Does anyone know a great microplate method for determining soil phosphorus (extractable and total)?
This is the method I follow to measure PO43--P: the soil subsamples are extracted with 100 ml of 0.5 M NaHCO3 at a ratio of 1:20, and the concentration in the extract is determined with the molybdenum blue colorimetric method (Allen et al., 1986).
Allen S.E., H.M. Grimshaw and A.P. Rowland. 1986. Chemical analysis. In: P.D. Moore and S.B. Chapman (eds.). Methods in Plant Ecology. Blackwell Scientific Publications, Oxford. pp. 285– 343.
The definition of P fractions in soils such as 'soluble' or 'available' is operational, so you need to follow a standard extraction protocol such as the one suggested by Lourdes, which I would describe as Olsen P. Boiling with concentrated strong, oxidising acids, or microwaving with these acids in pressure vessels, extracts most of the P, but complete extraction requires alkaline fusion and analysis of the melt. Either of the colorimetric methods provided by Ahmad or Lourdes can be used to measure extracted orthophosphate.
This is a very handy method to determine Bray-P , Total-P and P-sorption isotherms using microscale technique ( Microplate reader as multi-sample colorimeters ) , so that large number of samples can be analysed in a much shorter time without loosing the accuracy of analytical data. Using same microplate method, the soil microbial biomass -p as well as phosphatase activities in soil also , could be made possible. Bowman suggested rapid method of total P determination ( DOI: 10.21361 sssaj1988.03615995002000500/16x). find below the PDF providing excellent comparison of microplate method with microcentrifuges, multichannel pipetters and microplate readers.
- Badges
- Science topic
- Similar topics
- Agricultural Science
- Soil Science
- Soil Analysis