Modifications in the automated techniques for the analysis of soil phosphorus - (1)
1992
Sarir, M.S. | Pulford, I.D. | Flowers, T.H. (NWFP Agricultural Univ., Peshawar (Pakistan). Dept. of Soil Science)
The choice of wavelength, phototube and background color correction were investigated and methods were developed for phosphorus analysis on a Technicon Auto Analyzer. Measurement at 880 nm showed improvement in sensitivity over 650 nm, but this involved changing phototube as well as filters. A suitable combination of phototube and filter was decided upon by comparing the effect of different filters, phototubes and wavelengths. It was found that an 880 nm filter can be used effectively with high sensitivity with a CE 63 v phototube and either bulb, blue or yellow. Testing various color correction systems, it was found that acid ammonium sulphate with ascorbic acid can be used for background color correction. Comparing the absorbance of colored extract at different wavelengths, it was found that 880 nm is a more suitable wavelength for avoiding the need for background color correction.
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