Question

Why the soil samples dried at 105celcius for 8 hours?

Answer 1

The soil testing laboratories receive soil samples in wide range of physical conditions from a different persons, hence for lab analysis samples need to be dried and pulverized to make them homogeneous for easy analysis. The shade drying followed by sieving and removing extraneous materials like roots, pebbles etc is done as a part of sample prepation for analysis. The sample is dried under shade because drying at higher temperatues or exposing to direct sunlight is known to affect the test results as increased drying temperatues are known increase/affect exchangeable Potassium , ammonium nitrogen (NH4-N), mineralization of nitrogen, phosporous and zinc contents in the soil samples.