I have read from many literatures that in pot experiment it is advisable to calculate the rate of application of biochar in on weight basis. My experiment is to determine the effects and interaction of cadmium and biochar remediation on rice plant biology and physiology
I am applying cadmium at 10 25 and 30 mg/kg soil and Biochar will be applied in rates of 0.3%, 1.7%, 3.3% (kg of biochar per kg of soil) at equivalent to application rates of 30, 60, and 120 t biochar ha-1 assuming a soil bulk density of 1.2 g cm-3 up to a depth of 30 cm
Assuming a soil density of 1.2 g/cm3, a pot diameter of 18cm and height 15cm using 2.5 kg of soil my calculation shows at all rates of biochar (20, 60, and 120 t) I will be applying 25 grams of it. I feel my calculation is wrong.
Example of my calculation is for 20 t biochar
20*1000*1000 g per 2000000 kgs
For 2.5 kg soil the biochar required =20000000*2.5/2000000=25g/pot. and i get the same anser as 25g at all the different rates. this is wrong
Please kindly provide a detail calculation so I can understand and be able to do it myself
The biochar will presumably be alkaline. To publish the results you must separate the effect of the char, from that of the constituent alkali, on Cd behavior and availability.
To do this you need lime treatments that match the liming capacity of the different biochar additions. Liming capacity of the biochar is readily estimated by titrating it with strong acid.
The 'lime control' treatments should otherwise be managed identically to the biochar treatments.
Be sure to analyse the lime for trace elements, especially Cd.
Hi Aurelia Naa Ayikaikor Ayi-Bonte ,
we need to find out the amount of top soil in 1 ha:
mtop soil = dsoil x Vsoil = 1.2 g/cm3 x 10000 m2 x 0.3 m3 = 3.6 x 109 g / ha = 3.6 x 106 kg / ha.
Now we can calculate the amount of biochar that we need to add to one ha:
30 MT / ha x 1 / (3.6 x 106 kg / ha) x 106 g / MT = 8.3 g / kg.
For one bag we need to multiply the value with 2.5 kg / bag:
8.3 g / kg x 2.5 kg / bag = 20.8 g per bag.
In terms of economics you need to check whether 30 MT / ha is viable for bioremediation. Assuming a ton of biochar costs USD 300 one needs to spend USD 9000 / ha.
If you haven't taken the liming control into account for your experimental design I suggest to include it as mentioned by Paul Milham.
Kind regards, Rob.
Dear Sirs Paul Milham and Robert Thomas Bachmann ,
Please thank you so much for you input and suggestions. Your help is immensely appreciated I am grateful. Thank you I am done with my calculations now.
I had not taken the liming control into account for the experimental design but its not too late since Im yet to start pre-germination next week. Please can you provide me with articles to help with the lime control. i have no experience with this.
Thank you
Hi Aurelia Naa Ayikaikor Ayi-Bonte , you need to determine the calcium carbonate equivalence in your biochar (AOAC (1999) 955.01 Calcium Carbonate Equivalence (CCE) - (Neutralizing Value of Liming Materials). In Official methods of analysis of AOAC International, Washington : https://archive.org/stream/gov.law.aoac.methods.1.1990/aoac.methods.1.1990_djvu.txt;Article Comparative liming effect of four organic residues applied t...
;Article Effect of Biochar on Chemical Properties of Acidic Soil
) and apply a similar amount as CaCO3 in your liming control. I would still keep another negative control (just the soil) to know the effect of liming and biochar addition on your soil.
Dear Professor Robert Thomas Bachmann ,
Please I sent you a mail.
Thank you
Dear Aurelia Naa Ayikaikor Ayi-Bonte , have you managed to complete your experiment? Could biochar assist in the remediation of Cd polluted soil? Which application rate was most effective? All the best, Rob.
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