In this method a proprietary automatic extractor (as made or similar to that made by Concept Engineering, Nebraska, USA) is used to obtain the soil SE. Filter paper clears the extract and suction pulls the extract into the collecting syringe.
Some saturated pastes are difficult to extract, mostly due to soil dispersion and puddling. Repeated extraction is possible to obtain sufficient extract for subsequent analyses. Some SE obtained by automatic extraction may require final clearing via high-speed centrifuging or 0.20 μm Millipore filtration.
Follow Method 14A1 to prepare soil saturation pastes.
Figure 14.1 Configuration of apparatus when using an automatic extractor (or similar components) to obtain soil extraction extracts.
Assemble accessory equipment (soil paste extraction cup and syringes – Figure 14.1) on the automatic extractor, as instructed by manufacturer. Alternatively, improvise with similar components.
Transfer soil saturation paste/s to extraction cup/s and extract sample/s overnight. Use the manufacturer’s recommended setting if available.
Next morning, remove extracts from each collecting syringe. If not totally clear, pass through a 0.20 μm Millipore filter prior to preparation for analysis and reporting, as detailed in Method 14A1 and later in this chapter.