PHOSPHORUS ANALYSIS OF PLANT MATERIAL

Abstract

A sample of 0.1-0.5 gm. of dried plant material is treated with 5 ml. of 0.5 [image] Mg(NO3)2 and a little water in an evaporating dish. After evaporation to dryness on a steam bath, the material is ashed at 600[degree]-700[degree] C. The total P is taken up with 15 ml. of 2 [image] H2SO4, and an aliquot is analyzed colorimetrically by the modified Truog and Meyer method using a Klett-Summerson photoelectric colorimeter. Another sample of plant material is extracted with 1% by volume, H2SO4, and analyzed in the same manner. This inorganic P subtracted from total P provides a method for obtaining organic P by difference. Ferric iron does not interfere in this procedure, and the method is accurate to 2-3%.