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¶ Nitrogen ........ N |
Cadmium reduction method | ||||||||||||||
| N_REC = (YG x 1.25) - (N_surf + N_sub) + OMadj - PC - M | |||||||||||||||
| OM% | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 | 4.5 | 5.0 | 5.5 | 6.0 | > 6.0 | ||
| OMadj, lb N/ac | +30 | +23 | +12 | 0 | -13 | -27 | -39 | -49 | -55 | -57 | -53 | -42 | -42 | ||
| OMadj = ((OM% * 230)*(OM% * (0.048 + ( OM% * -0.0065)))) - 32.2 | |||||||||||||||
¶ Phosphorus ........ P |
Mehlich-3 (colorimetric method) | |||||||||||||||||
| P ppm | 0 | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | 60 | > 60 | ||||
| Yield goal: | Recommended rate, lb P2O5/ac | |||||||||||||||||
| 120 bu | 125 | 100 | 75 | 60 | 45 | 35 | 25 | 20 | 15 | 10 | 0 | 0 | 0 | 0 | ||||
| 160 bu | 140 | 110 | 90 | 70 | 55 | 45 | 35 | 30 | 20 | 10 | 0 | 0 | 0 | 0 | ||||
| 200 bu | 150 | 125 | 100 | 85 | 70 | 55 | 45 | 35 | 25 | 15 | 0 | 0 | 0 | 0 | ||||
| 240 bu | 160 | 135 | 115 | 95 | 80 | 65 | 55 | 40 | 30 | 15 | 0 | 0 | 0 | 0 | ||||
| 280 bu | 175 | 145 | 125 | 105 | 90 | 80 | 65 | 50 | 35 | 20 | 0 | 0 | 0 | 0 | ||||
| ppm_P <= OPT … P_REC = (P_A * exp(P_B * ppm_P)) + ((YG - BYG) * CR) | ||||||||||||||||||
| ppm_P > OPT … P_REC = [(P_A * exp(P_B * ppm_P)) * ((COL - ppm_P)/(COL - OPT))] + ((YG - BYG) * CR) | ||||||||||||||||||
¶ Potassium ........ K |
Ammonium acetate or Mehlich-3, ICP method | |||||||||||||||||
| K ppm | 0 | 20 | 40 | 60 | 80 | 100 | 120 | 140 | 160 | 180 | 200 | 220 | 240 | > 240 | ||||
| Yield goal: | Recommended rate, lb P2O5/ac | |||||||||||||||||
| 120 bu | 155 | 120 | 95 | 75 | 60 | 45 | 35 | 25 | 15 | 0 | 0 | 0 | 0 | 0 | ||||
| 160 bu | 160 | 125 | 100 | 80 | 65 | 50 | 40 | 30 | 20 | 10 | 0 | 0 | 0 | 0 | ||||
| 200 bu | 165 | 130 | 105 | 85 | 70 | 55 | 45 | 35 | 20 | 10 | 0 | 0 | 0 | 0 | ||||
| 240 bu | 170 | 140 | 110 | 90 | 75 | 60 | 50 | 40 | 25 | 10 | 0 | 0 | 0 | 0 | ||||
| 280 bu | 175 | 145 | 115 | 95 | 80 | 65 | 55 | 45 | 25 | 10 | 0 | 0 | 0 | 0 | ||||
| ppm_K <= OPT … K_REC = (K_A * exp(K_B * ppm_K)) + ((YG - BYG) * CR) | ||||||||||||||||||
| ppm_K > OPT … K_REC = [(K_A * exp(K_B * ppm_P)) * ((COL - ppm_K)/(COL - OPT))] + ((YG - BYG) * CR)CR) | ||||||||||||||||||
¶ Zinc ........ Zn |
DTPA or equivalent, ICP method | |||||||||||||||||
| Zn DTPA ppm | 0.0 | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 | 1.2 | 1.4 | 1.6 | 1.8 | 2.0 | 2.5 | 3.0 | > 3.0 | ||||
| Recommended rate, lb Zn/ac | ||||||||||||||||||
| pH <= 7.3 | 6.0 | 4.5 | 3.5 | 2.0 | 1.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||||
| pH > 7.3 | 7.5 | 6.0 | 4.5 | 3.0 | 1.5 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||||
| pH <= 7.3 … Zn_REC = Zn_A - (Zn_B * ppm_Zn) | ||||||||||||||||||
| pH > 7.3 … Zn_REC = (Zn_A - (Zn_B * ppm_Zn)) * 1.3 | ||||||||||||||||||
¶ Sulfur ........ S |
Ammonium acetate or Mehlich-3, ICP method | ||||||||
| S_REC = (YG x 0.13) - (S_surf + S_sub) - (OM% x 3) | |||||||||
| Minimum sulfur recommendation: For sandy soils (low cation exchange capacity, CEC of 12 or less) and less than 2% organic matter, use the following minimum sulfur recommendation if the recommendation calculated above is less than these values. Irrigation water with 6 to 8 ppm S or more may contain enough dissolved sulfur to meet much of the crop requirement. | |||||||||
| Typical soil texture | sand | loamy sand | sandy loam | loams, clays | |||||
