Hi,
I need to calculate the K factor in the USLE equation. I just have the soil type information. I can't use the monograph because I don't have the texture information. No available data of loam, silt and clay. Is there another way to calculate the K factor?
Please, can you guys give me some advice? Thanks
If by 'soil type" you mean soil series, you should be able to look up the textural classification. You could also refer to the soil survey if you have the location of the soil. Neither of these are as good as a measured texture, but they may get you close enough, depending on what it is you are using the information for.
Hello John, by soil type I mean Soil group classification. I have different soil groups (Histosols, Gleysols, etc) from the FAO classification. I want to know if is possible to calculate the erodability factor (kfactor) just with this information of soil groups. Or if this soil groups have already a textural classification?.
I want to use the K factor in the RUSLE ecuation for calculate the mean anual soil erosion of my study zone.
Many thanks for considering my request.
It is very difficult to describe soil erodibility without having the measures needed (for the Wischmeier nomgraph, for example OM% , texture classes, etc). Otherwise, K factor can be calculated using the basic USLE A=R.K. However, some areas have previous studies that produced soil maps where you can find reference to the soil texture, then you can match your soil`s texture against other soils studies in your region to get OM% values and structure description.
Get the soil information from FAO website and apply it in formula
Any secondary data source for K factor calculation may not be the right choice. Moreover any suggestion for desired conservation measures on such database will be a very risky proposition.
The soil erodibility factor (K) calculated from the following equation (Wischmeier and Smith, 1978)
100K=2.1X10-4(N1.N2)1.14 (12-OM) + 3.25(S-2)+2.5(P-3) (1.6)
Where,
K = Soil erodibility factor.
N1, N2 = Particle size parameter (% silt + % very fine sand).
OM = Percent organic matter content.
S = Soil structure code (very fine granular = 1; fine granular = 2; medium or coarse granular = 3;
blocky, platy, or massive = 4).
P = profile permeability class (rapid = 1; moderate to rapid = 2; moderate = 3; slow to moderate = 4; slow = 5; very slow =6).
Table 1 K – Factor for different soils in the watershed.
K – Factor
OM
Soil Texture 0.5 2 4
Fine Sand 0.16 0.14 0.10
Very Fine Sand 0.42 0.36 0.28
Loamy Sand 0.12 0.10 0.08
Loamy very fine sand 0.44 0.38 0.30
Sandy loam 0.27 0.24 0.19
Very fine sandy loam 0.47 0.41 0.33
Silt loam 0.48 0.42 0.33
Clay loam 0.28 0.25 0.21
Silt clay loam 0.37 0.32 0.26
Silty clay 0.25 0.23 0.19
A global site is available to study the soil tissue in the world
The link is :
https://soilgrids.org/#!/?layer=ORCDRC_M_sl4_250m&vector=1
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