Hello All, I am undertaking nutrient uptake study in pot culture with Soybean. I need to analyse plant available nutrients in soil and plant.
Presenting you a slightly clumsy situation and requesting for way forward. To estimate plant available nutrients in soil, I was prepared for availability of AAS and arranged for set up and chemicals of extraction accordingly. However because of some practical reasons, I have to use ICP. Now I am not sure if I can use the same extraction procedure and analyse the extractant using ICP. The objective is to analysis Plant available nutrients. The methods I am prepared for are as follows,
1) CEC by Sodium Exchange method
2) Available P: Bray's or Olsen's depending on pH
3) Avl. K: Ammonium acetate extractant
4) Avl. S: Barium sulphate precipitation method
5) Zn, Fe, Mn, Cu: DTPA extraction
6) Avl. B: sample boiled with activated charcoal and filtered
7) Avl. Mo: Ammonium acetate
[I am not sure about available N, Exch. Ca and Mg I planned with EDTA titration, however with ICP I ll be able to use some extraction and measure Ca, Mg and Na]
The reason for abiding to these methods is because I do not have my own coorelation studies and I am relying on fertilizer recommendations given by public labs in Maharashtra, India. The methods of analysis are as per their manual.
Thank you!
The methods I see are acceptable and are relevant to the soil type in your area (its been >30 years for me). The AOAC has both fertilizer and leaf methods of analysis listed. There are methods for exchangable N, Ca, and Mg. There is also a journal for soil analysis (JOACS I think). Check with your contract lab.
Yes! ICP gives the same result as AAS (almost), since ALL the atoms are in emission as the higher plasma temperature of ICP. Also check with your local university about soil types and whether these above tests are appropriate. As an example Bray P test was developed in the 60's at the University of Kansas (U.S.A.). I also remember it was the 'Journal of Agriculture and Food Science' not JOACS (Journal of the American Chemical Society).
Dear Rohan, here in Costa Rica we prefer don´t determinate Olsen P in ICP, principally because we use modified Olsen which contains Superfloc, this cause the obstruction of the tubing system of the ICP and contaminate all the subsequent analyses, I think you must evaluate if this situation also happens with normal Olsen
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