There is no standard density for soil because it will vary considerably depending on water content, degree of compactness, clay and sand content and many other factors.
One could argue that air has no weight, but it does have mass. At sea level and at 20 °C, dry air has a density of approximately 1.2 kg per cubic meter. Moisture actually makes it just a bit...
Kilograms is a measure of weight, cubic meters is a measure of volume. To give any better answers, the substance of the cubic meter would need to be known.