178 Code for depth level – Layers Soil Water
The linkage between the SWA and the SWC table is built by the key parameters of SWC.
This means that each observation/line in SWA can be linked to exactly one observation/line in SWC by the combination of country, plot, date, SW_pit, depth_layer, and replicate.
Each line in SWC is identified by such a specific combination of the respective values.
Each line in SWA is identified by such a specific combination of the respective values and, in addition, a specific value for matric pressure.
This data model implies that the depth layer code must be more or less unique.
It is not possible to have to samples (one from 10 to 20 cm and one from 15 to 20cm) at the same pit with the identic depth layer code „M12“. Only 3 codes are fixed which are the mandatory depth layers M02, M24, and M48 (see table below).
All others have to be defined by the submitting partner, making sure that each combination of country, plot, date, SW_pit, depth_layer, and replicate is unique in SWC and each observation in SWA can be linked to exactly one observation in SWC.
In general, the depth layer code is built by an “O” in case of organic layers or a “M” in case of mineral layers. Each succeed by two numbers.
The first number is the decimeter of the upper limit and the second number it the decimeter of the lower limit.
A mineral layer from 19 cm to 22 cm would be “M12”, the layer below from 22 to 35cm would be “M23”.
A layer below from 35 to 38cm would be “M33” and the next from 38 to 51cm would be “M35”.
The depth layer codes M02, M24, and M48 are exclusively defined for the upper and lower limits in the dictionary.
The code is specified in order to allow for a fast evaluation of mandatory soil water data classified as foreseen in the above table.
The sample ring depths allow a more detailed description.
Examples for SWC and SWA tables and the linkage of data between them:
!Sequence, country, plot, date, profile_pit, horizon, SW_pit, depth_layer, ring_depth_upper, ring_depth_lower, replicate, bulk_density, date_analysis, other_observations
1 22 901 010709 901A 1 901A M02 0 20 1 810 010809 testdata
2 22901 020709 901B 1 901B M02 0 20 1 820 020809 testdata
3 22 901 050709 901B 2 901B M24 20 40 1 850 050809 testdata
The data line below (sequence number 142) is linked by the values for country, plot, date, SW_pit, depth_layer, and replicate to the second observation in SWC:
!Sequence, country, plot, date, SW_pit, depth_layer, replicate, water_content, matric_pressure, date_analysis, other_observations
142 22 901 020709 901BM021 0.15 -1 020809 testdata