Sulfur is an essential constituent element of sulfur-containing amino acids and proteins, which directly
participates in the growth and development of crops and affects the quality of crops. Soil sulfur mainly
comes from parent material, irrigation water, atmospheric sedimentation and fertilization, which plays an
important role in agriculture, forestry and animal husbandry. Therefore, through the determination of the
effective sulfur content in the soil, the rational application of sulfur fertilizers plays a key role in improving
the yield and quality of crops.
2-
Sulfur extracted from the soil basically exists in the form of SO4 . In an acidic medium, SO42- reacts with
Ba2+ to form a white precipitate of BaSO4 with little solubility. The effective sulfur content of the soil is
determined by the barium sulfate turbidimetric method.
Reagents and Equipment Required but Not Provided:
Spectrophotometer, adjustable transferpettor, balance, mortar, centrifuge, water-bath/metal bath,
thermostatic oscillator, 1mL glass cuvette, sieve (40 mesh, or smaller), ice and distilled water.
Sample preparation:
Fresh soil samples are air-dried, sieved through a 40 mesh sieve. According to the quality of the soil
samples (g): the volume of the extract solution (mL)=1:5 (recommended to weigh about 0.2 g of soil
sample and add 1 mL of extract solution), and shake to extract 1 h, then centrifuge at 10000 g and 25°C for
10 min. Take the supernatant for measurement.
