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ΒΆ Introduction
Survey of analysis results from Iowa surface and groundwater samples submitted to ServiTech Laboratories during 2013 to 2022, inclusive, for analysis of Livestock Suitability. The results are grouped by National Agricultural Statistics Service (USDA-NASS) reporting Districts.
ΒΆ Figure 1. Iowa USDA-NASS Districts
Interpretation of survey results:
- Median = 50th percentile
- Typical range = 25th and 75th percentiles
- Low - High = 5th and 95th percentiles
ΒΆ Table 1. Total dissolved solids, TDSc mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 545 | 450 β 1050 | 315 β 1755 |
| South Central | 865 | 570 β 1135 | 410 β 1745 |
| Southeast | 200 | ---- | ---- |
| Statewide | 735 | 480 β 1090 | 310 β 1735 |
("Acceptable" = 2000 - 4000 TDS mg/L)
ΒΆ Table 2. Sulfate, SO4 mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 110 | 28 β 630 | 4 β 1400 |
| South Central | 325 | 92 β 675 | 16 β 1335 |
| Southeast | 31 | ---- | ---- |
| Statewide | 260 | 37 β 638 | 10 β 1375 |
("Acceptable" = 200 - 500 SO4 mg/L)
ΒΆ Table 3. Nitrate-nitrogen, NO3-N mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 0.2 | 0.2 β 4.2 | 0.2 β 15.0 |
| South Central | 1.1 | 0.2 β 5.6 | 0.2 β 33.4 |
| Southeast | 0.4 | ---- | ---- |
| Statewide | 0.2 | 0.2 β 5.2 | 0.2 β 22.8 |
("Acceptable" = 30 - 70 NO3-N mg/L)
ΒΆ Table 4. Chloride, Cl mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 10 | 3 β 25 | 1 β 60 |
| South Central | 16 | 7 β 28 | 3 β 58 |
| Southeast | 20 | ---- | ---- |
| Statewide | 14 | 6 β 26 | 1 β 58 |
("Acceptable" = 125 - 250 Cl mg/L)
ΒΆ Table 5. Calcium, Ca mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 114 | 88 β 230 | 64 β 314 |
| South Central | 148 | 110 β 205 | 23 β 358 |
| Southeast | 27 | ---- | ---- |
| Statewide | 140 | 100 β 208 | 26 β 335 |
("Acceptable" = 80 - 120 Ca mg/L)
ΒΆ Table 6. Magnesium. Mg mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 32 | 26 β 72 | 16 β 121 |
| South Central | 47 | 36 β 66 | 7 β 130 |
| Southeast | 8 | ---- | ---- |
| Statewide | 43 | 28 β 69 | 8 β 128 |
("Acceptable" = 50 - 120 Mg mg/L)
ΒΆ Table 7. Potassium, K mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 5 | 2 β 11 | 1 β 19 |
| South Central | 10 | 5 β 16 | 1 β 20 |
| Southeast | 4 | ---- | ---- |
| Statewide | 7 | 4 β 13 | 1 β 20 |
("Acceptable" = 80 - 120 K mg/L)
ΒΆ Table 8. Sodium, Na mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 43 | 14 β 94 | 10 β 222 |
| South Central | 44 | 18 β 116 | 4 β 392 |
| Southeast | 10 | ---- | ---- |
| Statewide | 41 | 15 β 99 | 8 β 233 |
("Acceptable" = Na plus Mg less than 50% of TDS)
ΒΆ Table 9. Iron, Fe mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 1.14 | 0.34 β 3.00 | 0.10 β 23.40 |
| South Central | 0.28 | 0.09 β 1.50 | 0.05 β 3.72 |
| Southeast | 0.13 | ---- | ---- |
| Statewide | 0.56 | 0.12 β 1.79 | 0.05 β 11.93 |
("Acceptable" = 0.20 - 0.40 Fe mg/L)
ΒΆ Table 10. Manganese, Mn mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 0.242 | 0.130 β 0.450 | 0.008 β 2.000 |
| South Central | 0.065 | 0.005 β 0.238 | 0.005 β 1.045 |
| Southeast | 0.006 | ---- | ---- |
| Statewide | 0.160 | 0.021 β 0.364 | 0.005 β 1.425 |
("Acceptable" = 0.025 - 0.050 Mn mg/L)
ΒΆ Table 11. Hardness, as CaCO3 grains/gallon |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 25.0 | 20.0 β 51.0 | 13.2 β 75.6 |
| South Central | 33.0 | 24.0 β 45.3 | 4.8 β 83.3 |
| Southeast | 5.7 | ---- | ---- |
| Statewide | 31.0 | 21.0 β 46.0 | 5.6 β 81.0 |
("Moderately hard" = 3.5 - 7.0 CaCO3 grains/gallon)
ΒΆ Table 12. Hardness, as CaCO3 mg/L |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 430 | 340 β 880 | 225 β 1280 |
| South Central | 560 | 410 β 775 | 80 β 1445 |
| Southeast | 95 | ---- | ---- |
| Statewide | 530 | 360 β 790 | 95 β 1400 |
("Moderately hard" = 60 to 120 CaCO3 mg/L)
ΒΆ Table 13. Electrical conductivity, EC ΞΌmho/cm |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 850 | 705 β 1640 | 495 β 2745 |
| South Central | 1355 | 895 β 1775 | 640 β 2715 |
| Southeast | 310 | ---- | ---- |
| Statewide | 1150 | 745 β 1705 | 485 β 2710 |
("Acceptable" = 1300 - 2600 ΞΌmho/cm)
ΒΆ Table 14. Water pH |
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| Iowa Districts | Median | Typical range | Low - High |
| Southwest | 7.8 | 7.6 β 7.9 | 7.2 β 8.2 |
| South Central | 7.9 | 7.7 β 8.0 | 7.2 β 8.3 |
| Southeast | 7.9 | ---- | ---- |
| Statewide | 7.8 | 7.7 β 8.0 | 7.2 β 8.2 |
("Neutral" pH = 6.5 - 7.5)
ΒΆ Table 15. Conversion Factors |
| 1 mg/L β 1 ppm |
| 1 mg/L = 1,000 Β΅g/L |
| 1 mmho/cm = 1 dS/m |
| 1 mmho/cm = 1,000 Β΅mho/cm lb/ac-in = mg/L x 0.2267 lb/ac-ft = mg/L x 2.7204 |
| lime equivalent, lb/ac-ft = HCO3 mg/L x 2.2304 |
| 1 acre-inch = 27,154 gallons |
| 1 acre-foot = 325,848 gallons |
ΒΆ Table 16. Sample Count |
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| Southwest | 51 |
| South Central | 70 |
| Southeast | 3 |
| Statewide | 124 |