⇦ Back to Fertilizer Lime Amendment Technology and Use Home
The following ag‐lime rate recommendations are calculated from the Sikora‐2 soil pH and buffer pH analysis results, based on an assumed 8‐inch soil sampling depth. The recommended rates are expected to adjust the measured soil pH to the target pH for about three to five years when the lime is soil incorporated to the 8‐inch soil depth. This time period may be shorter or longer, depending on field conditions. Adjust application rates for actual sample depth and for lime quality.
¶ Table 1. Buffer pH, Sikora‐2 |
|||||||||||||
| 5.2 | 5.4 | 5.6 | 5.8 | 6.0 | 6.2 | 6.4 | 6.6 | 7.8 | 7.0 | 7.2 | 7.4 | 7.6 | |
| Target pH = 7.0 | -------------------- Tons 100% ECC Lime per Acre*,** -------------------- | ||||||||||||
| 7.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| 6.9 | 4.2 | 4.2 | 4.2 | 4.2 | 4.2 | 2.8 | 1.3 | 0.8 | 0.5 | 0.3 | 0.1 | 0.0 | 0.0 |
| 6.5 | 4.2 | 4.2 | 4.2 | 4.2 | 4.2 | 3.8 | 2.8 | 2.0 | 1.4 | 0.9 | 0.5 | 0.2 | 0.0 |
| 6.0 | 4.2 | 4.2 | 4.2 | 4.2 | 4.2 | 4.0 | 3.3 | 2.6 | 1.9 | 1.3 | 0.8 | 0.3 | 0.0 |
| 5.5 | 4.2 | 4.2 | 4.2 | 4.2 | 4.2 | 4.0 | 3.4 | 2.8 | 2.1 | 1.5 | 0.9 | 0.4 | 0.0 |
| 5.0 | 4.2 | 4.2 | 4.2 | 4.2 | 4.2 | 4.1 | 3.5 | 2.9 | 2.3 | 1.6 | 1.0 | 0.4 | 0.0 |
| Target pH = 6.5 | -------------------- Tons 100% ENM Lime per Acre** -------------------- | ||||||||||||
| 6.5 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| 6.4 | 4.4 | 4.4 | 4.4 | 2.4 | 1.4 | 0.9 | 0.6 | 0.4 | 0.3 | 0.2 | 0.1 | 0.0 | 0.0 |
| 6.0 | 4.4 | 4.4 | 4.4 | 4.0 | 3.2 | 2.5 | 1.9 | 1.4 | 1.0 | 0.7 | 0.4 | 0.1 | 0.0 |
| 5.5 | 4.4 | 4.4 | 4.4 | 4.3 | 3.8 | 3.2 | 2.6 | 2.0 | 1.5 | 1.0 | 0.6 | 0.2 | 0.0 |
| 5.0 | 4.4 | 4.4 | 4.4 | 4.3 | 4.0 | 3.5 | 2.9 | 2.3 | 1.8 | 1.3 | 0.8 | 0.3 | 0.0 |
| 4.5 | 4.4 | 4.4 | 4.4 | 4.4 | 4.1 | 3.6 | 3.1 | 2.5 | 2.0 | 1.4 | 0.9 | 0.4 | 0.0 |
| Target pH = 6.0 | -------------------- Tons 100% ECC Lime per Acre*,** -------------------- | ||||||||||||
| 6.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| 5.9 | 3.8 | 2.2 | 1.4 | 1.0 | 0.7 | 0.5 | 0.4 | 0.3 | 0.2 | 0.1 | 0.1 | 0.0 | 0.0 |
| 5.5 | 4.3 | 4.1 | 3.5 | 2.8 | 2.3 | 1.8 | 1.4 | 1.1 | 0.8 | 0.5 | 0.3 | 0.1 | 0.0 |
| 5.0 | 4.4 | 4.4 | 4.1 | 3.6 | 3.1 | 2.6 | 2.1 | 1.7 | 1.2 | 0.9 | 0.5 | 0.2 | 0.0 |
| 4.5 | 4.5 | 4.5 | 4.3 | 3.9 | 3.5 | 3.0 | 2.5 | 2.0 | 1.5 | 1.1 | 0.7 | 0.3 | 0.0 |
| 4.0 | 4.5 | 4.5 | 4.4 | 4.1 | 3.7 | 3.2 | 2.7 | 2.2 | 1.7 | 1.3 | 0.8 | 0.3 | 0.0 |
*ECC (Effective Calcium Carbonate); designation for limestone quality:
The following terms can be directly substituted for "ECC", depending on the location:
• ECCE, Effective Calcium Carbonate Equivalent
• NI, Neutralizing Index
• RNV, Relative Neutralizing Value
• ENP, Effective Neutralizing Power
