Please I obtained soil from a depth of 20cm and placed 5kg of the soil in pots of 29cm in height and labeled them. Please should I be calculating the fertilizer and biochar application rates according to the height of the pot (29cm) or according to the depth at which the soil was collected (20cm)? Please kindly find attached the calculations I have made and kindly advise.
Thank you for your time.
_________________________________________________________
Example Biochar application rate calculations
Height of pot = 29cm
1h = 10000 m2
Assuming soil bulk density of 1.2 g/cm3
Volume = 10000 m2 × (29cm × 10-2) = 2.9 × 103m3
m = p × v
m = 1.2 g/cm3 x (2.9 × 103 × 1 × 106) cm3
m = 3.48 × 106 kg
_________________________________________________________
or Use 20cm which is the depth at which the soil was collected and end up with
Volume = 10000 m2 × (20cm × 10-2) = 2.9 × 103m3
m = p × v
m = 1.2 g/cm3 x (2.0 × 103 × 1 × 106) cm3
m = 2.4 × 106 kg
_________________________________________________________
Dear Sir Paul Milham so I should consider using the soil depth.
Volume = 10000 m2 × (20cm × 10-2) = 2.9 × 103m3
m = p × v
m = 1.2 g/cm3 x (2.0 × 103 × 1 × 106) cm3
m = 2.4 × 106 kg
You may do this but in publications your treatments should usually be expressed in concentration, e.g. g kg-1
Dear Aurelia, as Dr. P. Milham, (see ResearchGate ) has already established, it is logical and simpler to calculate a soil mass of 5 kg and a depth of soil level of 20 cm. The figure of its "field" depth of 20 cm only makes sense that in field conditions the soil bulk density = SBD was 1.2 x10^3 kg/m^3. In that case, the mass of 1 ha of soil is 10^4 m^2 x 0.20 m x 1.2x10^3 kg/m^3 = 2.4x10^6 kg, as you stated. Thus, when calculating the applied dose of remediating matter (biochar, fertilizer), the ratio between the 5 kg of soil in the experimental pot and the 2.4x10^6 kg mass of 1 ha must be taken into account. Theoretically, the SBD in the experimental container could be quite different (probably lower) than the SBD in the field during actual sampling, but that is another question. Considering the height of the soil level in the pot (29 cm) would only make sense if you wanted to check the value of the actual SBD in the container. If the mass of soil in the pot was 5 (kg), the container was a regular cylinder with a bottom and top diameter R (m), then the actual SBD (r) in the container would be
r = m/V = 5 kg/[(3.14x (R/2)^2 m^2 x 0.29 m.] If the two SBD values were significantly different from each other, this should be kept in mind in the conclusions of the experiment.
Good Luck and Best Wishes,
Karel.
Dear Professors
Please, thank you for your explanation. I am grateful.
- Badges
- Science topic