Question
How do you add the npk of different fertilizers together. I have bone meal, kelp meal, cottonseed meal, If i mixed them all together with equal amounts how to figure the npk for that? What if i mixes them with different amounts?

Answer
Dear Shelly:

The three numbers that you see on a fertilizer label, such as 5-5-5, tell you what proportion of each macronutrient the fertilizer contains. The first number is always nitrogen (N), the second is phosphorus (P) and the third is potassium (K). This "N-P-K" ratio reflects the available nutrients 梑y weight梒ontained in that fertilizer. For example, if a 100-pound bag of fertilizer has an N-P-K ratio of 5-7-4, it contains 5 pounds of nitrate, 7 pounds of phosphate (which contains phosphorous), 4 pounds of potash (which contains potassium) and 84 pounds of filler.

Note that the N-P-K ratio of organic fertilizers is typically lower than that of a synthetic fertilizer. This is because by law, the ratio can only express nutrients that are immediately available. Most organic fertilizers contain slow-release nutrients that will become available over time. They also contain many trace elements that might not be supplied by synthetic fertilizers.

To specifically answer your question regarding the mixture of various organic fertilizers and calculating NPK I'm sending you to the EHow website that will provide you with the procedure / formula for calculating NPK when you mix multiple fertilizers:

    http://www.ehow.co.uk/how_8128041_calculate-npk-ratio.html

Happy gardening!

Sincerely,

Mack Jean
AllExperts
Master Gardener
Tennessee