Question

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Followup To

Question -
    Do different brands of fertilizers (their ingridients) vary greatly enough to have a very significant difference on the growth of beans? I will be testing Miracle-Gro, Scotts All Purpose, and plain water.
         Thanks,
         Brian


Answer -
Fertilizer ingredients are listed on the lable.
Yes, fertilizer ingredients vary from brand to brand and type of fertilizer to type of fertilizer.

Most notable is the 3 main ingredients in fertilizer: nitrogen (N), phosphorous (P) and potassum (K). These are the primary nutrients in fertilizers as they typically are consumed in largest amounts by the plants (and thus depleted from the soil fastest).

All fertilizers comes with 3 numbers prominently displayed: N-P-K always in that order.

Flowering and fruit plants prefer fertilizer with higher 2nd and 3rd numbers whereas green plants, including lawns, prefer fertilizers with high first numbers. Example 29-3-4 (high nitrogen) vs 5-10-10 (fruit/flowering type). If you fertilized flowers with 29-3-4 you would have very few flowers (high nitrogen supresses flowering) and if you fertilized lawns with 5-20-20 you would build up excess phosphorous and potassium without giving enough nitrogen to the plants.

Fertilizer must be added according to the approximate amount of fertilizer nutrients being removed from the soil. Grass removes large quantities of nitrogen (first number: N) while flowering and fruiting plants remove relatively larger amounts of potassium (K) and phosphorous (P).

Depending on the potting soil you are using, beans may not "severely deplete" the existing nutrients in the soil so you may not be able to detect any noticable difference.

If you grow the beans in "inert" material such vermiculite, builders sand, or rockwool, you can make a reasonable comparison.

Water will not supply nutrients.

Miracle grow (15-30-15) is pretty balanced and contain more phosphorous which should be fine for beans.

All purpose (10-10-10) will have similar effects as miracle grow.

If you appreciated the answer above, can I ask your help in rating my reply. Thank you.
-- Kenneth

    Thanks for the information, I was wondering a couple more things. Firstly, All Purpose and Miracle-Gro have higher last two numbers (phosphorus and potassium)is this because large amounts of nitrogen can harm their development? Secondly, out of the Miracle-Gro and Scotts All Purpose, which do you think will affect the plants germination rate and overall growth more if they are in normal top soil in singly placed cups? I will be doing this study all the way to December so I may have more questions later. Thanks for the help and quick respose time!

         Thanks,
         Brian  

Answer
Neither should affect plant germination rates. Higher levels of potassium and phosphorous is used for plants which bears fruits and flowers because these nutrients are primarily consumed during fruit/flowering stages.

Having phosphorous available in the soil has shown to aid germination rates. I doubt you will have any different germination rates due to the specific choice of fertilizer. Both would add more than enough to aid germination