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4. Calculation and correction of results
4.1 Correction of moisture content
Nutrient contents of soils can only be compared and evaluated if they relate to the same original condition of the soil with regard to
its water content.
Soil extract A and AF are produced from the non-dried soil sample, since several parameters may alter substantially during drying.
For rapid analysis soil extract B can also be produced from the non dried soil sample. As the moisture content of a sample may differ,
to get comparable results, the moisture content of the soil must be taken into account for all measured values from moist soil samples
(except pH value). The moisture content can be taken into account by multiplying the measured values in mg/kg by a moisture factor
according to the following tables.
The factor depends on the moisture content as determined in accordance to chapter 2.2.
Calculation:
Measured value in mg/kg x moisture factor = corrected result
Factors for correction of soil moisture
CaCl
2
Soil extract A
Moisture content in % (see 2.2, page 23)
Factor
CAL
Soil extract B
Moisture content in % (see 2.2, page 23)
Factor
CaCl
2
Soil extract AF
Moisture content in % (see 2.2, page 23)
Factor
Example:
Moisture content:
16 %
Measured value:
34.5 mg/kg N
Factor from table:
1.38
Corrected result:
34.5 mg/kg N x 1.38 = 47.6 mg/kg N
4.2 Calculation referring to areas
If the nutrient content per investigated area is of interest, it can be calculated from the concentration per kg (either with or without
moisture correction). For this purpose the size of the area must be known and a reasonable layer thickness must be defined (see 2.1,
page 23).
Calculation:
M x d x f x D x CF = R
M = Measured / corrected value [ mg/kg ]
d = Thickness of layer [ m ]
= Area [ m
2
]
f
3
D = Soil density [ kg/dm
]
CF = Correction factor [ 0.001 kg dm
R = Corrected result [ kg ]
Example 1:
M = 47,6 mg/kg N
d = 0.1 m
f
= 100 m x 100 m (= 1 ha)
3
D = 1.5 kg/dm
Content per area
47.6 mg/kg N x 0.1 m x 100 m x 100 m
3
x 1.5 kg/dm
x 0.001 kg dm
4.3 Conversion into different dimensions
P (phosphorus): mg/kg P → mg/kg P
mg/kg P
K (potassium):
mg/kg K → mg/kg K
mg/kg K
Manual VISOCOLOR
Manual VISOCOLOR
2
1.04 1.08 1.13 1.17 1.22 1.27 1.33 1.38 1.44 1.50 1.56 1.63 1.70
2
1.02 1.04 1.06 1.09 1.12 1.14 1.17 1.20 1.23 1.26 1.30 1.33 1.37
2
1.03 1.06 1.10 1.13 1.17 1.20 1.24 1.29 1.33 1.38 1.42 1.47 1.53
3
3
mg ]
/m
3
3
/m
mg = 71 kg N
O
f = 2.3
2
5
O
→ mg/kg P
f = 0.43
2
5
O
f = 1.2
2
O → mg/kg K
f = 0.83
2
®
reagent case for soil analysis 02.19
Mixing ratio 1 + 1
4
6
8
10
Mixing ratio 1 + 20
4
6
8
10
Mixing ratio 1 + 2
4
6
8
10
Example 2:
M = 120 mg/kg P
d = 0.3 m
f
= 100 m x 25 m (= 1 Morgen)
3
D = 1.3 kg/dm
Content per area
120 mg/kg P x 0.3 m x 100 m x 25 m
3
x 1.3 kg/dm
x 0.001 kg dm
®
reagent case for soil analysis
12
14
16
18
12
14
16
18
12
14
16
18
3
3
/m
mg = 117 kg P
20
22
24
26
20
22
24
26
20
22
24
26
31
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