| When CEC is: | 0 - 4 | 4 - 8 | 8 - 12 | > 12 | meq/100g | ||||
| Minimum suggested rate: | 20 - 25 | 15 - 20 | 10 - 15 | use calculation | lb S/ac | ||||
¶ Magnesium ........ Mg |
Ammonium acetate or Mehlich-3, ICP method | |||||||||||||||||
| ppm Mg | 0 | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | 60 | > 60 | ||||
| lb MgO/ac | 20 | 20 | 15 | 15 | 15 | 10 | 10 | 10 | 5 | 5 | 5 | 0 | 0 | 0 | ||||
| Mg_REC = Mg_A - (Mg_B * ppm_Mg) | ||||||||||||||||||
¶ Calcium ........ Ca |
Ammonium acetate or Mehlich-3, ICP method | |||||||||||||||||
| ppm Ca | 0 | 30 | 60 | 90 | 120 | 150 | 180 | 210 | 240 | 270 | 300 | 350 | > 350 | 0 | ||||
| lb Ca/ac | 600 | 540 | 480 | 420 | 360 | 300 | 240 | 180 | 120 | 60 | 0 | 0 | 0 | 600 | ||||
| Mn_REC = Mn_A - (Mn_B * ppm_Mn) | ||||||||||||||||||
¶ Iron ........ Fe |
DTPA or Mehlich-3, ICP method | |||||||||||||
| ppm DTPA Fe | < 3 | 3 - 5 | 5 - 10 | 10 - 25 | > 25 | |||||||||
| ppm Meh-3 Fe | < 20 | 20 - 40 | 40 - 80 | 80 - 160 | > 160 | |||||||||
| Excess lime: rating | ----- iron deficiency chlorosis (IDC) potential ----- | |||||||||||||
| NO …. | moderate | low | very low | very low | unlikely | |||||||||
| LO …. | high | moderate | low | very low | unlikely | |||||||||
| HI …. | very high | very high | high | mod - low | unlikely | |||||||||
| Soil tests are not used to recommend iron fertilizers, but can help indicate the potential for iron deficiency chlorosis (IDC). IDC symptoms are greater with young plants, cool and wet conditions, restricted root system growth, and high soil nitrate. | ||||||||||||||
¶ Manganese ........ Mn |
DTPA or Mehlich-3, ICP method | ||||||||||||||||
| ppm DTPA Mn | 0.0 | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 | 1.2 | 1.4 | 1.5 | 2.0 | 2.5 | 3.0 | > 3.0 | ||||
| lb Mn/ac | 15 | 13 | 10 | 8 | 5 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ||||
| ppm Meh-3 Mn | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 | 110 | 120 | > 120 | ||||
| lb Mn/ac | 15 | 13 | 10 | 8 | 5 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ||||
| Mn_REC = Mn_A - (Mn_B * ppm_Mn) | |||||||||||||||||
¶ Copper ........ Cu |
DTPA or Mehlich-3, ICP method | |||||||||||||||
| ppm Cu | 0.00 | 0.05 | 0.10 | 0.15 | 0.20 | 0.25 | 0.30 | 0.35 | 0.40 | 0.45 | 0.50 | 1.00 | > 1.0 | |||
| lb Cu/ac | 1.0 | 0.8 | 0.8 | 0.5 | 0.3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |||
| Cu_REC = Cu_A - (Cu_B * ppm_Cu) | ||||||||||||||||
¶ Boron ........ B |
Mehlich-3 or DTPA-sorbital, ICP method | ||||||||||||||||
| ppm B (Meh-3) | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 | 1.1 | 1.2 | 1.3 | ||||
| lb B/ac | 2.3 | 1.7 | 1.0 | 0.3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||||
| ppm B (DTPA-sorbital) | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 | 1.1 | 1.2 | 1.3 | ||||
| lb B/ac | 2.6 | 2.1 | 1.7 | 1.2 | 0.8 | 0.3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||||
| B_REC = B_A - (B_B * ppm_B) | |||||||||||||||||
¶ Soluble salts, mmho/cm |
1:1 soil:water slurry method | |||||||||||||||
| The following range of soluble salt levels suggest conditions where salinity may affect growth or yield of established crops. Additional soil analyis is recommended. Contact the Servitech Laboratory for details. Further information is available at cropfile.servitech.com, Soil Resource Management. If irrigated, suggest analyzing the water for Irrigation Suitability. |
