NPK requiremts

I repost this as I now think I figured out why the P got so low.

1000 kg grass dry weight removed from the soil take away:

30kg Nitrogen(N)
3,5kg Phosphorus(P)
30kg Potassium(K)
4kg Sulfur(S)
Or in grams 30'000g(N), 3'500g(P), 30'000g(K), 4'000g(S)

Reduce it to a kilo dry weight grass we get
30g(N)-3,5g(P)-30g(K) and 4g(S)

Most of us don't grow 1 kilo plants so let us do a final reduction to a 100g dry weight plant

3g(N)-0,35g(P)-3g(K) and 0.4g(S) that is what it takes to make 100 grams grass.

These numbers are for grass(for horse and cows).
Can this be useful when growing Cannabis if we adjust the numbers?

Why do the P get so low?
I think the answer is when harvesting grass you don’t remove the roots, so what ever is left of P in the grassroots will stay in the soil and when broken down the P will be available for the next growth.
Meaning if we start a new container or land we need to add more P to get a good root development, but when we reuse the soil we need far less.
P is(unlike N and K)very immobile.

Another factor is the blooming, grass don’t usually bloom(unless the farmer makes grass seeds). So some extra P have to be added for the blooming.

As a summary to grow 100 gram cannabis we need
3 grams N
3 grams K
0,3-3 gram P depending on if we reuse the soil or if we start from scratch.
0,4 grams S

Please help adjusting these numbers if you have any idea how much 100 g Cannabis contains(compared to 100 g grass).
Have anyone done a lab test to check what nutrients a Cannabis plant contain?

 

[Hybrid]

Ok, so I've been searching the net for some hard facts about NPK consumption and I see there is a similarity in most crops.
When it comes to P I still have not found any crop having a huge P compared to N and K so I wonder why there are so much focus on Phosphorus in Cannabis growing when Potassium seems to play a bigger role(gram per gram).
Here are some examples of NPK removal per 1000sqm from the soil in different crops

400kg Barley + straw 9,3N-2P-3,5K(all numbers in kilos, e.g. 9,3 kg Nitrogen, 2 kg Phosphorus, 3,5 kg Potassium)
3000kg Potato 10,5N-1,8P-15K
4000kg Carrots including the greens 30N-1,4P-12K

You see the picture, P is always lower than N and K
But then Cannabis might be different, so I took a look at tomato growing which is said to be very similar to cannabis growing, and I found this site giving lots of info on the topic
https://apps1.cdfa.ca.gov/FertilizerResearch/docs/Tomato.html

And as we see also here P is much lower than N and K, but P is still important but in much less amount.
And I bring some numbers from the link(and I use the highest numbers suggested for each element)
N preplant 30lbs/13,6kg per acre, one acre is about 4000sqm so I divide 13,6/4 = 3,4 kg per 1000 sqm = 3,4 grams/sqm
N starter 15lbs/6,8kg/acre = 1,7kg per 1000 sqm = 1,7 grams/sqm
N in bloom and fruiting 175lbs/84kg /acre = 21 kg per 1000sqm = 21 grams/sqm
I do not count any foliar N spraying so added up the total N per 1000sqm is 26kg or 26 grams/sqm

P preplant 44lbs/20kg/acre = 5kg/1000sqm = 5 grams/sqm
P starter 18lbs/8kg/acre = 2kg/1000sqm = 2grams/sqm
Note how they do not apply any more P as there is already enough P in the soil so added up it give a total of 7kg/1000sqm or 7 grams/sqm

Under preplant section they already tell the total K removed from harvest is up to 270lbs
So total K 270lbs/122kg/acre = 30,5kg/1000sqm or 30 grams/sqm

The total NPK consumption from seed to harvest then give a 26-7-30 ratio or rounded up and scaled down to a square foot, similar to a 3 gallon bucket give a suggested 3 grams N, 1 gram P and 3 grams K per bucket