jug.

The question I have is how to equate the 2.1 lbs/gallon of Nitrogen in the liquid mix to the equivalent of the same weight of 35-0-5 granular fertilizer recommendation? I don't think the soil analysis wants me to apply 3 lbs of granular Nitrogen per 1000 sq ft because 3 lbs of the 35-0-5 Nitrogen fertilizer should have 35% Nitrogen or 14 lbs of Nitrogen per bag (40 lb bag*35/100). This would come out to about 1 lb of actual Nitrogen per 1,000 sq ft. So I believe that I would need to apply my liquid Nitrogen at 1 lb per 1,000 sq. ft.

Am I on the right track here?  Reply With Quote

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3. Calculate the size, in square feet, of the area to be fertilized. For a square or rectangular planting space, do this by multiplying the length of the rectangle, in feet, by its width.

Divide the recommended amount of a given nutrient by the percentage of the nutrient in your fertilizer. For example, many lawns need a minimum of two pounds of nitrogen per 1,000 square feet. You would need to divide two pounds by the percentage of nitrogen in your fertilizer to get the amount of fertilizer required for a 1,000-square-foot space. If the fertilizer contains 10 percent nitrogen, you would divide two pounds by .10 and discover that you need 20 pounds for a 1,000-square-foot space: 2 lbs/.10 = 20 lbs per 1,000 square feet.

Calculate the amount of fertilizer needed for the precise amount of space you have by dividing the size of your garden by the size given in the fertilizer recommendation. Then, multiply this number by the application rate of the fertilizer. For example, you would determine the amount of fertilizer to use for a 500-square-foot space and an application rate of 10 pounds per 1,000 square feet by dividing 500 by 1,000 and multiplying by 10: 10(500/1,000) = 5 lbs.

Here is an example on liquid just change the numbers below to the product you have,, VV
You are not able to accurately weigh a small amount of liquid, so you need to convert volume to weight. The net weight of the bottle is 9 pounds, and the volume is 1 gallon. This means that your fertilizer weighs 9 pounds per gallon. There are 4 quarts in a gallon, so 9 pounds divided by 4 is 2.25 pounds of fertilizer liquid in 1 quart. Your product is 16 percent nitrogen by weight, so 16/100 = 0.16, and 0.16 x 2.25 is 0.36. This means that 1 quart of fertilizer supplies 0.36 pounds of nitrogen.  Reply With Quote

4. ## Switched to liquid fertilizer--is my math correct?

While I do appreciate the assistance I already found that information by Googling for it here:

http://homeguides.sfgate.com/calcula...tes-49239.html

I am just trying to confirm if my conversion from the analysis recommendation is correct.  Reply With Quote

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6. not sure if you got this sorted yet. 30-0-5 is 30 percent nitrogen. at a rate of 3lbs/100sqft that's .9lbs, which is close to your estimate of 1lb per/1000 that you calculated, but in a much more direct method. for the potassium, we want 5% of 3lbs, so that's 3*.05, which gives us .15lbs/1000sqft.  Reply With Quote

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