Sandy soils | 1.15 - 1.85 mmho/cm | ||||||||||||||
| Loamy soils | 1.20 - 2.00 mmho/cm | |||||||||||||||
| Clayey soils | 1.30 - 2.10 mmho/cm | |||||||||||||||
¶ RECOMMENDATION RATE CALCULATION FACTORS |
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| Nutrient | Method* | A | B | OPT | COL | BYG | CR | ||||||
| Phosphorus, P | Mehlich-3, colorimetric | 151 | -0.04 | 23 | 51 | 200 | 0.3 | ||||||
| Olson bicarbonate | 145.5 | -0.085 | 11 | 25 | 200 | 0.3 | |||||||
| Bray-1 | 151 | -0.045 | 20 | 45 | 200 | 0.3 | |||||||
| Mehlich-3, ICP | 157 | -0.037 | 26 | 56 | 200 | 0.3 | |||||||
| Potassium, K | Mehlich-3 | 165 | -0.011 | 130 | 195 | 200 | 0.135 | ||||||
| Calcium, Ca | or | 600 | -2 | --- | --- | --- | --- | ||||||
| Magnesium, Mg | ammonium acetate | 20 | -0.35 | --- | --- | --- | --- | ||||||
| Zinc, Zn | DTPA | 7 | -6 | --- | --- | --- | --- | ||||||
| Manganese, Mn | Mehlich-3 | 17 | -0.85 | --- | --- | --- | --- | ||||||
| DTPA | 15 | -12.5 | --- | --- | --- | --- | |||||||
| Copper, Cu | Meh-3 or DTPA | 1 | -3.75 | --- | --- | --- | --- | ||||||
| Boron | Mehlich-3 | 1 | -3.5 | --- | --- | --- | --- | ||||||
| DTPA-sorbitol | 1.5 | -6.67 | --- | --- | --- | --- | |||||||
¶ CALCULATION TERMS |
|
| REC | Rate recommendation for broadcast application of actual nutrient; as "lb N/ac", "lb P2O5/ac", "lb K2O/ac", "lb Zn/ac", etc. Must adjust calculated rate for analysis (as N-P2O5-K2O) of fertilizer material to be applied. |
| _surf | Calculated amount of nitrogen or sulfur in surface sample increment (0 - 6 in., 0 - 8 in, etc.) as "lb/ac", where: lb/ac = ppm * 0.3 * depth increment as inches. |
| _sub | Calculated amount of nitrogen or sulfur in profile below surface increment (e.g., 6 - 24 in. or 8 - 24 in.) as "lb/ac", where: lb/ac = ppm * 0.3 * depth increment as inches. |
| OMadj | Nutrient adjustment for organic matter mineralization; as "lb/ac" |
| MC | Nutrient credit for manure or organic materials to be applied before planting; as "lb/ton" |
| PC | Adjustment for crop grown in previous season; as "lb/ac". |
| _A | Maximum recommended rate (at 0 ppm); as "lb/ac" (i.e., y axis intercept) |
| _B | Rate adjustment for soil test value; as "lb/ac" (i.e., equation slope value) |
| _ppm | Soil test value; as "ppm" (parts per million); equivalent to "mg/kg" (milligrams per kilogram) |
| OPT | Lower end of optimum soil test range; as "ppm" |
| COL | Cut-off level; as "ppm". (Soil test value where nutrient recommendation is forced to zero.) |
| YG | Projected or desired yield goal, as "lb/ac", "ton/ac", etc. Should be based on yield history. |
| BYG | Base yield goal, as "lb/ac", "ton/ac", etc. |
| CR | Full or partial crop removal adjusted for yield goal; as "lb/bu", "lb/ton", etc. See cropfile.servitech.com for typical ranges of nutrient removed by harvested crop. |
Early planting: Consider applying part of the recommended nitrogen (N), phosphate (P2O5), and sulfur (S) fertilizer in a band at planting. Avoid placing excess fertilizer in direct contact with seed to prevent potential seedlng injury.
Field corn (Zea mays): 1 bushel = 56 lb at 15.5% moisture; 1000 lb = 17.9 bu
Note: Computer-generated recommendations and those calculated in the Crop File may differ slightly due to numerical rounding or other reasons. Immobile nutrient interpretations based on 8 inch surface sample depth.