Soil phosphorus includes organic and inorganic phosphorus. the inorganic phosphorous can directly used by
plants. Soil organic phosphorus is mineralized and decomposed into inorganic phosphorus. Determine the
total phosphorus, organic phosphorus and inorganic phosphorus in the same time can fully reflect the
condition of soil phosphorus nutrition.
Molybdenum blue is used to determine phosphorus. One sample of soil is taken and the content of inorganic
phosphorus is determined by extraction method. The content of total phosphorus was measured by taking
another sample after burning at high temperature. The content of organic phosphorus is calculated by
subtracting the content of inorganic phosphorus from the total phosphorus content.
Required reagents and equipments:
Spectrophotometer, centrifuge, water bath, scale, transferpettor, 550℃ high temperature electric stove, 1mL
glass cuvette, distilled water and 100 meshes sieve (or smaller).
