Soil samples collected for analysis are stored in bags. It is not always possible to dry them or send them to the lab immediately. Will that affect SOC determination? or can soil samples be dried some days (weeks) later? are there scientific references on this question?
The practice is to dry, or preserve if you cannot dry. If you are in a hot climate, rapid drying using opened calico bags on a shaded surface that allows good air-flow (e.g. a table with narrow slats or bamboo splits) works well. Freezing also works and there is literature on other approaches.
Without a commercial freezer it is impractical to preserve large amounts of soil.
If you cannot dry them immediately, it is a good practice to freeze your samples until you are able to dry. The problem with analysing moist samples is that you may miscalculate the weight of soils since their moisture is different from one sample to another. Another way is to take a subsample of each and measure their moisture (oven drying) and send another subsample for measuring SOM. In this way, you need to subtract the weight of moisture from the soil.
@ Paulo, you cannot stored moist soil sample for more than 48hours for organic matter analysis as microbial population may increase in it which also started to contribute additional organic matter. Moisture is an important factor to compute the content, to nullified it, you have to measure the moisture percentage before starting of analysis of your sample and that should be taken care during a calculation. The most common process involved in analysis of organic matter is reduction of potassium dichromate by organic matter compounds and subsequent determination of unreduced dichromate by oxidation-reduction titration with ferrus ammonium sulphate. The data are normally converted to percentage of organic matter using a constant factor, assuming that organic matter contains 58% organic carbon. Therefore, moisture content and increase in microbial population affect the results.
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