Post on 18-Jan-2016
10 cm3 soil
10 mL Sikora buffer
Lime Recommendations with1 M KCl soil pH and Sikora buffer
pH
1 M KCl soil pH Sikora buffer pH
10 mL M KCl
1
Advantages
2. Accounts for pH buffer capacity of soil
1. Solves problem with low pH in fall
2
3
4
D1
D0 D1
D3
D0
D3
Average pH for Southeastern KY counties
5
pH
8
7
6
5
4
0 1 2 3 4 5 6
cmol/kg OH-
0 1 2 3 4 5 6
cmol/kg H+
1 M KCl soil pH
SMP
Mehlich
Adams-Evans
Typic Fragiudalfsilt loam
CEC = 7 cmol/kg
6
pH
8
7
6
5
4
0 1 2 3 4 5 6
cmol/kg OH-
0 1 2 3 4 5 6
cmol/kg H+
1 M KCl soil pH
SMP
Typic Fragiudalfsilt loam
CEC = 7 cmol/kg
7
Empirical correlations
Mechanistic approach
Lime required
Buf
fer
pH
Lime added
Soi
l pH
1 M KCl soil pH Buffer pH
Lime response curve
8
Lime Recommendations withsoil pH and soil-buffer pH
Soil-water pH
Soil-buffer pH
5.6
6.8
9
10
Should the same amount of lime be recommended for the two soils below?
Soil-water pH
Soil-buffer pH
5.6
6.8
4.5
6.8
Soil 1 Soil 2
11
buffer pH soil-
water pH 5.5 5.7 5.9 6.1 6.3 6.5 6.7 6.9
4.5. 4.67 4.00 4.00 3.33 2.67 2.67 2.00 2.00
4.7. 4.67 4.00 4.00 3.33 2.67 2.67 2.00 2.00
4.9. 4.67 4.00 4.00 3.33 2.67 2.67 2.00 2.00
5.1. 4.67 4.00 3.33 3.33 2.67 2.00 2.00 1.33
5.3. 4.67 4.00 3.33 2.67 2.67 2.00 2.00 1.33
5.5. 4.00 3.33 3.33 2.67 2.67 2.00 1.33 1.33
5.7. 4.00 3.33 2.67 2.67 2.00 2.00 1.33 1.33
5.9. 3.33 2.67 2.00 2.00 1.33 1.33 0.67
6.1. 2.00 2.00 1.33 1.33 0.67 0.67
Kentucky LR table based on soil-water pH and Sikora buffer pH
12
Double-buffer method for Lime Recommendations
Soil pH
Soil-buffer pH 1
5.2
5.4
Soil-buffer pH 2 6.4
These two used to assess pH buffer capacity of soil
13
pH
8
7
6
5
4
0 1 2 3 4 5 6
cmol/kg OH-
0 1 2 3 4 5 6
cmol/kg H+
SMP
SMP with initial pH of 6
soil- water pH
14
pH
8
7
6
5
4
0 1 2 3 4 5 6
cmol/kg OH-
0 1 2 3 4 5 6
cmol/kg H+
Sikora = SMP
1 M KCl soil pH = 4.3
Soil-buffer pH = 6.4
15
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8
pH
Soil acidity or added alkalinity(cmol/kg)
Target pH = 5.5
Added alkalinity (cmol/kg)
16
Lime response curve from 1 M KCl soil pH and Sikora buffer pHTitration of soil with KOH in 1 M KCl
Titration of soil with KOH in water
17
1:1 line
18
Fig. 4
1:1
line
c)
Correction factor for long-term field neutralization
LR =Alkalinity to pH 5.5 xCorrection Factor
LR using 1 M KCl soil pH and Sikora buffer pH (cmol/kg)
Current KY LR ----------------------------1 M KCl soil pH and Sikora buffer pH LR
19
Correction factor
Current KY LR
SMP double buffer LR
20
Data from Thompson, Kissel, Cabrera, and Sonon (2010)
