paphioboy;594344]Correct me if I'm wrong but I think that despite supplying high P in liquid form, does not mean all of it is immediately available to the plant. More likely, in contact with the growing medium (in most cases, soil), the P becomes mineralized then acts more like a slow-release source. For conventional crops, the available phosphate (P2O5) pool is usually very small compared to the total phosphate content.
It's true that the P in most clay soils is tied up and unavailable or only slowly however in soilless media - orchid mixes - all the P applied in soluble form is highly available.
The N/P determined to be optimal for various hydroponic food or flower crops ranges from about 0.15 to about 2.
Out of Cucumber, Tomato, Lettuce, Carnation, Rose, Gerbera, and Chrysanthemum, Lettuce needed the highest P/N ratio. N-284 ml/L and P-62 ml/L which gives a P/N of 0.21.
I other words, adding more P to the solution begins to reduce the growth and the crop harvest through either imbalance or toxicity.
Now. After inquiring, Phillipe told me that this malipoense was fed with either 20-20-20 or 10-52-10. (I'm sure he won't mind me saying that)
http://www.slippertalk.com/forum/showthread.php?t=41413&highlight=malipoense
I don't know about other people but my malipo is not growing like that (although it's doing well)
20-20-20 has a P/N ratio of 0.44 and 10-52-10 is 5.2. .........CORRECTION! 10.52.10 is P/N 2.28
0.44 is already high and reduces growth in many plants. (and remember I'm talking about the P/N ratio NOT the concentration) Obviously, 2.28 is so incredibly high that it would severely damage some plants within a very short time. But looking at the growth on that malipoense and reading again what Xavier talked about with the response from some parvies and brachys with a 10-52-10 fertilizer, It seems obvious that there is still much we don't understand!
It's not a question of worrying PB. It's a desire to understand.
