How to translate soil elements in ppm to Kg of fertilizers per acre needed for a crop?

Question

Say, for example I have following soil analysis

Nitrogen 130 ppm

Phosphorus 15 ppm

Sulphur 4 ppm

Potassium 80 ppm

Calcium 1500 ppm

Magnesium 25 ppm

Crop requirement is

Nitrogen

Phosphorus 30 to 40 ppm

Sulphur 8 to 12 ppm

Potassium 150 ppm

Calcium 2000 ppm

Magnesium 50 to 100 ppm

Please explain with sample calculations

Answer 1

1 ppm= .0000000000000000001 per acre

hope it helps!

Answer 2

First let me say that you need to use one system, either lbs/acre or Kg/hectare. Mixing them up is going to give you a lot of headaches. So my answer is for pounds per acre.

ppm (parts per million) - Results for major and minor elements are reported in ppm on an elemental basis. This unit of measurement is equivalent to pounds of nutrient per million pounds of soil. One acre of mineral soil 6 to 7 inches deep weighs about two million pounds. Therefore,

to convert parts per million readings to pounds per acre, multiply by two.

This makes your calculations simple. Example: Phosphorus you have 15 ppm and you need (lets call it 40 ppm). So you need to add 25 ppm/acre. That means you need to add 50 pounds of P/ acre. That is 50 pounds of actual P per acre, not P2O5, as it comes in fertilizer. I assume you can make that conversion.