Richard

The N-P-K in fertilizers is percent by weight of Nitrogen, Phosphate, and Potash. Consequently, mixing fertilizers to obtain a certain result must be performed by weight, not volume.

Let's suppose you mix 1 lb each of 10-10-10 and 20-20-20. The result will be 2 pounds of 15-15-15.

Now let's suppose you mix 1 lb of 10-10-10 with 9 lbs of 20-20-20. The result will be 10 lbs of 19-19-19, since
((1 x 10%) + (9 x 20%))/10 = 19%.

With regard to the question in this thread: you cannot create an organic fertilizer with 20-5-30 because there is no organic source of nitrogen to achieve 20% nitrogen in a fertilizer mix.

Further, as a I said two years ago - the "20-5-30" was a water soluble formula made from dehydrated minerals. It is processed differently in a soil than an organic fertilizer. A better choice of N-P-K in organic fertilizer for bananas would be 4-4-7.

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