(i) Calculate the weight of each soil sample as under:
Soil sample (g) = [Soil + container + methanol] (g) - [container + methanol] (g)
(ii) To report the sample results on a dry weight basis, collect one duplicate sample not preserved with methanol from each sample location for moisture determination (see extraction with neutral EDTA). Tightly seal the container to prevent the loss of soil moisture.
(iii) Weigh a 5 g portion of the wet sample in a tared container. Dry at 105°C in an oven. Allow to cool in a desiccator and weigh again until constant weight.
(iv) Determine percent dry weight by the following formula:
where SFW is soil fresh weight (5 g) and SDW is soil dry weight.
(v) Calculate the sample concentration on a dry weight basis.
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