I second Andrew on this. The NPK numbers are not ratios, but rather
percentages. Numbers like 10-10-10 mean that the fertilizer has 10% of
each NPK component. 5-10-5 does not contain the same amount of NPK as
1-2-1. If you're talking ratio, yes the ratios are the same, but the
total amount of NPK is much higher in the 5-10-5 fert. Also, FWIW,
higher NPK numbers don't mean the fert is of higher quality. Typically
synthetic ferts have higher NPK numbers than organic ferts, but it can
be argued that organic ferts are better in quality because they have
other nutrients that plants require for good health.

Layne

On 14 May 2006 16:12:49 -0700, wrote:

Remember though that these numbers are ratios. The actual quantities of
nutrients could be higher or lower. A soil test is the best place to
start. Say, for instance the 5-10-5 could also say 1-2-1, and still be
the the same ratio, but the quantity would be higher for each of
5-10-5.