|
| Physical fractionation method |
| | Plaza et al. [18] (PL) | Six et al. [9] density (SD) | Six et al. [9] microaggregate isolator (SMI) | Sohi et al. [19] (SO) | Zimmermann et al. [15] (ZM) |
|
| Sample prep | Soil air-dried and sieved (<2 mm) | Air-dried soil not sieved | Air-dried soil not sieved | Field fresh soils not sieved | Soil air-dried and sieved (<2 mm) |
|
| Initial size fractionation | | Wet sieved into four size classes: | Wet sieved into four size classes: | | Lightly sonicated at 22 J·ml−1 then wet sieved into two size classes: |
| Large macroaggregates (>2000 μm) | Large macroaggregates (>2000 μm) | Intra-aggregate, free POM, and sand associated (>63 μm) |
| Small macroaggregates (250–2000 μm) | Small macroaggregates (250–2000 μm) | Dissolved, clay and silt associated (<63 μm) |
| Microaggregates (53–250 μm) | Microaggregates (53–250 μm) |
| Silt and clay (<53 μm) | Silt and clay (<53 μm) |
|
| Density fluid used | SPT 1.85 g·cm−3 | SPT 1.85 g·cm−3 | None | NaI 1.80 g·cm−3 | SPT 1.80 g·cm−3 |
|
| Aggregate classes | Distinguishes between macroaggregates (250–2000 μm) and microaggregates (<250 μm) | Distinguishes between large macroaggregates (>2000 μm), small macroaggregates (250–2000 μm), and microaggregates (53–250 μm) | Distinguishes between large macroaggregates (>2000 μm), small macroaggregates (250–2000 μm), microaggregates (53–250 μm), and microaggregates contained within macroaggregates | All aggregates in one fraction | All aggregates in one fraction |
|
| Aggregate dispersion method | Macroaggregates use a microaggregate isolator (breaks up macroaggregates whilst keeping microaggregates contained within intact) | Placed under a vacuum (138 kPa) | Macroaggregates use a microaggregate isolator (breaks up macroaggregates whilst keeping the microaggregates contained within intact) | Sonication at 1500 J·g−1 | None |
| Microaggregates: sonication at 1500 J·g−1 | Microaggregates: 0.5% NaHMP to disperse |
|
| Mineral fraction | Sand, silt, and clay | Sand, silt, and clay | Silt and clay (sand makes up part of the aggregate fractions) | Sand, silt, and clay | Silt and clay (sand makes up part of the aggregate fractions) |
|
