Porosity as a reactive interface
Soil porosity determines how much internal surface is exposed to water, gases, and dissolved ions. A mineral soil with particle density near 2.65 g/cm³ typically shows total porosity from 35% to 55%, while organic-rich horizons often exceed 60% because solids density is lower and aggregates create more voids.
Density method for laboratory reporting
The calculator applies n = 1 − (ρb/ρs). If a core has bulk density 1.30 g/cm³ and particle density 2.65 g/cm³, porosity is 0.509 and the pore space is 50.94% of total volume. When ρb rises to 1.60 g/cm³, porosity drops to 39.62%, which can reduce gas exchange and nitrification.
Volume method for saturated cores
When void volume and total volume are measured directly, n = Vv/Vt avoids density assumptions. For a 100 cm³ core holding 48 cm³ of voids, porosity is 0.48. Pairing the void volume with volumetric water content θv lets you estimate water-filled pore space, WFPS = 100·θv/n. At θv = 0.24 and n = 0.48, WFPS equals 50%, often balancing respiration and denitrification risk.
Void ratio and compaction sensitivity
Void ratio e = n/(1−n) is common in soil physics and geotechnical chemistry because it scales pore space against solids volume. At n = 0.40, e equals 0.667; at n = 0.55, e equals 1.222. Small changes in n can cause large changes in e, making e useful for tracking compaction, swelling clays, and aggregate collapse in wetting.
Interpreting ranges for texture and structure
Sandy soils may show 35%–45% porosity but transmit water quickly because pores are larger. Fine-textured clays can reach 45%–55% yet drain slowly because many pores are small. Well-aggregated loams often sit near 45%–55% with a mix of macro- and micropores, supporting both infiltration and nutrient retention. Compare results across horizons to identify crusting, tillage pans, or organic amendments.
Quality checks and practical outputs
The tool flags cases where bulk density exceeds particle density, which indicates inconsistent units or wet mass inputs. If you supply total volume, it also reports pore volume and solids volume, useful for converting concentrations to per-core inventories. Exporting results to CSV or PDF keeps calculation metadata with your sample label and timestamp, helping maintain traceable lab notebooks and reproducible field campaigns.