How does air dry soil differ from oven dry soil?
Keeping this in view, what is air dried soil?
In soil science and biogeochemistry, the term “air-drying” usually refers to the exposure of moist soil samples from the field to ambient air and drying of the sample at room temperature (20–25 °C) or for oven drying field moist soil samples at around 40 °C.
Subsequently, question is, why is the soil not dried prior to testing? Method of drying the soil samples before the tests are carried out have been clearly stated in ASTM standards, it is because drying the soils in different degree will alter their properties significantly. Some of the physical properties of soil will undergo changes that appear to be permanent.
Simply so, how long does it take to air dry soil?
The drying time depends on texture of soil; however, 3 weeks is a very long time. Try to disperse the soil over an aluminum foil with a thickness not more than 0.5 Cm. In this way your samples may dry off within 48 hours.
How does drying of soil sample affect the soil properties?
Air drying decreased soil pH and increased extractability of calcium, micronutrients, and metals. Many of the observed changes were probably a result of increasing surface acidity with drying.