It depends what the mass of the plants will be, the concentration of the minerals in the plants, and the efficiency of uptake. If you assume 40% efficiency that will be in the ballpark.

The mineral composition of green gram should be well-documented

If you want to follow the fertilizer recommendation, then you would base the rate on the area of the top of the pot. Or maybe the average area of the cross-section of the pot. ... You would convert e.g. kg/ha to e.g. g/cm2, and use the cm2 of the top of the pot.

Thanks for your answer sir, If we have a pot of d=19 cm, r =9.5 cm, h= 17 cm

A=pi r2h

=22/7*9.5*9.5*17

=4817 cm2

=0.48 m2

Recommended dose of fertilizer= 20:40:20 NPK/ha

We have 19:19:19 NPK (20:20:20 NPK)

1ha = 10,000 m2

10,000= 60 kg (combine NPK)

0.48 = 60/10,000* 0.48

= 0.00288 kg

= 2.88 g (combine NPK)

for remaining 20 kg P

10,000=20 kg P

0.48= 20/10,000*0.48

=0.96 g P

Is this calculation is right?

If I follow the calculation, you wouldn't "combine" the NPK. The recommendation is based on an amount of _each_ of N, P, and K. ... If the only fertilizer you can use is 19:19:19, then you can't get to the recommended 20:40:20. You would have to decide if you want to apply fertilizer based on the N amount or the P amount. Or you need to get an additional P fertilizer, like superphosphate or triple superphosphate.

Edit: Also, my suggestion was to use the area of the top or, say, middle of the pot. The formula you presented is actually for volume. (V ~ pi r2 h). A = pi r2. This would base the calculation on the "footprint" area, as the recommendation is based on a land area, hectares.

Edit2: But note that Juan C. Aciego Pietri suggests doing the calculation based on the mass of soil in the pot and the mass of soil in a hectare to a depth of 20 cm.

Calculate the weight of one hectare of soil: Psoil (kg ha)=Da * 0.2m * 10000m2, assuming a Da (bulk density of your soil, at 0.2m depth), then calculate the amounts of N, P and K for 2 kg potted soil: N pot (kg )=(2kg soil * 20 kg N ha) / Psoil(kg ha), then calculate the amount of fertilizer needed: Kg Fertilizer=( N pot (kg) * 100 kg Fertilizer ) / 19 kg N (in 100 fertilizer). Use same formula for P and K. Since double P is needed, you would have to use another fertilizer to add the remaining 20 kg, but if you use a phosphate that contains N or P then you would have to take this excess contribution into account to carry out the calculations again using the 19:19:19 fertilizer formula . You could use phosphoric acid or calcium phosphate to avoid this.

Naziya Tarannum

Dpends on the amount of plants you going to install, the weight of one hectare soil and the NPK content. However, It is best to define NPK using the TDS amount AND THEN GO FOR A Kjeldahl.

The recommended dose is based on weight of the ha-m soil (10,000x BD)= say x Mg or x*10^6 kg.

Now calculate the N recommendation per kg soil (recm. dose ÷ the above calculated soil weight)= sat y kg / kg soil.

Your applying N amount will be-

= y*(wt. of soil in pot, kg)= say z

Your applying fertilizer will be-

=[(100/19)* z] kg.

N and K both being same in the recommendation and in your own fertilizer, the above calculated fertilizer amount will also meet the recommended K requirement. However you need to apply the remaining 20P additionally from a straight fertilizer (say ssp), calculated in the same way. It will benever possible otherwise.

Or, you need to overfertilize with N to meet P requirements.

Regards