Predefined SALUS Layers

To reduce computation times SALUS uses pre-defined soil layer thickness internally in the model. Because the soil dynamics are more rapid near the surface the upper layers are thinner to capture these details. The layers are:

Layer Number	Layer Thickness (cm)	Depth to Top of Layer (cm)	Depth to Middle of Layer (cm)	Depth to Bottom of Layer(cm)
-1	“standing dead”
0	surface mulch
1	2	0	1	2
2	5	2	4.5	7
3	8	7	11	15
4	11	15	20.5	26
5	14	26	33	40
6	17	40	48.5	57
7	20	57	67	77
8	23	77	88.5	100
9	25	100	112.5	125
10	25	125	137.5	150
11	25	150	162.5	175
12	25	175	187.5	200
13	25	200	212.5	225
14	25	225	237.5	250
15	25	250	262.5	275
16	25	275	287.5	300
17	25	300	312.5	325
18	25	325	337.5	350
19	25	350	362.5	375
20	25	375	387.5	400

Where layer 0 is used for some properties for surface debris and layer -1 is used for some properties in crop stubble that is not lying on the ground (i.e. "Standing Dead")

Note: if, based on the depth of the soil, the last layer would much thinner than the layer above it, the thickness of the bottom two layers are equalized. For example for a 60 cm soil SALUS will internally create the "Actual" layers shown below:

Layer Number	Expected (cm)		Actual (cm)
	Thickness	Depth to Bottom	Thickness	Depth to Bottom
1	2	2	2	2
2	5	7	5	7
3	8	15	8	15
4	11	26	11	26
5	14	40	14	40
6	17	57	10	50
7	3	60	10	60

 See more details here.

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In the input files where soil layers are given (either in the .sdb.xml file or as the initial conditions in the .xdb.xml) the parameters for soil layers (% sand for example) are redistributed across the internal layers. The values are either copied where the internal layer completely overlaps the original soil layer or taking a a weighted average from the two (or more) original layers where the internal layers overlaps those layers.