Standardized Protocol for Soil Survey and Archaeological Diagnosis for the DOPAMICS Research Program

Soils are sampled every 50 meters along the research transect spanning from the ring ditch hill (RH) to an adjacent hill or slope with no or sparse evidence of pre-Columian occupation (i.e. adjacent Hill, AH), according to the position of the pickets (Cx= Cstart, C1, C2, etc.).

→ see "Standardized Protocol for Transect Set-up and Palm Inventory for the DOPAMICS Research Program"

Additional pits are collected in the landscape surrounding the central line on the ring ditch hill (RHx = RH1, RH2, etc.) and, eventually, on the adjacent hill (AHx= AH1, AH2, etc.).

<img src="https://static.yanyin.tech/literature_test/protocol_io_true/protocols.io.14egn768pv5d/Protocole%20terrain%20V2.jpg" alt="Figure 1. Sampling strategy. Soils are sampled with a riverside auger (terra-firme, circles) or a gouge auger (bottomland, squares). "Cx" refer to pits made along the transect (Cstart, C1, C2, etc.). "RHx" and "AHx" refer to additional pits pits on the ring ditch hill (RH1, RH2, etc.) and on the adjacent hill or slope (AH1, AH2, etc.)." loading="lazy" title="Figure 1. Sampling strategy. Soils are sampled with a riverside auger (terra-firme, circles) or a gouge auger (bottomland, squares). "Cx" refer to pits made along the transect (Cstart, C1, C2, etc.). "RHx" and "AHx" refer to additional pits pits on the ring ditch hill (RH1, RH2, etc.) and on the adjacent hill or slope (AH1, AH2, etc.)."/>

Every 50 meters along the central line (at the position of pickets "Cstart", "C1", "C2", etc.) and at the position of additional pits ("RH" and "AH"),

• Collect soil samples every 5 cm in depth, starting from the surface to 120 cm in depth
• Put the soil samples in zip-lock plastic bags
• With a large tip permanent marker, write down the sample ID on the plasic bag
• Record the GPS position of the pit

Samples from 0 to 60 cm are analyzed in the laboratory.

The remaining samples (60 - 120 cm) are stored for further analyses.

Weigh wet soil samples* Dry the soil samples drying oven at 50°C

• Sieve the soil (5 mm) to remove stones and roots and to extract archaelogical artefacts (i.e. ceramic shards)

• Extract macroscopic charcoals (>2mm) and soot deposits from the sieved fraction by hand

• Tranfer artifacts in sampling pots or zip-lock plastic bags

• With a large tip permanent marker, write down the soil sample ID on the pot

• Weigh dry soil samples

• ⇒ Note the wet and dry mass of the sample, the soil type (hydromorphic or ferralitic soil), presence/absence of stones, roots and artifacts in your lab book or in an excel spreadsheet

For each site,

• Identify soil layers with an increasing abundance of fragments of ceramics and charcoals in pits from the enclosure and slopes of the ring ditch (e.g. 0-45 cm deep)
• Select 10 charcoals >10mg (ideally between 20 and 100mg) for radiocarbon dating

With a colorimeter, measure the colour of each soil sample

⇒ Note the Munsell Color value in your lab book or in an excel spreadsheet

• Weigh 100 - 200 mg of each dry soil sample from 5 to 60 cm deep
• Transfer the sub-sample in a plastic bag for soil granulometry and chemistry analysis (pH, C, N, P, K, Mg, Ca, Na, Al)
• Write down the sample ID on the plastic bag

The remaining soil samples are used to extract micro-charcoals.

The abundance of microcharcoals was evaluated every 100 meters along the central line in soil samples from the surface to 60 cm deep.

For each soil sample,

• Measure 2.5 cm³ of soil sample with a graduated cylinder containing a solution of sodium hexametaphosphate (Na₆P₆O₁₈) at 40g/L
• Transfer in a 50 mL Falcon tube and fill the tube with sodium hexametaphosphate (40 g/L) up to 50 mL
• Incubate the sample on an orbital shaker at ambiant temperature for 12 hours
• Sieve the sample (160 µm)
• Transfer the sample in a Petri dish
• Oven dry the sample at 50° during 12 hours
• Put the Pietri dish on a grid background composed of 0.25 x 0.25 cm squares
• Count the number of microscopic charchaols with a 40X stereo microscope and a manual clicker counter

⇒ Note the Munsell Color value in your lab book or in an excel spreadsheet

The remaining soil samples are stored in the plastic bags for further analyses.