21
22
Lime Recommendations with1 M KCl soil pH and soil-buffer pH
1 M KCl Soil pH
Soil-buffer pH
4.6
6.8
5.5 soil-water pH=
23
1 M KCl soil pH and Sikora buffer pH for Lime Recommendations
Advantages
2. Accounts for pH buffer capacity of soil
1. Solves problem with low pH in fall
3. Background electrolyte good for quick and stable pH reading
24
extra
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8
pH
Soil acidity or added alkalinity (cmol/kg)
1 M KCl soil pH = 4.0
Soil-buffer pH = 7.0
Target pH = 5.5
buffer pH soil-
water pH 5.5 5.7 5.9 6.1 6.3 6.5 6.7 6.90
4.5. 4.67 4.00 4.00 3.33 2.67 2.67 2.00 2.00
4.7. 4.67 4.00 4.00 3.33 2.67 2.67 2.00 2.00
4.9. 4.67 4.00 4.00 3.33 2.67 2.67 2.00 2.00
5.1. 4.67 4.00 3.33 3.33 2.67 2.00 2.00 1.33
5.3. 4.67 4.00 3.33 2.67 2.67 2.00 2.00 1.33
5.5. 4.00 3.33 3.33 2.67 2.67 2.00 1.33 1.33
5.7. 4.00 3.33 2.67 2.67 2.00 2.00 1.33 1.33
5.9. 3.33 2.67 2.00 2.00 1.33 1.33 0.67
6.1. 2.00 2.00 1.33 1.33 0.67 0.67
Current LR table based on soil-water pH and Sikora buffer pH
Sikora II buffer pH
1 M KCl soil pH
soil-water
pH 5.5 5.7 5.9 6.1 6.3 6.5 6.7 6.9
3.47 4.5. 4.75 4.25 3.75 3.25 3.00 2.50 2.00 1.75
3.69 4.7. 4.75 4.25 3.75 3.25 3.00 2.50 2.00 1.50
3.91 4.9. 5.00 4.25 3.75 3.25 2.75 2.50 2.00 1.50
4.13 5.1. 5.00 4.00 3.75 3.25 2.75 2.25 2.00 1.50
4.35 5.3. 5.00 4.00 3.50 3.00 2.50 2.25 1.75 1.25
4.57 5.5. 5.00 4.00 3.50 3.00 2.50 2.00 1.75 1.25
4.79 5.7. 5.00 4.00 3.25 2.75 2.25 2.00 1.50 1.00
5.01 5.9. 3.75 3.00 2.50 2.00 1.50 1.25 1.00
5.23 6.1. 2.75 2.00 1.50 1.25 1.00 0.50
New LR table based on 1 M KCl soil pH and Sikora II buffer pH
Buffer pH response to acid
pH
8
7
6
5
4
0 1 2 3 4 5 6
cmol/kg H+
SMP
Buffer pH
pH
8
7
6
5
4
0 1 2 3 4 5 6
cmol/kg OH-
0 1 2 3 4 5 6
cmol/kg H+
SMP
“Lime response curve”
Cut out slides with double buffer explanation
pH
8
7
6
5
4
0 1 2 3 4 5 6
cmol/kg OH-
0 1 2 3 4 5 6
cmol/kg H+
SMP
SMP with initial pH of 6
Lime requirement for target pH of 6.5
pH
8
7
6
5
4
0 1 2 3 4 5 6
cmol/kg OH-
0 1 2 3 4 5 6
cmol/kg H+
SMP
SMP with initial pH of 6
Lime requirement for target pH of 6.5
?
?
water pH
salt pH
Advantages
1) Mechanistic approach for soils of varying buffer capacity
1 M KCl soil pH and Sikora buffer pH for Lime Recommendations
2) Solve problem with lower than expected soil pH during dry falls
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8
pH
Soil acidity or added alkalinity (cmol/kg)
1 M KCl soil pH = 4.3
Soil-buffer pH = 6.2
Lime response curve
(2 cmol/kg alkalinity = 1 ton/acre CaCO3)