• ELM, Effective Liming Material
**ENM (Effective Neutralizing Material); quality designation for limestone sold in Missouri. (See Crop File 2.03.013, Lime Quality Calculations & Conversions)
lb ENM/acre = tons 100% ECC lime/acre * 800
See also Crop File 1.01.210, "The Sikora Buffer pH methods" and Crop File 2.03.013, "Lime Quality Calculations & Conversions"
The steps and formulas for calculating the recommended Sikora‐2 lime rates are given below. The target soil pH, measured soil pH, and measured buffer pH values are necessary data. Several steps are required to calculate the lime recommendation, which must then be adjusted for soil sample depth (if different from 8 inches) and liming material quality (actual %ECC, %ENM, etc.).
ENTRY:
1. Enter the target soil pH
2. Enter the measured soil pH from the soil test results
3. Enter the measured Sikora‐2 buffer pH from the soil test results
CALCULATIONS:
4. IF measured soil pH greater than or equal to the target pH, THEN LimeRec = 0, ELSE continue calculations.
5. Calculate the minimum buffer pH
6. IF measured buffer pH is less than minimum buffer pH, THEN use minimum buffer pH, ELSE use measured buffer pH. 7. Calculate adjustment #1
8. Calculate adjustment #2
9. Calculate preliminary lime rate (PreLR)
10. Calculate the field correction factor (FCF)
11. IF measured pH is greater than target pH, THEN use 0 as FCF, ELSE use FCF_calc as FCF
12. Calculate final lime recommendation
13. Adjust final lime rate that is less than zero to equal zero
ENTRY: Term Formula (Excel format)
1. ?.? = pH_target
2. ?.? = pH_measured
3. ?.? = BpH_measured
CALCULATIONS:
4. Final_LR = pH_target
5. BpH_minimum = pH_measured
6. BpH_calc = IF (BpH_measured < BpH_minimum, BpH_minimum, BpH_measured)
7. Adj1 = ((pH_target ‐ pH_measured) * 1.02) * (BpH_calc ‐ 7.55)
8. Adj2 = BpH_calc ‐ [((pH_measured * 1.02) ‐ 1.03) * ‐0.372]
9. PreLR = Adj1 / Adj2
10. FCF_calc = 3.62 ‐ (Pre_LR * 0.367)
11. FCF = IF (pH_measured > pH_target, 0, FCF_calc)
12. LimeRec =(Pre_LR*FCF)/2
13. Final_LR = IF (LimeRec < 0, 0, LimeRec)
Adjusting recommended rate for liming material quality:
LRq = LR / (LQ / 100)
where:
LRq = quality‐adjusted lime rate recommendation
LR = calculated lime rate recommendation
LQ = quality of lime source as percent (e.g., "% ECC", "% ENM", "% ECCE", "% CCE", etc.)
Adjusting recommended rate for soil sampling depths other than 8 inches:
LRd = LR x (SD / 8)
where:
LRd = depth‐adjusted lime rate recommendation
LR = recommended lime rate for 8‐inch soil depth
SD = soil sample depth, inches
Sikora, F.J. 2014 “Sikora‐2 Buffer for Lime Requirement” in Soil Test Methods From the Southeastern United States. Southern Coop. Series Bulletin No. 419. Southern Ext. & Research Activity Info. Exchange Group – 6. Clemson Univ., Clemson SC.