phosphorus is an anion, it held almost exclusively in the nutrient solution, whereas cations, like potassium, is capable of being held on the collidial surfaces of the media... this is why anions (phosphates, nitrates, sulfates) are easily leached away... the rate of leaching is dependent on the media used, the volume of the container, and the amount of nutrient solution applied...
most plants use highest amounts of phosphorus to
a) establish roots,
b) elongation during 1st 2 wks of flower
c)fruit set, or last 2 wks of flower...
but, maybe just 50-100ppms, max.....
potassium can go up to 500ppm, or more, & not be toxic to plants, though it may cause antagonisms w/ other cations if too much applied (cal & mag)...
why are they mixed together? because they are electrically charged opposites. phosphates shouldnt be mixed w/ calcium, as precipitates may form. this is opposite of dissolving. the combination may form calcium phosphate, or gypsum, insoluble matter to plants' roots... if use maxi series, maybe mix very well & let dissolve for 30min-1hr, before feed... if possible, feed cal-mag-type fert separate than phosphates... shake gh fnb bottle "vigorusly", as the calcium is held @ bottom of bottle. that is how cal can be mixed w/ "p" in fnb...maybe...
phosphorus maybe used in "p/k" type mainly to "stress" a plant into producing more nodes, or flowers. not because plant needs more phosphrus. just needs constant supply @ certain moments during fruit set & development...p is not able to bond to mostly postively charged particles in media, so "leaches" away... due to repelling electrical charges...
the p% on bottles is only ~43% of the actual phosphrus that plants get, after dissociation in nutrient solution.... potassium label is only 83% of available k+, but since potassium can bond to collidial particles (found in media such as coco, perlite, soil, rocks, etc), it can be far more avialable to roots than p...
example:
gh flora nova bloom. npk on label is 4 - 8 - 7.
actual #'s:
4 - 3.5 - 6.6
or, approximately a 1:1:1:1:.5 formula...n:k:ca:mg...
this may be helpful:
calculating npk/nutrient profile
most plants use highest amounts of phosphorus to
a) establish roots,
b) elongation during 1st 2 wks of flower
c)fruit set, or last 2 wks of flower...
but, maybe just 50-100ppms, max.....
potassium can go up to 500ppm, or more, & not be toxic to plants, though it may cause antagonisms w/ other cations if too much applied (cal & mag)...
why are they mixed together? because they are electrically charged opposites. phosphates shouldnt be mixed w/ calcium, as precipitates may form. this is opposite of dissolving. the combination may form calcium phosphate, or gypsum, insoluble matter to plants' roots... if use maxi series, maybe mix very well & let dissolve for 30min-1hr, before feed... if possible, feed cal-mag-type fert separate than phosphates... shake gh fnb bottle "vigorusly", as the calcium is held @ bottom of bottle. that is how cal can be mixed w/ "p" in fnb...maybe...
phosphorus maybe used in "p/k" type mainly to "stress" a plant into producing more nodes, or flowers. not because plant needs more phosphrus. just needs constant supply @ certain moments during fruit set & development...p is not able to bond to mostly postively charged particles in media, so "leaches" away... due to repelling electrical charges...
the p% on bottles is only ~43% of the actual phosphrus that plants get, after dissociation in nutrient solution.... potassium label is only 83% of available k+, but since potassium can bond to collidial particles (found in media such as coco, perlite, soil, rocks, etc), it can be far more avialable to roots than p...
example:
gh flora nova bloom. npk on label is 4 - 8 - 7.
actual #'s:
4 - 3.5 - 6.6
or, approximately a 1:1:1:1:.5 formula...n:k:ca:mg...
this may be helpful:
calculating npk/nutrient profile